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PIC18F2221/2321/4221/4321 Family Data Sheet
Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
(c) 2009 Microchip Technology Inc.
DS39689F
Note the following details of the code protection feature on Microchip devices: * * * Microchip products meet the specification contained in their particular Microchip Data Sheet. Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. Microchip is willing to work with the customer who is concerned about the integrity of their code. Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as "unbreakable."
* *
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Trademarks The Microchip name and logo, the Microchip logo, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, rfPIC and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Octopus, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, PIC32 logo, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. (c) 2009, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company's quality system processes and procedures are for its PIC(R) MCUs and dsPIC(R) DSCs, KEELOQ(R) code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip's quality system for the design and manufacture of development systems is ISO 9001:2000 certified.
DS39689F-page 2
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
Power-Managed Modes:
* * * * * * * * Run: CPU On, Peripherals On Idle: CPU Off, Peripherals On Sleep: CPU Off, Peripherals Off Idle mode Currents Down to 2.5 A Typical Sleep mode Currents Down to 500 nA Typical Timer1 Oscillator: 1.8 A, 32 kHz, 2V Typical Watchdog Timer: 1.6 A, 2V Typical Two-Speed Oscillator Start-up
Peripheral Highlights (Continued):
* Master Synchronous Serial Port (MSSP) module Supporting 3-Wire SPI (all 4 modes) and I2CTM Master and Slave modes * Enhanced Addressable USART module: - Supports RS-485, RS-232 and LIN/J2602 - Auto-wake-up on Start bit - Auto-Baud Detect * 10-Bit, up to 13-Channel Analog-to-Digital Converter module (A/D): - Auto-acquisition capability - Conversion available during Sleep * Dual Analog Comparators with Input Multiplexing * Programmable 16-Level High/Low-Voltage Detection (HLVD) module: - Supports interrupt on High/Low-Voltage Detection
Flexible Oscillator Structure:
* Four Crystal modes, up to 40 MHz * 4x Phase Lock Loop (PLL) - Available for Crystal and Internal Oscillators * Two External RC modes, up to 4 MHz * Two External Clock modes, up to 40 MHz * Internal Oscillator Block: - 8 user-selectable frequencies, from 31 kHz to 8 MHz - Provides a complete range of clock speeds from 31 kHz to 32 MHz when used with PLL - User-tunable to compensate for frequency drift * Secondary Oscillator using Timer1 @ 32 kHz * Fail-Safe Clock Monitor - Allows for safe shutdown if peripheral clock stops
Special Microcontroller Features:
* C Compiler Optimized Architecture: - Optional extended instruction set designed to optimize re-entrant code * 100,000 Erase/Write Cycle Enhanced Flash Program Memory Typical * 1,000,000 Erase/Write Cycle Data EEPROM Memory Typical * Flash/Data EEPROM Retention: 100 Years Typical * Self-Programmable under Software Control * Priority Levels for Interrupts * 8 x 8 Single-Cycle Hardware Multiplier * Extended Watchdog Timer (WDT): - Programmable period from 4 ms to 131s * Single-Supply 5V In-Circuit Serial ProgrammingTM (ICSPTM) via Two Pins * In-Circuit Debug (ICD) via Two Pins * Wide Operating Voltage Range: 2.0V to 5.5V * Programmable Brown-out Reset (BOR) with Software Enable Option)
Peripheral Highlights:
High-Current Sink/Source 25 mA/25 mA Three Programmable External Interrupts Four Input Change Interrupts Up to 2 Capture/Compare/PWM (CCP) modules, one with Auto-Shutdown (28-pin devices) * Enhanced Capture/Compare/PWM (ECCP) module (40/44-pin devices only): - One, two or four PWM outputs - Selectable polarity - Programmable dead time - Auto-shutdown and auto-restart
-
* * * *
Device PIC18F2221 PIC18F2321 PIC18F4221 PIC18F4321
Flash # Single-Word SRAM EEPROM (bytes) Instructions (bytes) (bytes) 4K 8K 4K 8K 2048 4096 2048 4096 512 512 512 512 256 256 256 256
I/O 25 25 36 36
10-Bit A/D (ch) 10 10 13 13
CCP/ ECCP (PWM) 2/0 2/0 1/1 1/1
EUSART
Program Memory
Data Memory
MSSP SPI Y Y Y Y Master I2CTM Y Y Y Y
Comp. 2 2 2 2
Timers 8/16-Bit 1/3 1/3 1/3 1/3
1 1 1 1
(c) 2009 Microchip Technology Inc.
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PIC18F2221/2321/4221/4321 FAMILY
Pin Diagrams
28-Pin SPDIP, SOIC, SSOP
MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT VSS OSC1/CLKI/RA7 OSC2/CLKO/RA6 RC0/T1OSO/T13CKI RC1/T1OSI/CCP2 RC2/CCP1 RC3/SCK/SCL
1 2 3 4 5 6 7 8 9 10 11 12 13 14
28 27 26 25 24 23 22 21 20 19 18 17 16 15
RB7/KBI3/PGD RB6//KBI2/PGC RB5/KBI1/PGM RB4/KBI0/AN11 RB3/AN9/CCP2 RB2/INT2/AN8 RB1/INT1/AN10 RB0/INT0/FLT0/AN12 VDD VSS RC7/RX/DT RC6/TX/CK RC5/SDO RC4/SDI/SDA
28-Pin QFN
RA1/AN1 RA0/AN0 MCLR/VPP/RE3 RB7/KBI3/PGD RB6/KBI2/PGC RB5/KBI1/PGM RB4/KBI0/AN11 28 27 26 25 24 23 22 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT VSS OSC1/CLKI/RA7 OSC2/CLKO/RA6 1 2 3 4 5 6 7 21 20 19 18 17 16 15 RB3/AN9/CCP2(1) RB2/INT2/AN8 RB1/INT1/AN10 RB0/INT0/FLT0/AN12 VDD VSS RC7/RX/DT
PIC18F2221 PIC18F2321
8 9 10 11 12 13 14
Note 1:
RB3 is the alternate pin for CCP2 multiplexing.
RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1 RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6/TX/CK
PIC18F2221 PIC18F2321
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(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
Pin Diagrams (Continued)
40-Pin PDIP
MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT RE0/RD/AN5 RE1/WR/AN6 RE2/CS/AN7 VDD VSS OSC1/CLKI/RA7 OSC2/CLKO/RA6 RC0/T1OSO/T13CKI RC1/T1OSI/CCP2 RC2/CCP1/P1A RC3/SCK/SCL RD0/PSP0 RD1/PSP1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21
RB7/KBI3/PGD RB6/KBI2/PGC RB5/KBI1/PGM RB4/KBI0/AN11 RB3/AN9/CCP2 RB2/INT2/AN8 RB1/INT1/AN10 RB0/INT0/FLT0/AN12 VDD VSS RD7/PSP7/P1D RD6/PSP6/P1C RD5/PSP5/P1B RD4/PSP4 RC7/RX/DT RC6/TX/CK RC5/SDO RC4/SDI/SDA RD3/PSP3 RD2/PSP2
PIC18F4221
44-Pin QFN(2)
44 43 42 41 40 39 38 37 36 35 34
RC6/TX/CK RC5/SDO RC4/SDI/SDA RD3/PSP3 RD2/PSP2 RD1/PSP1 RD0/PSP0 RC3/SCK/SCL RC2/CCP1/P1A RC1/T1OSI/CCP2(1) RC0/T1OSO/T13CKI
PIC18F4321
Note 1: 2:
RB3 is the alternate pin for CCP2 multiplexing. For the QFN package, it is recommended that the bottom pad be connected to VSS.
(c) 2009 Microchip Technology Inc.
RB3/AN9/CCP2(1) NC RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+
12 13 14 15 16 17 18 19 20 21 22
RC7/RX/DT RD4/PSP4 RD5/PSP5/P1B RD6/PSP6/P1C RD7/PSP7/P1D VSS VDD VDD RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8
1 2 3 4 5 6 7 8 9 10 11
PIC18F4221 PIC18F4321
33 32 31 30 29 28 27 26 25 24 23
OSC2/CLKO/RA6 OSC1/CLKI/RA7 VSS VSS VDD VDD RE2/CS/AN7 RE1/WR/AN6 RE0/RD/AN5 RA5/AN4/SS/HLVDIN/C2OUT RA4/T0CKI/C1OUT
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Pin Diagrams (Continued)
44-Pin TQFP
44 43 42 41 40 39 38 37 36 35 34
RC6/TX/CK RC5/SDO RC4/SDI/SDA RD3/PSP3 RD2/PSP2 RD1/PSP1 RD0/PSP0 RC3/SCK/SCL RC2/CCP1/P1A RC1/T1OSI/CCP2(1) NC
Note
1:
RB3 is the alternate pin for CCP2 multiplexing.
NC NC RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+
12 13 14 15 16 17 18 19 20 21 22
RC7/RX/DT RD4/PSP4 RD5/PSP5/P1B RD6/PSP6/P1C RD7/PSP7/P1D VSS VDD RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8 RB3/AN9/CCP2(1)
1 2 3 4 5 6 7 8 9 10 11
PIC18F4221 PIC18F4321
33 32 31 30 29 28 27 26 25 24 23
NC RC0/T1OSO/T13CKI OSC2/CLKO/RA6 OSC1/CLKI/RA7 VSS VDD RE2/CS/AN7 RE1/WR/AN6 RE0/RD/AN5 RA5/AN4/SS/HLVDIN/C2OUT RA4/T0CKI/C1OUT
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(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
Table of Contents
1.0 Device Overview .......................................................................................................................................................................... 9 2.0 Guidelines for Getting Started with PIC18F Microcontrollers ..................................................................................................... 25 3.0 Oscillator Configurations ............................................................................................................................................................ 29 4.0 Power-Managed Modes ............................................................................................................................................................. 39 5.0 Reset .......................................................................................................................................................................................... 47 6.0 Memory Organization ................................................................................................................................................................. 59 7.0 Flash Program Memory.............................................................................................................................................................. 79 8.0 Data EEPROM Memory ............................................................................................................................................................. 89 9.0 8 x 8 Hardware Multiplier............................................................................................................................................................ 95 10.0 Interrupts .................................................................................................................................................................................... 97 11.0 I/O Ports ................................................................................................................................................................................... 111 12.0 Timer0 Module ......................................................................................................................................................................... 129 13.0 Timer1 Module ......................................................................................................................................................................... 133 14.0 Timer2 Module ......................................................................................................................................................................... 139 15.0 Timer3 Module ......................................................................................................................................................................... 141 16.0 Capture/Compare/PWM (CCP) Modules ................................................................................................................................. 145 17.0 Enhanced Capture/Compare/PWM (ECCP) Module................................................................................................................ 153 18.0 Master Synchronous Serial Port (MSSP) Module .................................................................................................................... 167 19.0 Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) ............................................................... 211 20.0 10-Bit Analog-to-Digital Converter (A/D) Module ..................................................................................................................... 233 21.0 Comparator Module.................................................................................................................................................................. 243 22.0 Comparator Voltage Reference Module................................................................................................................................... 249 23.0 High/Low-Voltage Detect (HLVD)............................................................................................................................................. 253 24.0 Special Features of the CPU.................................................................................................................................................... 259 25.0 Instruction Set Summary .......................................................................................................................................................... 279 26.0 Development Support............................................................................................................................................................... 329 27.0 Electrical Characteristics .......................................................................................................................................................... 333 28.0 Packaging Information.............................................................................................................................................................. 373 Appendix A: Revision History............................................................................................................................................................. 385 Appendix B: Device Differences ........................................................................................................................................................ 386 Appendix C: Conversion Considerations ........................................................................................................................................... 387 Appendix D: Migration from Baseline to Enhanced Devices.............................................................................................................. 387 Appendix E: Migration From Mid-Range to Enhanced Devices ......................................................................................................... 388 Appendix F: Migration From High-End to Enhanced Devices............................................................................................................ 388 Index ................................................................................................................................................................................................. 389 The Microchip Web Site ..................................................................................................................................................................... 399 Customer Change Notification Service .............................................................................................................................................. 399 Customer Support .............................................................................................................................................................................. 399 Reader Response .............................................................................................................................................................................. 400 PIC18F2221/2321/4221/4321 Product Identification System ............................................................................................................ 401
(c) 2009 Microchip Technology Inc.
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PIC18F2221/2321/4221/4321 FAMILY
TO OUR VALUED CUSTOMERS
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DS39689F-page 8
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
1.0 DEVICE OVERVIEW
1.1.2
This document contains device specific information for the following devices: * PIC18F2221 * PIC18F2321 * PIC18F4221 * PIC18F4321 * PIC18LF2221 * PIC18LF2321 * PIC18LF4221 * PIC18LF4321
MULTIPLE OSCILLATOR OPTIONS AND FEATURES
All of the devices in the PIC18F2221/2321/4221/4321 family offer ten different oscillator options, allowing users a wide range of choices in developing application hardware. These include: * Four Crystal modes, using crystals or ceramic resonators. * Two External Clock modes, offering the option of using two pins (oscillator input and a divide-by-4 clock output) or one pin (oscillator input, with the second pin reassigned as general I/O). * Two External RC Oscillator modes with the same pin options as the External Clock modes. * Two Internal Oscillator modes which provide an 8 MHz clock and an INTRC source (approximately 31 kHz), as well as a range of 6 user-selectable clock frequencies, between 125 kHz to 4 MHz, for a total of 8 clock frequencies. One or both of the oscillator pins can be used for general purpose I/O. * A Phase Lock Loop (PLL) frequency multiplier, available to both the high-speed crystal and internal oscillator modes, which allows clock speeds of up to 40 MHz. Used with the internal oscillator, the PLL gives users a complete selection of clock speeds, from 31 kHz to 32 MHz - all without using an external crystal or clock circuit. Besides its availability as a clock source, the internal oscillator block provides a stable reference source that gives the family additional features for robust operation: * Fail-Safe Clock Monitor: This option constantly monitors the main clock source against a reference signal provided by the internal oscillator. If a clock failure occurs, the controller is switched to the internal oscillator block, allowing for continued low-speed operation or a safe application shutdown. * Two-Speed Start-up: This option allows the internal oscillator to serve as the clock source from Power-on Reset, or wake-up from Sleep mode, until the primary clock source is available.
This family offers the advantages of all PIC18 microcontrollers - namely, high computational performance at an economical price - with the addition of highendurance, Enhanced Flash program memory. On top of these features, the PIC18F2221/2321/4221/4321 family introduces design enhancements that make these microcontrollers a logical choice for many high-performance, power sensitive applications.
1.1
1.1.1
New Core Features
nanoWatt TECHNOLOGY
All of the devices in the PIC18F2221/2321/4221/4321 family incorporate a range of features that can significantly reduce power consumption during operation. Key items include: * Alternate Run Modes: By clocking the controller from the Timer1 source or the internal oscillator block, power consumption during code execution can be reduced by as much as 90%. * Multiple Idle Modes: The controller can also run with its CPU core disabled but the peripherals still active. In these states, power consumption can be reduced even further, to as little as 4% of normal operation requirements. * On-the-Fly Mode Switching: The power-managed modes are invoked by user code during operation, allowing the user to incorporate power-saving ideas into their application's software design. * Low Consumption in Key Modules: The power requirements for both Timer1 and the Watchdog Timer are minimized. See Section 27.0 "Electrical Characteristics" for values.
(c) 2009 Microchip Technology Inc.
DS39689F-page 9
PIC18F2221/2321/4221/4321 FAMILY
1.2 Other Special Features 1.3
* Memory Endurance: The Enhanced Flash cells for both program memory and data EEPROM are rated to last for many thousands of erase/write cycles - up to 100,000 for program memory and 1,000,000 for EEPROM. Data retention without refresh is conservatively estimated to be greater than 40 years. * Self-Programmability: These devices can write to their own program memory spaces under internal software control. By using a bootloader routine, located in the protected Boot Block at the top of program memory, it becomes possible to create an application that can update itself in the field. * Extended Instruction Set: The PIC18F2221/ 2321/4221/4321 family introduces an optional extension to the PIC18 instruction set, which adds 8 new instructions and an Indexed Addressing mode. This extension, enabled as a device configuration option, has been specifically designed to optimize re-entrant application code originally developed in high-level languages, such as C. * Enhanced CCP Module: In PWM mode, this module provides 1, 2 or 4 modulated outputs for controlling half-bridge and full-bridge drivers. Other features include auto-shutdown, for disabling PWM outputs on interrupt or other select conditions and auto-restart, to reactivate outputs once the condition has cleared. * Enhanced Addressable USART: This serial communication module is capable of standard RS-232 operation and provides support for the LIN/J2602 bus protocol. Other enhancements include automatic baud rate detection and a 16-bit Baud Rate Generator for improved resolution. When the microcontroller is using the internal oscillator block, the EUSART provides stable operation for applications that talk to the outside world without using an external crystal (or its accompanying power requirement). * 10-Bit A/D Converter: This module incorporates programmable acquisition time, allowing for a channel to be selected and a conversion to be initiated without waiting for a sampling period and thus, reducing code overhead. * Extended Watchdog Timer (WDT): This Enhanced version incorporates a 16-bit prescaler, allowing an extended time-out range that is stable across operating voltage and temperature. See Section 27.0 "Electrical Characteristics" for time-out periods.
Details on Individual Family Members
Devices in the PIC18F2221/2321/4221/4321 family are available in 28-pin and 40/44-pin packages. Block diagrams for the two groups are shown in Figure 1-1 and Figure 1-2. The devices are differentiated from each other in five ways: 1. Flash program memory (4 Kbytes for PIC18F2221/4221 devices, 8 Kbytes for PIC18F2321/4321). A/D channels (10 for 28-pin devices, 13 for 40/44-pin devices). I/O ports (3 bidirectional ports on 28-pin devices, 5 bidirectional ports on 40/44-pin devices). CCP and Enhanced CCP implementation (28-pin devices have 2 standard CCP modules, 40/44-pin devices have one standard CCP module and one ECCP module). Parallel Slave Port (present only on 40/44-pin devices).
2. 3. 4.
5.
All other features for devices in this family are identical. These are summarized in Table 1-1. The pinouts for all devices are listed in Table 1-2 and Table 1-3. Like all Microchip PIC18 devices, members of the PIC18F2221/2321/4221/4321 family are available as both standard and low-voltage devices. Standard devices with Enhanced Flash memory, designated with an "F" in the part number (such as PIC18F2321), accommodate an operating VDD range of 4.2V to 5.5V. Low-voltage parts, designated by "LF" (such as PIC18LF2321), function over an extended VDD range of 2.0V to 5.5V.
DS39689F-page 10
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-1: DEVICE FEATURES
PIC18F2221 DC - 40 MHz 4096 2048 512 256 19 Ports A, B, C, (E) 4 2 0 PIC18F2321 DC - 40 MHz 8192 4096 512 256 19 Ports A, B, C, (E) 4 2 0 PIC18F4221 DC - 40 MHz 4096 2048 512 256 20 4 1 1 PIC18F4321 DC - 40 MHz 8192 4096 512 256 20 4 1 1 MSSP, Enhanced USART Yes 13 Input Channels POR, BOR, RESET Instruction, Stack Full, Stack Underflow (PWRT, OST), MCLR (optional), WDT Yes Yes 75 Instructions; 83 with Extended Instruction Set enabled 40-pin PDIP 44-pin QFN 44-pin TQFP Features Operating Frequency Program Memory (Bytes) Program Memory (Instructions) Data Memory (Bytes) Data EEPROM Memory (Bytes) Interrupt Sources I/O Ports Timers Capture/Compare/PWM Modules Enhanced Capture/Compare/ PWM Modules Serial Communications Parallel Communications (PSP) 10-bit Analog-to-Digital Module Resets (and Delays)
Ports A, B, C, D, E Ports A, B, C, D, E
MSSP, MSSP, MSSP, Enhanced USART Enhanced USART Enhanced USART No 10 Input Channels No 10 Input Channels Yes 13 Input Channels
POR, BOR, POR, BOR, POR, BOR, RESET Instruction, RESET Instruction, RESET Instruction, Stack Full, Stack Full, Stack Full, Stack Underflow Stack Underflow Stack Underflow (PWRT, OST), (PWRT, OST), (PWRT, OST), MCLR (optional), MCLR (optional), MCLR (optional), WDT WDT WDT Yes Yes 75 Instructions; 83 with Extended Instruction Set enabled 28-pin SPDIP 28-pin SOIC 28-pin SSOP 28-pin QFN Yes Yes 75 Instructions; 83 with Extended Instruction Set enabled 28-pin SPDIP 28-pin SOIC 28-pin SSOP 28-pin QFN Yes Yes 75 Instructions; 83 with Extended Instruction Set enabled 40-pin PDIP 44-pin QFN 44-pin TQFP
Programmable Low-Voltage Detect Programmable Brown-out Reset Instruction Set
Packages
(c) 2009 Microchip Technology Inc.
DS39689F-page 11
PIC18F2221/2321/4221/4321 FAMILY
FIGURE 1-1:
Table Pointer<21> inc/dec logic 21 20 8
PCLATU PCLATH
PIC18F2221/2321 (28-PIN) BLOCK DIAGRAM
Data Bus<8> Data Latch Data Memory (3.9 Kbytes) Address Latch 12 Data Address<12> 4 BSR 12 FSR0 FSR1 FSR2 inc/dec logic 4 Access Bank 12 PORTB RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8 RB3/AN9/CCP2(1) RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD PORTA RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT OSC2/CLKO(3)/RA6 OSC1/CLKI(3)/RA7
8
PCU PCH PCL Program Counter 31 Level Stack
Address Latch Program Memory (4 Kbytes) Data Latch 8 STKPTR
Table Latch ROM Latch
Instruction Bus <16>
Address Decode
IR 8
Instruction Decode & Control
State Machine Control Signals
PRODH PRODL 3 BITOP 8 8 x 8 Multiply 8 W 8 8 ALU<8> 8 8 8
PORTC RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1 RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT
OSC1(3) OSC2(3) T1OSI T1OSO MCLR(2) VDD, VSS
Internal Oscillator Block INTRC Oscillator 8 MHz Oscillator Single-Supply Programming In-Circuit Debugger
Power-up Timer Oscillator Start-up Timer Power-on Reset Watchdog Timer Brown-out Reset Fail-Safe Clock Monitor
Precision Band Gap Reference
PORTE MCLR/VPP/RE3(2)
BOR LVD
Data EEPROM
Timer0
Timer1
Timer2
Timer3
Comparator
CCP1
CCP2
MSSP
EUSART
ADC 10-Bit
Note
1: 2: 3:
CCP2 is multiplexed with RC1 when Configuration bit, CCP2MX, is set, or RB3 when CCP2MX is not set. RE3 is only available when MCLR functionality is disabled. OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O. Refer to Section 3.0 "Oscillator Configurations" for additional information.
DS39689F-page 12
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
FIGURE 1-2:
Table Pointer<21> inc/dec logic 21 20 8
PCLATU PCLATH
PIC18F4221/4321 (40/44-PIN) BLOCK DIAGRAM
Data Bus<8> Data Latch Data Memory (3.9 Kbytes) Address Latch 12 Data Address<12> 4 BSR 12 FSR0 FSR1 FSR2 inc/dec logic 4 Access Bank 12 PORTA RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT OSC2/CLKO(3)/RA6 OSC1/CLKI(3)/RA7 PORTB RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8 RB3/AN9/CCP2(1) RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD
8
PCU PCH PCL Program Counter 31 Level Stack
Address Latch Program Memory (8 Kbytes) Data Latch 8 STKPTR
Table Latch
Instruction Bus <16>
ROM Latch
Address Decode
PORTC RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1/P1A RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT
IR 8
Instruction Decode & Control
State Machine Control Signals
PRODH PRODL 3 BITOP 8 8 x 8 Multiply 8 W 8 8 ALU<8> 8 PORTE Precision Band Gap Reference 8 8 PORTD RD0/PSP0:RD4/PSP4 RD5/PSP5/P1B RD6/PSP6/P1C RD7/PSP7/P1D
OSC1(3) OSC2(3) T1OSI T1OSO MCLR(2) VDD, VSS
Internal Oscillator Block INTRC Oscillator 8 MHz Oscillator Single-Supply Programming In-Circuit Debugger
Power-up Timer Oscillator Start-up Timer Power-on Reset Watchdog Timer Brown-out Reset Fail-Safe Clock Monitor
RE0/RD/AN5 RE1/WR/AN6 RE2/CS/AN7 MCLR/VPP/RE3(2)
BOR LVD
Data EEPROM
Timer0
Timer1
Timer2
Timer3
Comparator
ECCP1
CCP2
MSSP
EUSART
ADC 10-Bit
Note
1: 2: 3:
CCP2 is multiplexed with RC1 when Configuration bit, CCP2MX, is set, or RB3 when CCP2MX is not set. RE3 is only available when MCLR functionality is disabled. OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O. Refer to Section 3.0 "Oscillator Configurations" for additional information.
(c) 2009 Microchip Technology Inc.
DS39689F-page 13
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-2: PIC18F2221/2321 PINOUT I/O DESCRIPTIONS
Pin Number Pin Name Pin Buffer SPDIP, Type Type SOIC, QFN SSOP 1 26 I P I 9 6 I ST Description
MCLR/VPP/RE3 MCLR VPP RE3 OSC1/CLKI/RA7 OSC1 CLKI
ST Analog
Master Clear (input) or programming voltage (input). Master Clear (Reset) input. This pin is an active-low Reset to the device. Programming voltage input. Digital input.
RA7 OSC2/CLKO/RA6 OSC2 CLKO 10 7
Oscillator crystal or external clock input. Oscillator crystal input or external clock source input. ST buffer when configured in RC mode; CMOS otherwise. I CMOS External clock source input. Always associated with pin function OSC1. (See related OSC1/CLKI, OSC2/CLKO pins.) I/O TTL General purpose I/O pin. O O -- -- Oscillator crystal or clock output. Oscillator crystal output. Connects to crystal or resonator in Crystal Oscillator mode. In RC, EC and INTIO modes, OSC2 pin outputs CLKO which has one-fourth the frequency of OSC1 and denotes the instruction cycle rate. General purpose I/O pin.
RA6
I/O
TTL
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
DS39689F-page 14
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-2: PIC18F2221/2321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number Pin Name Pin Buffer SPDIP, SOIC, QFN Type Type SSOP Description
PORTA is a bidirectional I/O port. RA0/AN0 RA0 AN0 RA1/AN1 RA1 AN1 RA2/AN2/VREF-/CVREF RA2 AN2 VREFCVREF RA3/AN3/VREF+ RA3 AN3 VREF+ RA4/T0CKI/C1OUT RA4 T0CKI C1OUT RA5/AN4/SS/HLVDIN/ C2OUT RA5 AN4 SS HLVDIN C2OUT RA6 RA7 2 27 I/O TTL I Analog 3 28 I/O TTL I Analog 4 1 I/O TTL I Analog I Analog O Analog 5 2 I/O TTL I Analog I Analog 6 3 I/O I O 7 4 I/O TTL I Analog I TTL I Analog O -- Digital I/O. Analog Input 4. SPI slave select input. High/Low-Voltage Detect input. Comparator 2 output. See the OSC2/CLKO/RA6 pin. See the OSC1/CLKI/RA7 pin. ST ST -- Digital I/O. Open-collector output. Timer0 external clock input. Comparator 1 output. Digital I/O. Analog Input 3. A/D reference voltage (high) input. Digital I/O. Analog Input 2. A/D reference voltage (low) input. Comparator reference voltage output. Digital I/O. Analog Input 1. Digital I/O. Analog Input 0.
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power I2C = ST with I2CTM or SMB levels O = Output Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
(c) 2009 Microchip Technology Inc.
DS39689F-page 15
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-2: PIC18F2221/2321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number Pin Name Pin Buffer SPDIP, SOIC, QFN Type Type SSOP Description
PORTB is a bidirectional I/O port. PORTB can be software programmed for internal weak pull-ups on all inputs. RB0/INT0/FLT0/AN12 RB0 INT0 FLT0 AN12 RB1/INT1/AN10 RB1 INT1 AN10 RB2/INT2/AN8 RB2 INT2 AN8 RB3/AN9/CCP2 RB3 AN9 CCP2(2) RB4/KBI0/AN11 RB4 KBI0 AN11 RB5/KBI1/PGM RB5 KBI1 PGM RB6/KBI2/PGC RB6 KBI2 PGC RB7/KBI3/PGD RB7 KBI3 PGD 21 18 I/O TTL I ST I ST I Analog 22 19 I/O TTL I ST I Analog 23 20 I/O TTL I ST I Analog 24 21 I/O TTL I Analog I/O ST 25 22 I/O TTL I TTL I Analog 26 23 I/O I I/O 27 24 I/O I I/O 28 25 I/O I I/O TTL TTL ST Digital I/O. Interrupt-on-change pin. In-circuit debugger and ICSP programming data pin. TTL TTL ST Digital I/O. Interrupt-on-change pin. In-circuit debugger and ICSP programming clock pin. TTL TTL ST Digital I/O. Interrupt-on-change pin. Low-Voltage ICSPTM programming enable pin. Digital I/O. Interrupt-on-change pin. Analog Input 11. Digital I/O. Analog Input 9. Capture 2 input/Compare 2 output/PWM2 output. Digital I/O. External Interrupt 2. Analog Input 8. Digital I/O. External Interrupt 1. Analog Input 10. Digital I/O. External Interrupt 0. PWM Fault input for CCP1. Analog Input 12.
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
DS39689F-page 16
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-2: PIC18F2221/2321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number Pin Name Pin Buffer SPDIP, Type Type SOIC, QFN SSOP Description
PORTC is a bidirectional I/O port. RC0/T1OSO/T13CKI RC0 T1OSO T13CKI RC1/T1OSI/CCP2 RC1 T1OSI CCP2(1) RC2/CCP1 RC2 CCP1 RC3/SCK/SCL RC3 SCK SCL RC4/SDI/SDA RC4 SDI SDA RC5/SDO RC5 SDO RC6/TX/CK RC6 TX CK RC7/RX/DT RC7 RX DT RE3 VSS VDD 11 8 I/O O I 12 9 I/O ST I Analog I/O ST 13 10 I/O I/O 14 11 I/O I/O I/O 15 12 I/O I I/O 16 13 I/O O 17 14 I/O O I/O 18 15 I/O I I/O -- 8, 19 20 -- 5, 16 17 -- P P ST ST ST -- -- -- Digital I/O. EUSART asynchronous receive. EUSART synchronous data (see related TX/CK). See MCLR/VPP/RE3 pin. Ground reference for logic and I/O pins. Positive supply for logic and I/O pins. ST -- ST Digital I/O. EUSART asynchronous transmit. EUSART synchronous clock (see related RX/DT). ST -- Digital I/O. SPI data out. ST ST I2C Digital I/O. SPI data in. I2C data I/O. ST ST I2C Digital I/O. Synchronous serial clock input/output for SPI mode. Synchronous serial clock input/output for I2CTM mode. ST ST Digital I/O. Capture 1 input/Compare 1 output/PWM1 output. Digital I/O. Timer1 oscillator analog input. Capture 2 input/Compare 2 output/PWM2 output. ST -- ST Digital I/O. Timer1 oscillator analog output. Timer1/Timer3 external clock input.
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
(c) 2009 Microchip Technology Inc.
DS39689F-page 17
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-3:
Pin Name MCLR/VPP/RE3 MCLR VPP RE3 OSC1/CLKI/RA7 OSC1 13 32 30 I
PIC18F4221/4321 PINOUT I/O DESCRIPTIONS
Pin Number PDIP 1 Pin Buffer Type Type QFN TQFP 18 18 I P I ST Description Master Clear (input) or programming voltage (input). Master Clear (Reset) input. This pin is an active-low Reset to the device. Programming voltage input. Digital input.
ST Analog
CLKI
I
RA7 OSC2/CLKO/RA6 OSC2 CLKO 14 33 31
I/O O O
Oscillator crystal or external clock input. Oscillator crystal input or external clock source input. ST buffer when configured in RC mode; analog otherwise. Analog External clock source input. Always associated with pin function OSC1. (See related OSC1/CLKI, OSC2/CLKO pins.) TTL General purpose I/O pin. -- -- Oscillator crystal or clock output. Oscillator crystal output. Connects to crystal or resonator in Crystal Oscillator mode. In RC, EC and INTIO modes, OSC2 pin outputs CLKO which has one-fourth the frequency of OSC1 and denotes the instruction cycle rate. General purpose I/O pin.
RA6
I/O
TTL
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
DS39689F-page 18
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-3:
Pin Name
PIC18F4221/4321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number PDIP Pin Buffer Type Type QFN TQFP Description PORTA is a bidirectional I/O port.
RA0/AN0 RA0 AN0 RA1/AN1 RA1 AN1 RA2/AN2/VREF-/CVREF RA2 AN2 VREFCVREF RA3/AN3/VREF+ RA3 AN3 VREF+ RA4/T0CKI/C1OUT RA4 T0CKI C1OUT RA5/AN4/SS/HLVDIN/ C2OUT RA5 AN4 SS HLVDIN C2OUT RA6 RA7
2
19
19 I/O I TTL Analog TTL Analog TTL Analog Analog Analog TTL Analog Analog ST ST -- Digital I/O. Analog Input 0. Digital I/O. Analog Input 1. Digital I/O. Analog Input 2. A/D reference voltage (low) input. Comparator reference voltage output. Digital I/O. Analog Input 3. A/D reference voltage (high) input. Digital I/O. Timer0 external clock input. Comparator 1 output.
3
20
20 I/O I
4
21
21 I/O I I O
5
22
22 I/O I I
6
23
23 I/O I O
7
24
24 I/O I I I O TTL Analog TTL Analog -- Digital I/O. Analog Input 4. SPI slave select input. High/Low-Voltage Detect input. Comparator 2 output. See the OSC2/CLKO/RA6 pin. See the OSC1/CLKI/RA7 pin.
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
(c) 2009 Microchip Technology Inc.
DS39689F-page 19
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-3:
Pin Name
PIC18F4221/4321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number PDIP Pin Buffer Type Type QFN TQFP Description PORTB is a bidirectional I/O port. PORTB can be software programmed for internal weak pull-ups on all inputs.
RB0/INT0/FLT0/AN12 RB0 INT0 FLT0 AN12 RB1/INT1/AN10 RB1 INT1 AN10 RB2/INT2/AN8 RB2 INT2 AN8 RB3/AN9/CCP2 RB3 AN9 CCP2(2) RB4/KBI0/AN11 RB4 KBI0 AN11 RB5/KBI1/PGM RB5 KBI1 PGM RB6/KBI2/PGC RB6 KBI2 PGC RB7/KBI3/PGD RB7 KBI3 PGD
33
9
8 I/O I I I TTL ST ST Analog TTL ST Analog TTL ST Analog TTL Analog ST TTL TTL Analog TTL TTL ST TTL TTL ST Digital I/O. External Interrupt 0. PWM Fault input for Enhanced CCP1. Analog input 12. Digital I/O. External Interrupt 1. Analog Input 10. Digital I/O. External Interrupt 2. Analog Input 8. Digital I/O. Analog Input 9. Capture 2 input/Compare 2 output/PWM2 output. Digital I/O. Interrupt-on-change pin. Analog input 11. Digital I/O. Interrupt-on-change pin. Low-Voltage ICSPTM Programming enable pin. Digital I/O. Interrupt-on-change pin. In-circuit debugger and ICSP programming clock pin. Digital I/O. Interrupt-on-change pin. In-circuit debugger and ICSP programming data pin.
34
10
9 I/O I I
35
11
10 I/O I I
36
12
11 I/O I I/O
37
14
14 I/O I I
38
15
15 I/O I I/O
39
16
16 I/O I I/O
40
17
17 I/O I I/O TTL TTL ST
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
DS39689F-page 20
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-3:
Pin Name
PIC18F4221/4321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number PDIP Pin Buffer Type Type QFN TQFP Description PORTC is a bidirectional I/O port.
RC0/T1OSO/T13CKI RC0 T1OSO T13CKI RC1/T1OSI/CCP2 RC1 T1OSI CCP2(1) RC2/CCP1/P1A RC2 CCP1 P1A RC3/SCK/SCL RC3 SCK SCL RC4/SDI/SDA RC4 SDI SDA RC5/SDO RC5 SDO RC6/TX/CK RC6 TX CK RC7/RX/DT RC7 RX DT
15
34
32 I/O O I ST -- ST ST CMOS ST ST ST -- ST ST I2C Digital I/O. Timer1 oscillator analog output. Timer1/Timer3 external clock input. Digital I/O. Timer1 oscillator analog input. Capture 2 input/Compare 2 output/PWM2 output. Digital I/O. Capture 1 input/Compare 1 output/PWM1 output. Enhanced CCP1 output. Digital I/O. Synchronous serial clock input/output for SPI mode. Synchronous serial clock input/output for I2CTM mode. Digital I/O. SPI data in. I2C data I/O. Digital I/O. SPI data out. Digital I/O. EUSART asynchronous transmit. EUSART synchronous clock (see related RX/DT). Digital I/O. EUSART asynchronous receive. EUSART synchronous data (see related TX/CK).
16
35
35 I/O I I/O
17
36
36 I/O I/O O
18
37
37 I/O I/O I/O
23
42
42 I/O I I/O ST ST I2C ST -- ST -- ST ST ST ST
24
43
43 I/O O
25
44
44 I/O O I/O
26
1
1 I/O I I/O
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
(c) 2009 Microchip Technology Inc.
DS39689F-page 21
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-3:
Pin Name
PIC18F4221/4321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number PDIP Pin Buffer Type Type QFN TQFP Description PORTD is a bidirectional I/O port or a Parallel Slave Port (PSP) for interfacing to a microprocessor port. These pins have TTL input buffers when the PSP module is enabled.
RD0/PSP0 RD0 PSP0 RD1/PSP1 RD1 PSP1 RD2/PSP2 RD2 PSP2 RD3/PSP3 RD3 PSP3 RD4/PSP4 RD4 PSP4 RD5/PSP5/P1B RD5 PSP5 P1B RD6/PSP6/P1C RD6 PSP6 P1C RD7/PSP7/P1D RD7 PSP7 P1D
19
38
38 I/O I/O ST TTL ST TTL ST TTL ST TTL ST TTL ST TTL -- ST TTL -- ST TTL -- Digital I/O. Parallel Slave Port data. Digital I/O. Parallel Slave Port data. Digital I/O. Parallel Slave Port data. Digital I/O. Parallel Slave Port data. Digital I/O. Parallel Slave Port data. Digital I/O. Parallel Slave Port data. Enhanced CCP1 output. Digital I/O. Parallel Slave Port data. Enhanced CCP1 output. Digital I/O. Parallel Slave Port data. Enhanced CCP1 output.
20
39
39 I/O I/O
21
40
40 I/O I/O
22
41
41 I/O I/O
27
2
2 I/O I/O
28
3
3 I/O I/O O
29
4
4 I/O I/O O
30
5
5 I/O I/O O
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
DS39689F-page 22
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
TABLE 1-3:
Pin Name
PIC18F4221/4321 PINOUT I/O DESCRIPTIONS (CONTINUED)
Pin Number PDIP Pin Buffer Type Type QFN TQFP Description PORTE is a bidirectional I/O port.
RE0/RD/AN5 RE0 RD AN5 RE1/WR/AN6 RE1 WR AN6 RE2/CS/AN7 RE2 CS AN7 RE3 VSS VDD NC
8
25
25 I/O I I ST TTL Analog ST TTL Analog ST TTL Analog -- -- -- -- Digital I/O. Read control for Parallel Slave Port (see also WR and CS pins). Analog Input 5. Digital I/O. Write control for Parallel Slave Port (see CS and RD pins). Analog Input 6. Digital I/O. Chip Select control for Parallel Slave Port (see related RD and WR). Analog Input 7. See MCLR/VPP/RE3 pin. Ground reference for logic and I/O pins. Positive supply for logic and I/O pins. No Connect.
9
26
26 I/O I I
10
27
27 I/O I I
--
--
-- 6, 29
-- P P --
12, 31 6, 30, 31 11, 32 --
7, 8, 7, 28 28, 29 13 12, 13, 33, 34
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels I = Input P = Power O = Output I2C = ST with I2CTM or SMB levels Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared.
(c) 2009 Microchip Technology Inc.
DS39689F-page 23
PIC18F2221/2321/4221/4321 FAMILY
NOTES:
DS39689F-page 24
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
2.0 GUIDELINES FOR GETTING STARTED WITH PIC18F MICROCONTROLLERS
Basic Connection Requirements
FIGURE 2-1: RECOMMENDED MINIMUM CONNECTIONS
C2(1) VDD
VDD MCLR
2.1
Getting started with the PIC18F2221/2321/4221/4321 family family of 8-bit microcontrollers requires attention to a minimal set of device pin connections before proceeding with development. The following pins must always be connected: * All VDD and VSS pins (see Section 2.2 "Power Supply Pins") * All AVDD and AVSS pins, regardless of whether or not the analog device features are used (see Section 2.2 "Power Supply Pins") * MCLR pin (see Section 2.3 "Master Clear (MCLR) Pin") These pins must also be connected if they are being used in the end application: * PGC/PGD pins used for In-Circuit Serial ProgrammingTM (ICSPTM) and debugging purposes (see Section 2.4 "ICSP Pins") * OSCI and OSCO pins when an external oscillator source is used (see Section 2.5 "External Oscillator Pins") Additionally, the following pins may be required: * VREF+/VREF- pins used when external voltage reference for analog modules is implemented Note: The AVDD and AVSS pins must always be connected, regardless of whether any of the analog modules are being used.
R1 R2
VSS
C1
VDD
PIC18FXXXX
VSS VSS VDD
C3(1)
C6(1)
AVDD
AVSS
VDD
C5(1)
C4(1)
Key (all values are recommendations): C1 through C6: 0.1 F, 20V ceramic C7: 10 F, 16V tantalum or ceramic R1: 10 k R2: 100 to 470 Note 1: The example shown is for a PIC18F device with five VDD/VSS and AVDD/AVSS pairs. Other devices may have more or less pairs; adjust the number of decoupling capacitors appropriately.
The minimum mandatory connections are shown in Figure 2-1.
(c) 2009 Microchip Technology Inc.
DS39689F-page 25
VSS
PIC18F2221/2321/4221/4321 FAMILY
2.2
2.2.1
Power Supply Pins
DECOUPLING CAPACITORS
2.3
Master Clear (MCLR) Pin
The use of decoupling capacitors on every pair of power supply pins, such as VDD, VSS, AVDD and AVSS, is required. Consider the following criteria when using decoupling capacitors: * Value and type of capacitor: A 0.1 F (100 nF), 10-20V capacitor is recommended. The capacitor should be a low-ESR device with a resonance frequency in the range of 200 MHz and higher. Ceramic capacitors are recommended. * Placement on the printed circuit board: The decoupling capacitors should be placed as close to the pins as possible. It is recommended to place the capacitors on the same side of the board as the device. If space is constricted, the capacitor can be placed on another layer on the PCB using a via; however, ensure that the trace length from the pin to the capacitor is no greater than 0.25 inch (6 mm). * Handling high-frequency noise: If the board is experiencing high-frequency noise (upward of tens of MHz), add a second ceramic type capacitor in parallel to the above described decoupling capacitor. The value of the second capacitor can be in the range of 0.01 F to 0.001 F. Place this second capacitor next to each primary decoupling capacitor. In high-speed circuit designs, consider implementing a decade pair of capacitances as close to the power and ground pins as possible (e.g., 0.1 F in parallel with 0.001 F). * Maximizing performance: On the board layout from the power supply circuit, run the power and return traces to the decoupling capacitors first, and then to the device pins. This ensures that the decoupling capacitors are first in the power chain. Equally important is to keep the trace length between the capacitor and the power pins to a minimum, thereby reducing PCB trace inductance.
The MCLR pin provides two specific device functions: device Reset, and device programming and debugging. If programming and debugging are not required in the end application, a direct connection to VDD may be all that is required. The addition of other components, to help increase the application's resistance to spurious Resets from voltage sags, may be beneficial. A typical configuration is shown in Figure 2-1. Other circuit designs may be implemented depending on the application's requirements. During programming and debugging, the resistance and capacitance that can be added to the pin must be considered. Device programmers and debuggers drive the MCLR pin. Consequently, specific voltage levels (VIH and VIL) and fast signal transitions must not be adversely affected. Therefore, specific values of R1 and C1 will need to be adjusted based on the application and PCB requirements. For example, it is recommended that the capacitor, C1, be isolated from the MCLR pin during programming and debugging operations by using a jumper (Figure 2-2). The jumper is replaced for normal run-time operations. Any components associated with the MCLR pin should be placed within 0.25 inch (6 mm) of the pin.
FIGURE 2-2:
VDD R1
EXAMPLE OF MCLR PIN CONNECTIONS
R2 JP C1
MCLR PIC18FXXXX
2.2.2
TANK CAPACITORS
Note 1:
On boards with power traces running longer than six inches in length, it is suggested to use a tank capacitor for integrated circuits including microcontrollers to supply a local power source. The value of the tank capacitor should be determined based on the trace resistance that connects the power supply source to the device and the maximum current drawn by the device in the application. In other words, select the tank capacitor so that it meets the acceptable voltage sag at the device. Typical values range from 4.7 F to 47 F.
R1 10 k is recommended. A suggested starting value is 10 k. Ensure that the MCLR pin VIH and VIL specifications are met. R2 470 will limit any current flowing into MCLR from the external capacitor, C, in the event of MCLR pin breakdown, due to Electrostatic Discharge (ESD) or Electrical Overstress (EOS). Ensure that the MCLR pin VIH and VIL specifications are met.
2:
DS39689F-page 26
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
2.4 ICSP Pins
The PGC and PGD pins are used for In-Circuit Serial Programming (ICSP) and debugging purposes. It is recommended to keep the trace length between the ICSP connector and the ICSP pins on the device as short as possible. If the ICSP connector is expected to experience an ESD event, a series resistor is recommended, with the value in the range of a few tens of ohms, not to exceed 100. Pull-up resistors, series diodes and capacitors on the PGC and PGD pins are not recommended as they will interfere with the programmer/debugger communications to the device. If such discrete components are an application requirement, they should be removed from the circuit during programming and debugging. Alternatively, refer to the AC/DC characteristics and timing requirements information in the respective device Flash programming specification for information on capacitive loading limits and pin input voltage high (VIH) and input low (VIL) requirements. For device emulation, ensure that the "Communication Channel Select" (i.e., PGC/PGD pins) programmed into the device matches the physical connections for the ICSP to the MPLAB(R) ICD 2, MPLAB ICD 3 or REAL ICETM emulator. For more information on the ICD 2, ICD 3 and REAL ICE emulator connection requirements, refer to the following documents that are available on the Microchip web site. * "MPLAB(R) ICD 2 In-Circuit Debugger User's Guide" (DS51331) * "Using MPLAB(R) ICD 2" (poster) (DS51265) * "MPLAB(R) ICD 2 Design Advisory" (DS51566) * "Using MPLAB(R) ICD 3" (poster) (DS51765) * "MPLAB(R) ICD 3 Design Advisory" (DS51764) * "MPLAB(R) REAL ICETM In-Circuit Emulator User's Guide" (DS51616) * "Using MPLAB(R) REAL ICETM In-Circuit Emulator" (poster) (DS51749) Use a grounded copper pour around the oscillator circuit to isolate it from surrounding circuits. The grounded copper pour should be routed directly to the MCU ground. Do not run any signal traces or power traces inside the ground pour. Also, if using a two-sided board, avoid any traces on the other side of the board where the crystal is placed. A suggested layout is shown in Figure 2-3. For additional information and design guidance on oscillator circuits, please refer to these Microchip Application Notes, available at the corporate web site (www.microchip.com): * AN826, "Crystal Oscillator Basics and Crystal Selection for rfPICTM and PICmicro(R) Devices" * AN849, "Basic PICmicro(R) Oscillator Design" * AN943, "Practical PICmicro(R) Oscillator Analysis and Design" * AN949, "Making Your Oscillator Work"
FIGURE 2-3:
SUGGESTED PLACEMENT OF THE OSCILLATOR CIRCUIT
Main Oscillator 13 Guard Ring Guard Trace Secondary Oscillator 14 15 16 17 18 19 20
2.6
Unused I/Os
2.5
External Oscillator Pins
Unused I/O pins should be configured as outputs and driven to a logic low state. Alternatively, connect a 1 k to 10 k resistor to VSS on unused pins and drive the output to logic low.
Many microcontrollers have options for at least two oscillators: a high-frequency primary oscillator and a low-frequency secondary oscillator (refer to Section 3.0 "Oscillator Configurations" for details). The oscillator circuit should be placed on the same side of the board as the device. Place the oscillator circuit close to the respective oscillator pins with no more than 0.5 inch (12 mm) between the circuit components and the pins. The load capacitors should be placed next to the oscillator itself, on the same side of the board.
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NOTES:
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3.0
3.1
OSCILLATOR CONFIGURATIONS
Oscillator Types
FIGURE 3-1:
CRYSTAL/CERAMIC RESONATOR OPERATION (XT, LP, HS OR HSPLL CONFIGURATION)
OSC1 To Internal Logic Sleep
The PIC18F2221/2321/4221/4321 family of devices can be operated in ten different oscillator modes. The user can program the Configuration bits, FOSC<3:0>, in Configuration Register 1H to select one of these ten modes: Low-Power Crystal Crystal/Resonator High-Speed Crystal/Resonator High-Speed Crystal/Resonator with PLL enabled 5. RC External Resistor/Capacitor with FOSC/4 output on RA6 6. RCIO External Resistor/Capacitor with I/O on RA6 7. INTIO1 Internal Oscillator with FOSC/4 output on RA6 and I/O on RA7 8. INTIO2 Internal Oscillator with I/O on RA6 and RA7 9. EC External Clock with FOSC/4 output 10. ECIO External Clock with I/O on RA6 1. 2. 3. 4. LP XT HS HSPLL
C1(1)
XTAL
RS(2) C2(1) Note 1: 2: 3: OSC2
RF(3)
PIC18FXXXX
See Table 3-1 and Table 3-2 for initial values of C1 and C2. A series resistor (RS) may be required for AT strip cut crystals. RF varies with the oscillator mode chosen.
TABLE 3-1:
CAPACITOR SELECTION FOR CERAMIC RESONATORS
Freq 3.58 MHz OSC1 22 pF OSC2 22 pF
Typical Capacitor Values Used: Mode XT
3.2
Crystal Oscillator/Ceramic Resonators
Capacitor values are for design guidance only. Different capacitor values may be required to produce acceptable oscillator operation. The user should test the performance of the oscillator over the expected VDD and temperature range for the application. Refer to the following application notes for oscillator specific information: * AN588, "PIC(R) Microcontroller Oscillator Design Guide" * AN826, "Crystal Oscillator Basics and Crystal Selection for rfPIC(R) and PIC(R) Devices" * AN849, "Basic PIC(R) Oscillator Design" * AN943, "Practical PIC(R) Oscillator Analysis and Design" * AN949, "Making Your Oscillator Work" See the notes following Table 3-2 for additional information. Note: When using resonators with frequencies above 3.5 MHz, the use of HS mode, rather than XT mode, is recommended. HS mode may be used at any VDD for which the controller is rated. If HS is selected, it is possible that the gain of the oscillator will overdrive the resonator. Therefore, a series resistor may be placed between the OSC2 pin and the resonator. As a good starting point, the recommended value of RS is 330.
In XT, LP, HS or HSPLL Oscillator modes, a crystal or ceramic resonator is connected to the OSC1 and OSC2 pins to establish oscillation. Figure 3-1 shows the pin connections. The oscillator design requires the use of a parallel cut crystal. Note: Use of a series cut crystal may give a frequency out of the crystal manufacturer's specifications.
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TABLE 3-2: CAPACITOR SELECTION FOR QUARTZ CRYSTALS
Crystal Freq 32 kHz 1 MHz 4 MHz 4 MHz 10 MHz 20 MHz 25 MHz Typical Capacitor Values Tested: C1 22 pF 22 pF 22 pF 22 pF 22 pF 22 pF 22 pF C2 22 pF 22 pF 22 pF 22 pF 22 pF 22 pF 22 pF
Clock from Ext. System Open
An external clock source may also be connected to the OSC1 pin in the HS mode, as shown in Figure 3-2. When operated in this mode, parameters D033 and D043 apply.
Osc Type LP XT HS
FIGURE 3-2:
EXTERNAL CLOCK INPUT OPERATION (HS OSC CONFIGURATION)
OSC1
PIC18FXXXX
OSC2 (HS Mode)
Capacitor values are for design guidance only. Different capacitor values may be required to produce acceptable oscillator operation. The user should test the performance of the oscillator over the expected VDD and temperature range for the application. Refer to the following application notes for oscillator specific information: * AN588, "PIC(R) Microcontroller Oscillator Design Guide" * AN826, "Crystal Oscillator Basics and Crystal Selection for rfPIC(R) and PIC(R) Devices" * AN849, "Basic PIC(R) Oscillator Design" * AN943, "Practical PIC(R) Oscillator Analysis and Design" * AN949, "Making Your Oscillator Work" See the notes following this table for additional information.
3.3
External Clock Input
The EC and ECIO Oscillator modes require an external clock source to be connected to the OSC1 pin. There is no oscillator start-up time required after a Power-on Reset or after an exit from Sleep mode. In the EC Oscillator mode, the oscillator frequency divided by 4 is available on the OSC2 pin. This signal may be used for test purposes or to synchronize other logic. Figure 3-3 shows the pin connections for the EC Oscillator mode.
FIGURE 3-3:
EXTERNAL CLOCK INPUT OPERATION (EC CONFIGURATION)
OSC1/CLKI
Clock from Ext. System FOSC/4
PIC18FXXXX
OSC2/CLKO
Note 1: Higher capacitance increases the stability of the oscillator but also increases the start-up time. 2: When operating below 3V VDD, or when using certain ceramic resonators at any voltage, it may be necessary to use the HS mode or switch to a crystal oscillator. 3: Since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components. 4: Rs may be required to avoid overdriving crystals with low drive level specification. 5: Always verify oscillator performance over the VDD and temperature range that is expected for the application.
The ECIO Oscillator mode functions like the EC mode, except that the OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 6 of PORTA (RA6). Figure 3-4 shows the pin connections for the ECIO Oscillator mode. When operated in this mode, parameters D033A and D043A apply.
FIGURE 3-4:
EXTERNAL CLOCK INPUT OPERATION (ECIO CONFIGURATION)
OSC1/CLKI
Clock from Ext. System RA6
PIC18FXXXX
I/O (OSC2)
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3.4 RC Oscillator 3.5 PLL Frequency Multiplier
For timing insensitive applications, the RC and RCIO Oscillator modes offer additional cost savings. The actual oscillator frequency is a function of several factors: * supply voltage * values of the external resistor (REXT) and capacitor (CEXT) * operating temperature Given the same device, operating voltage, temperature and component values, there will also be unit-to-unit frequency variations. These are due to factors such as: * normal manufacturing variation * difference in lead frame capacitance between package types (especially for low CEXT values) * variations within the tolerance of limits of REXT and CEXT In the RC Oscillator mode, the oscillator frequency divided by 4 is available on the OSC2 pin. This signal may be used for test purposes or to synchronize other logic. Figure 3-5 shows how the R/C combination is connected. A Phase Locked Loop (PLL) circuit is provided as an option for users who wish to use a lower frequency oscillator circuit or to clock the device up to its highest rated frequency from a crystal oscillator. This may be useful for customers who are concerned with EMI due to high-frequency crystals or users who require higher clock speeds from an internal oscillator.
3.5.1
HSPLL OSCILLATOR MODE
The HSPLL mode makes use of the HS mode oscillator for frequencies up to 10 MHz. A PLL then multiplies the oscillator output frequency by 4 to produce an internal clock frequency up to 40 MHz. The PLLEN bit is not available when this mode is configured as the primary clock source. The PLL is only available to the crystal oscillator when the FOSC<3:0> Configuration bits are programmed for HSPLL mode (= 0110).
FIGURE 3-7:
HSPLL BLOCK DIAGRAM
FIGURE 3-5:
VDD REXT
RC OSCILLATOR MODE
HS Oscillator Enable PLL Enable (from Configuration Register 1H) OSC2
OSC1 CEXT VSS FOSC/4 OSC2/CLKO
Internal Clock
HS Mode OSC1 Crystal Osc
FIN FOUT
Phase Comparator
PIC18FXXXX
/4
Loop Filter
The RCIO Oscillator mode (Figure 3-6) functions like the RC mode, except that the OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 6 of PORTA (RA6).
3.5.2
PLL AND INTOSC
FIGURE 3-6:
VDD REXT
RCIO OSCILLATOR MODE
OSC1 CEXT VSS RA6 I/O (OSC2)
Internal Clock
The PLL is also available to the internal oscillator block when the internal oscillator block is configured as the primary clock source. In this configuration, the PLL is enabled in software and generates a clock output of up to 32 MHz. The operation of INTOSC with the PLL is described in Section 3.6.4 "PLL in INTOSC Modes".
PIC18FXXXX
Recommended values: 3 k REXT 100 k 20 pF CEXT 300 pF
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MUX
Recommended values: 3 k REXT 100 k 20 pF CEXT 300 pF
VCO
SYSCLK
PIC18F2221/2321/4221/4321 FAMILY
3.6 Internal Oscillator Block
3.6.2 INTOSC OUTPUT FREQUENCY
The PIC18F2221/2321/4221/4321 family of devices includes an internal oscillator block which generates two different clock signals; either can be used as the microcontroller's clock source. This may eliminate the need for external oscillator circuits on the OSC1 and/or OSC2 pins. The main output (INTOSC) is an 8 MHz clock source, which can be used to directly drive the device clock. It also drives a postscaler, which can provide a range of clock frequencies from 31 kHz to 4 MHz. The INTOSC output is enabled when a clock frequency from 125 kHz to 8 MHz is selected. The INTOSC output can also be enabled when 31 kHz is selected, depending on the INTSRC bit (OSCTUNE<7>). The other clock source is the internal RC oscillator (INTRC), which provides a nominal 31 kHz output. INTRC is enabled if it is selected as the device clock source; it is also enabled automatically when any of the following are enabled: * * * * Power-up Timer Fail-Safe Clock Monitor Watchdog Timer Two-Speed Start-up The internal oscillator block is calibrated at the factory to produce an INTOSC output frequency of 8 MHz. The INTRC oscillator operates independently of the INTOSC source. Any changes in INTOSC across voltage and temperature are not necessarily reflected by changes in INTRC or vice versa.
3.6.3
OSCTUNE REGISTER
The INTOSC output has been calibrated at the factory but can be adjusted in the user's application. This is done by writing to TUN<4:0> (OSCTUNE<4:0>) in the OSCTUNE register (Register 3-1). When the OSCTUNE register is modified, the INTOSC frequency will begin shifting to the new frequency. Code execution continues during this shift. There is no indication that the shift has occurred. The INTRC is not affected by OSCTUNE. The OSCTUNE register also implements the INTSRC (OSCTUNE<7>) and PLLEN (OSCTUNE<6>) bits, which control certain features of the internal oscillator block. The INTSRC bit allows users to select which internal oscillator provides the clock source when the 31 kHz frequency option is selected. This is covered in greater detail in Section 3.7.1 "Oscillator Control Register". The PLLEN bit controls the operation of the Phase Locked Loop (PLL) in Internal Oscillator modes (see Figure 3-10).
These features are discussed in greater detail in Section 24.0 "Special Features of the CPU". The clock source frequency (INTOSC direct, INTRC direct or INTOSC postscaler) is selected by configuring the IRCF bits of the OSCCON register (page 37).
3.6.1
INTIO MODES
FIGURE 3-10:
Using the internal oscillator as the clock source eliminates the need for up to two external oscillator pins, which can then be used for digital I/O. Two distinct configurations are available: * In INTIO1 mode, the OSC2 pin outputs FOSC/4, while OSC1 functions as RA7 (see Figure 3-8) for digital input and output. * In INTIO2 mode, OSC1 functions as RA7 and OSC2 functions as RA6 (see Figure 3-9), both for digital input and output.
INTOSC AND PLL BLOCK DIAGRAM
8 or 4 MHz PLLEN (OSCTUNE<6>)
INTOSC
FIN FOUT
Phase Comparator
FIGURE 3-8:
RA7 FOSC/4
INTIO1 OSCILLATOR MODE
I/O (OSC1) OSC2
Loop Filter
PIC18FXXXX
CLKO OSC2
/4
VCO MUX
SYSCLK
FIGURE 3-9:
RA7 RA6
INTIO2 OSCILLATOR MODE
I/O (OSC1) I/O (OSC2)
MUX RA6
PIC18FXXXX
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3.6.4 PLL IN INTOSC MODES 3.6.5 INTOSC FREQUENCY DRIFT
The 4x Phase Locked Loop (PLL) can be used with the internal oscillator block to produce faster device clock speeds than are normally possible with the internal oscillator sources. When enabled, the PLL produces a clock speed of 16 MHz or 32 MHz. Unlike HSPLL mode, the PLL is controlled through software. The control bit, PLLEN (OSCTUNE<6>), is used to enable or disable its operation. If PLL is enabled and a Two-Speed Start-up from wake is performed, execution is delayed until the PLL starts. The PLL is available when the device is configured to use the internal oscillator block as its primary clock source (FOSC<3:0> = 1001 or 1000). Additionally, the PLL will only function when the selected output frequency is either 4 MHz or 8 MHz (OSCCON<6:4> = 111 or 110). If both of these conditions are not met, the PLL is disabled and the PLLEN bit remains clear (writes are ignored). The factory calibrates the internal oscillator block output (INTOSC) for 8 MHz. However, this frequency may drift as VDD or temperature changes and can affect the controller operation in a variety of ways. It is possible to adjust the INTOSC frequency by modifying the value in the OSCTUNE register. This has no effect on the INTRC clock source frequency. Tuning the INTOSC source requires knowing when to make the adjustment, in which direction it should be made and in some cases, how large a change is needed. Three compensation techniques are discussed in Section 3.6.5.1 "Compensating with the EUSART", Section 3.6.5.2 "Compensating with the Timers" and Section 3.6.5.3 "Compensating with the CCP Module in Capture Mode" but other techniques may be used.
REGISTER 3-1:
OSCTUNE: OSCILLATOR TUNING REGISTER
R/W-0 INTSRC bit 7 R/W-0 PLLEN(1) U-0 -- R/W-0 TUN4 R/W-0 TUN3 R/W-0 TUN2 R/W-0 TUN1 R/W-0 TUN0 bit 0
bit 7
INTSRC: Internal Oscillator Low-Frequency Source Select bit 1 = 31.25 kHz device clock derived from 8 MHz INTOSC source (divide-by-256 enabled) 0 = 31 kHz device clock derived directly from INTRC internal oscillator PLLEN: Frequency Multiplier PLL for INTOSC Enable bit(1) 1 = PLL enabled for INTOSC (4 MHz and 8 MHz only) 0 = PLL disabled Note 1: Available only in certain oscillator configurations; otherwise, this bit is unavailable and reads as `0'. See Section 3.6.4 "PLL in INTOSC Modes" for details.
bit 6
bit 5 bit 4-0
Unimplemented: Read as `0' TUN<4:0>: Frequency Tuning bits 01111 = Maximum frequency * * * * 00001 00000 = Center frequency. Oscillator module is running at the calibrated frequency. 11111 * * * * 10000 = Minimum frequency Legend: R = Readable bit -n = Value at POR
W = Writable bit `1' = Bit is set
U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
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3.6.5.1 Compensating with the EUSART 3.6.5.3
An adjustment may be required when the EUSART begins to generate framing errors or receives data with errors while in Asynchronous mode. Framing errors indicate that the device clock frequency is too high. To adjust for this, decrement the value in OSCTUNE to reduce the clock frequency. On the other hand, errors in data may suggest that the clock speed is too low. To compensate, increment OSCTUNE to increase the clock frequency.
Compensating with the CCP Module in Capture Mode
3.6.5.2
Compensating with the Timers
A CCP module can use free running Timer1 (or Timer3), clocked by the internal oscillator block and an external event with a known period (i.e., AC power frequency). The time of the first event is captured in the CCPRxH:CCPRxL registers and is recorded for use later. When the second event causes a capture, the time of the first event is subtracted from the time of the second event. Since the period of the external event is known, the time difference between events can be calculated. If the measured time is much greater than the calculated time, the internal oscillator block is running too fast. To compensate, decrement the OSCTUNE register. If the measured time is much less than the calculated time, the internal oscillator block is running too slow. To compensate, increment the OSCTUNE register.
This technique compares device clock speed to some reference clock. Two timers may be used; one timer is clocked by the peripheral clock, while the other is clocked by a fixed reference source, such as the Timer1 oscillator. Both timers are cleared, but the timer clocked by the reference generates interrupts. When an interrupt occurs, the internally clocked timer is read and both timers are cleared. If the internally clocked timer value is much greater than expected, then the internal oscillator block is running too fast. To adjust for this, decrement the OSCTUNE register.
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3.7 Clock Sources and Oscillator Switching
The secondary oscillators are those external sources not connected to the OSC1 or OSC2 pins. These sources may continue to operate even after the controller is placed in a power-managed mode. The PIC18F2221/2321/4221/4321 family of devices offers the Timer1 oscillator as a secondary oscillator. This oscillator, in all power-managed modes, is often the time base for functions such as a Real-Time Clock. Most often, a 32.768 kHz watch crystal is connected between the RC0/T1OSO/T13CKI and RC1/T1OSI pins. Like the LP mode oscillator circuit, loading capacitors are also connected from each pin to ground. The Timer1 oscillator is discussed in greater detail in Section 13.3 "Timer1 Oscillator". In addition to being a primary clock source, the internal oscillator block is available as a power-managed mode clock source. The INTRC source is also used as the clock source for several special features, such as the WDT and Fail-Safe Clock Monitor. The clock sources for the PIC18F2221/2321/4221/4321 family of devices are shown in Figure 3-11. See Section 24.0 "Special Features of the CPU" for Configuration register details.
The PIC18F2221/2321/4221/4321 family of devices includes a feature that allows the device clock source to be switched from the main oscillator to an alternate clock source. These devices also offer two alternate clock sources. When an alternate clock source is enabled, the various power-managed operating modes are available. Essentially, there are three clock sources for these devices: * Primary oscillators * Secondary oscillators * Internal oscillator block The primary oscillators include the External Crystal and Resonator modes, the External RC modes, the External Clock modes and the internal oscillator block. The particular mode is defined by the FOSC<3:0> Configuration bits. The details of these modes are covered earlier in this chapter.
FIGURE 3-11:
PIC18F2221/2321/4221/4321 FAMILY CLOCK DIAGRAM
Primary Oscillator OSC2 Sleep OSC1 Secondary Oscillator T1OSO T1OSCEN Enable Oscillator OSCCON<6:4> Internal Oscillator Block 8 MHz Source INTRC Source OSCTUNE<6> 4 x PLL
LP, XT, HS, RC, EC HSPLL, INTOSC/PLL T1OSC Peripherals
T1OSI
OSCCON<6:4> 8 MHz 4 MHz 2 MHz Postscaler 1 MHz 500 kHz 250 kHz 125 kHz 111 110 101 011 010 001 MUX 100
Internal Oscillator CPU
MUX
IDLEN Clock Control FOSC<3:0> OSCCON<1:0>
8 MHz (INTOSC)
31 kHz (INTRC)
1 31 kHz 000 0 OSCTUNE<7>
Clock Source Option for Other Modules
WDT, PWRT, FSCM and Two-Speed Start-up
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3.7.1 OSCILLATOR CONTROL REGISTER
The OSCCON register (Register 3-2) controls several aspects of the device clock's operation, both in full power operation and in power-managed modes. The System Clock Select bits, SCS<1:0>, select the clock source. The available clock sources are the primary clock (defined by the FOSC<3:0> Configuration bits), the secondary clock (Timer1 oscillator) and the internal oscillator block. The clock source changes immediately after either of the SCS<1:0> bits are changed, following a brief clock transition interval. The SCS bits are reset on all forms of Reset. The Internal Oscillator Frequency Select bits (IRCF<2:0>) select the frequency output of the internal oscillator block to drive the device clock. The choices are the INTRC source (31 kHz), the INTOSC source (8 MHz) or one of the frequencies derived from the INTOSC postscaler (31.25 kHz to 4 MHz). If the internal oscillator block is supplying the device clock, changing the states of these bits will have an immediate change on the internal oscillator's output. On device Resets, the default output frequency of the internal oscillator block is set at 1 MHz. When a nominal output frequency of 31 kHz is selected (IRCF<2:0> = 000), users may choose which internal oscillator acts as the source. This is done with the INTSRC bit in the OSCTUNE register (OSCTUNE<7>). Setting this bit selects INTOSC as a 31.25 kHz clock source derived from the INTOSC postscaler. Clearing INTSRC selects INTRC (nominally 31 kHz) as the clock source and disables the INTOSC to reduce current consumption. This option allows users to select the tunable and more precise INTOSC as a clock source, while maintaining power savings with a very low clock speed. Additionally, the INTOSC source will already be stable should a switch to a higher frequency be needed quickly. Regardless of the setting of INTSRC, INTRC always remains the clock source for features such as the Watchdog Timer and the Fail-Safe Clock Monitor. The OSTS, IOFS and T1RUN bits indicate which clock source is currently providing the device clock. The OSTS bit indicates that the Oscillator Start-up Timer and PLL Start-up Timer (if enabled) have timed out and the primary clock is providing the device clock in primary clock modes. The IOFS bit indicates when the internal oscillator block has stabilized and is providing the device clock in RC Clock modes. The T1RUN bit (T1CON<6>) indicates when the Timer1 oscillator is providing the device clock in secondary clock modes. In power-managed modes, only one of these three bits will be set at any time. If none of these bits are set, the INTRC is providing the clock or the internal oscillator block has just started and is not yet stable. The IDLEN bit controls whether the device goes into Sleep mode or one of the Idle modes when the SLEEP instruction is executed. The use of the flag and control bits in the OSCCON register is discussed in more detail in Section 4.0 "Power-Managed Modes". Note 1: The Timer1 oscillator must be enabled to select the secondary clock source. The Timer1 oscillator is enabled by setting the T1OSCEN bit in the Timer1 Control register (T1CON<3>). If the Timer1 oscillator is not enabled, then any attempt to select a secondary clock source will be ignored. 2: It is recommended that the Timer1 oscillator be operating and stable before selecting the secondary clock source or a very long delay may occur while the Timer1 oscillator starts.
3.7.2
OSCILLATOR TRANSITIONS
The PIC18F2221/2321/4221/4321 family of devices contains circuitry to prevent clock "glitches" when switching between clock sources. A short pause in the device clock occurs during the clock switch. The length of this pause is the sum of two cycles of the old clock source and three to four cycles of the new clock source. This formula assumes that the new clock source is stable. Clock transitions are discussed in greater detail in Section 4.1.2 "Entering Power-Managed Modes".
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REGISTER 3-2: OSCCON: OSCILLATOR CONTROL REGISTER
R/W-0 IDLEN bit 7 bit 7 IDLEN: Idle Enable bit 1 = Device enters an Idle mode when a SLEEP instruction is executed 0 = Device enters Sleep mode when a SLEEP instruction is executed IRCF<2:0>: Internal Oscillator Frequency Select bits 111 = 8 MHz (INTOSC drives clock directly) 110 = 4 MHz 101 = 2 MHz 100 = 1 MHz(3) 011 = 500 kHz 010 = 250 kHz 001 = 125 kHz 000 = 31 kHz (from either INTOSC/256 or INTRC directly)(2) OSTS: Oscillator Start-up Time-out Status bit(1) 1 = Oscillator Start-up Timer (OST) time-out has expired; primary oscillator is running 0 = Oscillator Start-up Timer (OST) time-out is running; primary oscillator is not ready IOFS: INTOSC Frequency Stable bit 1 = INTOSC frequency is stable 0 = INTOSC frequency is not stable SCS<1:0>: System Clock Select bits 1x = Internal oscillator block 01 = Secondary (Timer1) oscillator 00 = Primary oscillator Note 1: Reset state depends on state of the IESO Configuration bit. 2: Source selected by the INTSRC bit (OSCTUNE<7>), see text. 3: Default output frequency of INTOSC on Reset. Legend: R = Readable bit -n = Value at POR R/W-1 IRCF2 R/W-0 IRCF1 R/W-0 IRCF0 R(1) OSTS R-0 IOFS R/W-0 SCS1 R/W-0 SCS0 bit 0
bit 6-4
bit 3
bit 2
bit 1-0
W = Writable bit `1' = Bit is set
U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
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3.8 Effects of Power-Managed Modes on the Various Clock Sources 3.9 Power-up Delays
Power-up delays are controlled by two or three timers, so that no external Reset circuitry is required for most applications. The delays ensure that the device is kept in Reset until the device power supply is stable under normal circumstances and the primary clock is operating and stable. For additional information on power-up delays, see Section 5.5 "Device Reset Timers". The first timer is the Power-up Timer (PWRT) which provides a fixed delay on power-up (parameter 33, Table 27-10). It is enabled by clearing (= 0) the PWRTEN Configuration bit (CONFIG2L<0>).
When PRI_IDLE mode is selected, the designated primary oscillator continues to run without interruption. For all other power-managed modes, the oscillator using the OSC1 pin is disabled. The OSC1 pin (and OSC2 pin in Crystal Oscillator modes) will stop oscillating. In secondary clock modes (SEC_RUN and SEC_IDLE), the Timer1 oscillator is operating and providing the device clock. The Timer1 oscillator may also run in all power-managed modes if required to clock Timer1 or Timer3. In internal oscillator modes (RC_RUN and RC_IDLE), the internal oscillator block provides the device clock source. The 31 kHz INTRC output can be used directly to provide the clock and may be enabled to support various special features, regardless of the powermanaged mode (see Section 24.2 "Watchdog Timer (WDT)", Section 24.3 "Two-Speed Start-up" and Section 24.4 "Fail-Safe Clock Monitor" for more information). The INTOSC output at 8 MHz may be used directly to clock the device or may be divided down by the postscaler. The INTOSC output is disabled if the clock is provided directly from the INTRC output. The INTOSC output is also enabled for Two-Speed Start-up at 1 MHz after a Reset. If the Sleep mode is selected, all clock sources are stopped. Since all the transistor switching currents have been stopped, Sleep mode achieves the lowest current consumption of the device (only leakage currents). Enabling any on-chip feature that will operate during Sleep will increase the current consumed during Sleep. The INTRC is required to support WDT operation. The Timer1 oscillator may be operating to support a RealTime Clock. Other features may be operating that do not require a device clock source (i.e., MSSP slave, PSP, INTx pins and others). Peripherals that may add significant current consumption are listed in Section 27.2 "DC Characteristics".
3.9.1
DELAYS FOR POWER-UP AND RETURN TO PRIMARY CLOCK
The second timer is the Oscillator Start-up Timer (OST), intended to delay execution until the crystal oscillator is stable (LP, XT and HS modes). The OST does this by counting 1024 oscillator cycles before allowing the oscillator to clock the device. When the HSPLL Oscillator mode is selected, a third timer delays execution for an additional 2 ms following the HS mode OST delay, so the PLL can lock to the incoming clock frequency. At the end of these delays, the OSTS bit (OSCCON<3>) is set. There is a delay of interval TCSD (parameter 38, Table 27-10), once execution is allowed to start, when the controller becomes ready to execute instructions. This delay runs concurrently with any other delays. This may be the only delay that occurs when any of the EC, RC or INTIO modes are used as the primary clock source.
TABLE 3-3:
RC, INTIO1 RCIO INTIO2 ECIO EC LP, XT and HS Note:
OSC1 AND OSC2 PIN STATES IN SLEEP MODE
OSC1 Pin Floating, external resistor pulls high Floating, external resistor pulls high Configured as PORTA, bit 7 Floating, driven by external clock Floating, driven by external clock Feedback inverter disabled at quiescent voltage level OSC2 Pin At logic low (clock/4 output) Configured as PORTA, bit 6 Configured as PORTA, bit 6 Configured as PORTA, bit 6 At logic low (clock/4 output) Feedback inverter disabled at quiescent voltage level
OSC Mode
See Table 5-2 in Section 5.0 "Reset" for time-outs due to Sleep and MCLR Reset.
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4.0 POWER-MANAGED MODES
4.1.1 CLOCK SOURCES
PIC18F2221/2321/4221/4321 family devices offer a total of seven operating modes for more efficient power-management. These modes provide a variety of options for selective power conservation in applications where resources may be limited (i.e., battery-powered devices). There are three categories of power-managed modes: * Run modes * Idle modes * Sleep mode These categories define which portions of the device are clocked and sometimes, what speed. The Run and Idle modes may use any of the three available clock sources (primary, secondary or internal oscillator block); the Sleep mode does not use a clock source. The power-managed modes include several powersaving features offered on previous PIC(R) devices. One is the clock switching feature, offered in other PIC18 devices, allowing the controller to use the Timer1 oscillator in place of the primary oscillator. Also included is the Sleep mode, offered by all PIC devices, where all device clocks are stopped. The SCS<1:0 bits allow the selection of one of three clock sources for power-managed modes. They are: * the primary clock, as defined by the FOSC<3:0> Configuration bits * the secondary clock (the Timer1 oscillator) * the internal oscillator block (for RC modes)
4.1.2
ENTERING POWER-MANAGED MODES
Switching from one power-managed mode to another begins by loading the OSCCON register. The SCS1:SCS0 bits select the clock source and determine which Run or Idle mode is to be used. Changing these bits causes an immediate switch to the new clock source, assuming that it is running. The switch may also be subject to clock transition delays. These are discussed in Section 4.1.3 "Clock Transitions and Status Indicators" and subsequent sections. Entry to the power-managed Idle or Sleep modes is triggered by the execution of a SLEEP instruction. The actual mode that results depends on the status of the IDLEN bit. Depending on the current mode and the mode being switched to, a change to a power-managed mode does not always require setting all of these bits. Many transitions may be done by changing the oscillator select bits, or changing the IDLEN bit, prior to issuing a SLEEP instruction. If the IDLEN bit is already configured correctly, it may only be necessary to perform a SLEEP instruction to switch to the desired mode.
4.1
Selecting Power-Managed Modes
Selecting a power-managed mode requires two decisions: if the CPU is to be clocked or not and the selection of a clock source. The IDLEN bit (OSCCON<7>) controls CPU clocking, while the SCS<1:0 bits (OSCCON<1:0>) select the clock source. The individual modes, bit settings, clock sources and affected modules are summarized in Table 4-1.
TABLE 4-1:
Mode Sleep PRI_RUN
POWER-MANAGED MODES
OSCCON Bits IDLEN<7>(1) SCS<1:0> 0 N/A N/A 00 Module Clocking CPU Off Clocked Peripherals Off Clocked Available Clock and Oscillator Source None - All clocks are disabled Primary - LP, XT, HS, HSPLL, RC, EC and Internal Oscillator Block.(2) This is the normal full power execution mode. Secondary - Timer1 Oscillator Internal Oscillator Block(2) Primary - LP, XT, HS, HSPLL, RC, EC Secondary - Timer1 Oscillator Internal Oscillator Block(2)
SEC_RUN RC_RUN PRI_IDLE SEC_IDLE RC_IDLE Note 1: 2:
N/A N/A 1 1 1
01 1x 00 01 1x
Clocked Clocked Off Off Off
Clocked Clocked Clocked Clocked Clocked
IDLEN reflects its value when the SLEEP instruction is executed. Includes INTOSC and INTOSC postscaler, as well as the INTRC source.
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4.1.3 CLOCK TRANSITIONS AND STATUS INDICATORS
4.2
Run Modes
The length of the transition between clock sources is the sum of two cycles of the old clock source and three to four cycles of the new clock source. This formula assumes that the new clock source is stable. Three bits indicate the current clock source and its status. They are: * OSTS (OSCCON<3>) * IOFS (OSCCON<2>) * T1RUN (T1CON<6>) In general, only one of these bits will be set while in a given power-managed mode. When the OSTS bit is set, the primary clock is providing the device clock. When the IOFS bit is set, the INTOSC output is providing a stable 8 MHz clock source to a divider that actually drives the device clock. When the T1RUN bit is set, the Timer1 oscillator is providing the clock. If none of these bits are set, then either the INTRC clock source is clocking the device, or the INTOSC source is not yet stable. If the internal oscillator block is configured as the primary clock source by the FOSC<3:0> Configuration bits, then both the OSTS and IOFS bits may be set when in PRI_RUN or PRI_IDLE modes. This indicates that the primary clock (INTOSC) is generating a stable 8 MHz output. Switching the clock source to the Timer1 oscillator would clear the OSTS bit. Note 1: Caution should be used when modifying a single IRCF bit. If VDD is less than 3V, it is possible to select a higher clock speed than is supported by the low VDD. Improper device operation may result if the VDD/FOSC specifications are violated. 2: Executing a SLEEP instruction does not necessarily place the device into Sleep mode. It acts as the trigger to place the controller into either the Sleep mode or one of the Idle modes, depending on the setting of the IDLEN bit.
In the Run modes, clocks to both the core and peripherals are active. The difference between these modes is the clock source.
4.2.1
PRI_RUN MODE
The PRI_RUN mode is the normal, full power execution mode of the microcontroller. This is also the default mode upon a device Reset unless Two-Speed Start-up is enabled (see Section 24.3 "Two-Speed Start-up" or Section 24.4 "Fail-Safe Clock Monitor" for details). In this mode, the OSTS bit is set. The IOFS bit may be set if the internal oscillator block is the primary clock source (see Section 3.7.1 "Oscillator Control Register").
4.2.2
SEC_RUN MODE
The SEC_RUN mode is the compatible mode to the "clock switching" feature offered in other PIC18 devices. In this mode, the CPU and peripherals are clocked from the Timer1 oscillator. This gives users the option of lower power consumption while still using a high-accuracy clock source. SEC_RUN mode is entered by setting the SCS<1:0> bits to `01'. The device clock source is switched to the Timer1 oscillator (see Figure 4-1), the primary oscillator is shut down, the T1RUN bit (T1CON<6>) is set and the OSTS bit is cleared. Note: The Timer1 oscillator should already be running prior to entering SEC_RUN mode. If the T1OSCEN bit is not set when the SCS<1:0> bits are set to `01', entry to SEC_RUN mode will not occur. If the Timer1 oscillator is enabled, but not yet running, device clocks will be delayed until the oscillator has started. In such situations, initial oscillator operation is far from stable and unpredictable operation may result.
4.1.4
MULTIPLE SLEEP COMMANDS
The power-managed mode that is invoked with the SLEEP instruction is determined by the setting of the IDLEN bit at the time the instruction is executed. If another SLEEP instruction is executed, the device will enter the power-managed mode specified by IDLEN at that time. If IDLEN has changed, the device will enter the new power-managed mode specified by the new setting.
On transitions from SEC_RUN mode to PRI_RUN, the peripherals and CPU continue to be clocked from the Timer1 oscillator while the primary clock is started. When the primary clock becomes ready, a clock switch back to the primary clock occurs (see Figure 4-2). When the clock switch is complete, the T1RUN bit is cleared, the OSTS bit is set and the primary clock is providing the clock. The IDLEN and SCS bits are not affected by the wake-up; the Timer1 oscillator continues to run.
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FIGURE 4-1: TRANSITION TIMING FOR ENTRY TO SEC_RUN MODE
Q1 Q2 Q3 Q4 Q1 T1OSI OSC1 CPU Clock Peripheral Clock Program Counter 1 2 3 n-1 n Q2 Q3 Q4 Q1 Q2 Q3
Clock Transition(1)
PC
PC + 2
PC + 4
Note 1:
Clock transition typically occurs within 2-4 TOSC.
FIGURE 4-2:
TRANSITION TIMING FROM SEC_RUN MODE TO PRI_RUN MODE (HSPLL)
Q1 T1OSI OSC1 TOST(1) TPLL(1) 1 2 n-1 n Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3
PLL Clock Output CPU Clock Peripheral Clock Program Counter SCS<1:0> bits Changed PC OSTS bit Set
Clock Transition(2)
PC + 2
PC + 4
Note 1: 2:
TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale. Clock transition typically occurs within 2-4 TOSC.
4.2.3
RC_RUN MODE
In RC_RUN mode, the CPU and peripherals are clocked from the internal oscillator block using the INTOSC multiplexer. In this mode, the primary clock is shut down. When using the INTRC source, this mode provides the best power conservation of all the Run modes, while still executing code. It works well for user applications which are not highly timing sensitive or do not require high-speed clocks at all times. If the primary clock source is the internal oscillator block (either INTRC or INTOSC), there are no distinguishable differences between PRI_RUN and RC_RUN modes during execution. However, a clock switch delay will occur during entry to and exit from RC_RUN mode. Therefore, if the primary clock source is the internal oscillator block, the use of RC_RUN mode is not recommended.
This mode is entered by setting the SCS1 bit to `1'. Although it is ignored, it is recommended that the SCS0 bit also be cleared; this is to maintain software compatibility with future devices. When the clock source is switched to the INTOSC multiplexer (see Figure 4-3), the primary oscillator is shut down and the OSTS bit is cleared. The IRCF bits may be modified at any time to immediately change the clock speed. Note: Caution should be used when modifying a single IRCF bit. If VDD is less than 3V, it is possible to select a higher clock speed than is supported by the low VDD. Improper device operation may result if the VDD/FOSC specifications are violated.
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If the IRCF bits and the INTSRC bit are all clear, the INTOSC output is not enabled and the IOFS bit will remain clear; there will be no indication of the current clock source. The INTRC source is providing the device clocks. If the IRCF bits are changed from all clear (thus, enabling the INTOSC output) or if INTSRC is set, the IOFS bit becomes set after the INTOSC output becomes stable. Clocks to the device continue while the INTOSC source stabilizes after an interval of TIOBST (parameter 39, Table 27-10). If the IRCF bits were previously at a non-zero value, or if INTSRC was set before setting SCS1 and the INTOSC source was already stable, the IOFS bit will remain set. On transitions from RC_RUN mode to PRI_RUN mode, the device continues to be clocked from the INTOSC multiplexer while the primary clock is started. When the primary clock becomes ready, a clock switch to the primary clock occurs (see Figure 4-4). When the clock switch is complete, the IOFS bit is cleared, the OSTS bit is set and the primary clock is providing the device clock. The IDLEN and SCS bits are not affected by the switch. The INTRC source will continue to run if either the WDT or the Fail-Safe Clock Monitor is enabled.
FIGURE 4-3:
TRANSITION TIMING TO RC_RUN MODE
Q1 Q2 Q3 Q4 Q1 Q2 1 2 3 n-1 n Q3 Q4 Q1 Q2 Q3
INTRC OSC1 CPU Clock Peripheral Clock Program Counter PC
Clock Transition(1)
PC + 2
PC + 4
Note 1:
Clock transition typically occurs within 2-4 TOSC.
FIGURE 4-4:
TRANSITION TIMING FROM RC_RUN MODE TO PRI_RUN MODE
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3
INTOSC Multiplexer OSC1 TOST(1) PLL Clock Output CPU Clock Peripheral Clock Program Counter SCS<1:0> bits Changed PC OSTS bit Set PC + 2 PC + 4 TPLL(1) 1 2 n-1 n
Clock Transition(2)
Note 1: 2:
TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale. Clock transition typically occurs within 2-4 TOSC.
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4.3 Sleep Mode 4.4 Idle Modes
The power-managed Sleep mode in the PIC18F2221/ 2321/4221/4321 family devices is identical to the legacy Sleep mode offered in all other PIC devices. It is entered by clearing the IDLEN bit (the default state on device Reset) and executing the SLEEP instruction. This shuts down the selected oscillator (Figure 4-5). All clock source status bits are cleared. Entering the Sleep mode from any other mode does not require a clock switch. This is because no clocks are needed once the controller has entered Sleep. If the WDT is selected, the INTRC source will continue to operate. If the Timer1 oscillator is enabled, it will also continue to run. When a wake event occurs in Sleep mode (by interrupt, Reset or WDT time-out), the device will not be clocked until the clock source selected by the SCS<1:0> bits becomes ready (see Figure 4-6), or it will be clocked from the internal oscillator block if either the Two-Speed Start-up or the Fail-Safe Clock Monitor are enabled (see Section 24.0 "Special Features of the CPU"). In either case, the OSTS bit is set when the primary clock is providing the device clocks. The IDLEN and SCS bits are not affected by the wake-up. The Idle modes allow the controller's CPU to be selectively shut down while the peripherals continue to operate. Selecting a particular Idle mode allows users to further manage power consumption. If the IDLEN bit is set to a `1' when a SLEEP instruction is executed, the peripherals will be clocked from the clock source selected using the SCS<1:0> bits; however, the CPU will not be clocked. The clock source status bits are not affected. Setting IDLEN and executing a SLEEP instruction provides a quick method of switching from a given Run mode to its corresponding Idle mode. If the WDT is selected, the INTRC source will continue to operate. If the Timer1 oscillator is enabled, it will also continue to run. Since the CPU is not executing instructions, the only exits from any of the Idle modes are by interrupt, WDT time-out or a Reset. When a wake event occurs, CPU execution is delayed by an interval of TCSD (parameter 38, Table 27-10) while it becomes ready to execute code. When the CPU begins executing code, it resumes with the same clock source for the current Idle mode. For example, when waking from RC_IDLE mode, the internal oscillator block will clock the CPU and peripherals (in other words, RC_RUN mode). The IDLEN and SCS bits are not affected by the wake-up. While in any Idle mode or the Sleep mode, a WDT time-out will result in a WDT wake-up to the Run mode currently specified by the SCS<1:0> bits.
FIGURE 4-5:
OSC1 CPU Clock Peripheral Clock Sleep Program Counter PC
TRANSITION TIMING FOR ENTRY TO SLEEP MODE
Q1 Q2 Q3 Q4 Q1
PC + 2
FIGURE 4-6:
OSC1 PLL Clock Output CPU Clock Peripheral Clock Program Counter
TRANSITION TIMING FOR WAKE FROM SLEEP (HSPLL)
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
TOST(1)
TPLL(1)
PC Wake Event OSTS bit Set
PC + 2
PC + 4
PC + 6
Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.
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4.4.1 PRI_IDLE MODE 4.4.2 SEC_IDLE MODE
This mode is unique among the three low-power Idle modes, in that it does not disable the primary device clock. For timing sensitive applications, this allows for the fastest resumption of device operation with its more accurate primary clock source, since the clock source does not have to "warm-up" or transition from another oscillator. PRI_IDLE mode is entered from PRI_RUN mode by setting the IDLEN bit and executing a SLEEP instruction. If the device is in another Run mode, set IDLEN first, then clear the SCS bits and execute SLEEP. Although the CPU is disabled, the peripherals continue to be clocked from the primary clock source specified by the FOSC<3:0> Configuration bits. The OSTS bit remains set (see Figure 4-7). When a wake event occurs, the CPU is clocked from the primary clock source. A delay of interval TCSD (parameter 38, Table 27-10) is required between the wake event and when code execution starts. This is required to allow the CPU to become ready to execute instructions. After the wake-up, the OSTS bit remains set. The IDLEN and SCS bits are not affected by the wake-up (see Figure 4-8). In SEC_IDLE mode, the CPU is disabled but the peripherals continue to be clocked from the Timer1 oscillator. This mode is entered from SEC_RUN by setting the IDLEN bit and executing a SLEEP instruction. If the device is in another Run mode, set the IDLEN bit first, then set the SCS<1:0> bits to `01' and execute SLEEP. When the clock source is switched to the Timer1 oscillator, the primary oscillator is shut down, the OSTS bit is cleared and the T1RUN bit is set. When a wake event occurs, the peripherals continue to be clocked from the Timer1 oscillator. After an interval of TCSD following the wake event, the CPU begins executing code being clocked by the Timer1 oscillator. The IDLEN and SCS bits are not affected by the wake-up; the Timer1 oscillator continues to run (see Figure 4-8). Note: The Timer1 oscillator should already be running prior to entering SEC_IDLE mode. If the T1OSCEN bit is not set when writing the SCS<1:0> bits, entry to SEC_IDLE mode will not occur. If the Timer1 oscillator is enabled but not yet running, peripheral clocks will be delayed until the oscillator has started. In such situations, initial oscillator operation is far from stable and unpredictable operation may result.
FIGURE 4-7:
TRANSITION TIMING FOR ENTRY TO IDLE MODE
Q1 Q2 Q3 Q4 Q1
OSC1 CPU Clock Peripheral Clock Program Counter PC PC + 2
FIGURE 4-8:
TRANSITION TIMING FOR WAKE FROM IDLE TO RUN MODE
Q1 Q2 Q3 Q4
OSC1 CPU Clock Peripheral Clock Program Counter Wake Event PC TCSD
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4.4.3 RC_IDLE MODE
In RC_IDLE mode, the CPU is disabled but the peripherals continue to be clocked from the internal oscillator block using the INTOSC multiplexer. This mode allows for controllable power conservation during Idle periods. From RC_RUN, this mode is entered by setting the IDLEN bit and executing a SLEEP instruction. If the device is in another Run mode, first set IDLEN, then set the SCS1 bit and execute SLEEP. Although its value is ignored, it is recommended that SCS0 also be cleared; this is to maintain software compatibility with future devices. The INTOSC multiplexer may be used to select a higher clock frequency by modifying the IRCF bits before executing the SLEEP instruction. When the clock source is switched to the INTOSC multiplexer, the primary oscillator is shut down and the OSTS bit is cleared. If the IRCF bits are set to any non-zero value, or the INTSRC bit is set, the INTOSC output is enabled. The IOFS bit becomes set, after the INTOSC output becomes stable, after an interval of TIOBST (parameter 39, Table 27-10). Clocks to the peripherals continue while the INTOSC source stabilizes. If the IRCF bits were previously at a non-zero value, or INTSRC was set before the SLEEP instruction was executed and the INTOSC source was already stable, the IOFS bit will remain set. If the IRCF bits and INTSRC are all clear, the INTOSC output will not be enabled, the IOFS bit will remain clear and there will be no indication of the current clock source. When a wake event occurs, the peripherals continue to be clocked from the INTOSC multiplexer. After a delay of TCSD following the wake event, the CPU begins executing code being clocked by the INTOSC multiplexer. The IDLEN and SCS bits are not affected by the wake-up. The INTRC source will continue to run if either the WDT or the Fail-Safe Clock Monitor is enabled. On all exits from Idle or Sleep modes by interrupt, code execution branches to the interrupt vector if the GIE/ GIEH bit (INTCON<7>) is set. Otherwise, code execution continues or resumes without branching (see Section 10.0 "Interrupts"). A fixed delay of interval TCSD following the wake event is required when leaving Sleep and Idle modes. This delay is required for the CPU to prepare for execution. Instruction execution resumes on the first clock cycle following this delay.
4.5.2
EXIT BY WDT TIME-OUT
A WDT time-out will cause different actions depending on which power-managed mode the device is in when the time-out occurs. If the device is not executing code (all Idle modes and Sleep mode), the time-out will result in an exit from the power-managed mode (see Section 4.2 "Run Modes" and Section 4.3 "Sleep Mode"). If the device is executing code (all Run modes), the time-out will result in a WDT Reset (see Section 24.2 "Watchdog Timer (WDT)"). The WDT timer and postscaler are cleared by executing a SLEEP or CLRWDT instruction, the loss of a currently selected clock source (if the Fail-Safe Clock Monitor is enabled) and modifying the IRCF bits in the OSCCON register if the internal oscillator block is the device clock source.
4.5.3
EXIT BY RESET
Normally, the device is held in Reset by the Oscillator Start-up Timer (OST) until the primary clock becomes ready. At that time, the OSTS bit is set and the device begins executing code. If the internal oscillator block is the new clock source, the IOFS bit is set instead. The exit delay time from Reset to the start of code execution depends on both the clock sources before and after the wake-up and the type of oscillator if the new clock source is the primary clock. Exit delays are summarized in Table 4-2. Code execution can begin before the primary clock becomes ready. If either the Two-Speed Start-up (see Section 24.3 "Two-Speed Start-up") or Fail-Safe Clock Monitor (see Section 24.4 "Fail-Safe Clock Monitor") is enabled, the device may begin execution as soon as the Reset source has cleared. Execution is clocked by the INTOSC multiplexer driven by the internal oscillator block. Execution is clocked by the internal oscillator block until either the primary clock becomes ready or a power-managed mode is entered before the primary clock becomes ready; the primary clock is then shut down.
4.5
Exiting Idle and Sleep Modes
An exit from Sleep mode or any of the Idle modes is triggered by an interrupt, a Reset or a WDT time-out. This section discusses the triggers that cause exits from power-managed modes. The clocking subsystem actions are discussed in each of the power-managed modes (see Section 4.2 "Run Modes", Section 4.3 "Sleep Mode" and Section 4.4 "Idle Modes").
4.5.1
EXIT BY INTERRUPT
Any of the available interrupt sources can cause the device to exit from an Idle mode, or the Sleep mode to a Run mode. To enable this functionality, an interrupt source must be enabled by setting its enable bit in one of the INTCON or PIE registers. The exit sequence is initiated when the corresponding interrupt flag bit is set.
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4.5.4 EXIT WITHOUT AN OSCILLATOR START-UP DELAY
Certain exits from power-managed modes do not invoke the OST at all. There are two cases: * PRI_IDLE mode, where the primary clock source is not stopped; and * the primary clock source is not any of the LP, XT, HS or HSPLL modes. In these instances, the primary clock source either does not require an oscillator start-up delay since it is already running (PRI_IDLE), or normally does not require an oscillator start-up delay (RC, EC and INTIO Oscillator modes). However, a fixed delay of interval TCSD following the wake event is still required when leaving Sleep and Idle modes to allow the CPU to prepare for execution. Instruction execution resumes on the first clock cycle following this delay.
TABLE 4-2:
EXIT DELAY ON WAKE-UP BY RESET FROM SLEEP MODE OR ANY IDLE MODE (BY CLOCK SOURCES)
Clock Source after Wake-up LP, XT, HS HSPLL EC, RC INTOSC(2) LP, XT, HS TOST(3) TOST + trc(3) TCSD(1) TIOBST(4) TOST(3) TOST + trc(3) TCSD(1) None TOST(3) TOST + trc(3) TCSD(1) TIOBST(4) IOFS OSTS IOFS OSTS IOFS OSTS HSPLL EC, RC INTOSC(2) LP, XT, HS HSPLL EC, RC INTOSC(2) LP, XT, HS Exit Delay Clock Ready Status Bit (OSCCON) OSTS IOFS
Clock Source before Wake-up Primary Device Clock (PRI_IDLE mode)
TCSD(1)
T1OSC
INTOSC(3)
None (Sleep mode) Note 1: 2: 3: 4:
HSPLL EC, RC INTOSC(2)
TCSD (parameter 38) is a required delay when waking from Sleep and all Idle modes and runs concurrently with any other required delays (see Section 4.4 "Idle Modes"). On Reset, INTOSC defaults to 1 MHz. Includes both the INTOSC 8 MHz source and postscaler derived frequencies. TOST is the Oscillator Start-up Timer (parameter 32). trc is the PLL Lock-out Timer (parameter F12); it is also designated as TPLL. Execution continues during TIOBST (parameter 39), the INTOSC stabilization period.
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5.0 RESET
devices The PIC18F2221/2321/4221/4321 family differentiate between various kinds of Reset: a) b) c) d) e) f) g) h) A simplified block diagram of the On-Chip Reset Circuit is shown in Figure 5-1.
5.1
RCON Register
Power-on Reset (POR) MCLR Reset during normal operation MCLR Reset during power-managed modes Watchdog Timer (WDT) Reset (during execution) Programmable Brown-out Reset (BOR) RESET Instruction Stack Full Reset Stack Underflow Reset
Device Reset events are tracked through the RCON register (Register 5-1). The lower five bits of the register indicate that a specific Reset event has occurred. In most cases, these bits can only be cleared by the event and must be set by the application after the event. The state of these flag bits, taken together, can be read to indicate the type of Reset that just occurred. This is described in more detail in Section 5.6 "Reset State of Registers". The RCON register also has control bits for setting interrupt priority (IPEN) and software control of the BOR (SBOREN). Interrupt priority is discussed in Section 10.0 "Interrupts". BOR is covered in Section 5.4 "Brown-out Reset (BOR)".
This section discusses Resets generated by MCLR, POR and BOR and covers the operation of the various start-up timers. Stack Reset events are covered in Section 6.1.2.4 "Stack Full and Underflow Resets". WDT Resets are covered in Section 24.2 "Watchdog Timer (WDT)".
FIGURE 5-1:
RESET Instruction Stack Pointer
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
Stack Full/Underflow Reset
External Reset MCLR MCLRE ( )_IDLE Sleep WDT Time-out VDD Rise Detect VDD Brown-out Reset BOREN OST/PWRT OST OSC1 32 s INTRC
(1)
POR Pulse
S
1024 Cycles R Q
10-bit Ripple Counter
Chip_Reset
PWRT
65.5 ms
11-Bit Ripple Counter
Enable PWRT Enable OST(2) Note 1: 2: This is the INTRC source from the internal oscillator block and is separate from the RC oscillator of the CLKI pin. See Table 5-2 for time-out situations.
(c) 2009 Microchip Technology Inc.
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REGISTER 5-1: RCON: RESET CONTROL REGISTER
R/W-0 IPEN bit 7 bit 7 IPEN: Interrupt Priority Enable bit 1 = Enable priority levels on interrupts 0 = Disable priority levels on interrupts (PIC16CXXX Compatibility mode) SBOREN: BOR Software Enable bit(1) If BOREN<1:0> = 01: 1 = BOR is enabled 0 = BOR is disabled If BOREN<1:0> = 00, 10 or 11: Bit is disabled and read as `0'. Unimplemented: Read as `0' RI: RESET Instruction Flag bit 1 = The RESET instruction was not executed (set by firmware only) 0 = The RESET instruction was executed causing a device Reset (must be set in software after a Brown-out Reset occurs) TO: Watchdog Time-out Flag bit 1 = Set by power-up, CLRWDT instruction or SLEEP instruction 0 = A WDT time-out occurred PD: Power-Down Detection Flag bit 1 = Set by power-up or by the CLRWDT instruction 0 = Set by execution of the SLEEP instruction POR: Power-on Reset Status bit(2) 1 = A Power-on Reset has not occurred (set by firmware only) 0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs) BOR: Brown-out Reset Status bit 1 = A Brown-out Reset has not occurred (set by firmware only) 0 = A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs) Note 1: If SBOREN is enabled, its Reset state is `1'; otherwise, it is `0'. 2: The actual Reset value of POR is determined by the type of device Reset. See the notes following this register and Section 5.6 "Reset State of Registers" for additional information. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-1(1) SBOREN U-0 -- R/W-1 RI R-1 TO R-1 PD R/W-0(2) POR R/W-0 BOR bit 0
bit 6
bit 5 bit 4
bit 3
bit 2
bit 1
bit 0
Note 1: It is recommended that the POR bit be set after a Power-on Reset has been detected so that subsequent Power-on Resets may be detected. 2: Brown-out Reset is said to have occurred when BOR is `0' and POR is `1' (assuming that POR was set to `1' by software immediately after Power-on Reset).
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5.2 Master Clear (MCLR)
FIGURE 5-2:
The MCLR pin provides a method for triggering an external Reset of the device. A Reset is generated by holding the pin low. These devices have a noise filter in the MCLR Reset path which detects and ignores small pulses. The MCLR pin is not driven low by any internal Resets, including the WDT. In PIC18F2221/2321/4221/4321 family devices, the MCLR input can be disabled with the MCLRE Configuration bit. When MCLR is disabled, the pin becomes a digital input. See Section 11.5 "PORTE, TRISE and LATE Registers" for more information.
EXTERNAL POWER-ON RESET CIRCUIT (FOR SLOW VDD POWER-UP)
VDD
VDD D
R R1 C MCLR
PIC18FXXXX
Note 1:
5.3
Power-on Reset (POR)
2:
A Power-on Reset pulse is generated on-chip whenever VDD rises above a certain threshold. This allows the device to start in the initialized state when VDD is adequate for operation. To take advantage of the POR circuitry, tie the MCLR pin through a resistor (1 k to 10 k) to VDD. This will eliminate external RC components usually needed to create a Power-on Reset delay. A minimum rise rate for VDD is specified (parameter D004). For a slow rise time, see Figure 5-2. When the device starts normal operation (i.e., exits the Reset condition), device operating parameters (voltage, frequency, temperature, etc.) must be met to ensure operation. If these conditions are not met, the device must be held in Reset until the operating conditions are met. Power-on Reset events are captured by the POR bit (RCON<1>). The state of the bit is set to `0' whenever a POR occurs; it does not change for any other Reset event. POR is not reset to `1' by any hardware event. To capture multiple events, the user manually resets the bit to `1' in software following any POR.
External Power-on Reset circuit is required only if the VDD power-up slope is too slow. The diode D helps discharge the capacitor quickly when VDD powers down. R < 40 k is recommended to make sure that the voltage drop across R does not violate the device's electrical specification. R1 1 k will limit any current flowing into MCLR from external capacitor C, in the event of MCLR/VPP pin breakdown, due to Electrostatic Discharge (ESD) or Electrical Overstress (EOS).
3:
(c) 2009 Microchip Technology Inc.
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5.4 Brown-out Reset (BOR)
PIC18F2221/2321/4221/4321 family devices implement a BOR circuit that provides the user with a number of configuration and power-saving options. The BOR is controlled by the BORV<1:0> and BOREN<1:0> Configuration bits. There are a total of four BOR configurations which are summarized in Table 5-1. The BOR threshold is set by the BORV<1:0> bits. If BOR is enabled (any values of BOREN<1:0>, except `00'), any drop of VDD below VBOR (parameter D005) for greater than TBOR (parameter 35) will reset the device. A Reset may or may not occur if VDD falls below VBOR for less than TBOR. The chip will remain in Brown-out Reset until VDD rises above VBOR. If the Power-up Timer is enabled, it will be invoked after VDD rises above VBOR; it then will keep the chip in Reset for an additional time delay, TPWRT (parameter 33). If VDD drops below VBOR while the Power-up Timer is running, the chip will go back into a Brown-out Reset and the Power-up Timer will be initialized. Once VDD rises above VBOR, the Power-up Timer will execute the additional time delay. BOR and the Power-on Timer (PWRT) are independently configured. Enabling BOR Reset does not automatically enable the PWRT. change BOR configuration. It also allows the user to tailor device power consumption in software by eliminating the incremental current that the BOR consumes. While the BOR current is typically very small, it may have some impact in low-power applications. Note: Even when BOR is under software control, the Brown-out Reset voltage level is still set by the BORV<1:0> Configuration bits. It cannot be changed in software.
5.4.2
DETECTING BOR
When Brown-out Reset is enabled, the BOR bit always resets to `0' on any Brown-out Reset or Power-on Reset event. This makes it difficult to determine if a Brown-out Reset event has occurred just by reading the state of BOR alone. A more reliable method is to simultaneously check the state of both POR and BOR. This assumes that the POR bit is reset to `1' in software immediately after any Power-on Reset event. If BOR is `0' while POR is `1', it can be reliably assumed that a Brown-out Reset event has occurred.
5.4.3
DISABLING BOR IN SLEEP MODE
5.4.1
SOFTWARE ENABLED BOR
When BOREN<1:0> = 01, the BOR can be enabled or disabled by the user in software. This is done with the control bit, SBOREN (RCON<6>). Setting SBOREN enables the BOR to function as previously described. Clearing SBOREN disables the BOR entirely. The SBOREN bit operates only in this mode; otherwise it is read as `0'. Placing the BOR under software control gives the user the additional flexibility of tailoring the application to its environment without having to reprogram the device to
When BOREN<1:0> = 10, the BOR remains under hardware control and operates as previously described. Whenever the device enters Sleep mode, however, the BOR is automatically disabled. When the device returns to any other operating mode, BOR is automatically re-enabled. This mode allows for applications to recover from brown-out situations, while actively executing code, when the device requires BOR protection the most. At the same time, it saves additional power in Sleep mode by eliminating the small incremental BOR current.
TABLE 5-1:
BOR CONFIGURATIONS
Status of SBOREN (RCON<6>) Unavailable Available Unavailable Unavailable BOR Operation BOR disabled; must be enabled by reprogramming the Configuration bits. BOR enabled in software; operation controlled by SBOREN. BOR enabled in hardware in Run and Idle modes, disabled during Sleep mode. BOR enabled in hardware; must be disabled by reprogramming the Configuration bits.
BOR Configuration BOREN1 0 0 1 1 BOREN0 0 1 0 1
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5.5 Device Reset Timers
5.5.3 PLL LOCK TIME-OUT
PIC18F2221/2321/4221/4321 family devices incorporate three separate on-chip timers that help regulate the Power-on Reset process. Their main function is to ensure that the device clock is stable before code is executed. These timers are: * Power-up Timer (PWRT) * Oscillator Start-up Timer (OST) * PLL Lock Time-out With the PLL enabled in HSPLL mode, the time-out sequence following a Power-on Reset is slightly different from other oscillator modes. A separate timer is used to provide a fixed time-out that is sufficient for the PLL to lock to the main oscillator frequency. This PLL lock time-out (TPLL) is typically 2 ms and follows the oscillator start-up time-out.
5.5.4
1. 2.
TIME-OUT SEQUENCE
5.5.1
POWER-UP TIMER (PWRT)
On power-up, the time-out sequence is as follows: After the POR pulse has cleared, PWRT time-out is invoked (if enabled). Then, the OST is activated.
The Power-up Timer (PWRT) of the PIC18F2221/ 2321/4221/4321 family devices is an 11-bit counter which uses the INTRC source as the clock input. This yields an approximate time interval of 2048 x 32 s = 65.6 ms. While the PWRT is counting, the device is held in Reset. The power-up time delay depends on the INTRC clock and will vary from chip to chip due to temperature and process variation. See DC parameter 33 for details. The PWRT is enabled by clearing the PWRTEN Configuration bit.
The total time-out will vary based on oscillator configuration and the status of the PWRT. Figure 5-3, Figure 5-4, Figure 5-5, Figure 5-6 and Figure 5-7 all depict time-out sequences on power-up, with the Power-up Timer enabled and the device operating in HS Oscillator mode. Figures 5-3 through 5-6 also apply to devices operating in XT or LP modes. For devices in RC mode and with the PWRT disabled, there will be no time-out at all. Since the time-outs occur from the POR pulse, if MCLR is kept low long enough, all time-outs will expire. Bringing MCLR high will begin execution immediately (Figure 5-5). This is useful for testing purposes or to synchronize more than one PIC18FXXXX device operating in parallel.
5.5.2
OSCILLATOR START-UP TIMER (OST)
The Oscillator Start-up Timer (OST) provides a 1024 oscillator cycle (from OSC1 input) delay after the PWRT delay is over (parameter 33). This ensures that the crystal oscillator or resonator has started and stabilized. The OST time-out is invoked only for XT, LP, HS and HSPLL modes and only on Power-on Reset, or on exit from most power-managed modes.
TABLE 5-2:
TIME-OUT IN VARIOUS SITUATIONS
Power-up(2) and Brown-out Reset PWRTEN = 0 66 ms(1) + 1024 TOSC + 2 66 ms(1) 66 ms(1) 66 ms(1) ms(2) 66 ms(1) + 1024 TOSC PWRTEN = 1 1024 TOSC + 2 ms(2) 1024 TOSC -- -- -- Exit from Power-Managed Mode 1024 TOSC + 2 ms(2) 1024 TOSC -- -- --
Oscillator Configuration HSPLL HS, XT, LP EC, ECIO RC, RCIO INTIO1, INTIO2 Note 1: 2:
66 ms (65.5 ms) is the nominal Power-up Timer (PWRT) delay. 2 ms is the nominal time required for the PLL to lock.
(c) 2009 Microchip Technology Inc.
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FIGURE 5-3:
VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT OST TIME-OUT INTERNAL RESET TOST
TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD, VDD RISE < TPWRT)
FIGURE 5-4:
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1
VDD MCLR INTERNAL POR
TPWRT TOST
PWRT TIME-OUT OST TIME-OUT INTERNAL RESET
FIGURE 5-5:
VDD MCLR INTERNAL POR
TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2
TPWRT PWRT TIME-OUT OST TIME-OUT INTERNAL RESET
TOST
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(c) 2009 Microchip Technology Inc.
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FIGURE 5-6: SLOW RISE TIME (MCLR TIED TO VDD, VDD RISE > TPWRT)
5V VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET 0V
FIGURE 5-7:
TIME-OUT SEQUENCE ON POR w/PLL ENABLED (MCLR TIED TO VDD)
VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT OST TIME-OUT TOST TPLL
PLL TIME-OUT INTERNAL RESET Note: TOST = 1024 clock cycles. TPLL 2 ms max. First three stages of the PWRT timer.
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5.6 Reset State of Registers
Most registers are unaffected by a Reset. Their status is unknown on POR and unchanged by all other Resets. The other registers are forced to a "Reset state" depending on the type of Reset that occurred. Most registers are not affected by a WDT wake-up, since this is viewed as the resumption of normal operation. Status bits from the RCON register, RI, TO, PD, POR and BOR, are set or cleared differently in different Reset situations, as indicated in Table 5-3. These bits are used in software to determine the nature of the Reset. Table 5-4 describes the Reset states for all of the Special Function Registers. These are categorized by Power-on and Brown-out Resets, Master Clear and WDT Resets and WDT wake-ups.
TABLE 5-3:
STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION FOR RCON REGISTER
Condition Program Counter 0000h 0000h 0000h 0000h 0000h 0000h 0000h 0000h 0000h 0000h PC + 2 PC + 2(1) RCON Register RI 1 0 1 u u u u u u u u u TO 1 u 1 1 1 0 u u u u 0 u PD 1 u 1 u 0 u u u u u 0 0 STKPTR Register STKUNF 0 u u u u u u u 1 1 u u POR BOR STKFUL 0 u u u u u u u u u u u 0 u 0 u u u u u u u u u 0 u u u u u u 1 u u u u
Power-on Reset RESET Instruction Brown-out MCLR during power-managed Run modes MCLR during power-managed Idle modes and Sleep mode WDT Time-out during full power or power-managed Run mode MCLR during full power execution Stack Full Reset (STVREN = 1) Stack Underflow Reset (STVREN = 1) Stack Underflow Error (not an actual Reset, STVREN = 0) WDT time-out during power-managed Idle or Sleep modes Interrupt exit from power-managed modes
Legend: u = unchanged Note 1: When the wake-up is due to an interrupt and the GIEH or GIEL bits are set, the PC is loaded with the interrupt vector (008h or 0018h). 2: Reset state is `1' for POR and unchanged for all other Resets when software BOR is enabled (BOREN<1:0> Configuration bits = 01 and SBOREN = 1); otherwise, the Reset state is `0'.
DS39689F-page 54
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TABLE 5-4:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS
Applicable Devices Power-on Reset, Brown-out Reset MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt
TOSU TOSH TOSL STKPTR PCLATU PCLATH PCL TBLPTRU TBLPTRH TBLPTRL TABLAT PRODH PRODL INTCON INTCON2 INTCON3 INDF0 POSTINC0 POSTDEC0 PREINC0 PLUSW0 FSR0H FSR0L WREG INDF1 POSTINC1 POSTDEC1 PREINC1 PLUSW1
2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321
---0 0000 0000 0000 0000 0000 00-0 0000 --00 0000 0000 0000 0000 0000 --00 0000 0000 0000 0000 0000 0000 0000 xxxx xxxx xxxx xxxx 0000 000x 1111 -1-1 11-0 0-00 N/A N/A N/A N/A N/A ---- 0000 xxxx xxxx xxxx xxxx N/A N/A N/A N/A N/A
---0 0000 0000 0000 0000 0000 uu-0 0000 --00 0000 0000 0000 0000 0000 --00 0000 0000 0000 0000 0000 0000 0000 uuuu uuuu uuuu uuuu 0000 000u 1111 -1-1 11-0 0-00 N/A N/A N/A N/A N/A ---- 0000 uuuu uuuu uuuu uuuu N/A N/A N/A N/A N/A
---0 uuuu(3) uuuu uuuu(3) uuuu uuuu(3) uu-u uuuu(3) --uu uuuu uuuu uuuu PC + 2(2) --uu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu(1) uuuu -u-u(1) uu-u u-uu(1) N/A N/A N/A N/A N/A ---- uuuu uuuu uuuu uuuu uuuu N/A N/A N/A N/A N/A
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). 2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). 3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. 4: See Table 5-3 for Reset value for specific condition. 5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'.
(c) 2009 Microchip Technology Inc.
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TABLE 5-4:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Applicable Devices Power-on Reset, Brown-out Reset MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt
FSR1H FSR1L BSR INDF2 POSTINC2 POSTDEC2 PREINC2 PLUSW2 FSR2H FSR2L STATUS TMR0H TMR0L T0CON OSCCON HLVDCON WDTCON RCON(4) TMR1H TMR1L T1CON TMR2 PR2 T2CON SSPBUF SSPADD SSPSTAT SSPCON1 SSPCON2
2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321
---- 0000 xxxx xxxx ---- 0000 N/A N/A N/A N/A N/A ---- 0000 xxxx xxxx ---x xxxx 0000 0000 xxxx xxxx 1111 1111 0100 q000 0-00 0101 ---- ---0 0q-1 11q0 xxxx xxxx xxxx xxxx 0000 0000 0000 0000 1111 1111 -000 0000 xxxx xxxx 0000 0000 0000 0000 0000 0000 0000 0000
---- 0000 uuuu uuuu ---- 0000 N/A N/A N/A N/A N/A ---- 0000 uuuu uuuu ---u uuuu 0000 0000 uuuu uuuu 1111 1111 0100 q000 0-00 0101 ---- ---0 0q-q qquu uuuu uuuu uuuu uuuu u0uu uuuu 0000 0000 1111 1111 -000 0000 uuuu uuuu 0000 0000 0000 0000 0000 0000 0000 0000
---- uuuu uuuu uuuu ---- uuuu N/A N/A N/A N/A N/A ---- uuuu uuuu uuuu ---u uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuqu u-uu uuuu ---- ---u uq-u qquu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu 1111 1111 -uuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). 2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). 3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. 4: See Table 5-3 for Reset value for specific condition. 5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'.
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TABLE 5-4:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Applicable Devices Power-on Reset, Brown-out Reset MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt
ADRESH ADRESL ADCON0 ADCON1 ADCON2 CCPR1H CCPR1L CCP1CON CCPR2H CCPR2L CCP2CON BAUDCON ECCP1DEL ECCP1AS CVRCON CMCON TMR3H TMR3L T3CON SPBRGH SPBRG RCREG TXREG TXSTA RCSTA EEADR EEDATA EECON2 EECON1
2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321
xxxx xxxx xxxx xxxx --00 0000 --00 0qqq 0-00 0000 xxxx xxxx xxxx xxxx 0000 0000 --00 0000 xxxx xxxx xxxx xxxx --00 0000 0100 0-00 0000 0000 0000 0000 0000 00-0000 0000 0000 0111 xxxx xxxx xxxx xxxx 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 000x 0000 0000 0000 0000 0000 0000 xx-0 x000
uuuu uuuu uuuu uuuu --00 0000 --00 0qqq 0-00 0000 uuuu uuuu uuuu uuuu 0000 0000 --00 0000 uuuu uuuu uuuu uuuu --00 0000 0100 0-00 0000 0000 0000 0000 0000 00-0000 0000 0000 0111 uuuu uuuu uuuu uuuu uuuu uuuu 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 000x 0000 0000 0000 0000 0000 0000 uu-0 u000
uuuu uuuu uuuu uuuu --uu uuuu --uu uuuu u-uu uuuu uuuu uuuu uuuu uuuu uuuu uuuu --uu uuuu uuuu uuuu uuuu uuuu --uu uuuu --uu uuuu uuuu uuuu uuuu uuuu uuuu uu-uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu 0000 0000 uu-0 u000
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). 2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). 3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. 4: See Table 5-3 for Reset value for specific condition. 5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'.
(c) 2009 Microchip Technology Inc.
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TABLE 5-4:
Register
INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)
Applicable Devices Power-on Reset, Brown-out Reset MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt
IPR2 PIR2 PIE2 IPR1 PIR1 PIE1 OSCTUNE TRISE TRISD TRISC TRISB TRISA LATE LATD LATC LATB LATA(5) PORTE PORTD PORTC PORTB PORTA(5)
(5)
2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321 2221 2321 4221 4321
11-1 1111 00-0 0000 00-0 0000 1111 1111 -111 1111 0000 0000 -000 0000 0000 0000 -000 0000 00-0 0000 0000 -111 1111 1111 1111 1111 1111 1111 1111 1111(5) ---- -xxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx(5) ---- xxxx ---- x--xxxx xxxx xxxx xxxx xxxx xxxx xx0x 0000(5)
11-1 1111 00-0 0000 00-0 0000 1111 1111 -111 1111 0000 0000 -000 0000 0000 0000 -000 0000 00-0 0000 0000 -111 1111 1111 1111 1111 1111 1111 1111 1111(5) ---- -uuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu(5) ---- uuuu ---- u--uuuu uuuu uuuu uuuu uuuu uuuu uu0u 0000(5)
uu-u uuuu uu-u uuuu(1) uu-u uuuu uuuu uuuu -uuu uuuu uuuu uuuu(1) -uuu uuuu(1) uuuu uuuu -uuu uuuu uu-u uuuu uuuu -uuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu(5) ---- -uuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu(5) ---- uuuu ---- u--uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu(5)
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). 2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). 3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. 4: See Table 5-3 for Reset value for specific condition. 5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'.
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6.0 MEMORY ORGANIZATION
6.1 Program Memory Organization
There are three types of memory in PIC18 Enhanced microcontroller devices: * Program Memory * Data RAM * Data EEPROM As Harvard architecture devices, the data and program memories use separate busses; this allows for concurrent access of the two memory spaces. The data EEPROM, for practical purposes, can be regarded as a peripheral device, since it is addressed and accessed through a set of control registers. Additional detailed information on the operation of the Flash program memory is provided in Section 7.0 "Flash Program Memory". Data EEPROM is discussed separately in Section 8.0 "Data EEPROM Memory". PIC18 microcontrollers implement a 21-bit program counter, which is capable of addressing a 2-Mbyte program memory space. Accessing a location between the upper boundary of the physically implemented memory and the 2-Mbyte address will return all `0's (a NOP instruction). The PIC18F2221 and PIC18F4221 each have 4 Kbytes of Flash memory and can store up to 2048 single-word instructions. The PIC18F2321 and PIC18F4321 each have 8 Kbytes of Flash memory and can store up to 4096 single-word instructions. PIC18 devices have two interrupt vectors. The Reset vector address is at 0000h and the interrupt vector addresses are at 0008h and 0018h. The program memory maps for PIC18F2221/4221 and PIC18F2321/4321 devices are shown in Figure 6-1.
FIGURE 6-1:
PROGRAM MEMORY MAP AND STACK FOR PIC18F2221/2321/4221/4321 FAMILY DEVICES
PIC18FX221 PIC18FX321
PC<20:0> 21 CALL,RCALL,RETURN RETFIE,RETLW Stack Level 1
* * *
PC<20:0> 21 CALL,RCALL,RETURN RETFIE,RETLW Stack Level 1
* * *
Stack Level 31 Reset Vector 0000h
Stack Level 31 Reset Vector 0000h
High-Priority Interrupt Vector 0008h Low-Priority Interrupt Vector 0018h On-Chip Program Memory 0FFFh 1000h
High-Priority Interrupt Vector 0008h Low-Priority Interrupt Vector 0018h
On-Chip Program Memory User Memory Space User Memory Space
1FFFh 2000h
Read `0'
Read `0'
1FFFFFh 200000h
1FFFFFh 200000h
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6.1.1 PROGRAM COUNTER
The Program Counter (PC) specifies the address of the instruction to fetch for execution. The PC is 21 bits wide and is contained in three separate 8-bit registers. The low byte, known as the PCL register, is both readable and writable. The high byte, or PCH register, contains the PC<15:8> bits; it is not directly readable or writable. Updates to the PCH register are performed through the PCLATH register. The upper byte is called PCU. This register contains the PC<20:16> bits; it is also not directly readable or writable. Updates to the PCU register are performed through the PCLATU register. The contents of PCLATH and PCLATU are transferred to the program counter by any operation that writes PCL. Similarly, the upper two bytes of the program counter are transferred to PCLATH and PCLATU by an operation that reads PCL. This is useful for computed offsets to the PC (see Section 6.1.4.1 "Computed GOTO"). The PC addresses bytes in the program memory. To prevent the PC from becoming misaligned with word instructions, the Least Significant bit of PCL is fixed to a value of `0'. The PC increments by 2 to address sequential instructions in the program memory. The CALL, RCALL, GOTO and program branch instructions write to the program counter directly. For these instructions, the contents of PCLATH and PCLATU are not transferred to the program counter. The stack operates as a 31-word by 21-bit RAM and a 5-bit Stack Pointer, STKPTR. The stack space is not part of either program or data space. The Stack Pointer is readable and writable and the address on the top of the stack is readable and writable through the Top-ofStack Special Function Registers. Data can also be pushed to, or popped from the stack, using these registers. A CALL type instruction causes a push onto the stack; the Stack Pointer is first incremented and the location pointed to by the Stack Pointer is written with the contents of the PC (already pointing to the instruction following the CALL). A RETURN type instruction causes a pop from the stack; the contents of the location pointed to by the STKPTR are transferred to the PC and then the Stack Pointer is decremented. The Stack Pointer is initialized to `00000' after all Resets. There is no RAM associated with the location corresponding to a Stack Pointer value of `00000'; this is only a Reset value. Status bits indicate if the stack is full or has overflowed or has underflowed.
6.1.2.1
Top-of-Stack Access
6.1.2
RETURN ADDRESS STACK
The return address stack allows any combination of up to 31 program calls and interrupts to occur. The PC is pushed onto the stack when a CALL or RCALL instruction is executed or an interrupt is Acknowledged. The PC value is pulled off the stack on a RETURN, RETLW or a RETFIE instruction. PCLATU and PCLATH are not affected by any of the RETURN or CALL instructions.
Only the top of the return address stack (TOS) is readable and writable. A set of three registers, TOSU:TOSH:TOSL, hold the contents of the stack location pointed to by the STKPTR register (Figure 6-2). This allows users to implement a software stack if necessary. After a CALL, RCALL or interrupt, the software can read the pushed value by reading the TOSU:TOSH:TOSL registers. These values can be placed on a user-defined software stack. At return time, the software can return these values to TOSU:TOSH:TOSL and do a return. The user must disable the global interrupt enable bits while accessing the stack to prevent inadvertent stack corruption.
FIGURE 6-2:
RETURN ADDRESS STACK AND ASSOCIATED REGISTERS
Return Address Stack <20:0> 11111 11110 11101
Top-of-Stack Registers TOSU 00h TOSH 1Ah TOSL 34h Top-of-Stack 001A34h 000D58h
Stack Pointer STKPTR<4:0> 00010
00011 00010 00001 00000
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6.1.2.2 Return Stack Pointer (STKPTR)
The STKPTR register (Register 6-1) contains the Stack Pointer value, the STKFUL (Stack Full) status bit and the STKUNF (Stack Underflow) status bits. The value of the Stack Pointer can be 0 through 31. The Stack Pointer increments before values are pushed onto the stack and decrements after values are popped off the stack. On Reset, the Stack Pointer value will be zero. The user may read and write the Stack Pointer value. This feature can be used by a Real-Time Operating System (RTOS) for return stack maintenance. After the PC is pushed onto the stack 31 times (without popping any values off the stack), the STKFUL bit is set. The STKFUL bit is cleared by software or by a POR. The action that takes place when the stack becomes full depends on the state of the STVREN (Stack Overflow Reset Enable) Configuration bit. (Refer to Section 24.1 "Configuration Bits" for a description of the device Configuration bits.) If STVREN is set (default), the 31st push will push the (PC + 2) value onto the stack, set the STKFUL bit and reset the device. The STKFUL bit will remain set and the Stack Pointer will be set to zero. If STVREN is cleared, the STKFUL bit will be set on the 31st push and the Stack Pointer will increment to 31. Any additional pushes will not overwrite the 31st push and STKPTR will remain at 31. When the stack has been popped enough times to unload the stack, the next pop will return a value of zero to the PC and sets the STKUNF bit, while the Stack Pointer remains at zero. The STKUNF bit will remain set until cleared by software or until a POR occurs. Note: Returning a value of zero to the PC on an underflow has the effect of vectoring the program to the Reset vector, where the stack conditions can be verified and appropriate actions can be taken. This is not the same as a Reset, as the contents of the SFRs are not affected.
6.1.2.3
PUSH and POP Instructions
Since the Top-of-Stack is readable and writable, the ability to push values onto the stack and pull values off the stack without disturbing normal program execution is a desirable feature. The PIC18 instruction set includes two instructions, PUSH and POP, that permit the TOS to be manipulated under software control. TOSU, TOSH and TOSL can be modified to place data or a return address on the stack. The PUSH instruction places the current PC value onto the stack. This increments the Stack Pointer and loads the current PC value onto the stack. The POP instruction discards the current TOS by decrementing the Stack Pointer. The previous value pushed onto the stack then becomes the TOS value.
REGISTER 6-1:
STKPTR: STACK POINTER REGISTER
R/C-0 STKFUL(1) bit 7 R/C-0 STKUNF(1) U-0 -- R/W-0 SP4 R/W-0 SP3 R/W-0 SP2 R/W-0 SP1 R/W-0 SP0 bit 0
bit 7
STKFUL: Stack Full Flag bit(1) 1 = Stack became full or overflowed 0 = Stack has not become full or overflowed STKUNF: Stack Underflow Flag bit(1) 1 = Stack underflow occurred 0 = Stack underflow did not occur Unimplemented: Read as `0' SP<4:0>: Stack Pointer Location bits Note 1: Bit 7 and bit 6 are cleared by user software or by a POR. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented `0' = Bit is cleared C = Clearable only bit x = Bit is unknown
bit 6
bit 5 bit 4-0
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6.1.2.4 Stack Full and Underflow Resets 6.1.4
Device Resets on stack overflow and stack underflow conditions are enabled by setting the STVREN bit in Configuration Register 4L. When STVREN is set, a full or underflow will set the appropriate STKFUL or STKUNF bit and then cause a device Reset. When STVREN is cleared, a full or underflow condition will set the appropriate STKFUL or STKUNF bit but not cause a device Reset. The STKFUL or STKUNF bits are cleared by the user software or a Power-on Reset.
LOOK-UP TABLES IN PROGRAM MEMORY
There may be programming situations that require the creation of data structures, or look-up tables, in program memory. For PIC18 devices, look-up tables can be implemented in two ways: * Computed GOTO * Table Reads
6.1.4.1
Computed GOTO
6.1.3
FAST REGISTER STACK
A Fast Register Stack is provided for the STATUS, WREG and BSR registers, to provide a "fast return" option for interrupts. The stack for each register is only one level deep and is neither readable nor writable. It is loaded with the current value of the corresponding register when the processor vectors for an interrupt. All interrupt sources will push values into the stack registers. The values in the registers are then loaded back into their associated registers if the RETFIE, FAST instruction is used to return from the interrupt. If both low and high-priority interrupts are enabled, the stack registers cannot be used reliably to return from low-priority interrupts. If a high-priority interrupt occurs while servicing a low-priority interrupt, the Stack register values stored by the low-priority interrupt will be overwritten. In these cases, users must save the key registers in software during a low-priority interrupt. If interrupt priority is not used, all interrupts may use the Fast Register Stack for returns from interrupt. If no interrupts are used, the Fast Register Stack can be used to restore the STATUS, WREG and BSR registers at the end of a subroutine call. To use the Fast Register Stack for a subroutine call, a CALL label, FAST instruction must be executed to save the STATUS, WREG and BSR registers to the Fast Register Stack. A RETURN, FAST instruction is then executed to restore these registers from the Fast Register Stack. Example 6-1 shows a source code example that uses the Fast Register Stack during a subroutine call and return.
A computed GOTO is accomplished by adding an offset to the program counter. An example is shown in Example 6-2. A look-up table can be formed with an ADDWF PCL instruction and a group of RETLW nn instructions. The W register is loaded with an offset into the table before executing a call to that table. The first instruction of the called routine is the ADDWF PCL instruction. The next instruction executed will be one of the RETLW nn instructions that returns the value `nn' to the calling function. The offset value (in WREG) specifies the number of bytes that the program counter should advance and should be multiples of 2 (LSb = 0). In this method, only one data byte may be stored in each instruction location and room on the return address stack is required.
EXAMPLE 6-2:
MOVF CALL nn00h ADDWF RETLW RETLW RETLW . . .
COMPUTED GOTO USING AN OFFSET VALUE
OFFSET, W TABLE PCL nnh nnh nnh
ORG TABLE
6.1.4.2
Table Reads and Table Writes
EXAMPLE 6-1:
CALL SUB1, FAST * * SUB1
FAST REGISTER STACK CODE EXAMPLE
;STATUS, WREG, BSR ;SAVED IN FAST REGISTER ;STACK
A better method of storing data in program memory allows two bytes of data to be stored in each instruction location. Look-up table data may be stored two bytes per program word by using table reads and writes. The Table Pointer (TBLPTR) register specifies the byte address and the Table Latch (TABLAT) register contains the data that is read from or written to program memory. Data is transferred to or from program memory one byte at a time. Table read and table write operations are discussed further in Section 7.1 "Table Reads and Table Writes".
* * RETURN, FAST ;RESTORE VALUES SAVED ;IN FAST REGISTER STACK
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6.2
6.2.1
PIC18 Instruction Cycle
CLOCKING SCHEME
6.2.2
INSTRUCTION FLOW/PIPELINING
The microcontroller clock input, whether from an internal or external source, is internally divided by four to generate four non-overlapping quadrature clocks (Q1, Q2, Q3 and Q4). Internally, the program counter is incremented on every Q1; the instruction is fetched from the program memory and latched into the Instruction Register (IR) during Q4. The instruction is decoded and executed during the following Q1 through Q4. The clocks and instruction execution flow are shown in Figure 6-3.
An "Instruction Cycle" consists of four Q cycles: Q1 through Q4. The instruction fetch and execute are pipelined in such a manner that a fetch takes one instruction cycle, while the decode and execute take another instruction cycle. However, due to the pipelining, each instruction effectively executes in one cycle. If an instruction causes the program counter to change (e.g., GOTO), then two cycles are required to complete the instruction (Example 6-3). A fetch cycle begins with the Program Counter (PC) incrementing in Q1. In the execution cycle, the fetched instruction is latched into the Instruction Register (IR) in cycle Q1. This instruction is then decoded and executed during the Q2, Q3 and Q4 cycles. Data memory is read during Q2 (operand read) and written during Q4 (destination write).
FIGURE 6-3:
OSC1 Q1 Q2 Q3 Q4 PC OSC2/CLKO (RC mode)
CLOCK/INSTRUCTION CYCLE
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Internal Phase Clock
PC PC + 2 PC + 4
Execute INST (PC - 2) Fetch INST (PC)
Execute INST (PC) Fetch INST (PC + 2)
Execute INST (PC + 2) Fetch INST (PC + 4)
EXAMPLE 6-3:
INSTRUCTION PIPELINE FLOW
TCY0 TCY1 Execute 1 Fetch 2 Execute 2 Fetch 3 Execute 3 Fetch 4 Flush (NOP) Fetch SUB_1 Execute SUB_1 TCY2 TCY3 TCY4 TCY5
1. MOVLW 55h 2. MOVWF PORTB 3. BRA 4. BSF SUB_1
Fetch 1
PORTA, BIT3 (Forced NOP)
5. Instruction @ address SUB_1
All instructions are single cycle, except for any program branches. These take two cycles since the fetch instruction is "flushed" from the pipeline while the new instruction is being fetched and then executed.
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6.2.3 INSTRUCTIONS IN PROGRAM MEMORY
The program memory is addressed in bytes. Instructions are stored as two bytes or four bytes in program memory. The Least Significant Byte of an instruction word is always stored in a program memory location with an even address (LSb = 0). To maintain alignment with instruction boundaries, the PC increments in steps of 2 and the LSb will always read `0' (see Section 6.1.1 "Program Counter"). Figure 6-4 shows an example of how instruction words are stored in the program memory. The CALL and GOTO instructions have the absolute program memory address embedded into the instruction. Since instructions are always stored on word boundaries, the data contained in the instruction is a word address. The word address is written to PC<20:1>, which accesses the desired byte address in program memory. Instruction #2 in Figure 6-4 shows how the instruction GOTO 0006h is encoded in the program memory. Program branch instructions, which encode a relative address offset, operate in the same manner. The offset value stored in a branch instruction represents the number of single-word instructions that the PC will be offset by. Section 24.0 "Instruction Set Summary" provides further details of the instruction set.
FIGURE 6-4:
INSTRUCTIONS IN PROGRAM MEMORY
LSB = 1 Program Memory Byte Locations LSB = 0 Word Address 000000h 000002h 000004h 000006h 000008h 00000Ah 00000Ch 00000Eh 000010h 000012h 000014h
Instruction 1: Instruction 2: Instruction 3:
MOVLW GOTO MOVFF
055h 0006h 123h, 456h
0Fh EFh F0h C1h F4h
55h 03h 00h 23h 56h
6.2.4
TWO-WORD INSTRUCTIONS
The standard PIC18 instruction set has four two-word instructions: CALL, MOVFF, GOTO and LSFR. In all cases, the second word of the instructions always has `1111' as its four Most Significant bits; the other 12 bits are literal data, usually a data memory address. The use of `1111' in the 4 MSbs of an instruction specifies a special form of NOP. If the instruction is executed in proper sequence - immediately after the first word - the data in the second word is accessed and used by
the instruction sequence. If the first word is skipped for some reason and the second word is executed by itself, a NOP is executed instead. This is necessary for cases when the two-word instruction is preceded by a conditional instruction that changes the PC. Example 6-4 shows how this works. Note: See Section 6.6 "PIC18 Instruction Execution and the Extended Instruction Set" for information on two-word instructions in the extended instruction set.
EXAMPLE 6-4:
CASE 1: Object Code 0110 0110 0000 1100 0001 0010 1111 0100 0101 0010 0100 0000 CASE 2: Object Code 0110 1100 1111 0010 0110 0001 0100 0100 0000 0010 0101 0000
TWO-WORD INSTRUCTIONS
Source Code 0000 0011 0110 0000 TSTFSZ MOVFF ADDWF REG1 ; is RAM location 0? REG1, REG2 ; No, skip this word ; Execute this word as a NOP REG3 ; continue code
Source Code 0000 0011 0110 0000 TSTFSZ MOVFF ADDWF REG1 ; is RAM location 0? REG1, REG2 ; Yes, execute this word ; 2nd word of instruction REG3 ; continue code
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6.3
Note:
Data Memory Organization
The operation of some aspects of data memory are changed when the PIC18 extended instruction set is enabled. See Section 6.5 "Data Memory and the Extended Instruction Set" for more information.
6.3.1
BANK SELECT REGISTER (BSR)
The data memory in PIC18 devices is implemented as static RAM. Each register in the data memory has a 12-bit address, allowing up to 4096 bytes of data memory. The memory space is divided into as many as 16 banks that contain 256 bytes each; PIC18F2221/ 2321/4221/4321 family devices implement 2 banks. Figure 6-5 shows the data memory organization for the PIC18F2221/2321/4221/4321 family devices. The data memory contains Special Function Registers (SFRs) and General Purpose Registers (GPRs). The SFRs are used for control and status of the controller and peripheral functions, while GPRs are used for data storage and scratchpad operations in the user's application. Any read of an unimplemented location will read as `0's. The instruction set and architecture allow operations across all banks. The entire data memory may be accessed by Direct, Indirect or Indexed Addressing modes. Addressing modes are discussed later in this subsection. To ensure that commonly used registers (SFRs and select GPRs) can be accessed in a single cycle, PIC18 devices implement an Access Bank. This is a 256-byte memory space that provides fast access to SFRs and the lower portion of GPR Bank 0 without using the BSR. Section 6.3.2 "Access Bank" provides a detailed description of the Access RAM.
Large areas of data memory require an efficient addressing scheme to make rapid access to any address possible. Ideally, this means that an entire address does not need to be provided for each read or write operation. For PIC18 devices, this is accomplished with a RAM banking scheme. This divides the memory space into 16 contiguous banks of 256 bytes. Depending on the instruction, each location can be addressed directly by its full 12-bit address, or an 8-bit low-order address and a 4-bit Bank Pointer. Most instructions in the PIC18 instruction set make use of the Bank Pointer, known as the Bank Select Register (BSR). This SFR holds the four Most Significant bits of a location's address; the instruction itself includes the 8 Least Significant bits. Only the four lower bits of the BSR are implemented (BSR3:BSR0). The upper four bits are unused; they will always read `0' and cannot be written to. The BSR can be loaded directly by using the MOVLB instruction. The value of the BSR indicates the bank in data memory; the 8 bits in the instruction show the location in the bank and can be thought of as an offset from the bank's lower boundary. The relationship between the BSR's value and the bank division in data memory is shown in Figure 6-6. Since up to 16 registers may share the same low-order address, the user must always be careful to ensure that the proper bank is selected before performing a data read or write. For example, writing what should be program data to an 8-bit address of F9h, while the BSR is 0Fh, will end up resetting the program counter. While any bank can be selected, only those banks that are actually implemented can be read or written to. Writes to unimplemented banks are ignored, while reads from unimplemented banks will return `0's. Even so, the STATUS register will still be affected as if the operation was successful. The data memory map in Figure 6-5 indicates which banks are implemented. In the core PIC18 instruction set, only the MOVFF instruction fully specifies the 12-bit address of the source and target registers. This instruction ignores the BSR completely when it executes. All other instructions include only the low-order address as an operand and must use either the BSR or the Access Bank to locate their target registers.
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FIGURE 6-5: DATA MEMORY MAP FOR PIC18F2221/2321/4221/4321 FAMILY DEVICES
When a = 0, The BSR is ignored and the Access Bank is used. The first 128 bytes are General Purpose RAM (from Bank 0). 000h 07Fh 080h 0FFh 100h 1FFh The second 128 bytes are Special Function Registers (from Bank 15). When a = 1, The BSR specifies the Bank used by the instruction.
BSR<3:0> = 0000 = 0001 00h Bank 0 FFh Bank 1
Data Memory Map Access RAM GPR GPR
Access Bank 7Fh Access RAM High 80h (SFRs) FFh Access RAM Low 00h
= 0010 = 1110
Bank 2 to Bank 14
Unused Read `00h'
= 1111
00h Bank 15 FFh
Unused SFR
EFFh F00h F7Fh F80h FFFh
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FIGURE 6-6:
7
USE OF THE BANK SELECT REGISTER (DIRECT ADDRESSING)
BSR(1) 0 7 000h 100h 200h From Opcode(2) 0
0
0
0
0
(2)
0
0
0
1
Data Memory
00h Bank 0 Bank 1 FFh 00h FFh 00h
1
1
1
1
1
1
1
1
Bank Select
Bank 2 through Bank 14
F00h FFFh Note 1: 2: Bank 15
00h FFh
The Access RAM bit of the instruction can be used to force an override of the selected bank (BSR<3:0>) to the registers of the Access Bank. The MOVFF instruction embeds the entire 12-bit address in the instruction.
6.3.2
ACCESS BANK
While the use of the BSR with an embedded 8-bit address allows users to address the entire range of data memory, it also means that the user must always ensure that the correct bank is selected. Otherwise, data may be read from or written to the wrong location. This can be disastrous if a GPR is the intended target of an operation, but an SFR is written to instead. Verifying and/or changing the BSR for each read or write to data memory can become very inefficient. To streamline access for the most commonly used data memory locations, the data memory is configured with an Access Bank, which allows users to access a mapped block of memory without specifying a BSR. The Access Bank consists of the first 128 bytes of memory (00h-7Fh) in Bank 0 and the last 128 bytes of memory (80h-FFh) in Block 15. The lower half is known as the "Access RAM" and is composed of GPRs. This upper half is also where the device's SFRs are mapped. These two areas are mapped contiguously in the Access Bank and can be addressed in a linear fashion by an 8-bit address (Figure 6-5). The Access Bank is used by core PIC18 instructions that include the Access RAM bit (the `a' parameter in the instruction). When `a' is equal to `1', the instruction uses the BSR and the 8-bit address included in the opcode for the data memory address. When `a' is `0',
however, the instruction is forced to use the Access Bank address map; the current value of the BSR is ignored entirely. Using this "forced" addressing allows the instruction to operate on a data address in a single cycle, without updating the BSR first. For 8-bit addresses of 80h and above, this means that users can evaluate and operate on SFRs more efficiently. The Access RAM below 80h is a good place for data values that the user might need to access rapidly, such as immediate computational results or common program variables. Access RAM also allows for faster and more code efficient context saving and switching of variables. The mapping of the Access Bank is slightly different when the extended instruction set is enabled (XINST Configuration bit = 1). This is discussed in more detail in Section 6.5.3 "Mapping the Access Bank in Indexed Literal Offset Addressing Mode".
6.3.3
GENERAL PURPOSE REGISTER FILE
PIC18 devices may have banked memory in the GPR area. This is data RAM which is available for use by all instructions. GPRs start at the bottom of Bank 0 (address 000h) and grow upwards towards the bottom of the SFR area. GPRs are not initialized by a Power-on Reset and are unchanged on all other Resets.
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6.3.4 SPECIAL FUNCTION REGISTERS
The Special Function Registers (SFRs) are registers used by the CPU and peripheral modules for controlling the desired operation of the device. These registers are implemented as static RAM. SFRs start at the top of data memory (FFFh) and extend downward to occupy the top half of Bank 15 (F80h to FFFh). A list of these registers is given in Table 6-1 and Table 6-2. The SFRs can be classified into two sets: those associated with the "core" device functionality (ALU, Resets and interrupts) and those related to the peripheral functions. The reset and interrupt registers are described in their respective chapters, while the ALU's STATUS register is described later in this section. Registers related to the operation of a peripheral feature are described in the chapter for that peripheral. The SFRs are typically distributed among the peripherals whose functions they control. Unused SFR locations are unimplemented and read as `0's.
TABLE 6-1:
Address FFFh FFEh FFDh FFCh FFBh FFAh FF9h FF8h FF7h FF6h FF5h FF4h FF3h FF2h FF1h FF0h FEFh FEEh FEDh FECh FEBh FEAh FE9h FE8h FE7h FE6h FE5h FE4h FE3h FE2h FE1h FE0h Note 1: 2: 3:
SPECIAL FUNCTION REGISTER MAP FOR PIC18F2221/2321/4221/4321 FAMILY DEVICES
Name TOSU TOSH TOSL STKPTR PCLATU PCLATH PCL TBLPTRU TBLPTRH TBLPTRL TABLAT PRODH PRODL INTCON INTCON2 INTCON3 INDF0(1) POSTINC0(1) POSTDEC0(1) PREINC0(1) PLUSW0(1) FSR0H FSR0L WREG INDF1(1) POSTINC1(1) POSTDEC1(1) PREINC1(1) PLUSW1(1) FSR1H FSR1L BSR Address Name
(1)
Address
Name
Address F9Fh F9Eh F9Dh F9Ch F9Bh F9Ah F99h F98h F97h F96h F95h F94h F93h F92h F91h F90h F8Fh F8Eh F8Dh F8Ch F8Bh F8Ah F89h F88h F87h F86h F85h F84h F83h F82h F81h F80h
Name IPR1 PIR1 PIE1 --(2) OSCTUNE --(2) --(2) --(2) --(2) TRISE(3) TRISD(3) TRISC TRISB TRISA --(2) --(2) --(2) --(2) LATE(3) LATD(3) LATC LATB LATA --(2) --(2) --(2) --(2) PORTE PORTD(3) PORTC PORTB PORTA
FDFh INDF2 FDEh POSTINC2(1) FDDh POSTDEC2(1) FDCh PREINC2(1) FDBh PLUSW2(1) FDAh FSR2H FD9h FSR2L FD8h STATUS FD7h TMR0H FD6h TMR0L FD5h T0CON FD4h --(2) FD3h OSCCON FD2h HLVDCON FD1h WDTCON FD0h RCON FCFh TMR1H FCEh TMR1L FCDh T1CON FCCh TMR2 FCBh PR2 FCAh T2CON FC9h SSPBUF FC8h SSPADD FC7h SSPSTAT FC6h SSPCON1 FC5h SSPCON2 FC4h ADRESH FC3h ADRESL FC2h ADCON0 FC1h ADCON1 FC0h ADCON2
FBFh CCPR1H FBEh CCPR1L FBDh CCP1CON FBCh CCPR2H FBBh CCPR2L FBAh CCP2CON FB9h --(2) FB8h BAUDCON FB7h ECCP1DEL(3) FB6h ECCP1AS(3) FB5h CVRCON FB4h CMCON FB3h TMR3H FB2h TMR3L FB1h T3CON FB0h SPBRGH FAFh SPBRG FAEh RCREG FADh TXREG FACh TXSTA FABh RCSTA FAAh --(2) FA9h EEADR FA8h EEDATA FA7h EECON2(1) FA6h EECON1 FA5h --(2) FA4h --(2) FA3h --(2) FA2h IPR2 FA1h PIR2 FA0h PIE2
This is not a physical register. Unimplemented registers are read as `0'. This register is not available on 28-pin devices.
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TABLE 6-2:
File Name TOSU TOSH TOSL STKPTR PCLATU PCLATH PCL TBLPTRU TBLPTRH TBLPTRL TABLAT PRODH PRODL INTCON INTCON2 INTCON3 INDF0 POSTINC0 PREINC0 PLUSW0 FSR0H FSR0L WREG INDF1 POSTINC1 PREINC1 PLUSW1 FSR1H FSR1L BSR INDF2 POSTINC2 PREINC2 PLUSW2 FSR2H FSR2L STATUS Legend: Note 1: 2: 3: 4: 5: 6: Bit 7 --
REGISTER FILE SUMMARY (PIC18F2221/2321/4221/4321)
Bit 6 -- Bit 5 -- Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR ---0 0000 0000 0000 0000 0000 SP4 SP3 SP2 SP1 SP0 00-0 0000 --00 0000 0000 0000 0000 0000 bit 21 Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) --00 0000 0000 0000 0000 0000 0000 0000 xxxx xxxx xxxx xxxx TMR0IE INTEDG1 -- INT0IE INTEDG2 INT2IE RBIE -- INT1IE TMR0IF TMR0IP -- INT0IF -- INT2IF RBIF RBIP INT1IF 0000 000x 1111 -1-1 11-0 0-00 N/A N/A N/A N/A N/A ---- 0000 xxxx xxxx xxxx xxxx N/A N/A N/A N/A N/A ---- 0000 xxxx xxxx Bank Select Register ---- 0000 N/A N/A N/A N/A N/A ---- 0000 xxxx xxxx OV Z DC C ---x xxxx Details on page: 55, 60 55, 60 55, 60 55, 61 55, 60 55, 60 55, 60 55, 82 55, 82 55, 82 55, 82 55, 95 55, 95 55, 99 55, 100 55, 101 55, 74 55, 74 55, 74 55, 74 55, 74 55, 74 55, 74 55 55, 74 55, 74 55, 74 55, 74 55, 74 56, 74 56, 74 56, 65 56, 74 56, 74 56, 74 56, 74 56, 74 56, 74 56, 74 56, 72
Top-of-Stack Upper Byte (TOS<20:16>)
Top-of-Stack High Byte (TOS<15:8>) Top-of-Stack Low Byte (TOS<7:0>) STKFUL(6) -- STKUNF(6) -- -- Holding Register for PC<21:16>
Holding Register for PC<15:8> PC Low Byte (PC<7:0>) -- -- Program Memory Table Pointer High Byte (TBLPTR<15:8>) Program Memory Table Pointer Low Byte (TBLPTR<7:0>) Program Memory Table Latch Product Register High Byte Product Register Low Byte GIE/GIEH RBPU INT2IP PEIE/GIEL INTEDG0 INT1IP
Uses contents of FSR0 to address data memory - value of FSR0 not changed (not a physical register) Uses contents of FSR0 to address data memory - value of FSR0 post-incremented (not a physical register) Uses contents of FSR0 to address data memory - value of FSR0 pre-incremented (not a physical register) Uses contents of FSR0 to address data memory - value of FSR0 pre-incremented (not a physical register) - value of FSR0 offset by W -- Working Register Uses contents of FSR1 to address data memory - value of FSR1 not changed (not a physical register) Uses contents of FSR1 to address data memory - value of FSR1 post-incremented (not a physical register) Uses contents of FSR1 to address data memory - value of FSR1 pre-incremented (not a physical register) Uses contents of FSR1 to address data memory - value of FSR1 pre-incremented (not a physical register) - value of FSR1 offset by W -- -- -- -- -- -- -- -- Indirect Data Memory Address Pointer 1 High Byte Indirect Data Memory Address Pointer 1 Low Byte Uses contents of FSR2 to address data memory - value of FSR2 not changed (not a physical register) Uses contents of FSR2 to address data memory - value of FSR2 post-incremented (not a physical register) Uses contents of FSR2 to address data memory - value of FSR2 pre-incremented (not a physical register) Uses contents of FSR2 to address data memory - value of FSR2 pre-incremented (not a physical register) - value of FSR2 offset by W -- -- -- -- -- -- -- N Indirect Data Memory Address Pointer 2 High Byte Indirect Data Memory Address Pointer 2 Low Byte -- -- -- Indirect Data Memory Address Pointer 0 High Byte Indirect Data Memory Address Pointer 0 Low Byte
POSTDEC0 Uses contents of FSR0 to address data memory - value of FSR0 post-decremented (not a physical register)
POSTDEC1 Uses contents of FSR1 to address data memory - value of FSR1 post-decremented (not a physical register)
POSTDEC2 Uses contents of FSR2 to address data memory - value of FSR2 post-decremented (not a physical register)
x = unknown, u = unchanged, -- = unimplemented, q = value depends on condition The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 5.4 "Brown-out Reset (BOR)". These registers and/or bits are not implemented on 28-pin devices and are read as `0'. Reset values are shown for 40/44-pin devices; individual unimplemented bits should be interpreted as `-'. The PLLEN bit is only available in specific oscillator configurations; otherwise, it is disabled and reads as `0'. See Section 3.6.4 "PLL in INTOSC Modes". The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0); otherwise, RE3 reads as `0'. This bit is read-only. RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. Bit 7 and bit 6 are cleared by user software or by a POR.
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TABLE 6-2:
File Name TMR0H TMR0L T0CON OSCCON HLVDCON WDTCON RCON TMR1H TMR1L T1CON TMR2 PR2 T2CON SSPBUF SSPADD SSPSTAT SSPCON1 SSPCON2 ADRESH ADRESL ADCON0 ADCON1 ADCON2 CCPR1H CCPR1L CCP1CON CCPR2H CCPR2L CCP2CON BAUDCON ECCP1DEL ECCP1AS CVRCON CMCON TMR3H TMR3L T3CON Legend: Note 1: 2: 3: 4: 5: 6: Bit 7
REGISTER FILE SUMMARY (PIC18F2221/2321/4221/4321) (CONTINUED)
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR 0000 0000 xxxx xxxx T0CS IRCF1 IRVST -- -- T0SE IRCF0 HLVDEN -- RI PSA OSTS HLVDL3 -- TO T0PS2 IOFS HLVDL2 -- PD T0PS1 SCS1 HLVDL1 -- POR T0PS0 SCS0 HLVDL0 SWDTEN BOR 1111 1111 0100 q000 0-00 0101 --- ---0 xxxx xxxx xxxx xxxx T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 0000 0000 1111 1111 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 xxxx xxxx 0000 0000 BF SSPM0 SEN 0000 0000 0000 0000 0000 0000 xxxx xxxx xxxx xxxx CHS3 VCFG1 ACQT2 CHS2 VCFG0 ACQT1 CHS1 PCFG3 ACQT0 CHS0 PCFG2 ADCS2 GO/DONE PCFG1 ADCS1 ADON PCFG0 ADCS0 --00 0000 --00 0qqq 0-00 0000 xxxx xxxx xxxx xxxx CCP1M3 CCP1M2 CCP1M1 CCP1M0 0000 0000 xxxx xxxx xxxx xxxx CCP2M3 BRG16 PDC3(2) PSSAC1 CVR3 CIS CCP2M2 -- PDC2(2) PSSAC0 CVR2 CM2 CCP2M1 WUE PDC1(2) PSSBD1(2) CVR1 CM1 CCP2M0 ABDEN PDC0(2) CVR0 CM0 --00 0000 0100 0-00 0000 0000 0000 0000 0000 0111 xxxx xxxx xxxx xxxx T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON 0000 0000 Details on page: 56, 131 56, 131 56, 129 37, 56 56, 253 56, 270 56, 137 56, 137 56, 133 56, 140 56, 140 56, 139 56, 175, 176 56, 176 56, 168, 177 56, 169, 178 56, 179 57, 242 57, 242 57, 233 57, 234 57, 235 57, 146 57, 146 57, 145, 153 57, 146 57, 146 57, 145 57, 214 57, 162 57, 163 57, 249 57, 243 57, 143 57, 143 57, 141
Timer0 Register High Byte Timer0 Register Low Byte TMR0ON IDLEN VDIRMAG -- IPEN T08BIT IRCF2 -- -- SBOREN(1)
0q-1 11q0 48, 54, 108
Timer1 Register High Byte Timer1 Register Low Byte RD16 Timer2 Register Timer2 Period Register -- T2OUTPS3 MSSP Receive Buffer/Transmit Register MSSP Address Register in I2CTM Slave mode. MSSP Baud Rate Reload Register in I2C Master mode. SMP WCOL GCEN CKE SSPOV ACKSTAT D/A SSPEN ACKDT/ ADMSK5 P CKP ACKEN/ ADMSK4 S SSPM3 RCEN/ ADMSK3 R/W SSPM2 PEN/ ADMSK2 UA SSPM1 RSEN/ ADMSK1 T1RUN
A/D Result Register High Byte A/D Result Register Low Byte -- -- ADFM -- -- --
Capture/Compare/PWM Register 1 High Byte Capture/Compare/PWM Register 1 Low Byte P1M1(2) P1M0(2) DC1B1 DC1B0
Capture/Compare/PWM Register 2 High Byte Capture/Compare/PWM Register 2 Low Byte -- ABDOVF PRSEN ECCPASE CVREN C2OUT -- RCIDL PDC6(2) ECCPAS2 CVROE C1OUT DC2B1 RXDTP PDC5(2) ECCPAS1 CVRR C2INV DC2B0 TXCKP PDC4(2) ECCPAS0 CVRSS C1INV
PSSBD0(2) 0000 0000
Timer3 Register High Byte Timer3 Register Low Byte RD16 T3CCP2
x = unknown, u = unchanged, -- = unimplemented, q = value depends on condition The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 5.4 "Brown-out Reset (BOR)". These registers and/or bits are not implemented on 28-pin devices and are read as `0'. Reset values are shown for 40/44-pin devices; individual unimplemented bits should be interpreted as `-'. The PLLEN bit is only available in specific oscillator configurations; otherwise, it is disabled and reads as `0'. See Section 3.6.4 "PLL in INTOSC Modes". The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0); otherwise, RE3 reads as `0'. This bit is read-only. RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. Bit 7 and bit 6 are cleared by user software or by a POR.
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TABLE 6-2:
File Name SPBRGH SPBRG RCREG TXREG TXSTA RCSTA EEADR EEDATA EECON2 EECON1 IPR2 PIR2 PIE2 IPR1 PIR1 PIE1 OSCTUNE TRISE(2) TRISD(2) TRISC TRISB TRISA LATE(2) LATD(2) LATC LATB LATA PORTE PORTD(2) PORTC PORTB PORTA Legend: Note 1: 2: 3: 4: 5: 6: Bit 7
REGISTER FILE SUMMARY (PIC18F2221/2321/4221/4321) (CONTINUED)
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR 0000 0000 0000 0000 0000 0000 0000 0000 TXEN SREN SYNC CREN SENDB ADDEN BRGH FERR TRMT OERR TX9D RX9D 0000 0010 0000 000x Details on page: 57, 216 57, 216 57, 224 57, 221 57, 212 57, 213
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte EUSART Receive Register EUSART Transmit Register CSRC SPEN TX9 RX9
EEPROM Address Register EEPROM Data Register EEPROM Control Register 2 (not a physical register) EEPGD OSCFIP OSCFIF OSCFIE PSPIP(2) PSPIF(2) PSPIE(2) INTSRC IBF CFGS CMIP CMIF CMIE ADIP ADIF ADIE PLLEN(3) OBF -- -- -- -- RCIP RCIF RCIE -- IBOV FREE EEIP EEIF EEIE TXIP TXIF TXIE TUN4 PSPMODE WRERR BCLIP BCLIF BCLIE SSPIP SSPIF SSPIE TUN3 -- WREN HLVDIP HLVDIF HLVDIE CCP1IP CCP1IF CCP1IE TUN2 TRISE2 WR TMR3IP TMR3IF TMR3IE TMR2IP TMR2IF TMR2IE TUN1 TRISE1 RD CCP2IP CCP2IF CCP2IE TMR1IP TMR1IF TMR1IE TUN0 TRISE0
0000 0000 57, 80, 89 0000 0000 57, 80, 89 0000 0000 57, 80, 89 xx-0 x000 57, 81, 90 11-1 1111 00-0 0000 00-0 0000 1111 1111 0000 0000 0000 0000 00-0 0000 0000 -111 1111 1111 1111 1111 1111 1111 1111 1111 PORTE Data Latch Register (Read and Write to Data Latch) ---- -xxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx RE0(2) RD0 RC0 RB0 RA0 ---- xxxx xxxx xxxx xxxx xxxx xxxx xxxx xx0x 0000 RD1 RC1 RB1 RA1 RE2(2) RD2 RC2 RB2 RA2 RE1(2) -- -- 58, 107 58, 103 58, 105 58, 106 58, 102 58, 104 33, 58 58, 124 58, 120 58, 117 58, 114 58, 111 58, 123 58, 120 58, 117 58, 114 58, 111 58, 123 58, 120 58, 117 58, 114 58, 111
PORTD Data Direction Control Register PORTC Data Direction Control Register PORTB Data Direction Control Register TRISA7(5) -- TRISA6(5) -- PORTA Data Direction Control Register --
PORTD Data Latch Register (Read and Write to Data Latch) PORTC Data Latch Register (Read and Write to Data Latch) PORTB Data Latch Register (Read and Write to Data Latch) LATA7(5) -- RD7 RC7 RB7 RA7(5) LATA6(5) -- RD6 RC6 RB6 RA6(5) PORTA Data Latch Register (Read and Write to Data Latch) -- RD5 RC5 RB5 RA5 -- RD4 RC4 RB4 RA4 RE3(4) RD3 RC3 RB3 RA3
x = unknown, u = unchanged, -- = unimplemented, q = value depends on condition The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 5.4 "Brown-out Reset (BOR)". These registers and/or bits are not implemented on 28-pin devices and are read as `0'. Reset values are shown for 40/44-pin devices; individual unimplemented bits should be interpreted as `-'. The PLLEN bit is only available in specific oscillator configurations; otherwise, it is disabled and reads as `0'. See Section 3.6.4 "PLL in INTOSC Modes". The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0); otherwise, RE3 reads as `0'. This bit is read-only. RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. Bit 7 and bit 6 are cleared by user software or by a POR.
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6.3.5 STATUS REGISTER
The STATUS register, shown in Register 6-2, contains the arithmetic status of the ALU. As with any other SFR, it can be the operand for any instruction. If the STATUS register is the destination for an instruction that affects the Z, DC, C, OV or N bits, the results of the instruction are not written; instead, the STATUS register is updated according to the instruction performed. Therefore, the result of an instruction with the STATUS register as its destination may be different than intended. As an example, CLRF STATUS will set the Z bit and leave the remaining Status bits unchanged (`000u u1uu'). It is recommended that only BCF, BSF, SWAPF, MOVFF and MOVWF instructions are used to alter the STATUS register, because these instructions do not affect the Z, C, DC, OV or N bits in the STATUS register. For other instructions that do not affect Status bits, see the instruction set summaries in Table 24-2 and Table 24-3. Note: The C and DC bits operate as the borrow and digit borrow bits, respectively, in subtraction.
REGISTER 6-2:
STATUS REGISTER
U-0 -- bit 7 U-0 -- U-0 -- R/W-x N R/W-x OV R/W-x Z R/W-x DC R/W-x C bit 0
bit 7-5 bit 4
Unimplemented: Read as `0' N: Negative bit This bit is used for signed arithmetic (2's complement). It indicates whether the result was negative (ALU MSB = 1). 1 = Result was negative 0 = Result was positive OV: Overflow bit This bit is used for signed arithmetic (2's complement). It indicates an overflow of the 7-bit magnitude which causes the sign bit (bit 7 of the result) to change state. 1 = Overflow occurred for signed arithmetic (in this arithmetic operation) 0 = No overflow occurred Z: Zero bit 1 = The result of an arithmetic or logic operation is zero 0 = The result of an arithmetic or logic operation is not zero DC: Digit Carry/borrow bit For ADDWF, ADDLW, SUBLW and SUBWF instructions: 1 = A carry-out from the 4th low-order bit of the result occurred 0 = No carry-out from the 4th low-order bit of the result Note: For borrow, the polarity is reversed. A subtraction is executed by adding the 2's complement of the second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either bit 4 or bit 3 of the source register.
bit 3
bit 2
bit 1
bit 0
C: Carry/borrow bit For ADDWF, ADDLW, SUBLW and SUBWF instructions: 1 = A carry-out from the Most Significant bit of the result occurred 0 = No carry-out from the Most Significant bit of the result occurred Note: For borrow, the polarity is reversed. A subtraction is executed by adding the 2's complement of the second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high or low-order bit of the source register.
Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
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6.4
Note:
Data Addressing Modes
The execution of some instructions in the core PIC18 instruction set are changed when the PIC18 extended instruction set is enabled. See Section 6.5 "Data Memory and the Extended Instruction Set" for more information.
The Access RAM bit `a' determines how the address is interpreted. When `a' is `1', the contents of the BSR (Section 6.3.1 "Bank Select Register (BSR)") are used with the address to determine the complete 12-bit address of the register. When `a' is `0', the address is interpreted as being a register in the Access Bank. Addressing that uses the Access RAM is sometimes also known as Direct Forced Addressing mode. A few instructions, such as MOVFF, include the entire 12-bit address (either source or destination) in their opcodes. In these cases, the BSR is ignored entirely. The destination of the operation's results is determined by the destination bit `d'. When `d' is `1', the results are stored back in the source register, overwriting its original contents. When `d' is `0', the results are stored in the W register. Instructions without the `d' argument have a destination that is implicit in the instruction; their destination is either the target register being operated on or the W register.
The data memory space can be addressed in several ways. For most instructions, the addressing mode is fixed. Other instructions may use up to three modes, depending on which operands are used and whether or not the extended instruction set is enabled. The addressing modes are: * * * * Inherent Literal Direct Indirect
An additional addressing mode, Indexed Literal Offset, is available when the extended instruction set is enabled (XINST Configuration bit = 1). Its operation is discussed in greater detail in Section 6.5.1 "Indexed Addressing with Literal Offset".
6.4.3
INDIRECT ADDRESSING
6.4.1
INHERENT AND LITERAL ADDRESSING
Many PIC18 control instructions do not need any argument at all; they either perform an operation that globally affects the device or they operate implicitly on one register. This addressing mode is known as Inherent Addressing. Examples include SLEEP, RESET and DAW. Other instructions work in a similar way but require an additional explicit argument in the opcode. This is known as Literal Addressing mode because they require some literal value as an argument. Examples include ADDLW and MOVLW, which respectively, add or move a literal value to the W register. Other examples include CALL and GOTO, which include a 20-bit program memory address.
Indirect addressing allows the user to access a location in data memory without giving a fixed address in the instruction. This is done by using File Select Registers (FSRs) as pointers to the locations to be read or written to. Since the FSRs are themselves located in RAM as Special Function Registers, they can also be directly manipulated under program control. This makes FSRs very useful in implementing data structures, such as tables and arrays in data memory. The registers for indirect addressing are also implemented with Indirect File Operands (INDFs) that permit automatic manipulation of the pointer value with auto-incrementing, auto-decrementing or offsetting with another value. This allows for efficient code, using loops, such as the example of clearing an entire RAM bank in Example 6-5.
EXAMPLE 6-5:
HOW TO CLEAR RAM (BANK 1) USING INDIRECT ADDRESSING
FSR0, 100h ; POSTINC0 ; Clear INDF ; register then ; inc pointer FSR0H, 1 ; All done with ; Bank1? NEXT ; NO, clear next ; YES, continue
6.4.2
DIRECT ADDRESSING
NEXT
Direct addressing specifies all or part of the source and/or destination address of the operation within the opcode itself. The options are specified by the arguments accompanying the instruction. In the core PIC18 instruction set, bit-oriented and byteoriented instructions use some version of direct addressing by default. All of these instructions include some 8-bit literal address as their Least Significant Byte. This address specifies either a register address in one of the banks of data RAM (Section 6.3.3 "General Purpose Register File") or a location in the Access Bank (Section 6.3.2 "Access Bank") as the data source for the instruction.
LFSR CLRF
BTFSS BRA CONTINUE
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6.4.3.1 FSR Registers and the INDF Operand 6.4.3.2 FSR Registers and POSTINC, POSTDEC, PREINC and PLUSW
At the core of indirect addressing are three sets of registers: FSR0, FSR1 and FSR2. Each represents a pair of 8-bit registers, FSRnH and FSRnL. The four upper bits of the FSRnH register are not used so each FSR pair holds a 12-bit value. This represents a value that can address the entire range of the data memory in a linear fashion. The FSR register pairs, then, serve as pointers to data memory locations. Indirect addressing is accomplished with a set of Indirect File Operands, INDF0 through INDF2. These can be thought of as "virtual" registers: they are mapped in the SFR space but are not physically implemented. Reading or writing to a particular INDF register actually accesses its corresponding FSR register pair. A read from INDF1, for example, reads the data at the address indicated by FSR1H:FSR1L. Instructions that use the INDF registers as operands actually use the contents of their corresponding FSR as a pointer to the instruction's target. The INDF operand is just a convenient way of using the pointer. Because indirect addressing uses a full 12-bit address, data RAM banking is not necessary. Thus, the current contents of the BSR and the Access RAM bit have no effect on determining the target address. In addition to the INDF operand, each FSR register pair also has four additional indirect operands. Like INDF, these are "virtual" registers that cannot be indirectly read or written to. Accessing these registers actually accesses the associated FSR register pair, but also performs a specific action on its stored value. They are: * POSTDEC: accesses the FSR value, then automatically decrements it by 1 afterwards * POSTINC: accesses the FSR value, then automatically increments it by 1 afterwards * PREINC: increments the FSR value by 1, then uses it in the operation * PLUSW: adds the signed value of the W register (range of -127 to 128) to that of the FSR and uses the new value in the operation. In this context, accessing an INDF register uses the value in the FSR registers without changing them. Similarly, accessing a PLUSW register gives the FSR value offset by that in the W register; neither value is actually changed in the operation. Accessing the other virtual registers changes the value of the FSR registers. Operations on the FSRs with POSTDEC, POSTINC and PREINC affect the entire register pair; that is, rollovers of the FSRnL register from FFh to 00h carry over to the FSRnH register. On the other hand, results of these operations do not change the value of any flags in the STATUS register (e.g., Z, N, OV, etc.).
FIGURE 6-7:
INDIRECT ADDRESSING
000h ADDWF, INDF1, 1 Bank 0 100h Bank 1 200h Bank 2
Using an instruction with one of the indirect addressing registers as the operand....
...uses the 12-bit address stored in the FSR pair associated with that register....
FSR1H:FSR1L 7 0 7 0
300h
xxxx1110
11001100
Bank 3 through Bank 13
...to determine the data memory location to be used in that operation. In this case, the FSR1 pair contains ECCh. This means the contents of location ECCh will be added to that of the W register and stored back in ECCh. E00h Bank 14 F00h FFFh Bank 15
Data Memory
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The PLUSW register can be used to implement a form of indexed addressing in the data memory space. By manipulating the value in the W register, users can reach addresses that are fixed offsets from pointer addresses. In some applications, this can be used to implement some powerful program control structure, such as software stacks, inside of data memory.
6.5.1
INDEXED ADDRESSING WITH LITERAL OFFSET
6.4.3.3
Operations by FSRs on FSRs
Indirect addressing operations that target other FSRs or virtual registers represent special cases. For example, using an FSR to point to one of the virtual registers will not result in successful operations. As a specific case, assume that FSR0H:FSR0L contains FE7h, the address of INDF1. Attempts to read the value of the INDF1 using INDF0 as an operand will return 00h. Attempts to write to INDF1 using INDF0 as the operand will result in a NOP. On the other hand, using the virtual registers to write to an FSR pair may not occur as planned. In these cases, the value will be written to the FSR pair but without any incrementing or decrementing. Thus, writing to INDF2 or POSTDEC2 will write the same value to the FSR2H:FSR2L. Since the FSRs are physical registers mapped in the SFR space, they can be manipulated through all direct operations. Users should proceed cautiously when working on these registers, particularly if their code uses indirect addressing. Similarly, operations by indirect addressing are generally permitted on all other SFRs. Users should exercise the appropriate caution that they do not inadvertently change settings that might affect the operation of the device.
Enabling the PIC18 extended instruction set changes the behavior of indirect addressing using the FSR2 register pair within Access RAM. Under the proper conditions, instructions that use the Access Bank - that is, most bit-oriented and byte-oriented instructions - can invoke a form of indexed addressing using an offset specified in the instruction. This special addressing mode is known as Indexed Addressing with Literal Offset, or Indexed Literal Offset mode. When using the extended instruction set, this addressing mode requires the following: * The use of the Access Bank is forced (`a' = 0); and * The file address argument is less than or equal to 5Fh. Under these conditions, the file address of the instruction is not interpreted as the lower byte of an address (used with the BSR in direct addressing), or as an 8-bit address in the Access Bank. Instead, the value is interpreted as an offset value to an Address Pointer, specified by FSR2. The offset and the contents of FSR2 are added to obtain the target address of the operation.
6.5.2
INSTRUCTIONS AFFECTED BY INDEXED LITERAL OFFSET MODE
6.5
Data Memory and the Extended Instruction Set
Any of the core PIC18 instructions that can use direct addressing are potentially affected by the Indexed Literal Offset Addressing mode. This includes all byte-oriented and bit-oriented instructions, or almost one-half of the standard PIC18 instruction set. Instructions that only use Inherent or Literal Addressing modes are unaffected. Additionally, byte-oriented and bit-oriented instructions are not affected if they do not use the Access Bank (Access RAM bit is `1'), or include a file address of 60h or above. Instructions meeting these criteria will continue to execute as before. A comparison of the different possible addressing modes when the extended instruction set is enabled is shown in Figure 6-8. Those who desire to use bit-oriented or byte-oriented instructions in the Indexed Literal Offset mode should note the changes to assembler syntax for this mode. This is described in more detail in Section 24.2.1 "Extended Instruction Syntax".
Enabling the PIC18 extended instruction set (XINST Configuration bit = 1) significantly changes certain aspects of data memory and its addressing. Specifically, the use of the Access Bank for many of the core PIC18 instructions is different. This is due to the introduction of a new addressing mode for the data memory space. What does not change is just as important. The size of the data memory space is unchanged, as well as its linear addressing. The SFR map remains the same. Core PIC18 instructions can still operate in both Direct and Indirect Addressing mode; inherent and literal instructions do not change at all. Indirect addressing with FSR0 and FSR1 also remain unchanged.
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FIGURE 6-8: COMPARING ADDRESSING OPTIONS FOR BIT-ORIENTED AND BYTE-ORIENTED INSTRUCTIONS (EXTENDED INSTRUCTION SET ENABLED)
EXAMPLE INSTRUCTION: ADDWF, f, d, a (Opcode: 0010 01da ffff ffff)
When `a' = 0 and `f' 60h: The instruction executes in Direct Forced mode. `f' is interpreted as a location in the Access RAM between 060h and 0FFh. This is the same as locations 060h to 07Fh (Bank 0) and F80h to FFFh (Bank 15) of data memory. Locations below 60h are not available in this addressing mode.
000h 060h 080h 100h Bank 1 through Bank 14 00h 60h 80h
Bank 0
Valid range for `f'
F00h Bank 15 F80h SFRs FFFh Data Memory
Access RAM
FFh
When `a' = 0 and `f' 5Fh: The instruction executes in Indexed Literal Offset mode. `f' is interpreted as an offset to the address value in FSR2. The two are added together to obtain the address of the target register for the instruction. The address can be anywhere in the data memory space. Note that in this mode, the correct syntax is now: ADDWF [k], d where `k' is the same as `f'.
000h Bank 0 080h 100h Bank 1 through Bank 14 FSR2H F00h Bank 15 F80h SFRs FFFh Data Memory FSR2L 001001da ffffffff
When `a' = 1 (all values of `f'): The instruction executes in Direct mode (also known as Direct Long mode). `f' is interpreted as a location in one of the 16 banks of the data memory space. The bank is designated by the Bank Select Register (BSR). The address can be in any implemented bank in the data memory space.
000h Bank 0 080h 100h Bank 1 through Bank 14
BSR 00000000
001001da ffffffff
F00h Bank 15 F80h SFRs FFFh Data Memory
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6.5.3 MAPPING THE ACCESS BANK IN INDEXED LITERAL OFFSET ADDRESSING MODE
Remapping of the Access Bank applies only to operations using the Indexed Literal Offset Addressing mode. Operations that use the BSR (Access RAM bit is `1') will continue to use direct addressing as before.
The use of Indexed Literal Offset Addressing mode effectively changes how the first 96 locations of Access RAM (00h to 5Fh) are mapped. Rather than containing just the contents of the bottom half of Bank 0, this mode maps the contents from Bank 0 and a user-defined "window" that can be located anywhere in the data memory space. The value of FSR2 establishes the lower boundary of the addresses mapped into the window, while the upper boundary is defined by FSR2 plus 95 (5Fh). Addresses in the Access RAM above 5Fh are mapped as previously described (see Section 6.3.2 "Access Bank"). An example of Access Bank remapping in this addressing mode is shown in Figure 6-9.
6.6
PIC18 Instruction Execution and the Extended Instruction Set
Enabling the extended instruction set adds eight additional commands to the existing PIC18 instruction set. These instructions are executed as described in Section 24.2 "Extended Instruction Set".
FIGURE 6-9:
Example Situation:
REMAPPING THE ACCESS BANK WITH INDEXED LITERAL OFFSET ADDRESSING MODE
000h 05Fh 07Fh 100h 120h 17Fh 200h Bank 0 Bank 0 Bank 1 Window Bank 1 Bank 1 "Window" 5Fh Bank 0 Bank 2 through Bank 14 7Fh 80h 00h
ADDWF f, d, a FSR2H:FSR2L = 120h Locations in the region from the FSR2 Pointer (120h) to the pointer plus 05Fh (17Fh) are mapped to the bottom of the Access RAM (000h-05Fh). Locations in Bank 0, from 060h to 07Fh, are mapped as usual to the middle of the Access Bank. Special Function Registers at F80h through FFFh are mapped to 80h through FFh, as usual. Bank 0 addresses below 5Fh can still be addressed by using the BSR.
SFRs FFh
Access Bank
F00h Bank 15 F80h FFFh SFRs
Data Memory
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NOTES:
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7.0 FLASH PROGRAM MEMORY
7.1 Table Reads and Table Writes
The Flash program memory is readable, writable and erasable during normal operation over the entire VDD range. A read from program memory is executed on one byte at a time. A write to program memory is executed on blocks of 8 bytes at a time. Program memory is erased in blocks of 64 bytes at a time. A bulk erase operation may not be issued from user code. Writing or erasing program memory will cease instruction fetches until the operation is complete. The program memory cannot be accessed during the write or erase, therefore, code cannot execute. An internal programming timer terminates program memory writes and erases. A value written to program memory does not need to be a valid instruction. Executing a program memory location that forms an invalid instruction results in a NOP. In order to read and write program memory, there are two operations that allow the processor to move bytes between the program memory space and the data RAM: * Table Read (TBLRD) * Table Write (TBLWT) The program memory space is 16 bits wide, while the data RAM space is 8 bits wide. Table reads and table writes move data between these two memory spaces through an 8-bit register (TABLAT). Table read operations retrieve data from program memory and place it into the data RAM space. Figure 7-1 shows the operation of a table read with program memory and data RAM. Table write operations store data from the data memory space into holding registers in program memory. The procedure to write the contents of the holding registers into program memory is detailed in Section 7.5 "Writing to Flash Program Memory". Figure 7-2 shows the operation of a table write with program memory and data RAM. Table operations work with byte entities. A table block containing data, rather than program instructions, is not required to be word-aligned. Therefore, a table block can start and end at any byte address. If a table write is being used to write executable code into program memory, program instructions will need to be word-aligned.
FIGURE 7-1:
TABLE READ OPERATION
Instruction: TBLRD*
Table Pointer(1) TBLPTRU TBLPTRH TBLPTRL
Program Memory Table Latch (8-bit) TABLAT
Program Memory (TBLPTR)
Note 1: Table Pointer register points to a byte in program memory.
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FIGURE 7-2: TABLE WRITE OPERATION
Instruction: TBLWT* Program Memory Holding Registers Table Pointer(1) TBLPTRU TBLPTRH TBLPTRL Table Latch (8-bit) TABLAT
Program Memory (TBLPTR)
Note 1: Table Pointer actually points to one of 64 holding registers, the address of which is determined by TBLPTRL<5:0>. The process for physically writing data to the program memory array is discussed in Section 7.5 "Writing to Flash Program Memory".
7.2
Control Registers
Several control registers are used in conjunction with the TBLRD and TBLWT instructions. These include the: * * * * EECON1 register EECON2 register TABLAT register TBLPTR registers
The FREE bit, when set, will allow a program memory erase operation. When FREE is set, the erase operation is initiated on the next WR command. When FREE is clear, only writes are enabled. The WREN bit, when set, will allow a write operation. On power-up, the WREN bit is clear. The WRERR bit is set in hardware when the WR bit is set and cleared when the internal programming timer expires and the write operation is complete. Note: During normal operation, the WRERR bit may read as `1'. This can indicate that a write operation was prematurely terminated by a Reset, or a write operation was attempted improperly.
7.2.1
EECON1 AND EECON2 REGISTERS
The EECON1 register (Register 7-1) is the control register for memory accesses. The EECON2 register is not a physical register; it is used exclusively in the memory write and erase sequences. Reading EECON2 will read all `0's. The EEPGD control bit determines if the access will be a program or data EEPROM memory access. When clear, any subsequent operations will operate on the data EEPROM memory. When set, any subsequent operations will operate on the program memory. The CFGS control bit determines if the access will be to the Configuration/Calibration registers or to program memory/data EEPROM memory. When set, subsequent operations will operate on Configuration registers regardless of EEPGD (see Section 24.0 "Special Features of the CPU"). When clear, memory selection access is determined by EEPGD.
The WR control bit initiates write operations. The bit cannot be cleared, only set, in software; it is cleared in hardware at the completion of the write operation. Note: The EEIF interrupt flag bit (PIR2<4>) is set when the write is complete. It must be cleared in software.
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REGISTER 7-1: EECON1: DATA EEPROM CONTROL REGISTER 1
R/W-x EEPGD bit 7 bit 7 EEPGD: Flash Program or Data EEPROM Memory Select bit 1 = Access Flash program memory 0 = Access data EEPROM memory CFGS: Flash Program/Data EEPROM or Configuration Select bit 1 = Access Configuration registers 0 = Access Flash program or data EEPROM memory Unimplemented: Read as `0' FREE: Flash Row Erase Enable bit 1 = Erase the program memory row addressed by TBLPTR on the next WR command (cleared by completion of erase operation) 0 = Perform write-only WRERR: Flash Program/Data EEPROM Error Flag bit 1 = A write operation is prematurely terminated (any Reset during self-timed programming in normal operation, or an improper write attempt) 0 = The write operation completed Note: bit 2 When a WRERR occurs, the EEPGD and CFGS bits are not cleared. This allows tracing of the error condition. R/W-x CFGS U-0 -- R/W-0 FREE R/W-x WRERR R/W-0 WREN R/S-0 WR R/S-0 RD bit 0
bit 6
bit 5 bit 4
bit 3
WREN: Flash Program/Data EEPROM Write Enable bit 1 = Allows write cycles to Flash program/data EEPROM 0 = Inhibits write cycles to Flash program/data EEPROM WR: Write Control bit 1 = Initiates a data EEPROM erase/write cycle or a program memory erase/write cycle. (The operation is self-timed and the bit is cleared by hardware once write is complete. The WR bit can only be set (not cleared) in software.) 0 = Write cycle to the EEPROM is complete RD: Read Control bit 1 = Initiates an EEPROM read (Read takes one cycle. RD is cleared in hardware. The RD bit can only be set (not cleared) in software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.) 0 = Does not initiate an EEPROM read Legend: R = Readable bit -n = Value at POR W = Writable bit U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown `1' = Bit is set S = Bit can be set by software, but not cleared
bit 1
bit 0
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7.2.2 TABLAT - TABLE LATCH REGISTER 7.2.4 TABLE POINTER BOUNDARIES
The Table Latch (TABLAT) is an 8-bit register mapped into the SFR space. The Table Latch register is used to hold 8-bit data during data transfers between program memory and data RAM. TBLPTR is used in reads, writes and erases of the Flash program memory. When a TBLRD is executed, all 22 bits of the TBLPTR determine which byte is read from program memory into TABLAT. When the timed write to program memory begins (via the WR bit), the 19 MSbs of the TBLPTR (TBLPTR<21:3>) determine which program memory block of 8 bytes is written to. The Table Pointer register's three LSBs (TBLPTR<2:0>) are ignored. For more detail, see Section 7.5 "Writing to Flash Program Memory". When an erase of program memory is executed, the 16 MSbs of the Table Pointer register (TBLPTR<21:6>) point to the 64-byte block that will be erased. The Least Significant bits (TBLPTR<5:0>) are ignored. Figure 7-3 describes the relevant boundaries of TBLPTR based on Flash program memory operations.
7.2.3
TBLPTR - TABLE POINTER REGISTER
The Table Pointer (TBLPTR) register addresses a byte within the program memory. The TBLPTR is comprised of three SFR registers: Table Pointer Upper Byte, Table Pointer High Byte and Table Pointer Low Byte (TBLPTRU:TBLPTRH:TBLPTRL). These three registers join to form a 22-bit wide pointer. The low-order 21 bits allow the device to address up to 2 Mbytes of program memory space. The 22nd bit allows access to the device ID, the user ID and the Configuration bits. The Table Pointer register, TBLPTR, is used by the TBLRD and TBLWT instructions. These instructions can update the TBLPTR in one of four ways based on the table operation. These operations are shown in Table 7-1. These operations on the TBLPTR only affect the low-order 21 bits.
TABLE 7-1:
Example TBLRD* TBLWT* TBLRD*+ TBLWT*+ TBLRD*TBLWT*TBLRD+* TBLWT+*
TABLE POINTER OPERATIONS WITH TBLRD AND TBLWT INSTRUCTIONS
Operation on Table Pointer TBLPTR is not modified TBLPTR is incremented after the read/write TBLPTR is decremented after the read/write TBLPTR is incremented before the read/write
FIGURE 7-3:
21
TABLE POINTER BOUNDARIES BASED ON OPERATION
TBLPTRU 16 15 TBLPTRH 8 7 TBLPTRL 0
TABLE ERASE TBLPTR<21:6> TABLE WRITE TBLPTR<21:3> TABLE READ - TBLPTR<21:0>
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7.3 Reading the Flash Program Memory
TBLPTR points to a byte address in program space. Executing TBLRD places the byte pointed to into TABLAT. In addition, TBLPTR can be modified automatically for the next table read operation. The internal program memory is typically organized by words. The Least Significant bit of the address selects between the high and low bytes of the word. Figure 7-4 shows the interface between the internal program memory and the TABLAT.
The TBLRD instruction is used to retrieve data from program memory and place it into data RAM. Table reads from program memory are performed one byte at a time.
FIGURE 7-4:
READS FROM FLASH PROGRAM MEMORY
Program Memory
(Even Byte Address)
(Odd Byte Address)
TBLPTR = xxxxx1
TBLPTR = xxxxx0
Instruction Register (IR)
FETCH
TBLRD
TABLAT Read Register
EXAMPLE 7-1:
MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF READ_WORD
READING A FLASH PROGRAM MEMORY WORD
CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL ; Load TBLPTR with the base ; address of the word
TBLRD*+ MOVF MOVWF TBLRD*+ MOVF MOVWF
TABLAT, W WORD_EVEN TABLAT, W WORD_ODD
; read into TABLAT and increment ; get data ; read into TABLAT and increment ; get data
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7.4 Erasing Flash Program Memory
7.4.1
The minimum erase block is 32 words or 64 bytes. Only through the use of an external programmer, or through ICSP control, can larger blocks of program memory be bulk erased. Word erase in the Flash array is not supported. When initiating an erase sequence from the microcontroller itself, a block of 64 bytes of program memory is erased. The Most Significant 16 bits of the TBLPTR<21:6> point to the block being erased. TBLPTR<5:0> are ignored. The EECON1 register commands the erase operation. The EEPGD bit must be set to point to the Flash program memory. The WREN bit must be set to enable write operations. The FREE bit is set to select an erase operation. For protection, the write initiate sequence for EECON2 must be used. A long write is necessary for erasing the internal Flash. Instruction execution is halted while in a long write cycle. The long write will be terminated by the internal programming timer.
FLASH PROGRAM MEMORY ERASE SEQUENCE
The sequence of events for erasing a block of internal program memory location is: 1. 2. Load Table Pointer register with address of row being erased. Set the EECON1 register for the erase operation: * set EEPGD bit to point to program memory; * clear the CFGS bit to access program memory; * set WREN bit to enable writes; * set FREE bit to enable the erase. Disable interrupts. Write 55h to EECON2. Write 0AAh to EECON2. Set the WR bit. This will begin the row erase cycle. The CPU will stall for duration of the erase (about 2 ms using internal timer). Re-enable interrupts.
3. 4. 5. 6. 7. 8.
EXAMPLE 7-2:
ERASING A FLASH PROGRAM MEMORY ROW
MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL EECON1, EECON1, EECON1, EECON1, INTCON, 55h EECON2 0AAh EECON2 EECON1, INTCON, EEPGD CFGS WREN FREE GIE ; load TBLPTR with the base ; address of the memory block
ERASE_ROW BSF BCF BSF BSF BCF MOVLW MOVWF MOVLW MOVWF BSF BSF ; ; ; ; ; point to Flash program memory access Flash program memory enable write to memory enable Row Erase operation disable interrupts
Required Sequence
; write 55h ; write 0AAh ; start erase (CPU stall) ; re-enable interrupts
WR GIE
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7.5 Writing to Flash Program Memory
The minimum programming block is 4 words or 8 bytes. Word or byte programming is not supported. Table writes are used internally to load the holding registers needed to program the Flash memory. There are 8 holding registers used by the table writes for programming. Since the Table Latch (TABLAT) is only a single byte, the TBLWT instruction may need to be executed 8 times for each programming operation. All of the table write operations will essentially be short writes because only the holding registers are written. At the end of updating the 8 holding registers, the EECON1 register must be written to in order to start the programming operation with a long write. The long write is necessary for programming the internal Flash. Instruction execution is halted while in a long write cycle. The long write will be terminated by the internal programming timer. The EEPROM on-chip timer controls the write time. The write/erase voltages are generated by an on-chip charge pump, rated to operate over the voltage range of the device. Note: The default value of the holding registers on device Resets and after write operations is FFh. A write of FFh to a holding register does not modify that byte. This means that individual bytes of program memory may be modified, provided that the modification does not attempt to change any bit from a `0' to a `1'. When modifying individual bytes, it is not necessary to load all 8 holding registers before executing a write operation.
FIGURE 7-5:
TABLE WRITES TO FLASH PROGRAM MEMORY
TABLAT Write Register
8
TBLPTR = xxxxx0 TBLPTR = xxxxx1
8
TBLPTR = xxxxx2
8
TBLPTR = xxxxx7
8
Holding Register
Holding Register
Holding Register
Holding Register
Program Memory
7.5.1
FLASH PROGRAM MEMORY WRITE SEQUENCE
The sequence of events for programming an internal program memory location should be: 1. 2. 3. 4. 5. 6. 7. Read 64 bytes into RAM. Update data values in RAM as necessary. Load Table Pointer register with address being erased. Execute the row erase procedure. Load Table Pointer register with address of first byte being written. Write the 8 bytes into the holding registers. Set the EECON1 register for the write operation: * set EEPGD bit to point to program memory; * clear the CFGS bit to access program memory; * set WREN to enable byte writes. Disable interrupts.
Write 55h to EECON2. Write 0AAh to EECON2. Set the WR bit. This will begin the write cycle. The CPU will stall for duration of the write (about 2 ms using internal timer). 13. Repeat from step 5 seven more times. 14. Re-enable interrupts. 15. Verify the memory (table read). This procedure will require about 18 ms to update one row of 64 bytes of memory. An example of the required code is given in Example 7-3. Note: Before setting the WR bit, the Table Pointer address needs to be within the intended address range of the 8 bytes in the holding register.
9. 10. 11. 12.
8.
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EXAMPLE 7-3: WRITING TO FLASH PROGRAM MEMORY
MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF READ_BLOCK TBLRD*+ MOVF MOVWF DECFSZ BRA MODIFY_WORD MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF ERASE_BLOCK MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF BCF BSF BSF BSF BCF MOVLW MOVWF MOVLW MOVWF BSF NOP BSF WRITE_BUFFER_BACK MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF PROGRAM_LOOP MOVLW MOVWF WRITE_WORD_TO_HREGS MOVF MOVWF TBLWT+* CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL EECON1, CFGS EECON1, EEPGD EECON1, WREN EECON1, FREE INTCON, GIE 55h EECON2 0AAh EECON2 EECON1, WR INTCON, GIE 8 COUNTER_HI BUFFER_ADDR_HIGH FSR0H BUFFER_ADDR_LOW FSR0L 8 COUNTER POSTINC0, W TABLAT ; load TBLPTR with the base ; address of the memory block DATA_ADDR_HIGH FSR0H DATA_ADDR_LOW FSR0L NEW_DATA_LOW POSTINC0 NEW_DATA_HIGH INDF0 ; point to buffer TABLAT, W POSTINC0 COUNTER READ_BLOCK ; ; ; ; ; read into TABLAT, and inc get data store data and increment FSR0 done? repeat D'64' COUNTER BUFFER_ADDR_HIGH FSR0H BUFFER_ADDR_LOW FSR0L CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL ; number of bytes in erase block ; point to buffer
; Load TBLPTR with the base ; address of the memory block
; 6 LSB = 0
; update buffer word and increment FSR0 ; update buffer word
; 6 LSB = 0 ; ; ; ; ; ; ; point to PROG/EEPROM memory point to Flash program memory enable write to memory enable Row Erase operation disable interrupts Required sequence write 55h
; write AAh ; start erase (CPU stall) ; re-enable interrupts ; number of write buffer groups of 8 bytes ; point to buffer
; number of bytes in holding register
DECFSZ COUNTER GOTO WRITE_WORD_TO_HREGS
; ; ; ; ; ;
get low byte of buffer data and increment FSR0 present data to table latch short write to internal TBLWT holding register, increment TBLPTR loop until buffers are full
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EXAMPLE 7-3:
PROGRAM_MEMORY BCF MOVLW MOVWF MOVLW MOVWF BSF NOP BSF DECFSZ GOTO BCF INTCON, GIE 55h EECON2 0AAh EECON2 EECON1, WR INTCON, GIE COUNTER_HI PROGRAM_LOOP EECON1, WREN ; disable interrupts ; required sequence ; write 55h ; write AAh ; start program (CPU stall) ; re-enable interrupts ; loop until done ; disable write to memory
WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
7.5.2
WRITE VERIFY
7.5.4
Depending on the application, good programming practice may dictate that the value written to the memory should be verified against the original value. This should be used in applications where excessive writes can stress bits near the specification limit.
PROTECTION AGAINST SPURIOUS WRITES
To protect against spurious writes to Flash program memory, the write initiate sequence must also be followed. See Section 24.0 "Special Features of the CPU" for more detail.
7.5.3
UNEXPECTED TERMINATION OF WRITE OPERATION
7.6
If a write is terminated by an unplanned event, such as loss of power or an unexpected Reset, the memory location just programmed should be verified and reprogrammed if needed. If the write operation is interrupted by a MCLR Reset or a WDT Time-out Reset during normal operation, the user can check the WRERR bit and rewrite the location(s) as needed.
Flash Program Operation During Code Protection
See Section 24.5 "Program Verification and Code Protection" for details on code protection of Flash program memory.
TABLE 7-2:
Name TBLPTRU
REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY
Bit 7 -- Bit 6 -- Bit 5 bit 21 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page 55 55 55 55 INT0IE FREE EEIP EEIF EEIE RBIE WRERR BCLIP BCLIF BCLIE TMR0IF WREN HLVDIP HLVDIF HLVDIE INT0IF WR TMR3IP TMR3IF TMR3IE RBIF RD CCP2IP CCP2IF CCP2IE 55 57 57 58 58 58
Program Memory Table Pointer Upper Byte (TBLPTR<20:16>)
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>) TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>) TABLAT INTCON EECON2 EECON1 IPR2 PIR2 PIE2 Program Memory Table Latch GIE/GIEH PEIE/GIEL TMR0IE EEPGD OSCFIP OSCFIF OSCFIE CFGS CMIP CMIF CMIE -- -- -- -- EEPROM Control Register 2 (not a physical register)
Legend: -- = unimplemented, read as `0'. Shaded cells are not used during Flash/EEPROM access.
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8.0 DATA EEPROM MEMORY
The data EEPROM is a nonvolatile memory array, separate from the data RAM and program memory, that is used for long-term storage of program data. It is not directly mapped in either the register file or program memory space but is indirectly addressed through the Special Function Registers (SFRs). The EEPROM is readable and writable during normal operation over the entire VDD range. Four SFRs are used to read and write to the data EEPROM as well as the program memory. They are: * * * * EECON1 EECON2 EEDATA EEADR The EECON1 register (Register 8-1) is the control register for data and program memory access. Control bit EEPGD determines if the access will be to program or data EEPROM memory. When clear, operations will access the data EEPROM memory. When set, program memory is accessed. Control bit CFGS determines if the access will be to the Configuration registers or to program memory/data EEPROM memory. When set, subsequent operations access Configuration registers. When CFGS is clear, the EEPGD bit selects either program Flash or data EEPROM memory. The WREN bit, when set, will allow a write operation. On power-up, the WREN bit is clear. The WRERR bit is set in hardware when the WREN bit is set and cleared when the internal programming timer expires and the write operation is complete. Note: During normal operation, the WRERR bit is read as `1'. This can indicate that a write operation was prematurely terminated by a Reset, or a write operation was attempted improperly.
The data EEPROM allows byte read and write. When interfacing to the data memory block, EEDATA holds the 8-bit data for read/write and the EEADR register holds the address of the EEPROM location being accessed. The EEPROM data memory is rated for high erase/write cycle endurance. A byte write automatically erases the location and writes the new data (erase-before-write). The write time is controlled by an on-chip timer. It will vary with voltage and temperature as well as from chip to chip. Please refer to parameter D122 (Table 27-1 in Section 27.0 "Electrical Characteristics") for exact limits.
The WR control bit initiates write operations. The bit cannot be cleared, only set, in software; it is cleared in hardware at the completion of the write operation. Note: The EEIF interrupt flag bit (PIR2<4>) is set when the write is complete. It must be cleared in software.
8.1
EECON1 and EECON2 Registers
Access to the data EEPROM is controlled by two registers: EECON1 and EECON2. These are the same registers which control access to the program memory and are used in a similar manner for the data EEPROM.
Control bits, RD and WR, start read and erase/write operations, respectively. These bits are set by firmware and cleared by hardware at the completion of the operation. The RD bit cannot be set when accessing program memory (EEPGD = 1). Program memory is read using table read instructions. See Section 7.1 "Table Reads and Table Writes" regarding table reads. The EECON2 register is not a physical register. It is used exclusively in the memory write and erase sequences. Reading EECON2 will read all `0's.
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REGISTER 8-1: EECON1: DATA EEPROM CONTROL REGISTER 1
R/W-x EEPGD bit 7 bit 7 EEPGD: Flash Program or Data EEPROM Memory Select bit 1 = Access Flash program memory 0 = Access data EEPROM memory CFGS: Flash Program/Data EEPROM or Configuration Select bit 1 = Access Configuration registers 0 = Access Flash program or data EEPROM memory Unimplemented: Read as `0' FREE: Flash Row Erase Enable bit 1 = Erase the program memory row addressed by TBLPTR on the next WR command (cleared by completion of erase operation) 0 = Perform write only WRERR: Flash Program/Data EEPROM Error Flag bit 1 = A write operation is prematurely terminated (any Reset during self-timed programming in normal operation, or an improper write attempt) 0 = The write operation completed Note: bit 2 When a WRERR occurs, the EEPGD and CFGS bits are not cleared. This allows tracing of the error condition. R/W-x CFGS U-0 -- R/W-0 FREE R/W-x WRERR R/W-0 WREN R/S-0 WR R/S-0 RD bit 0
bit 6
bit 5 bit 4
bit 3
WREN: Flash Program/Data EEPROM Write Enable bit 1 = Allows write cycles to Flash program/data EEPROM 0 = Inhibits write cycles to Flash program/data EEPROM WR: Write Control bit 1 = Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle (The operation is self-timed and the bit is cleared by hardware once write is complete. The WR bit can only be set (not cleared) in software.) 0 = Write cycle to the EEPROM is complete RD: Read Control bit 1 = Initiates an EEPROM read (Read takes one cycle. RD is cleared in hardware. The RD bit can only be set (not cleared) in software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.) 0 = Does not initiate an EEPROM read Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 1
bit 0
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8.2 Reading the Data EEPROM Memory
Additionally, the WREN bit in EECON1 must be set to enable writes. This mechanism prevents accidental writes to data EEPROM due to unexpected code execution (i.e., runaway programs). The WREN bit should be kept clear at all times, except when updating the EEPROM. The WREN bit is not cleared by hardware. After a write sequence has been initiated, EECON1, EEADR and EEDATA cannot be modified. The WR bit will be inhibited from being set unless the WREN bit is set. The WREN bit must be set on a previous instruction. Both WR and WREN cannot be set with the same instruction. At the completion of the write cycle, the WR bit is cleared in hardware and the EEPROM Interrupt Flag bit, EEIF, is set. The user may either enable this interrupt, or poll this bit. EEIF must be cleared by software.
To read a data memory location, the user must write the address to the EEADR register, clear the EEPGD control bit (EECON1<7>) and then set control bit, RD (EECON1<0>). The data is available on the very next instruction cycle; therefore, the EEDATA register can be read by the next instruction. EEDATA will hold this value until another read operation, or until it is written to by the user (during a write operation). The basic process is shown in Example 8-1.
8.3
Writing to the Data EEPROM Memory
To write an EEPROM data location, the address must first be written to the EEADR register and the data written to the EEDATA register. The sequence in Example 8-2 must be followed to initiate the write cycle. The write will not begin if this sequence is not exactly followed (write 55h to EECON2, write 0AAh to EECON2, then set WR bit) for each byte. It is strongly recommended that interrupts be disabled during this code segment.
8.4
Write Verify
Depending on the application, good programming practice may dictate that the value written to the memory should be verified against the original value. This should be used in applications where excessive writes can stress bits near the specification limit.
EXAMPLE 8-1:
MOVLW MOVWF BCF BCF BSF MOVF
DATA EEPROM READ
DATA_EE_ADDR EEADR EECON1, EEPGD EECON1, CFGS EECON1, RD EEDATA, W ; ; ; ; ; ; Data Memory Address to read Point to DATA memory Access EEPROM EEPROM Read W = EEDATA
EXAMPLE 8-2:
DATA EEPROM WRITE
MOVLW MOVWF MOVLW MOVWF BCF BCF BSF BCF MOVLW MOVWF MOVLW MOVWF BSF BTFSC GOTO BSF DATA_EE_ADDR EEADR DATA_EE_DATA EEDATA EECON1, EEPGD EECON1, CFGS EECON1, WREN INTCON, 55h EECON2 0AAh EECON2 EECON1, EECON1, $-2 INTCON, GIE ; ; ; ; ; ; ; ; ; ; ; ; ; ; Data Memory Address to write Data Memory Value to write Point to DATA memory Access EEPROM Enable writes Disable Interrupts Write 55h Write 0AAh Set WR bit to begin write Wait for write to complete
Required Sequence
WR WR GIE
; Enable Interrupts ; User code execution ; Disable writes on write complete (EEIF set)
BCF
EECON1, WREN
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8.5 Operation During Code-Protect 8.7 Using the Data EEPROM
Data EEPROM memory has its own code-protect bits in Configuration Words. External read and write operations are disabled if code protection is enabled. The microcontroller itself can both read and write to the internal data EEPROM, regardless of the state of the code-protect Configuration bit. Refer to Section 24.0 "Special Features of the CPU" for additional information. The data EEPROM is a high-endurance, byte addressable array that has been optimized for the storage of frequently changing data. Such data is typically updated at least one time within the number of writes defined by specification, D124. If any location storing data is not written at least this often, the data EEPROM array must be refreshed. For this reason, values that change infrequently, or not at all, should be stored in Flash program memory. A simple data EEPROM refresh routine is shown in Example 8-3. Note: If data EEPROM is only used to store constants and/or data that changes often, an array refresh is likely not required. See specification, D124.
8.6
Protection Against Spurious Write
To protect against spurious EEPROM writes, various mechanisms have been implemented. On power-up, the WREN bit is cleared. In addition, writes to the EEPROM are blocked during the Power-up Timer period (TPWRT, parameter 33). The write initiate sequence and the WREN bit together help prevent an accidental write during Brown-out Reset, power glitch or software malfunction.
EXAMPLE 8-3:
CLRF BCF BCF BCF BSF LOOP BSF MOVLW MOVWF MOVLW MOVWF BSF BTFSC BRA INCFSZ BRA BCF BSF
DATA EEPROM REFRESH ROUTINE
EEADR EECON1, EECON1, INTCON, EECON1, CFGS EEPGD GIE WREN ; ; ; ; ; ; ; ; ; ; ; ; ; Start at address 0 Set for memory Set for Data EEPROM Disable interrupts Enable writes Loop to refresh array Read current address Write 55h Write 0AAh Set WR bit to begin write Wait for write to complete
EECON1, RD 55h EECON2 0AAh EECON2 EECON1, WR EECON1, WR $-2 EEADR, F LOOP EECON1, WREN INTCON, GIE
; Increment address ; Not zero, do it again ; Disable writes ; Enable interrupts
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TABLE 8-1:
Name INTCON EEADR EEDATA EECON2 EECON1 IPR2 PIR2 PIE2
REGISTERS ASSOCIATED WITH DATA EEPROM MEMORY
Bit 7 Bit 6 Bit 5 TMR0IE Bit 4 INT0IE Bit 3 RBIE Bit 2 TMR0IF Bit 1 INT0IF Bit 0 RBIF Reset Values on page 55 57 57 57 WREN HLVDIP HLVDIF HLVDIE WR TMR3IP TMR3IF TMR3IE RD CCP2IP CCP2IF CCP2IE 57 58 58 58 -- -- -- -- FREE EEIP EEIF EEIE WRERR BCLIP BCLIF BCLIE
GIE/GIEH PEIE/GIEL EEPROM Data Register
EEPROM Address Register EEPROM Control Register 2 (not a physical register) EEPGD OSCFIP OSCFIF OSCFIE CFGS CMIP CMIF CMIE
Legend: -- = unimplemented, read as `0'. Shaded cells are not used during Flash/EEPROM access.
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NOTES:
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9.0
9.1
8 x 8 HARDWARE MULTIPLIER
Introduction
EXAMPLE 9-1:
MOVF MULWF ARG1, W ARG2
8 x 8 UNSIGNED MULTIPLY ROUTINE
; ; ARG1 * ARG2 -> ; PRODH:PRODL
All PIC18 devices include an 8 x 8 hardware multiplier as part of the ALU. The multiplier performs an unsigned operation and yields a 16-bit result that is stored in the product register pair, PRODH:PRODL. The multiplier's operation does not affect any flags in the STATUS register. Making multiplication a hardware operation allows it to be completed in a single instruction cycle. This has the advantages of higher computational throughput and reduced code size for multiplication algorithms and allows the PIC18 devices to be used in many applications previously reserved for digital signal processors. A comparison of various hardware and software multiply operations, along with the savings in memory and execution time, is shown in Table 9-1.
EXAMPLE 9-2:
MOVF MULWF BTFSC SUBWF MOVF BTFSC SUBWF ARG1, W ARG2 ARG2, SB PRODH, F ARG2, W ARG1, SB PRODH, F
8 x 8 SIGNED MULTIPLY ROUTINE
; ; ; ; ; ARG1 * ARG2 -> PRODH:PRODL Test Sign Bit PRODH = PRODH - ARG1
9.2
Operation
; Test Sign Bit ; PRODH = PRODH ; - ARG2
Example 9-1 shows the instruction sequence for an 8 x 8 unsigned multiplication. Only one instruction is required when one of the arguments is already loaded in the WREG register. Example 9-2 shows the sequence to do an 8 x 8 signed multiplication. To account for the sign bits of the arguments, each argument's Most Significant bit (MSb) is tested and the appropriate subtractions are done.
TABLE 9-1:
Routine
PERFORMANCE COMPARISON FOR VARIOUS MULTIPLY OPERATIONS
Multiply Method Without hardware multiply Hardware multiply Without hardware multiply Hardware multiply Without hardware multiply Hardware multiply Without hardware multiply Hardware multiply Program Memory (Words) 13 1 33 6 21 28 52 35 Cycles (Max) 69 1 91 6 242 28 254 40 Time @ 40 MHz 6.9 s 100 ns 9.1 s 600 ns 24.2 s 2.8 s 25.4 s 4.0 s @ 10 MHz 27.6 s 400 ns 36.4 s 2.4 s 96.8 s 11.2 s 102.6 s 16.0 s @ 4 MHz 69 s 1 s 91 s 6 s 242 s 28 s 254 s 40 s
8 x 8 unsigned 8 x 8 signed 16 x 16 unsigned 16 x 16 signed
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Example 9-3 shows the sequence to do a 16 x 16 unsigned multiplication. Equation 9-1 shows the algorithm that is used. The 32-bit result is stored in four registers (RES3:RES0).
EQUATION 9-2:
16 x 16 SIGNED MULTIPLICATION ALGORITHM
EQUATION 9-1:
16 x 16 UNSIGNED MULTIPLICATION ALGORITHM
RES3:RES0 = =
ARG1H:ARG1L * ARG2H:ARG2L (ARG1H * ARG2H * 216) + (ARG1H * ARG2L * 28) + (ARG1L * ARG2H * 28) + (ARG1L * ARG2L)
RES3:RES0 = ARG1H:ARG1L * ARG2H:ARG2L = (ARG1H * ARG2H * 216) + (ARG1H * ARG2L * 28) + (ARG1L * ARG2H * 28) + (ARG1L * ARG2L) + (-1 * ARG2H<7> * ARG1H:ARG1L * 216) + (-1 * ARG1H<7> * ARG2H:ARG2L * 216)
EXAMPLE 9-4:
MOVF MULWF MOVFF MOVFF ; MOVF MULWF MOVFF MOVFF ; MOVF MULWF MOVF ADDWF MOVF ADDWFC CLRF ADDWFC ; MOVF MULWF MOVF ADDWF MOVF ADDWFC CLRF ADDWFC ; BTFSS BRA MOVF SUBWF MOVF SUBWFB ; SIGN_ARG1 BTFSS BRA MOVF SUBWF MOVF SUBWFB ; CONT_CODE :
16 x 16 SIGNED MULTIPLY ROUTINE
; ARG1L * ARG2L -> ; PRODH:PRODL ; ;
EXAMPLE 9-3:
MOVF MULWF MOVFF MOVFF ; MOVF MULWF MOVFF MOVFF ; MOVF MULWF MOVF ADDWF MOVF ADDWFC CLRF ADDWFC ; MOVF MULWF MOVF ADDWF MOVF ADDWFC CLRF ADDWFC
16 x 16 UNSIGNED MULTIPLY ROUTINE
; ARG1L * ARG2L-> ; PRODH:PRODL ; ;
ARG1L, W ARG2L PRODH, RES1 PRODL, RES0 ARG1H, W ARG2H PRODH, RES3 PRODL, RES2 ARG1L, W ARG2H PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F ARG1H, W ARG2L PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F ARG2H, 7 SIGN_ARG1 ARG1L, W RES2 ARG1H, W RES3
ARG1L, W ARG2L PRODH, RES1 PRODL, RES0 ARG1H, W ARG2H PRODH, RES3 PRODL, RES2 ARG1L, W ARG2H PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F ARG1H, W ARG2L PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F
; ARG1H * ARG2H -> ; PRODH:PRODL ; ;
; ARG1H * ARG2H-> ; PRODH:PRODL ; ;
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
ARG1L * ARG2H-> PRODH:PRODL Add cross products
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
ARG1L * ARG2H -> PRODH:PRODL Add cross products
ARG1H * ARG2L -> PRODH:PRODL Add cross products
ARG1H * ARG2L-> PRODH:PRODL Add cross products
Example 9-4 shows the sequence to do a 16 x 16 signed multiply. Equation 9-2 shows the algorithm used. The 32-bit result is stored in four registers (RES3:RES0). To account for the sign bits of the arguments, the MSb for each argument pair is tested and the appropriate subtractions are done.
; ARG2H:ARG2L neg? ; no, check ARG1 ; ; ;
ARG1H, 7 CONT_CODE ARG2L, W RES2 ARG2H, W RES3
; ARG1H:ARG1L neg? ; no, done ; ; ;
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10.0 INTERRUPTS
The PIC18F2221/2321/4221/4321 family devices have multiple interrupt sources and an interrupt priority feature that allows most interrupt sources to be assigned a high-priority level or a low-priority level. The high-priority interrupt vector is at 0008h and the lowpriority interrupt vector is at 0018h. High-priority interrupt events will interrupt any low-priority interrupts that may be in progress. There are ten registers which are used to control interrupt operation. These registers are: * * * * * * * RCON INTCON INTCON2 INTCON3 PIR1, PIR2 PIE1, PIE2 IPR1, IPR2 When the IPEN bit is cleared (default state), the interrupt priority feature is disabled and interrupts are compatible with PIC(R) mid-range devices. In Compatibility mode, the interrupt priority bits for each source have no effect. INTCON<6> is the PEIE bit, which enables/disables all peripheral interrupt sources. INTCON<7> is the GIE bit, which enables/disables all interrupt sources. All interrupts branch to address 0008h in Compatibility mode. When an interrupt is responded to, the global interrupt enable bit is cleared to disable further interrupts. If the IPEN bit is cleared, this is the GIE bit. If interrupt priority levels are used, this will be either the GIEH or GIEL bit. High-priority interrupt sources can interrupt a lowpriority interrupt. Low-priority interrupts are not processed while high-priority interrupts are in progress. The return address is pushed onto the stack and the PC is loaded with the interrupt vector address (0008h or 0018h). Once in the Interrupt Service Routine, the source(s) of the interrupt can be determined by polling the interrupt flag bits. The interrupt flag bits must be cleared in software before re-enabling interrupts to avoid recursive interrupts. The "return from interrupt" instruction, RETFIE, exits the interrupt routine and sets the GIE bit (GIEH or GIEL if priority levels are used), which re-enables interrupts. For external interrupt events, such as the INTx pins or the PORTB input change interrupt, the interrupt latency will be three to four instruction cycles. The exact latency is the same for one or two-cycle instructions. Individual interrupt flag bits are set, regardless of the status of their corresponding enable bit or the GIE bit. Note: Do not use the MOVFF instruction to modify any of the interrupt control registers while any interrupt is enabled. Doing so may cause erratic microcontroller behavior.
It is recommended that the Microchip header files supplied with MPLAB(R) IDE be used for the symbolic bit names in these registers. This allows the assembler/ compiler to automatically take care of the placement of these bits within the specified register. In general, interrupt sources have three bits to control their operation. They are: * Flag bit to indicate that an interrupt event occurred * Enable bit that allows program execution to branch to the interrupt vector address when the flag bit is set * Priority bit to select high priority or low priority The interrupt priority feature is enabled by setting the IPEN bit (RCON<7>). When interrupt priority is enabled, there are two bits which enable interrupts globally. Setting the GIEH bit (INTCON<7>) enables all interrupts that have the priority bit set (high priority). Setting the GIEL bit (INTCON<6>) enables all interrupts that have the priority bit cleared (low priority). When the interrupt flag, enable bit and appropriate global interrupt enable bit are set, the interrupt will vector immediately to address 0008h or 0018h, depending on the priority bit setting. Individual interrupts can be disabled through their corresponding enable bits.
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FIGURE 10-1: PIC18 INTERRUPT LOGIC
Wake-up if in Idle or Sleep modes
TMR0IF TMR0IE TMR0IP RBIF RBIE RBIP INT0IF INT0IE INT1IF INT1IE INT1IP INT2IF INT2IE INT2IP
SSPIF SSPIE SSPIP ADIF ADIE ADIP RCIF RCIE RCIP Additional Peripheral Interrupts High-Priority Interrupt Generation Low-Priority Interrupt Generation
Interrupt to CPU Vector to Location 0008h
GIE/GIEH IPEN IPEN PEIE/GIEL IPEN
SSPIF SSPIE SSPIP TMR0IF TMR0IE TMR0IP RBIF RBIE RBIP INT1IF INT1IE INT1IP INT2IF INT2IE INT2IP Interrupt to CPU Vector to Location 0018h
ADIF ADIE ADIP RCIF RCIE RCIP
GIE/GIEH PEIE/GIEL
Additional Peripheral Interrupts
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10.1 INTCON Registers
Note: The INTCON registers are readable and writable registers, which contain various enable, priority and flag bits. Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global interrupt enable bit. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature allows for software polling.
REGISTER 10-1:
INTCON: INTERRUPT CONTROL REGISTER
R/W-0 GIE/GIEH bit 7 R/W-0 PEIE/GIEL R/W-0 TMR0IE R/W-0 INT0IE R/W-0 RBIE R/W-0 TMR0IF R/W-0 INT0IF R/W-x RBIF bit 0
bit 7
GIE/GIEH: Global Interrupt Enable bit When IPEN = 0: 1 = Enables all unmasked interrupts 0 = Disables all interrupts When IPEN = 1: 1 = Enables all high-priority interrupts 0 = Disables all interrupts PEIE/GIEL: Peripheral Interrupt Enable bit When IPEN = 0: 1 = Enables all unmasked peripheral interrupts 0 = Disables all peripheral interrupts When IPEN = 1: 1 = Enables all low-priority peripheral interrupts 0 = Disables all low-priority peripheral interrupts TMR0IE: TMR0 Overflow Interrupt Enable bit 1 = Enables the TMR0 overflow interrupt 0 = Disables the TMR0 overflow interrupt INT0IE: INT0 External Interrupt Enable bit 1 = Enables the INT0 external interrupt 0 = Disables the INT0 external interrupt RBIE: RB Port Change Interrupt Enable bit 1 = Enables the RB port change interrupt 0 = Disables the RB port change interrupt TMR0IF: TMR0 Overflow Interrupt Flag bit 1 = TMR0 register has overflowed (must be cleared in software) 0 = TMR0 register did not overflow INT0IF: INT0 External Interrupt Flag bit 1 = The INT0 external interrupt occurred (must be cleared in software) 0 = The INT0 external interrupt did not occur RBIF: RB Port Change Interrupt Flag bit 1 = At least one of the RB<7:4> pins changed state (must be cleared in software) 0 = None of the RB<7:4> pins have changed state Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
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REGISTER 10-2: INTCON2: INTERRUPT CONTROL REGISTER 2
R/W-1 RBPU bit 7 bit 7 RBPU: PORTB Pull-up Enable bit 1 = All PORTB pull-ups are disabled 0 = PORTB pull-ups are enabled by individual port latch values INTEDG0: External Interrupt 0 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge INTEDG1: External Interrupt 1 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge INTEDG2: External Interrupt 2 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge Unimplemented: Read as `0' TMR0IP: TMR0 Overflow Interrupt Priority bit 1 = High priority 0 = Low priority Unimplemented: Read as `0' RBIP: RB Port Change Interrupt Priority bit 1 = High priority 0 = Low priority Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-1 INTEDG0 R/W-1 INTEDG1 R/W-1 INTEDG2 U-0 -- R/W-1 TMR0IP U-0 -- R/W-1 RBIP bit 0
bit 6
bit 5
bit 4
bit 3 bit 2
bit 1 bit 0
Note:
Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global interrupt enable bit. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature allows for software polling.
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REGISTER 10-3: INTCON3: INTERRUPT CONTROL REGISTER 3
R/W-1 INT2IP bit 7 bit 7 INT2IP: INT2 External Interrupt Priority bit 1 = High priority 0 = Low priority INT1IP: INT1 External Interrupt Priority bit 1 = High priority 0 = Low priority Unimplemented: Read as `0' INT2IE: INT2 External Interrupt Enable bit 1 = Enables the INT2 external interrupt 0 = Disables the INT2 external interrupt INT1IE: INT1 External Interrupt Enable bit 1 = Enables the INT1 external interrupt 0 = Disables the INT1 external interrupt Unimplemented: Read as `0' INT2IF: INT2 External Interrupt Flag bit 1 = The INT2 external interrupt occurred (must be cleared in software) 0 = The INT2 external interrupt did not occur INT1IF: INT1 External Interrupt Flag bit 1 = The INT1 external interrupt occurred (must be cleared in software) 0 = The INT1 external interrupt did not occur Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-1 INT1IP U-0 -- R/W-0 INT2IE R/W-0 INT1IE U-0 -- R/W-0 INT2IF R/W-0 INT1IF bit 0
bit 6
bit 5 bit 4
bit 3
bit 2 bit 1
bit 0
Note:
Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global interrupt enable bit. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature allows for software polling.
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10.2 PIR Registers
The PIR registers contain the individual flag bits for the peripheral interrupts. Due to the number of peripheral interrupt sources, there are two Peripheral Interrupt Request (Flag) registers (PIR1 and PIR2). Note 1: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the Global Interrupt Enable bit, GIE (INTCON<7>). 2: User software should ensure the appropriate interrupt flag bits are cleared prior to enabling an interrupt and after servicing that interrupt.
REGISTER 10-4:
PIR1: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 1
R/W-0 PSPIF(1) bit 7 R/W-0 ADIF R-0 RCIF R-0 TXIF R/W-0 SSPIF R/W-0 CCP1IF R/W-0 TMR2IF R/W-0 TMR1IF bit 0
bit 7
PSPIF: Parallel Slave Port Read/Write Interrupt Flag bit(1) 1 = A read or a write operation has taken place (must be cleared in software) 0 = No read or write has occurred Note 1: This bit is unimplemented on 28-pin devices and will read as `0'. ADIF: A/D Converter Interrupt Flag bit 1 = An A/D conversion completed (must be cleared in software) 0 = The A/D conversion is not complete RCIF: EUSART Receive Interrupt Flag bit 1 = The EUSART receive buffer, RCREG, is full (cleared when RCREG is read) 0 = The EUSART receive buffer is empty TXIF: EUSART Transmit Interrupt Flag bit 1 = The EUSART transmit buffer, TXREG, is empty (cleared when TXREG is written) 0 = The EUSART transmit buffer is full SSPIF: Master Synchronous Serial Port Interrupt Flag bit 1 = The transmission/reception is complete (must be cleared in software) 0 = Waiting to transmit/receive CCP1IF: CCP1 Interrupt Flag bit Capture mode: 1 = A TMR1 register capture occurred (must be cleared in software) 0 = No TMR1 register capture occurred Compare mode: 1 = A TMR1 register compare match occurred (must be cleared in software) 0 = No TMR1 register compare match occurred PWM mode: Unused in this mode. TMR2IF: TMR2 to PR2 Match Interrupt Flag bit 1 = TMR2 to PR2 match occurred (must be cleared in software) 0 = No TMR2 to PR2 match occurred TMR1IF: TMR1 Overflow Interrupt Flag bit 1 = TMR1 register overflowed (must be cleared in software) 0 = TMR1 register did not overflow Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
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REGISTER 10-5: PIR2: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 2
R/W-0 OSCFIF bit 7 bit 7 R/W-0 CMIF U-0 -- R/W-0 EEIF R/W-0 BCLIF R/W-0 HLVDIF R/W-0 TMR3IF R/W-0 CCP2IF bit 0
OSCFIF: Oscillator Fail Interrupt Flag bit 1 = Device oscillator failed, clock input has changed to INTOSC (must be cleared in software) 0 = Device clock operating CMIF: Comparator Interrupt Flag bit 1 = Comparator input has changed (must be cleared in software) 0 = Comparator input has not changed Unimplemented: Read as `0' EEIF: Data EEPROM/Flash Write Operation Interrupt Flag bit 1 = The write operation is complete (must be cleared in software) 0 = The write operation is not complete or has not been started BCLIF: Bus Collision Interrupt Flag bit 1 = A bus collision occurred (must be cleared in software) 0 = No bus collision occurred HLVDIF: High/Low-Voltage Detect Interrupt Flag bit 1 = A high/low-voltage condition occurred; direction determined by VDIRMAG bit (HLVDCON<7>) 0 = A high/low-voltage condition has not occurred TMR3IF: TMR3 Overflow Interrupt Flag bit 1 = TMR3 register overflowed (must be cleared in software) 0 = TMR3 register did not overflow CCP2IF: CCP2 Interrupt Flag bit Capture mode: 1 = A TMR1 register capture occurred (must be cleared in software) 0 = No TMR1 register capture occurred Compare mode: 1 = A TMR1 register compare match occurred (must be cleared in software) 0 = No TMR1 register compare match occurred PWM mode: Unused in this mode. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5 bit 4
bit 3
bit 2
bit 1
bit 0
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10.3 PIE Registers
The PIE registers contain the individual enable bits for the peripheral interrupts. Due to the number of peripheral interrupt sources, there are two Peripheral Interrupt Enable registers (PIE1 and PIE2). When IPEN = 0, the PEIE bit must be set to enable any of these peripheral interrupts.
REGISTER 10-6:
PIE1: PERIPHERAL INTERRUPT ENABLE REGISTER 1
R/W-0 PSPIE(1) bit 7 R/W-0 ADIE R/W-0 RCIE R/W-0 TXIE R/W-0 SSPIE R/W-0 CCP1IE R/W-0 TMR2IE R/W-0 TMR1IE bit 0
bit 7
PSPIE: Parallel Slave Port Read/Write Interrupt Enable bit(1) 1 = Enables the PSP read/write interrupt 0 = Disables the PSP read/write interrupt Note 1: This bit is unimplemented on 28-pin devices and will read as `0'. ADIE: A/D Converter Interrupt Enable bit 1 = Enables the A/D interrupt 0 = Disables the A/D interrupt RCIE: EUSART Receive Interrupt Enable bit 1 = Enables the EUSART receive interrupt 0 = Disables the EUSART receive interrupt TXIE: EUSART Transmit Interrupt Enable bit 1 = Enables the EUSART transmit interrupt 0 = Disables the EUSART transmit interrupt SSPIE: Master Synchronous Serial Port Interrupt Enable bit 1 = Enables the MSSP interrupt 0 = Disables the MSSP interrupt CCP1IE: CCP1 Interrupt Enable bit 1 = Enables the CCP1 interrupt 0 = Disables the CCP1 interrupt TMR2IE: TMR2 to PR2 Match Interrupt Enable bit 1 = Enables the TMR2 to PR2 match interrupt 0 = Disables the TMR2 to PR2 match interrupt TMR1IE: TMR1 Overflow Interrupt Enable bit 1 = Enables the TMR1 overflow interrupt 0 = Disables the TMR1 overflow interrupt Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
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REGISTER 10-7: PIE2: PERIPHERAL INTERRUPT ENABLE REGISTER 2
R/W-0 OSCFIE bit 7 bit 7 OSCFIE: Oscillator Fail Interrupt Enable bit 1 = Enabled 0 = Disabled CMIE: Comparator Interrupt Enable bit 1 = Enabled 0 = Disabled Unimplemented: Read as `0' EEIE: Data EEPROM/Flash Write Operation Interrupt Enable bit 1 = Enabled 0 = Disabled BCLIE: Bus Collision Interrupt Enable bit 1 = Enabled 0 = Disabled HLVDIE: High/Low-Voltage Detect Interrupt Enable bit 1 = Enabled 0 = Disabled TMR3IE: TMR3 Overflow Interrupt Enable bit 1 = Enabled 0 = Disabled CCP2IE: CCP2 Interrupt Enable bit 1 = Enabled 0 = Disabled Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-0 CMIE U-0 -- R/W-0 EEIE R/W-0 BCLIE R/W-0 HLVDIE R/W-0 TMR3IE R/W-0 CCP2IE bit 0
bit 6
bit 5 bit 4
bit 3
bit 2
bit 1
bit 0
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10.4 IPR Registers
The IPR registers contain the individual priority bits for the peripheral interrupts. Due to the number of peripheral interrupt sources, there are two Peripheral Interrupt Priority registers (IPR1 and IPR2). Using the priority bits requires that the Interrupt Priority Enable (IPEN) bit be set.
REGISTER 10-8:
IPR1: PERIPHERAL INTERRUPT PRIORITY REGISTER 1
R/W-1 PSPIP(1) bit 7 R/W-1 ADIP R/W-1 RCIP R/W-1 TXIP R/W-1 SSPIP R/W-1 CCP1IP R/W-1 TMR2IP R/W-1 TMR1IP bit 0
bit 7
PSPIP: Parallel Slave Port Read/Write Interrupt Priority bit(1) 1 = High priority 0 = Low priority Note 1: This bit is unimplemented on 28-pin devices and will read as `0'. ADIP: A/D Converter Interrupt Priority bit 1 = High priority 0 = Low priority RCIP: EUSART Receive Interrupt Priority bit 1 = High priority 0 = Low priority TXIP: EUSART Transmit Interrupt Priority bit 1 = High priority 0 = Low priority
bit 6
bit 5
bit 4
bit 3
SSPIP: Master Synchronous Serial Port Interrupt Priority bit 1 = High priority 0 = Low priority CCP1IP: CCP1 Interrupt Priority bit 1 = High priority 0 = Low priority TMR2IP: TMR2 to PR2 Match Interrupt Priority bit 1 = High priority 0 = Low priority TMR1IP: TMR1 Overflow Interrupt Priority bit 1 = High priority 0 = Low priority Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 2
bit 1
bit 0
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REGISTER 10-9: IPR2: PERIPHERAL INTERRUPT PRIORITY REGISTER 2
R/W-1 OSCFIP bit 7 bit 7 OSCFIP: Oscillator Fail Interrupt Priority bit 1 = High priority 0 = Low priority CMIP: Comparator Interrupt Priority bit 1 = High priority 0 = Low priority Unimplemented: Read as `0' EEIP: Data EEPROM/Flash Write Operation Interrupt Priority bit 1 = High priority 0 = Low priority BCLIP: Bus Collision Interrupt Priority bit 1 = High priority 0 = Low priority HLVDIP: High/Low-Voltage Detect Interrupt Priority bit 1 = High priority 0 = Low priority TMR3IP: TMR3 Overflow Interrupt Priority bit 1 = High priority 0 = Low priority CCP2IP: CCP2 Interrupt Priority bit 1 = High priority 0 = Low priority Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-1 CMIP U-0 -- R/W-1 EEIP R/W-1 BCLIP R/W-1 HLVDIP R/W-1 TMR3IP R/W-1 CCP2IP bit 0
bit 6
bit 5 bit 4
bit 3
bit 2
bit 1
bit 0
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10.5 RCON Register
The RCON register contains flag bits which are used to determine the cause of the last Reset or wake-up from Idle or Sleep modes. RCON also contains the IPEN bit which enables interrupt priorities. The operation of the SBOREN bit and the Reset flag bits is discussed in more detail in Section 5.1 "RCON Register".
REGISTER 10-10: RCON: RESET CONTROL REGISTER
R/W-0 IPEN bit 7 bit 7 IPEN: Interrupt Priority Enable bit 1 = Enable priority levels on interrupts 0 = Disable priority levels on interrupts (PIC16XXX Compatibility mode) SBOREN: Software BOR Enable bit(1) For details of bit operation, see Register 5-1. Unimplemented: Read as `0' RI: RESET Instruction Flag bit For details of bit operation, see Register 5-1. TO: Watchdog Time-out Flag bit For details of bit operation, see Register 5-1. PD: Power-down Detection Flag bit For details of bit operation, see Register 5-1. POR: Power-on Reset Status bit(2) For details of bit operation, see Register 5-1. BOR: Brown-out Reset Status bit For details of bit operation, see Register 5-1. Note 1: If SBOREN is enabled, its Reset state is `1'; otherwise, it is `0'. 2: Actual Reset values are determined by device configuration and the nature of the device Reset. See Register 5-1 for additional information. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-1(1) SBOREN U-0 -- R/W-1 RI R-1 TO R-1 PD R/W-0(2) POR R/W-0 BOR bit 0
bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
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10.6 INTx Pin Interrupts 10.7 TMR0 Interrupt
External interrupts on the RB0/INT0, RB1/INT1 and RB2/INT2 pins are edge-triggered. If the corresponding INTEDGx bit in the INTCON2 register is set (= 1), the interrupt is triggered by a rising edge; if the bit is clear, the trigger is on the falling edge. When a valid edge appears on the RBx/INTx pin, the corresponding flag bit, INTxF, is set. This interrupt can be disabled by clearing the corresponding enable bit, INTxE. Flag bit, INTxF, must be cleared in software in the Interrupt Service Routine before re-enabling the interrupt. All external interrupts (INT0, INT1 and INT2) can wakeup the processor from Idle or Sleep modes if bit INTxE was set prior to going into those modes. If the Global Interrupt Enable bit, GIE, is set, the processor will branch to the interrupt vector following wake-up. Interrupt priority for INT1 and INT2 is determined by the value contained in the interrupt priority bits, INT1IP (INTCON3<6>) and INT2IP (INTCON3<7>). There is no priority bit associated with INT0. It is always a high-priority interrupt source. In 8-bit mode (which is the default), an overflow in the TMR0 register (FFh 00h) will set flag bit, TMR0IF. In 16-bit mode, an overflow in the TMR0H:TMR0L register pair (FFFFh 0000h) will set TMR0IF. The interrupt can be enabled/disabled by setting/clearing enable bit, TMR0IE (INTCON<5>). Interrupt priority for Timer0 is determined by the value contained in the interrupt priority bit, TMR0IP (INTCON2<2>). See Section 12.0 "Timer0 Module" for further details on the Timer0 module.
10.8
PORTB Interrupt-on-Change
An input change on PORTB<7:4> sets flag bit, RBIF (INTCON<0>). The interrupt can be enabled/disabled by setting/clearing enable bit, RBIE (INTCON<3>). Interrupt priority for PORTB interrupt-on-change is determined by the value contained in the interrupt priority bit, RBIP (INTCON2<0>).
10.9
Context Saving During Interrupts
During interrupts, the return PC address is saved on the stack. Additionally, the WREG, STATUS and BSR registers are saved on the fast return stack. If a fast return from interrupt is not used (see Section 6.3 "Data Memory Organization"), the user may need to save the WREG, STATUS and BSR registers on entry to the Interrupt Service Routine. Depending on the user's application, other registers may also need to be saved. Example 10-1 saves and restores the WREG, STATUS and BSR registers during an Interrupt Service Routine.
EXAMPLE 10-1:
SAVING STATUS, WREG AND BSR REGISTERS IN RAM
; W_TEMP is in virtual bank ; STATUS_TEMP located anywhere ; BSR_TMEP located anywhere
MOVWF W_TEMP MOVFF STATUS, STATUS_TEMP MOVFF BSR, BSR_TEMP ; ; USER ISR CODE ; MOVFF BSR_TEMP, BSR MOVF W_TEMP, W MOVFF STATUS_TEMP, STATUS
; Restore BSR ; Restore WREG ; Restore STATUS
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NOTES:
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11.0 I/O PORTS
Depending on the device selected and features enabled, there are up to five ports available. Some pins of the I/O ports are multiplexed with an alternate function from the peripheral features on the device. In general, when a peripheral is enabled, that pin may not be used as a general purpose I/O pin. Each port has three registers for its operation. These registers are: * TRIS register (Data Direction register) * PORT register (reads the levels on the pins of the device) * LAT register (Data Latch register) The Data Latch (LAT register) is useful for read-modifywrite operations on the value that the I/O pins are driving. A simplified model of a generic I/O port, without the interfaces to other peripherals, is shown in Figure 11-1. Reading the PORTA register reads the status of the pins, whereas writing to it, will write to the port latch. The Data Latch (LATA) register is also memory mapped. Read-modify-write operations on the LATA register read and write the latched output value for PORTA. The RA4 pin is multiplexed with the Timer0 module clock input and one of the comparator outputs to become the RA4/T0CKI/C1OUT pin. Pins RA6 and RA7 are multiplexed with the main oscillator pins. They are enabled as oscillator or I/O pins by the selection of the main oscillator in the Configuration register (see Section 24.1 "Configuration Bits" for details). When they are not used as port pins, RA6 and RA7 and their associated TRIS and LAT bits are read as `0'. The other PORTA pins are multiplexed with analog inputs, the analog VREF+ and VREF- inputs and the comparator voltage reference output. The operation of pins RA<3:0> and RA5 as A/D converter inputs is selected by clearing or setting the control bits in the ADCON1 register (A/D Control Register 1). Pins RA0 through RA5 may also be used as comparator inputs or outputs by setting the appropriate bits in the CMCON register. To use RA<3:0> as digital inputs, it is also necessary to turn off the comparators. Note:
D CK Data Latch D WR TRIS CK TRIS Latch RD TRIS Input Buffer Q Q I/O pin(1)
FIGURE 11-1:
GENERIC I/O PORT OPERATION
RD LAT Data Bus WR LAT or PORT
On a Power-on Reset, RA5 and RA<3:0> are configured as analog inputs and read as `0'. RA4 is configured as a digital input.
The RA4/T0CKI/C1OUT pin is a Schmitt Trigger input. All other PORTA pins have TTL input levels and full CMOS output drivers. The TRISA register controls the direction of the PORTA pins, even when they are being used as analog inputs. The user must ensure the bits in the TRISA register are maintained set when using them as analog inputs.
EXAMPLE 11-1:
CLRF
Q D
INITIALIZING PORTA
Initialize PORTA by clearing output data latches Alternate method to clear output data latches Configure all A/D for digital inputs Configure comparators for digital input Value used to initialize data direction Set RA<7:6,3:0> as inputs RA<5:4> as outputs
CLRF
EN EN RD PORT Note 1: I/O pins have diode protection to VDD and VSS.
11.1
PORTA, TRISA and LATA Registers
MOVLW MOVWF MOVWF MOVWF MOVLW
PORTA is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISA. Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISA bit (= 0) will make the corresponding PORTA pin an output (i.e., put the contents of the output latch on the selected pin).
MOVWF
; ; ; LATA ; ; ; 0Fh ; ADCON1 ; 07h ; CMCON ; 0CFh ; ; ; TRISA ; ;
PORTA
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TABLE 11-1:
Pin RA0/AN0
PORTA I/O SUMMARY
Function RA0 AN0 TRIS Setting 0 1 1 0 1 AN1 1 0 1 AN2 VREFCVREF 1 1 x 0 1 AN3 VREF+ 1 1 0 1 T0CKI C1OUT 1 0 0 1 AN4 SS HLVDIN C2OUT 1 1 1 0 0 1 OSC2 CLKO x x 0 1 OSC1 CLKI x x I/O O I I O I I O I I I O O I I I O I I O O I I I I O O I O O O I I I I/O Type DIG TTL ANA DIG TTL ANA DIG TTL ANA ANA ANA DIG TTL ANA ANA DIG ST ST DIG DIG TTL ANA TTL ANA DIG DIG TTL ANA DIG DIG TTL ANA ANA Description LATA<0> data output; not affected by analog input. PORTA<0> data input; disabled when analog input enabled. A/D Input Channel 0 and Comparator C1- input. Default input configuration on POR; does not affect digital output. LATA<1> data output; not affected by analog input. PORTA<1> data input; disabled when analog input enabled. A/D Input Channel 1 and Comparator C2- input. Default input configuration on POR; does not affect digital output. LATA<2> data output; not affected by analog input. Disabled when CVREF output enabled. PORTA<2> data input. Disabled when analog functions enabled; disabled when CVREF output enabled. A/D Input Channel 2 and Comparator C2+ input. Default input configuration on POR; not affected by analog output. A/D and comparator voltage reference low input. Comparator voltage reference output. Enabling this feature disables digital I/O. LATA<3> data output; not affected by analog input. PORTA<3> data input; disabled when analog input enabled. A/D Input Channel 3 and Comparator C1+ input. Default input configuration on POR. A/D and comparator voltage reference high input. LATA<4> data output. PORTA<4> data input; default configuration on POR. Timer0 clock input. Comparator 1 output; takes priority over port data. LATA<5> data output; not affected by analog input. PORTA<5> data input; disabled when analog input enabled. A/D Input Channel 4. Default configuration on POR. Slave Select input for MSSP (MSSP module). High/Low-Voltage Detect external trip point input. Comparator 2 output; takes priority over port data. LATA<6> data output. Enabled in RCIO, INTIO2 and ECIO modes only. PORTA<6> data input. Enabled in RCIO, INTIO2 and ECIO modes only. Main oscillator feedback output connection (XT, HS and LP modes). System cycle clock output (FOSC/4) in RC, INTIO1 and EC Oscillator modes. LATA<7> data output. Disabled in external oscillator modes. PORTA<7> data input. Disabled in external oscillator modes. Main oscillator input connection. Main clock input connection.
RA1/AN1
RA1
RA2/AN2/ VREF-/CVREF
RA2
RA3/AN3/VREF+
RA3
RA4/T0CKI/C1OUT
RA4
RA5/AN4/SS/ HLVDIN/C2OUT
RA5
OSC2/CLKO/RA6
RA6
OSC1/CLKI/RA7
RA7
Legend:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; x = Don't care (TRIS bit does not affect port direction or is overridden for this option).
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TABLE 11-2:
Name PORTA LATA TRISA ADCON1 CMCON CVRCON
SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Bit 7 RA7(1) LATA7 -- C2OUT CVREN
(1)
Bit 6 RA6(1)
Bit 5 RA5
Bit 4 RA4
Bit 3 RA3
Bit 2 RA2
Bit 1 RA1
Bit 0 RA0
Reset Values on page 58 58 58 57 57 57
LATA6(1) PORTA Data Latch Register (Read and Write to Data Latch) -- C1OUT CVROE VCFG1 C2INV CVRR VCFG0 C1INV CVRSS PCFG3 CIS CVR3 PCFG2 CM2 CVR2 PCFG1 CM1 CVR1 PCFG0 CM0 CVR0
TRISA7(1) TRISA6(1) PORTA Data Direction Register
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTA. Note 1: RA<7:6> and their associated latch and data direction bits are enabled as I/O pins based on oscillator configuration; otherwise, they are read as `0'.
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11.2 PORTB, TRISB and LATB Registers
Four of the PORTB pins (RB<7:4>) have an interrupton-change feature. Only pins configured as inputs can cause this interrupt to occur (i.e., any RB<7:4> pin configured as an output is excluded from the interrupton-change comparison). The input pins (of RB<7:4>) are compared with the old value latched on the last read of PORTB. The "mismatch" outputs of RB<7:4> are ORed together to generate the RB Port Change Interrupt with Flag bit, RBIF (INTCON<0>). This interrupt can wake the device from Sleep mode or any of the Idle modes. The user, in the Interrupt Service Routine, can clear the interrupt in the following manner: a) b) c) Any read or write of PORTB (except with the MOVFF (ANY), PORTB instruction). 1 TCY. Clear flag bit, RBIF.
PORTB is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISB. Setting a TRISB bit (= 1) will make the corresponding PORTB pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISB bit (= 0) will make the corresponding PORTB pin an output (i.e., put the contents of the output latch on the selected pin). The Data Latch register (LATB) is also memory mapped. Read-modify-write operations on the LATB register read and write the latched output value for PORTB.
EXAMPLE 11-2:
CLRF PORTB ; ; ; LATB ; ; ; 0Fh ; ADCON1 ; ; ; 0CFh ; ; ; TRISB ; ; ;
INITIALIZING PORTB
Initialize PORTB by clearing output data latches Alternate method to clear output data latches Set RB<4:0> as digital I/O pins (required if config bit PBADEN is set) Value used to initialize data direction Set RB<3:0> as inputs RB<5:4> as outputs RB<7:6> as inputs
CLRF
MOVLW MOVWF
A mismatch condition will continue to set flag bit, RBIF. Reading PORTB and waiting 1 TCY will end the mismatch condition and allow flag bit, RBIF, to be cleared. Also, if the port pin returns to its original state, the mismatch condition will be cleared. The interrupt-on-change feature is recommended for wake-up on key depression operation and operations where PORTB is only used for the interrupt-on-change feature. Polling of PORTB is not recommended while using the interrupt-on-change feature. RB3 can be configured by the Configuration bit, CCP2MX, as the alternate peripheral pin for the CCP2 module (CCP2MX = 0).
MOVLW
MOVWF
Each of the PORTB pins has a weak internal pull-up. A single control bit can turn on all the pull-ups. This is performed by clearing bit, RBPU (INTCON2<7>). The weak pull-up is automatically turned off when the port pin is configured as an output. The pull-ups are disabled on a Power-on Reset. Note: On a Power-on Reset, RB<4:0> are configured as analog inputs by default and read as `0'; RB<7:5> are configured as digital inputs. By clearing the Configuration bit, PBADEN, RB<4:0> will alternatively be configured as digital inputs on POR.
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TABLE 11-3:
Pin RB0/INT0/FLT0/ AN12
PORTB I/O SUMMARY
Function RB0 TRIS Setting 0 1 INT0 FLT0 AN12 1 1 1 0 1 INT1 AN10 1 1 0 1 INT2 AN8 1 1 0 1 AN9 CCP2
(2)
I/O O I I I I O I I I O I I I O I I O I O I I I O I I I O I I I O I I O I
I/O Type DIG TTL ST ST ANA DIG TTL ST ANA DIG TTL ST ANA DIG TTL ANA DIG ST DIG TTL TTL ANA DIG TTL TTL ST DIG TTL TTL ST DIG TTL TTL DIG ST
Description LATB<0> data output; not affected by analog input. PORTB<0> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) External Interrupt 0 input. Enhanced PWM Fault input (ECCP1 module); enabled in software. A/D Input Channel 12.(1) LATB<1> data output; not affected by analog input. PORTB<1> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) External Interrupt 1 input. A/D Input Channel 10.(1) LATB<2> data output; not affected by analog input. PORTB<2> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) External Interrupt 2 input. A/D Input Channel 8.(1) LATB<3> data output; not affected by analog input. PORTB<3> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) A/D Input Channel 9.(1) CCP2 compare and PWM output. CCP2 capture input. LATB<4> data output; not affected by analog input. PORTB<4> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) Interrupt-on-change pin. A/D Input Channel 11.(1) LATB<5> data output. PORTB<5> data input; weak pull-up when RBPU bit is cleared. Interrupt-on-change pin. Single-Supply Programming mode entry (ICSPTM). Enabled by LVP Configuration bit; all other pin functions disabled. LATB<6> data output. PORTB<6> data input; weak pull-up when RBPU bit is cleared. Interrupt-on-change pin. Serial execution (ICSPTM) clock input for ICSP and ICD operation.(3) LATB<7> data output. PORTB<7> data input; weak pull-up when RBPU bit is cleared. Interrupt-on-change pin. Serial execution data output for ICSP and ICD operation.(3) Serial execution data input for ICSP and ICD operation.(3)
RB1/INT1/AN10
RB1
RB2/INT2/AN8
RB2
RB3/AN9/CCP2
RB3
1 0 1 0 1
RB4/KBI0/AN11
RB4
KBI0 AN11 RB5/KBI1/PGM RB5 KBI1 PGM RB6/KBI2/PGC RB6 KBI2 PGC RB7/KBI3/PGD RB7 KBI3 PGD Legend: Note 1: 2: 3:
1 1 0 1 1 x 0 1 1 x 0 1 1 x x
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). Configuration on POR is determined by the PBADEN Configuration bit. Pins are configured as analog inputs by default when PBADEN is set and digital inputs when PBADEN is cleared. Alternate assignment for CCP2 when the CCP2MX Configuration bit is `0'. Default assignment is RC1. All other pin functions are disabled when ICSP or ICD are enabled.
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TABLE 11-4:
Name PORTB LATB TRISB INTCON INTCON2 INTCON3 ADCON1
SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Bit 7 RB7 Bit 6 RB6 Bit 5 RB5 Bit 4 RB4 Bit 3 RB3 Bit 2 RB2 Bit 1 RB1 Bit 0 RB0 Reset Values on page 58 58 58 INT0IE INT2IE VCFG0 RBIE -- INT1IE PCFG3 TMR0IF TMR0IP -- PCFG2 INT0IF -- INT2IF PCFG1 RBIF RBIP INT1IF PCFG0 55 55 55 57
PORTB Data Latch Register (Read and Write to Data Latch) PORTB Data Direction Register GIE/GIEH PEIE/GIEL RBPU INT2IP -- INT1IP -- TMR0IE -- VCFG1 INTEDG0 INTEDG1 INTEDG2
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTB.
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11.3 PORTC, TRISC and LATC Registers
Note: On a Power-on Reset, these pins are configured as digital inputs.
PORTC is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISC. Setting a TRISC bit (= 1) will make the corresponding PORTC pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISC bit (= 0) will make the corresponding PORTC pin an output (i.e., put the contents of the output latch on the selected pin). The Data Latch register (LATC) is also memory mapped. Read-modify-write operations on the LATC register read and write the latched output value for PORTC. PORTC is multiplexed with several peripheral functions (Table 11-5). The pins have Schmitt Trigger input buffers. RC1 is normally configured by Configuration bit, CCP2MX, as the default peripheral pin of the CCP2 module (default/erased state, CCP2MX = 1). When enabling peripheral functions, care should be taken in defining TRIS bits for each PORTC pin. Some peripherals override the TRIS bit to make a pin an output, while other peripherals override the TRIS bit to make a pin an input. The user should refer to the corresponding peripheral section for additional information.
The contents of the TRISC register are affected by peripheral overrides. Reading TRISC always returns the current contents, even though a peripheral device may be overriding one or more of the pins.
EXAMPLE 11-3:
CLRF PORTC ; ; ; ; ; ; ; ; ; ; ; ;
INITIALIZING PORTC
Initialize PORTC by clearing output data latches Alternate method to clear output data latches Value used to initialize data direction Set RC<3:0> as inputs RC<5:4> as outputs RC<7:6> as inputs
CLRF
LATC
MOVLW
0CFh
MOVWF
TRISC
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TABLE 11-5:
Pin RC0/T1OSO/ T13CKI
PORTC I/O SUMMARY
Function RC0 T1OSO T13CKI TRIS Setting 0 1 x 1 0 1 T1OSI CCP2(1) x 0 1 0 1 CCP1 P1A(2) 0 1 0 I/O O I O I O I I O I O I O I O I/O Type DIG ST ANA ST DIG ST ANA DIG ST DIG ST DIG ST DIG LATC<0> data output. PORTC<0> data input. Timer1 oscillator output; enabled when Timer1 oscillator enabled. Disables digital I/O. Timer1/Timer3 counter input. LATC<1> data output. PORTC<1> data input. Timer1 oscillator input; enabled when Timer1 oscillator enabled. Disables digital I/O. CCP2 compare and PWM output; takes priority over port data. CCP2 capture input. LATC<2> data output. PORTC<2> data input. CCP1 compare or PWM output; takes priority over port data. CCP1 capture input. ECCP1 Enhanced PWM output, Channel A. May be configured for tri-state during Enhanced PWM shutdown events. Takes priority over port data. LATC<3> data output. PORTC<3> data input. SPI clock output (MSSP module); takes priority over port data. SPI clock input (MSSP module). I2CTM clock output (MSSP module); takes priority over port data. I2C clock input (MSSP module); input type depends on module setting. LATC<4> data output. PORTC<4> data input. SPI data input (MSSP module). I2C data output (MSSP module); takes priority over port data. LATC<5> data output. PORTC<5> data input. SPI data output (MSSP module); takes priority over port data. LATC<6> data output. PORTC<6> data input. Asynchronous serial transmit data output (EUSART module); takes priority over port data. User must configure as output. Synchronous serial clock output (EUSART module); takes priority over port data. Synchronous serial clock input (EUSART module). LATC<7> data output. PORTC<7> data input. Asynchronous serial receive data input (EUSART module). Synchronous serial data output (EUSART module); takes priority over port data. Synchronous serial data input (EUSART module). User must configure as an input. Description
RC1/T1OSI/CCP2
RC1
RC2/CCP1/P1A
RC2
RC3/SCK/SCL
RC3 SCK SCL
0 1 0 1 0 1 0 1 1 1 1 0 1 0 0 1 1 1 1
O I O I O I O I I O I O I O O I O O I O I I O I
DIG ST DIG ST DIG I2C/SMB DIG ST ST DIG DIG ST DIG DIG ST DIG DIG ST DIG ST ST DIG ST
RC4/SDI/SDA
RC4 SDI SDA
I2C/SMB I2C data input (MSSP module); input type depends on module setting.
RC5/SDO
RC5 SDO
RC6/TX/CK
RC6 TX CK
RC7/RX/DT
RC7 RX DT
0 1 1 1 1
Legend: Note 1: 2:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; I2C/SMB = I2C/SMBus input buffer; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). Default assignment for CCP2 when the CCP2MX Configuration bit is set. Alternate assignment is RB3. Enhanced PWM output is available only on PIC18F4221/4321 devices.
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TABLE 11-6:
Name PORTC LATC TRISC
SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Bit 7 RC7 Bit 6 RC6 Bit 5 RC5 Bit 4 RC4 Bit 3 RC3 Bit 2 RC2 Bit 1 RC1 Bit 0 RC0 Reset Values on page 58 58 58
PORTC Data Latch Register (Read and Write to Data Latch) PORTC Data Direction Register
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11.4
Note:
PORTD, TRISD and LATD Registers
PORTD is only available on 40/44-pin devices.
PORTD is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISD. Setting a TRISD bit (= 1) will make the corresponding PORTD pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISD bit (= 0) will make the corresponding PORTD pin an output (i.e., put the contents of the output latch on the selected pin). The Data Latch register (LATD) is also memory mapped. Read-modify-write operations on the LATD register read and write the latched output value for PORTD. All pins on PORTD are implemented with Schmitt Trigger input buffers. Each pin is individually configurable as an input or output. Three of the PORTD pins are multiplexed with outputs P1B, P1C and P1D of the Enhanced CCP module. The operation of these additional PWM output pins is covered in greater detail in Section 17.0 "Enhanced Capture/Compare/PWM (ECCP) Module". Note: On a Power-on Reset, these pins are configured as digital inputs.
PORTD can also be configured as an 8-bit wide microprocessor port (Parallel Slave Port) by setting control bit, PSPMODE (TRISE<4>). In this mode, the input buffers are TTL. See Section 11.6 "Parallel Slave Port" for additional information on the Parallel Slave Port (PSP). Note: When the Enhanced PWM mode is used with either dual or quad outputs, the PSP functions of PORTD are automatically disabled.
EXAMPLE 11-4:
CLRF PORTD ; ; ; ; ; ; ; ; ; ; ; ;
INITIALIZING PORTD
Initialize PORTD by clearing output data latches Alternate method to clear output data latches Value used to initialize data direction Set RD<3:0> as inputs RD<5:4> as outputs RD<7:6> as inputs
CLRF
LATD
MOVLW
0CFh
MOVWF
TRISD
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TABLE 11-7:
Pin RD0/PSP0
PORTD I/O SUMMARY
Function RD0 PSP0 TRIS Setting 0 1 x x 0 1 PSP1 x x 0 1 PSP2 x x 0 1 PSP3 x x 0 1 PSP4 x x 0 1 PSP5 P1B x x 0 I/O O I O I O I O I O I O I O I O I O I O I O I O I O I/O Type DIG ST DIG TTL DIG ST DIG TTL DIG ST DIG TTL DIG ST DIG TTL DIG ST DIG TTL DIG ST DIG TTL DIG LATD<0> data output. PORTD<0> data input. PSP read data output (LATD<0>); takes priority over port data. PSP write data input. LATD<1> data output. PORTD<1> data input. PSP read data output (LATD<1>); takes priority over port data. PSP write data input. LATD<2> data output. PORTD<2> data input. PSP read data output (LATD<2>); takes priority over port data. PSP write data input. LATD<3> data output. PORTD<3> data input. PSP read data output (LATD<3>); takes priority over port data. PSP write data input. LATD<4> data output. PORTD<4> data input. PSP read data output (LATD<4>); takes priority over port data. PSP write data input. LATD<5> data output. PORTD<5> data input. PSP read data output (LATD<5>); takes priority over port data. PSP write data input. ECCP1 Enhanced PWM output, Channel B; takes priority over port and PSP data. May be configured for tri-state during Enhanced PWM shutdown events. LATD<6> data output. PORTD<6> data input. PSP read data output (LATD<6>); takes priority over port data. PSP write data input. ECCP1 Enhanced PWM output, channel C; takes priority over port and PSP data. May be configured for tri-state during Enhanced PWM shutdown events. LATD<7> data output. PORTD<7> data input. PSP read data output (LATD<7>); takes priority over port data. PSP write data input. ECCP1 Enhanced PWM output, Channel D; takes priority over port and PSP data. May be configured for tri-state during Enhanced PWM shutdown events. Description
RD1/PSP1
RD1
RD2/PSP2
RD2
RD3/PSP3
RD3
RD4/PSP4
RD4
RD5/PSP5/P1B
RD5
RD6/PSP6/P1C
RD6 PSP6 P1C
0 1 x x 0
O I O I O
DIG ST DIG TTL DIG
RD7/PSP7/P1D
RD7 PSP7 P1D
0 1 x x 0
O I O I O
DIG ST DIG TTL DIG
Legend:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; x = Don't care (TRIS bit does not affect port direction or is overridden for this option).
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TABLE 11-8:
Name PORTD LATD TRISD TRISE CCP1CON
SUMMARY OF REGISTERS ASSOCIATED WITH PORTD
Bit 7 RD7 Bit 6 RD6 Bit 5 RD5 Bit 4 RD4 Bit 3 RD3 Bit 2 RD2 Bit 1 RD1 Bit 0 RD0 Reset Values on page 58 58 58 PSPMODE DC1B0 -- CCP1M3 TRISE2 CCP1M2 TRISE1 CCP1M1 TRISE0 CCP1M0 58 57
PORTD Data Latch Register (Read and Write to Data Latch) PORTD Data Direction Register IBF P1M1 OBF P1M0 IBOV DC1B1
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTD.
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11.5 PORTE, TRISE and LATE Registers
The fourth pin of PORTE (MCLR/VPP/RE3) is an input only pin. Its operation is controlled by the MCLRE Configuration bit. When selected as a port pin (MCLRE = 0), it functions as a digital input only pin; as such, it does not have TRIS or LAT bits associated with its operation. Otherwise, it functions as the device's Master Clear input. In either configuration, RE3 also functions as the programming voltage input during programming. Note: On a Power-on Reset, RE3 is enabled as a digital input only if Master Clear functionality is disabled.
Depending on the particular PIC18F2221/2321/4221/ 4321 family device selected, PORTE is implemented in two different ways. For 40/44-pin devices, PORTE is a 4-bit wide port. Three pins (RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/ AN7) are individually configurable as inputs or outputs. These pins have Schmitt Trigger input buffers. When selected as analog inputs, these pins will read as `0'. The corresponding Data Direction register is TRISE. Setting a TRISE bit (= 1) will make the corresponding PORTE pin an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing a TRISE bit (= 0) will make the corresponding PORTE pin an output (i.e., put the contents of the output latch on the selected pin). TRISE controls the direction of the RE pins, even when they are being used as analog inputs. The user must make sure to keep the pins configured as inputs when using them as analog inputs. Note: On a Power-on Reset, RE<2:0> are configured as analog inputs.
EXAMPLE 11-5:
CLRF ; ; ; LATE ; ; ; 0Fh ; ADCON1 ; 03h ; ; ; TRISE ; ; ; PORTE
INITIALIZING PORTE
Initialize PORTE by clearing output data latches Alternate method to clear output data latches Configure A/D for digital inputs Value used to initialize data direction Set RE<0> as inputs RE<1> as outputs RE<2> as inputs
CLRF
MOVLW MOVWF MOVLW
MOVWF
The upper four bits of the TRISE register also control the operation of the Parallel Slave Port. Their operation is explained in Register 11-1. The Data Latch register (LATE) is also memory mapped. Read-modify-write operations on the LATE register, read and write the latched output value for PORTE.
11.5.1
PORTE IN 28-PIN DEVICES
For 28-pin devices, PORTE is only available when Master Clear functionality is disabled (MCLRE = 0). In these cases, PORTE is a single bit, input only port comprised of RE3 only. The pin operates as previously described.
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REGISTER 11-1: TRISE REGISTER (40/44-PIN DEVICES ONLY)
R-0 IBF bit 7 bit 7 IBF: Input Buffer Full Status bit 1 = A word has been received and waiting to be read by the CPU 0 = No word has been received OBF: Output Buffer Full Status bit 1 = The output buffer still holds a previously written word 0 = The output buffer has been read IBOV: Input Buffer Overflow Detect bit (in Microprocessor mode) 1 = A write occurred when a previously input word has not been read (must be cleared in software) 0 = No overflow occurred PSPMODE: Parallel Slave Port Mode Select bit 1 = Parallel Slave Port mode 0 = General Purpose I/O mode Unimplemented: Read as `0' TRISE2: RE2 Direction Control bit 1 = Input 0 = Output TRISE1: RE1 Direction Control bit 1 = Input 0 = Output TRISE0: RE0 Direction Control bit 1 = Input 0 = Output Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R-0 OBF R/W-0 IBOV R/W-0 PSPMODE U-0 -- R/W-1 TRISE2 R/W-1 TRISE1 R/W-1 TRISE0 bit 0
bit 6
bit 5
bit 4
bit 3 bit 2
bit 1
bit 0
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TABLE 11-9:
Pin RE0/RD/AN5
PORTE I/O SUMMARY
Function RE0 RD AN5 TRIS Setting 0 1 1 1 0 1 WR AN6 1 1 0 1 CS AN7 1 1 -- -- --(2) I/O O I I I O I I I O I I I I I I I/O Type DIG ST TTL ANA DIG ST TTL ANA DIG ST TTL ANA ST ANA ST Description LATE<0> data output; not affected by analog input. PORTE<0> data input; disabled when analog input enabled. PSP read enable input (PSP enabled). A/D Input Channel 5; default input configuration on POR. LATE<1> data output; not affected by analog input. PORTE<1> data input; disabled when analog input enabled. PSP write enable input (PSP enabled). A/D Input Channel 6; default input configuration on POR. LATE<2> data output; not affected by analog input. PORTE<2> data input; disabled when analog input enabled. PSP write enable input (PSP enabled). A/D Input Channel 7; default input configuration on POR. External Master Clear input; enabled when MCLRE Configuration bit is set. High-voltage detection; used for ICSPTM mode entry detection. Always available, regardless of pin mode. PORTE<3> data input; enabled when MCLRE Configuration bit is clear.
RE1/WR/AN6
RE1
RE2/CS/AN7
RE2
MCLR/VPP/RE3(1)
MCLR VPP RE3
Legend: Note 1: 2:
DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). RE3 is available on both 28-pin and 40/44-pin devices. All other PORTE pins are only implemented on 40/44-pin devices. RE3 does not have a corresponding TRIS bit to control data direction.
TABLE 11-10: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE
Name PORTE LATE
(2)
Bit 7 -- -- IBF --
Bit 6 -- -- OBF --
Bit 5 -- -- IBOV VCFG1
Bit 4 -- -- PSPMODE VCFG0
Bit 3 RE3(1,2) -- -- PCFG3
Bit 2 RE2
Bit 1 RE1
Bit 0 RE0
Reset Values on page 58 58 58 57
PORTE Data Latch Register (Read and Write to Data Latch) TRISE2 PCFG2 TRISE1 PCFG1 TRISE0 PCFG0
TRISE ADCON1
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTE. Note 1: Implemented only when Master Clear functionality is disabled (MCLRE Configuration bit = 0). 2: RE3 is the only PORTE bit implemented on both 28-pin and 40/44-pin devices. All other bits are implemented only when PORTE is implemented (i.e., 40/44-pin devices).
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11.6
Note:
Parallel Slave Port
The Parallel Slave Port is only available on 40/44-pin devices.
The timing for the control signals in Write and Read modes is shown in Figure 11-3 and Figure 11-4, respectively.
In addition to its function as a general I/O port, PORTD can also operate as an 8-bit wide Parallel Slave Port (PSP) or microprocessor port. PSP operation is controlled by the 4 upper bits of the TRISE register (Register 11-1). Setting control bit, PSPMODE (TRISE<4>), enables PSP operation as long as the Enhanced CCP module is not operating in Dual Output or Quad Output PWM mode. In Slave mode, the port is asynchronously readable and writable by the external world. The PSP can directly interface to an 8-bit microprocessor data bus. The external microprocessor can read or write the PORTD latch as an 8-bit latch. Setting the control bit, PSPMODE, enables the PORTE I/O pins to become control inputs for the microprocessor port. When set, port pin RE0 is the RD input, RE1 is the WR input and RE2 is the CS (Chip Select) input. For this functionality, the corresponding data direction bits of the TRISE register (TRISE<2:0>) must be configured as inputs (set). The A/D port configuration bits, PFCG<3:0> (ADCON1<3:0>), must also be set to a value in the range of `1010' through `1111'. A write to the PSP occurs when both the CS and WR lines are first detected low and ends when either are detected high. The PSPIF and IBF flag bits are both set when the write ends. A read from the PSP occurs when both the CS and RD lines are first detected low. The data in PORTD is read out and the OBF bit is clear. If the user writes new data to PORTD to set OBF, the data is immediately read out; however, the OBF bit is not set. When either the CS or RD lines are detected high, the PORTD pins return to the input state and the PSPIF bit is set. User applications should wait for PSPIF to be set before servicing the PSP. When this happens, the IBF and OBF bits can be polled and the appropriate action taken.
FIGURE 11-2:
PORTD AND PORTE BLOCK DIAGRAM (PARALLEL SLAVE PORT)
One bit of PORTD
Data Bus
D CK
Q RDx pin
WR LATD or WR PORTD
Data Latch Q D EN EN
TTL
RD PORTD
RD LATD
Set Interrupt Flag PSPIF (PIR1<7>)
PORTE Pins Read TTL RD CS WR
Chip Select TTL Write TTL
Note:
I/O pins have diode protection to VDD and VSS.
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FIGURE 11-3: PARALLEL SLAVE PORT WRITE WAVEFORMS
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
CS WR RD PORTD<7:0> IBF OBF PSPIF
FIGURE 11-4:
PARALLEL SLAVE PORT READ WAVEFORMS
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
CS WR RD PORTD<7:0> IBF OBF PSPIF
TABLE 11-11: REGISTERS ASSOCIATED WITH PARALLEL SLAVE PORT
Name PORTD LATD TRISD PORTE LATE TRISE INTCON PIR1 PIE1 IPR1 ADCON1 Legend: Note 1: Bit 7 RD7 Bit 6 RD6 Bit 5 RD5 Bit 4 RD4 Bit 3 RD3 Bit 2 RD2 Bit 1 RD1 Bit 0 RD0 Reset Values on page 58 58 58 -- -- PSPMODE INT0IE TXIF TXIE TXIP VCFG0 RE3 -- -- RBIE SSPIF SSPIE SSPIP PCFG3 RE2 RE1 RE0 58 58 58 55 58 58 58 57 PORTE Data Latch Register (Read and Write to Data Latch) TRISE2 TMR0IF CCP1IF CCP1IE CCP1IP PCFG2 TRISE1 INT0IF TMR2IF TMR2IE TMR2IP PCFG1 TRISE0 RBIF TMR1IF TMR1IE TMR1IP PCFG0
PORTD Data Latch Register (Read and Write to Data Latch) PORTD Data Direction Register -- -- IBF GIE/GIEH PSPIF(1) PSPIE(1) PSPIP(1) -- -- -- OBF PEIE/GIEL ADIF ADIE ADIP -- -- -- IBOV TMR0IF RCIF RCIE RCIP VCFG1
-- = unimplemented, read as `0'. Shaded cells are not used by the Parallel Slave Port. These bits are unimplemented on 28-pin devices and read as `0'.
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NOTES:
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12.0 TIMER0 MODULE
The Timer0 module incorporates the following features: * Software selectable operation as a timer or counter in both 8-bit or 16-bit modes * Readable and writable registers * Dedicated 8-bit, software programmable prescaler * Selectable clock source (internal or external) * Edge select for external clock * Interrupt-on-overflow The T0CON register (Register 12-1) controls all aspects of the module's operation, including the prescale selection. It is both readable and writable. A simplified block diagram of the Timer0 module in 8-bit mode is shown in Figure 12-1. Figure 12-2 shows a simplified block diagram of the Timer0 module in 16-bit mode.
REGISTER 12-1:
T0CON: TIMER0 CONTROL REGISTER
R/W-1 TMR0ON bit 7 R/W-1 T08BIT R/W-1 T0CS R/W-1 T0SE R/W-1 PSA R/W-1 T0PS2 R/W-1 T0PS1 R/W-1 T0PS0 bit 0
bit 7
TMR0ON: Timer0 On/Off Control bit 1 = Enables Timer0 0 = Stops Timer0 T08BIT: Timer0 8-Bit/16-Bit Control bit 1 = Timer0 is configured as an 8-bit timer/counter 0 = Timer0 is configured as a 16-bit timer/counter T0CS: Timer0 Clock Source Select bit 1 = Transition on T0CKI pin 0 = Internal instruction cycle clock (CLKO) T0SE: Timer0 Source Edge Select bit 1 = Increment on high-to-low transition on T0CKI pin 0 = Increment on low-to-high transition on T0CKI pin PSA: Timer0 Prescaler Assignment bit 1 = TImer0 prescaler is NOT assigned. Timer0 clock input bypasses prescaler. 0 = Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output. T0PS<2:0>: Timer0 Prescaler Select bits 111 = 1:256 Prescale value 110 = 1:128 Prescale value 101 = 1:64 Prescale value 100 = 1:32 Prescale value 011 = 1:16 Prescale value 010 = 1:8 Prescale value 001 = 1:4 Prescale value 000 = 1:2 Prescale value Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5
bit 4
bit 3
bit 2-0
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12.1 Timer0 Operation
Timer0 can operate as either a timer or a counter; the mode is selected with the T0CS bit (T0CON<5>). In Timer mode (T0CS = 0), the module increments on every clock by default unless a different prescaler value is selected (see Section 12.3 "Prescaler"). If the TMR0 register is written to, the increment is inhibited for the following two instruction cycles. The user can work around this by writing an adjusted value to the TMR0 register. The Counter mode is selected by setting the T0CS bit (= 1). In this mode, Timer0 increments either on every rising or falling edge of pin RA4/T0CKI. The incrementing edge is determined by the Timer0 Source Edge Select bit, T0SE (T0CON<4>); clearing this bit selects the rising edge. Restrictions on the external clock input are discussed below. An external clock source can be used to drive Timer0; however, it must meet certain requirements to ensure that the external clock can be synchronized with the internal phase clock (TOSC). There is a delay between synchronization and the onset of incrementing the timer/counter.
12.2
Timer0 Reads and Writes in 16-Bit Mode
TMR0H is not the actual high byte of Timer0 in 16-bit mode; it is actually a buffered version of the real high byte of Timer0 which is not directly readable nor writable (refer to Figure 12-2). TMR0H is updated with the contents of the high byte of Timer0 during a read of TMR0L. This provides the ability to read all 16 bits of Timer0 without having to verify that the read of the high and low byte were valid, due to a rollover between successive reads of the high and low byte. Similarly, a write to the high byte of Timer0 must also take place through the TMR0H Buffer register. The high byte is updated with the contents of TMR0H when a write occurs to TMR0L. This allows all 16 bits of Timer0 to be updated at once.
FIGURE 12-1:
TIMER0 BLOCK DIAGRAM (8-BIT MODE)
FOSC/4 0 1 1 Sync with Internal Clocks (2 TOSC Delay) 8 8 Internal Data Bus TMR0L Set TMR0IF on Overflow
T0CKI pin T0SE T0CS T0PS<2:0> PSA
Programmable Prescaler 3
0
Note:
Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
FIGURE 12-2:
FOSC/4
TIMER0 BLOCK DIAGRAM (16-BIT MODE)
0 1 1 Sync with Internal Clocks (2 TOSC Delay) Read TMR0L Write TMR0L 8 8 TMR0H 8 8 Internal Data Bus TMR0L TMR0 High Byte 8 Set TMR0IF on Overflow
T0CKI pin T0SE T0CS T0PS<2:0> PSA
Programmable Prescaler 3
0
Note:
Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.
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12.3 Prescaler
12.3.1
An 8-bit counter is available as a prescaler for the Timer0 module. The prescaler is not directly readable or writable; its value is set by the PSA and T0PS<2:0> bits (T0CON<3:0>) which determine the prescaler assignment and prescale ratio. Clearing the PSA bit assigns the prescaler to the Timer0 module. When it is assigned, prescale values from 1:2 through 1:256 in power-of-2 increments are selectable. When assigned to the Timer0 module, all instructions writing to the TMR0 register (e.g., CLRF TMR0, MOVWF TMR0, BSF TMR0, etc.) clear the prescaler count. Note: Writing to TMR0 when the prescaler is assigned to Timer0 will clear the prescaler count but will not change the prescaler assignment.
SWITCHING PRESCALER ASSIGNMENT
The prescaler assignment is fully under software control and can be changed "on-the-fly" during program execution.
12.4
Timer0 Interrupt
The TMR0 interrupt is generated when the TMR0 register overflows from FFh to 00h in 8-bit mode, or from FFFFh to 0000h in 16-bit mode. This overflow sets the TMR0IF flag bit. The interrupt can be masked by clearing the TMR0IE bit (INTCON<5>). Before reenabling the interrupt, the TMR0IF bit must be cleared in software by the Interrupt Service Routine. Since Timer0 is shut down in Sleep mode, the TMR0 interrupt cannot awaken the processor from Sleep.
TABLE 12-1:
Name TMR0L TMR0H INTCON T0CON TRISA
REGISTERS ASSOCIATED WITH TIMER0
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page 56 56 INT0IE T0SE RA4 RBIE PSA RA3 TMR0IF T0PS2 RA2 INT0IF T0PS1 RA1 RBIF T0PS0 RA0 55 56 58 T0CS RA5
Timer0 Register Low Byte Timer0 Register High Byte GIE/GIEH PEIE/GIEL TMR0IE TMR0ON RA7(1) T08BIT RA6(1)
Legend: Shaded cells are not used by Timer0. Note 1: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'.
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NOTES:
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13.0 TIMER1 MODULE
The Timer1 timer/counter module incorporates these features: * Software selectable operation as a 16-bit timer or counter * Readable and writable 8-bit registers (TMR1H and TMR1L) * Selectable clock source (internal or external) with device clock or Timer1 oscillator internal options * Interrupt-on-overflow * Reset on CCP Special Event Trigger * Device clock status flag (T1RUN) A simplified block diagram of the Timer1 module is shown in Figure 13-1. A block diagram of the module's operation in Read/Write mode is shown in Figure 13-2. The module incorporates its own low-power oscillator to provide an additional clocking option. The Timer1 oscillator can also be used as a low-power clock source for the microcontroller in power-managed operation. Timer1 can also be used to provide Real-Time Clock (RTC) functionality to applications with only a minimal addition of external components and code overhead. Timer1 is controlled through the T1CON Control register (Register 13-1). It also contains the Timer1 Oscillator Enable bit (T1OSCEN). Timer1 can be enabled or disabled by setting or clearing control bit, TMR1ON (T1CON<0>).
REGISTER 13-1:
T1CON: TIMER1 CONTROL REGISTER
R/W-0 RD16 bit 7 R-0 T1RUN R/W-0 T1CKPS1 R/W-0 T1CKPS0 R/W-0 T1OSCEN R/W-0 T1SYNC R/W-0 TMR1CS R/W-0 TMR1ON bit 0
bit 7
RD16: 16-Bit Read/Write Mode Enable bit 1 = Enables register read/write of TImer1 in one 16-bit operation 0 = Enables register read/write of Timer1 in two 8-bit operations T1RUN: Timer1 System Clock Status bit 1 = Device clock is derived from Timer1 oscillator 0 = Device clock is derived from another source T1CKPS<1:0>: Timer1 Input Clock Prescale Select bits 11 = 1:8 Prescale value 10 = 1:4 Prescale value 01 = 1:2 Prescale value 00 = 1:1 Prescale value T1OSCEN: Timer1 Oscillator Enable bit 1 = Timer1 oscillator is enabled 0 = Timer1 oscillator is shut off The oscillator inverter and feedback resistor are turned off to eliminate power drain. T1SYNC: Timer1 External Clock Input Synchronization Select bit When TMR1CS = 1: 1 = Do not synchronize external clock input 0 = Synchronize external clock input When TMR1CS = 0: This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0. TMR1CS: Timer1 Clock Source Select bit 1 = External clock from pin RC0/T1OSO/T13CKI (on the rising edge) 0 = Internal clock (FOSC/4) TMR1ON: Timer1 On bit 1 = Enables Timer1 0 = Stops Timer1 Legend: R = Readable bit -n = Value at POR
bit 6
bit 5-4
bit 3
bit 2
bit 1
bit 0
W = Writable bit `1' = Bit is set
U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
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13.1 Timer1 Operation
Timer1 can operate in one of these modes: * Timer * Synchronous Counter * Asynchronous Counter The operating mode is determined by the clock select bit, TMR1CS (T1CON<1>). When TMR1CS is cleared (= 0), Timer1 increments on every internal instruction cycle (Fosc/4). When the bit is set, Timer1 increments on every rising edge of the Timer1 external clock input or the Timer1 oscillator, if enabled. When Timer1 is enabled, the RC1/T1OSI and RC0/ T1OSO/T13CKI pins become inputs. This means the values of TRISC<1:0> are ignored and the pins are read as `0'.
FIGURE 13-1:
TIMER1 BLOCK DIAGRAM
Timer1 Oscillator On/Off Timer1 Clock Input 1 FOSC/4 Internal Clock T1OSCEN(1) T1CKPS<1:0> T1SYNC TMR1ON TMR1CS Prescaler 1, 2, 4, 8 0 2 Peripheral Clock Timer1 On/Off 1 Synchronize Detect
T1OSO/T13CKI
0
T1OSI
Clear TMR1 (CCP Special Event Trigger)
TMR1L
TMR1 High Byte
Set TMR1IF on Overflow
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
FIGURE 13-2:
TIMER1 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Oscillator Timer1 Clock Input 1 FOSC/4 Internal Clock T1OSCEN(1) T1CKPS<1:0> T1SYNC TMR1ON TMR1CS Prescaler 1, 2, 4, 8 0 2 Peripheral Clock Timer1 On/Off 1 Synchronize Detect 0
T1OSO/T13CKI
T1OSI
Clear TMR1 (CCP Special Event Trigger)
TMR1L
TMR1 High Byte 8
Set TMR1IF on Overflow
Read TMR1L Write TMR1L 8 8 TMR1H 8 8 Internal Data Bus
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
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13.2 Timer1 16-Bit Read/Write Mode
TABLE 13-1:
Osc Type LP Timer1 can be configured for 16-bit reads and writes (see Figure 13-2). When the RD16 control bit (T1CON<7>) is set, the address for TMR1H is mapped to a buffer register for the high byte of Timer1. A read from TMR1L will load the contents of the high byte of Timer1 into the Timer1 high byte buffer. This provides the user with the ability to accurately read all 16 bits of Timer1 without having to determine whether a read of the high byte, followed by a read of the low byte, has become invalid due to a rollover between reads. A write to the high byte of Timer1 must also take place through the TMR1H Buffer register. The Timer1 high byte is updated with the contents of TMR1H when a write occurs to TMR1L. This allows a user to write all 16 bits to both the high and low bytes of Timer1 at once. The high byte of Timer1 is not directly readable or writable in this mode. All reads and writes must take place through the Timer1 High Byte Buffer register. Writes to TMR1H do not clear the Timer1 prescaler. The prescaler is only cleared on writes to TMR1L.
CAPACITOR SELECTION FOR THE TIMER OSCILLATOR
Freq 32 kHz 27 C1 pF(1) C2 27 pF(1)
Note 1: Microchip suggests these values as a starting point in validating the oscillator circuit. 2: Higher capacitance increases the stability of the oscillator but also increases the start-up time. 3: Since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components. 4: Capacitor values are for design guidance only.
13.3.1
USING TIMER1 AS A CLOCK SOURCE
13.3
Timer1 Oscillator
An on-chip crystal oscillator circuit is incorporated between pins T1OSI (input) and T1OSO (amplifier output). It is enabled by setting the Timer1 Oscillator Enable bit, T1OSCEN (T1CON<3>). The oscillator is a low-power circuit rated for 32 kHz crystals. It will continue to run during all power-managed modes. The circuit for a typical LP oscillator is shown in Figure 13-3. Table 13-1 shows the capacitor selection for the Timer1 oscillator. The user must provide a software time delay to ensure proper start-up of the Timer1 oscillator.
The Timer1 oscillator is also available as a clock source in power-managed modes. By setting the clock select bits, SCS<1:0> (OSCCON<1:0>), to `01', the device switches to SEC_RUN mode; both the CPU and peripherals are clocked from the Timer1 oscillator. If the IDLEN bit (OSCCON<7>) is cleared and a SLEEP instruction is executed, the device enters SEC_IDLE mode. Additional details are available in Section 4.0 "Power-Managed Modes". Whenever the Timer1 oscillator is providing the clock source, the Timer1 system clock status flag, T1RUN (T1CON<6>), is set. This can be used to determine the controller's current clocking mode. It can also indicate the clock source being currently used by the Fail-Safe Clock Monitor. If the Clock Monitor is enabled and the Timer1 oscillator fails while providing the clock, polling the T1RUN bit will indicate whether the clock is being provided by the Timer1 oscillator or another source.
FIGURE 13-3:
EXTERNAL COMPONENTS FOR THE TIMER1 LP OSCILLATOR
PIC18FXXXX
T1OSI XTAL 32.768 kHz T1OSO
C1 27 pF
13.3.2
LOW-POWER TIMER1 OPTION
C2 27 pF Note: See the Notes with Table 13-1 for additional information about capacitor selection.
The Timer1 oscillator can operate at two distinct levels of power consumption based on device configuration. When the LPT1OSC Configuration bit is set, the Timer1 oscillator operates in a low-power mode. When LPT1OSC is not set, Timer1 operates at a higher power level. Power consumption for a particular mode is relatively constant, regardless of the device's operating mode. The default Timer1 configuration is the higher power mode. As the low-power Timer1 mode tends to be more sensitive to interference, high noise environments may cause some oscillator instability. The low-power option is, therefore, best suited for low noise applications where power conservation is an important design consideration.
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13.3.3 TIMER1 OSCILLATOR LAYOUT CONSIDERATIONS
13.5
Resetting Timer1 Using the CCP Special Event Trigger
The Timer1 oscillator circuit draws very little power during operation. Due to the low-power nature of the oscillator, it may also be sensitive to rapidly changing signals in close proximity. The oscillator circuit, shown in Figure 13-3, should be located as close as possible to the microcontroller. There should be no circuits passing within the oscillator circuit boundaries other than VSS or VDD. If a high-speed circuit must be located near the oscillator (such as the CCP1 pin in Output Compare or PWM mode, or the primary oscillator using the OSC2 pin), a grounded guard ring around the oscillator circuit, as shown in Figure 13-4, may be helpful when used on a single-sided PCB or in addition to a ground plane.
If either of the CCP modules is configured to use Timer1 and generate a Special Event Trigger in Compare mode (CCP1M<3:0> or CCP2M<3:0> = 1011), this signal will reset Timer1. The trigger from CCP2 will also start an A/D conversion if the A/D module is enabled (see Section 16.3.4 "Special Event Trigger" for more information). The module must be configured as either a timer or a synchronous counter to take advantage of this feature. When used this way, the CCPRH:CCPRL register pair effectively becomes a period register for Timer1. If Timer1 is running in Asynchronous Counter mode, this Reset operation may not work. In the event that a write to Timer1 coincides with a Special Event Trigger, the write operation will take precedence. Note: The Special Event Triggers from the CCP2 module will not set the TMR1IF interrupt flag bit (PIR1<0>).
FIGURE 13-4:
OSCILLATOR CIRCUIT WITH GROUNDED GUARD RING
VDD VSS OSC1 OSC2
13.6
Using Timer1 as a Real-Time Clock
RC0 RC1
RC2 Note: Not drawn to scale.
Adding an external LP oscillator to Timer1 (such as the one described in Section 13.3 "Timer1 Oscillator") gives users the option to include RTC functionality to their applications. This is accomplished with an inexpensive watch crystal to provide an accurate time base and several lines of application code to calculate the time. When operating in Sleep mode and using a battery or supercapacitor as a power source, it can completely eliminate the need for a separate RTC device and battery backup. The application code routine, RTCisr, shown in Example 13-1, demonstrates a simple method to increment a counter at one-second intervals using an Interrupt Service Routine. Incrementing the TMR1 register pair to overflow, triggers the interrupt and calls the routine, which increments the seconds counter by one. Additional counters for minutes and hours are incremented as the previous counter overflow. Since the register pair is 16 bits wide, counting up to overflow the register directly from a 32.768 kHz clock would take 2 seconds. To force the overflow at the required one-second intervals, it is necessary to preload it. The simplest method is to set the MSb of TMR1H with a BSF instruction. Note that the TMR1L register is never preloaded or altered. Doing so may introduce cumulative errors over many cycles. For this method to be accurate, Timer1 must operate in Asynchronous mode and the Timer1 overflow interrupt must be enabled (PIE1<0> = 1), as shown in the routine, RTCinit. The Timer1 oscillator must also be enabled and running at all times.
13.4
Timer1 Interrupt
The TMR1 register pair (TMR1H:TMR1L) increments from 0000h to FFFFh and rolls over to 0000h. The Timer1 interrupt, if enabled, is generated on overflow which is latched in interrupt flag bit, TMR1IF (PIR1<0>). This interrupt can be enabled or disabled by setting or clearing the Timer1 Interrupt Enable bit, TMR1IE (PIE1<0>).
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EXAMPLE 13-1:
RTCinit MOVLW MOVWF CLRF MOVLW MOVWF CLRF CLRF MOVLW MOVWF BSF RETURN RTCisr BSF BCF INCF MOVLW CPFSGT RETURN CLRF INCF MOVLW CPFSGT RETURN CLRF INCF MOVLW CPFSGT RETURN CLRF RETURN TMR1H, 7 PIR1, TMR1IF secs, F .59 secs secs mins, F .59 mins mins hours, F .23 hours hours ; ; ; ; ; ; ; ; ; ; ; ; Preload for 1 sec overflow Clear interrupt flag Increment seconds 60 seconds elapsed? No, done Clear seconds Increment minutes 60 minutes elapsed? No, done clear minutes Increment hours 24 hours elapsed? 80h TMR1H TMR1L b'00001111' T1CON secs mins .12 hours PIE1, TMR1IE ; Preload TMR1 register pair ; for 1 second overflow ; Configure for external clock, ; Asynchronous operation, external oscillator ; Initialize timekeeping registers ;
IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE
; Enable Timer1 interrupt
; No, done ; Reset hours ; Done
TABLE 13-2:
Name INTCON PIR1 PIE1 IPR1 TMR1L TMR1H T1CON
REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER
Bit 7 Bit 6 Bit 5 TMR0IE RCIF RCIE RCIP Bit 4 INT0IE TXIF TXIE TXIP Bit 3 RBIE SSPIF SSPIE SSPIP Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP Bit 1 INT0IF TMR2IF TMR2IE TMR2IP Bit 0 RBIF TMR1IF TMR1IE TMR1IP Reset Values on page 55 58 58 58 56 56 TMR1CS TMR1ON 56
GIE/GIEH PEIE/GIEL PSPIF(1) PSPIE(1) PSPIP(1) ADIF ADIE ADIP
Timer1 Register Low Byte Timer1 Register High Byte RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC
Legend: Shaded cells are not used by the Timer1 module. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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NOTES:
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14.0 TIMER2 MODULE
14.1 Timer2 Operation
The Timer2 timer module incorporates the following features: * 8-bit timer and period registers (TMR2 and PR2, respectively) * Readable and writable (both registers) * Software programmable prescaler (1:1, 1:4 and 1:16) * Software programmable postscaler (1:1 through 1:16) * Interrupt on TMR2 to PR2 match * Optional use as the shift clock for the MSSP module The module is controlled through the T2CON register (Register 14-1), which enables or disables the timer and configures the prescaler and postscaler. Timer2 can be shut off by clearing control bit, TMR2ON (T2CON<2>), to minimize power consumption. A simplified block diagram of the module is shown in Figure 14-1. In normal operation, TMR2 is incremented from 00h on each clock (FOSC/4). A 4-bit counter/prescaler on the clock input gives direct input, divide-by-4 and divide-by16 prescale options. These are selected by the prescaler control bits, T2CKPS<1:0> (T2CON<1:0>). The value of TMR2 is compared to that of the Period register, PR2, on each clock cycle. When the two values match, the comparator generates a match signal as the timer output. This signal also resets the value of TMR2 to 00h on the next cycle and drives the output counter/postscaler (see Section 14.2 "Timer2 Interrupt"). The TMR2 and PR2 registers are both directly readable and writable. The TMR2 register is cleared on any device Reset, while the PR2 register initializes at FFh. Both the prescaler and postscaler counters are cleared on the following events: * a write to the TMR2 register * a write to the T2CON register * any device Reset (Power-on Reset, MCLR Reset, Watchdog Timer Reset or Brown-out Reset) TMR2 is not cleared when T2CON is written.
REGISTER 14-1:
T2CON: TIMER2 CONTROL REGISTER
U-0 -- bit 7 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 T2CKPS0 bit 0 T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1
bit 7 bit 6-3
Unimplemented: Read as `0' T2OUTPS<3:0>: Timer2 Output Postscale Select bits 0000 = 1:1 Postscale 0001 = 1:2 Postscale * * * 1111 = 1:16 Postscale TMR2ON: Timer2 On bit 1 = Timer2 is on 0 = Timer2 is off T2CKPS<1:0>: Timer2 Clock Prescale Select bits 00 = Prescaler is 1 01 = Prescaler is 4 1x = Prescaler is 16 Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 2
bit 1-0
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14.2 Timer2 Interrupt 14.3 Timer2 Output
Timer2 can also generate an optional device interrupt. The Timer2 output signal (TMR2 to PR2 match) provides the input for the 4-bit output counter/postscaler. This counter generates the TMR2 match interrupt flag which is latched in TMR2IF (PIR1<1>). The interrupt is enabled by setting the TMR2 Match Interrupt Enable bit, TMR2IE (PIE1<1>). A range of 16 postscale options (from 1:1 through 1:16 inclusive) can be selected with the postscaler control bits, T2OUTPS<3:0> (T2CON<6:3>). The unscaled output of TMR2 is available primarily to the CCP modules, where it is used as a time base for operations in PWM mode. Timer2 can be optionally used as the shift clock source for the MSSP module operating in SPI mode. Additional information is provided in Section 18.0 "Master Synchronous Serial Port (MSSP) Module".
FIGURE 14-1:
TIMER2 BLOCK DIAGRAM
4 2 TMR2/PR2 Match Comparator 8 PR2
8
T2OUTPS<3:0> T2CKPS<1:0>
1:1 to 1:16 Postscaler
Set TMR2IF TMR2 Output (to PWM or MSSP)
FOSC/4
1:1, 1:4, 1:16 Prescaler
Reset TMR2
8
Internal Data Bus
TABLE 14-1:
Name
REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER
Bit 6 Bit 5 TMR0IE RCIF RCIE RCIP Bit 4 INT0IE TXIF TXIE TXIP Bit 3 RBIE SSPIF SSPIE SSPIP Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP Bit 1 INT0IF TMR2IF TMR2IE TMR2IP Bit 0 RBIF TMR1IF TMR1IE TMR1IP Reset Values on page 55 58 58 58 56 T2CKPS1 T2CKPS0 56 56
Bit 7
INTCON GIE/GIEH PEIE/GIEL PIR1 PIE1 IPR1 TMR2 T2CON PR2 PSPIF(1) PSPIE(1) PSPIP(1) -- ADIF ADIE ADIP
Timer2 Register T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON Timer2 Period Register
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the Timer2 module. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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15.0 TIMER3 MODULE
The Timer3 timer/counter module incorporates these features: * Software selectable operation as a 16-bit timer or counter * Readable and writable 8-bit registers (TMR3H and TMR3L) * Selectable clock source (internal or external) with device clock or Timer1 oscillator internal options * Interrupt-on-overflow * Module Reset on CCP Special Event Trigger A simplified block diagram of the Timer3 module is shown in Figure 15-1. A block diagram of the module's operation in Read/Write mode is shown in Figure 15-2. The Timer3 module is controlled through the T3CON register (Register 15-1). It also selects the clock source options for the CCP modules (see Section 16.1.1 "CCP Modules and Timer Resources" for more information).
REGISTER 15-1:
T3CON: TIMER3 CONTROL REGISTER
R/W-0 RD16 bit 7 R/W-0 T3CCP2 R/W-0 T3CKPS1 R/W-0 T3CKPS0 R/W-0 T3CCP1 R/W-0 T3SYNC R/W-0 TMR3CS R/W-0 TMR3ON bit 0
bit 7
RD16: 16-Bit Read/Write Mode Enable bit 1 = Enables register read/write of Timer3 in one 16-bit operation 0 = Enables register read/write of Timer3 in two 8-bit operations T3CCP<2:1>: Timer3 and Timer1 to CCPx Enable bits 1x = Timer3 is the capture/compare clock source for the CCP modules 01 = Timer3 is the capture/compare clock source for CCP2; Timer1 is the capture/compare clock source for CCP1 00 = Timer1 is the capture/compare clock source for the CCP modules T3CKPS<1:0>: Timer3 Input Clock Prescale Select bits 11 = 1:8 Prescale value 10 = 1:4 Prescale value 01 = 1:2 Prescale value 00 = 1:1 Prescale value T3SYNC: Timer3 External Clock Input Synchronization Control bit (Not usable if the device clock comes from Timer1/Timer3.) When TMR3CS = 1: 1 = Do not synchronize external clock input 0 = Synchronize external clock input When TMR3CS = 0: This bit is ignored. Timer3 uses the internal clock when TMR3CS = 0. TMR3CS: Timer3 Clock Source Select bit 1 = External clock input from Timer1 oscillator or T13CKI (on the rising edge after the first falling edge) 0 = Internal clock (FOSC/4) TMR3ON: Timer3 On bit 1 = Enables Timer3 0 = Stops Timer3 Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6,3
bit 5-4
bit 2
bit 1
bit 0
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15.1 Timer3 Operation
Timer3 can operate in one of three modes: * Timer * Synchronous Counter * Asynchronous Counter The operating mode is determined by the clock select bit, TMR3CS (T3CON<1>). When TMR3CS is cleared (= 0), Timer3 increments on every internal instruction cycle (FOSC/4). When the bit is set, Timer3 increments on every rising edge of the Timer1 external clock input or the Timer1 oscillator, if enabled. As with Timer1, the RC1/T1OSI and RC0/T1OSO/ T13CKI pins become inputs when the Timer1 oscillator is enabled. This means the values of TRISC<1:0> are ignored and the pins are read as `0'.
FIGURE 15-1:
TIMER3 BLOCK DIAGRAM (8-BIT READ/WRITE MODE)
Timer1 Oscillator Timer1 Clock Input 1 FOSC/4 Internal Clock T1OSCEN T3SYNC TMR3ON
(1)
1 Synchronize Detect 0
T1OSO/T13CKI
Prescaler 1, 2, 4, 8 0 2
T1OSI
TMR3CS
Sleep Input
T3CKPS<1:0>
Timer3 On/Off
CCP1/CCP2 Special Event Trigger CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
TMR3L
TMR3 High Byte
Set TMR3IF on Overflow
Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
FIGURE 15-2:
TIMER3 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)
Timer1 Oscillator Timer1 Clock Input 1 FOSC/4 Internal Clock T1OSCEN T3CKPS<1:0> T3SYNC TMR3ON
(1)
1 Synchronize Detect
T13CKI/T1OSO
Prescaler 1, 2, 4, 8 0 2
0
T1OSI
TMR3CS
Sleep Input
Timer3 On/Off
CCP1/CCP2 Special Event Trigger CCP1/CCP2 Select from T3CON<6,3>
Clear TMR3
TMR3L
TMR3 High Byte 8
Set TMR3IF on Overflow
Read TMR1L Write TMR1L 8 8 TMR3H 8 8 Internal Data Bus Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain.
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15.2 Timer3 16-Bit Read/Write Mode 15.4 Timer3 Interrupt
Timer3 can be configured for 16-bit reads and writes (see Figure 15-2). When the RD16 control bit (T3CON<7>) is set, the address for TMR3H is mapped to a buffer register for the high byte of Timer3. A read from TMR3L will load the contents of the high byte of Timer3 into the Timer3 High Byte Buffer register. This provides the user with the ability to accurately read all 16 bits of Timer1 without having to determine whether a read of the high byte, followed by a read of the low byte, has become invalid due to a rollover between reads. A write to the high byte of Timer3 must also take place through the TMR3H Buffer register. The Timer3 high byte is updated with the contents of TMR3H when a write occurs to TMR3L. This allows a user to write all 16 bits to both the high and low bytes of Timer3 at once. The high byte of Timer3 is not directly readable or writable in this mode. All reads and writes must take place through the Timer3 High Byte Buffer register. Writes to TMR3H do not clear the Timer3 prescaler. The prescaler is only cleared on writes to TMR3L. The TMR3 register pair (TMR3H:TMR3L) increments from 0000h to FFFFh and overflows to 0000h. The Timer3 interrupt, if enabled, is generated on overflow and is latched in interrupt flag bit, TMR3IF (PIR2<1>). This interrupt can be enabled or disabled by setting or clearing the Timer3 Interrupt Enable bit, TMR3IE (PIE2<1>).
15.5
Resetting Timer3 Using the CCP Special Event Trigger
If either of the CCP modules is configured to use Timer3 and to generate a Special Event Trigger in Compare mode (CCP1M<3:0> or CCP2M<3:0> = 1011), this signal will reset Timer3. It will also start an A/D conversion if the A/D module is enabled (see Section 16.3.4 "Special Event Trigger" for more information). The module must be configured as either a timer or synchronous counter to take advantage of this feature. When used this way, the CCPR2H:CCPR2L register pair effectively becomes a period register for Timer3. If Timer3 is running in Asynchronous Counter mode, the Reset operation may not work. In the event that a write to Timer3 coincides with a Special Event Trigger from a CCP module, the write will take precedence. Note: The Special Event Triggers from the CCP2 module will not set the TMR3IF interrupt flag bit (PIR2<1>).
15.3
Using the Timer1 Oscillator as the Timer3 Clock Source
The Timer1 internal oscillator may be used as the clock source for Timer3. The Timer1 oscillator is enabled by setting the T1OSCEN (T1CON<3>) bit. To use it as the Timer3 clock source, the TMR3CS bit must also be set. As previously noted, this also configures Timer3 to increment on every rising edge of the oscillator source. The Timer1 oscillator is described in Section 13.0 "Timer1 Module".
TABLE 15-1:
Name INTCON PIR2 PIE2 IPR2 TMR3L TMR3H T1CON T3CON
REGISTERS ASSOCIATED WITH TIMER3 AS A TIMER/COUNTER
Bit 7 Bit 6 Bit 5 TMR0IE -- -- -- Bit 4 INT0IE EEIF EEIE EEIP Bit 3 RBIE BCLIF BCLIE BCLIP Bit 2 TMR0IF HLVDIF HLVDIE HLVDIP Bit 1 INT0IF TMR3IF TMR3IE TMR3IP Bit 0 RBIF CCP2IF CCP2IE CCP2IP Reset Values on page 55 58 58 58 57 57 TMR1CS TMR3CS TMR1ON TMR3ON 56 57 T3CCP1 T3SYNC
GIE/GIEH PEIE/GIEL OSCFIF OSCFIE OSCFIP CMIF CMIE CMIP
Timer3 Register Low Byte Timer3 Register High Byte RD16 RD16 T1RUN T3CCP2 T1CKPS1 T1CKPS0 T1OSCEN T1SYNC T3CKPS1 T3CKPS0
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the Timer3 module.
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NOTES:
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16.0 CAPTURE/COMPARE/PWM (CCP) MODULES
The Capture and Compare operations described in this chapter apply to all standard and Enhanced CCP modules. Note: Throughout this section and Section 17.0 "Enhanced Capture/Compare/PWM (ECCP) Module", references to the register and bit names for CCP modules are referred to generically by the use of `x' or `y' in place of the specific module number. Thus, "CCPxCON" might refer to the control register for CCP1, CCP2 or ECCP1. "CCPxCON" is used throughout these sections to refer to the module control register, regardless of whether the CCP module is a standard or Enhanced implementation.
PIC18F2221/2321/4221/4321 family devices all have two CCP (Capture/Compare/PWM) modules. Each module contains a 16-bit register which can operate as a 16-bit Capture register, a 16-bit Compare register or a PWM Master/Slave Duty Cycle register. In 28-pin devices, the two standard CCP modules (CCP1 and CCP2) operate as described in this chapter. In 40/44-pin devices, CCP1 is implemented as an Enhanced CCP module with standard Capture and Compare modes and Enhanced PWM modes. The ECCP implementation is discussed in Section 17.0 "Enhanced Capture/Compare/PWM (ECCP) Module".
REGISTER 16-1:
CCPxCON REGISTER (CCP2 MODULE, CCP1 MODULE IN 28-PIN DEVICES)
U-0 -- bit 7 U-0 -- R/W-0 DCxB1 R/W-0 DCxB0 R/W-0 CCPxM3 R/W-0 CCPxM2 R/W-0 R/W-0 bit 0 CCPxM1 CCPxM0
bit 7-6 bit 5-4
Unimplemented: Read as `0' DCxB<1:0>: PWM Duty Cycle bit 1 and bit 0 for CCP Module x Capture mode: Unused. Compare mode: Unused. PWM mode: These bits are the two LSbs (bit 1 and bit 0) of the 10-bit PWM duty cycle. The eight MSbs (DCxB<9:2>) of the duty cycle are found in CCPRxL. CCPxM<3:0>: CCPx Module Mode Select bits 0000 = Capture/Compare/PWM disabled (resets CCP module) 0001 = Reserved 0010 = Compare mode, toggle output on match (CCPxIF bit is set) 0011 = Reserved 0100 = Capture mode, every falling edge 0101 = Capture mode, every rising edge 0110 = Capture mode, every 4th rising edge 0111 = Capture mode, every 16th rising edge 1000 = Compare mode: initialize CCP pin low; on compare match, force CCP pin high (CCPxIF bit is set) 1001 = Compare mode: initialize CCP pin high; on compare match, force CCP pin low (CCPxIF bit is set) 1010 = Compare mode: generate software interrupt on compare match (CCPxIF bit is set, CCP pin reflects I/O state) 1011 = Compare mode: trigger special event, reset timer, start A/D conversion on CCPx match (CCPxIF bit is set) 11xx = PWM mode Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 3-0
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16.1 CCP Module Configuration
Each Capture/Compare/PWM module is associated with a control register (generically, CCPxCON) and a data register (CCPRx). The data register, in turn, is comprised of two 8-bit registers: CCPRxL (low byte) and CCPRxH (high byte). All registers are both readable and writable. The assignment of a particular timer to a module is determined by the Timer to CCP enable bits in the T3CON register (Register 15-1). Both modules may be active at any given time and may share the same timer resource if they are configured to operate in the same mode (Capture/Compare or PWM) at the same time. The interactions between the two modules are summarized in Figure 16-1 and Figure 16-2. In Timer1 in Asynchronous Counter mode, the capture operation will not work.
16.1.1
CCP MODULES AND TIMER RESOURCES
16.1.2
CCP2 PIN ASSIGNMENT
The CCP modules utilize Timers 1, 2 or 3, depending on the mode selected. Timer1 and Timer3 are available to modules in Capture or Compare modes, while Timer2 is available for modules in PWM mode.
TABLE 16-1:
CCP MODE - TIMER RESOURCES
Timer Resource Timer1 or Timer3 Timer1 or Timer3 Timer2
The pin assignment for CCP2 (Capture input, Compare and PWM output) can change, based on device configuration. The CCP2MX Configuration bit determines which pin CCP2 is multiplexed to. By default, it is assigned to RC1 (CCP2MX = 1). If the Configuration bit is cleared, CCP2 is multiplexed with RB3. Changing the pin assignment of CCP2 does not automatically change any requirements for configuring the port pin. Users must always verify that the appropriate TRIS register is configured correctly for CCP2 operation, regardless of where it is located.
CCP/ECCP Mode Capture Compare PWM
TABLE 16-2:
Capture Capture
INTERACTIONS BETWEEN CCP1 AND CCP2 FOR TIMER RESOURCES
Interaction Each module can use TMR1 or TMR3 as the time base. The time base can be different for each CCP. CCP2 can be configured for the Special Event Trigger to reset TMR1 or TMR3 (depending upon which time base is used). Automatic A/D conversions on trigger event can also be done. Operation of CCP1 could be affected if it is using the same timer as a time base. CCP1 can be configured for the Special Event Trigger to reset TMR1 or TMR3 (depending upon which time base is used). Operation of CCP2 could be affected if it is using the same timer as a time base. Either module can be configured for the Special Event Trigger to reset the time base. Automatic A/D conversions on CCP2 trigger event can be done. Conflicts may occur if both modules are using the same time base. None None None None Both PWMs will have the same frequency and update rate (TMR2 interrupt). Capture Compare
CCP1 Mode CCP2 Mode
Compare
Capture
Compare
Compare
Capture Compare PWM(1) PWM
(1)
PWM(1) PWM(1) Capture Compare PWM
PWM(1) Note 1:
Includes standard and Enhanced PWM operation.
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16.2 Capture Mode
16.2.3 SOFTWARE INTERRUPT
In Capture mode, the CCPRxH:CCPRxL register pair captures the 16-bit value of the TMR1 or TMR3 registers when an event occurs on the corresponding CCPx pin. An event is defined as one of the following: * * * * every falling edge every rising edge every 4th rising edge every 16th rising edge When the Capture mode is changed, a false capture interrupt may be generated. The user should keep the CCPxIE interrupt enable bit clear to avoid false interrupts. The interrupt flag bit, CCPxIF, should also be cleared following any such change in operating mode.
16.2.4
CCP PRESCALER
The event is selected by the mode select bits, CCPxM<3:0> (CCPxCON<3:0>). When a capture is made, the interrupt request flag bit, CCPxIF, is set; it must be cleared in software. If another capture occurs before the value in register CCPRx is read, the old captured value is overwritten by the new captured value.
There are four prescaler settings in Capture mode. They are specified as part of the operating mode selected by the mode select bits (CCPxM<3:0>). Whenever the CCP module is turned off or Capture mode is disabled, the prescaler counter is cleared. This means that any Reset will clear the prescaler counter. Switching from one capture prescaler to another may generate an interrupt. Also, the prescaler counter will not be cleared; therefore, the first capture may be from a non-zero prescaler. Example 16-1 shows the recommended method for switching between capture prescalers. This example also clears the prescaler counter and will not generate the "false" interrupt.
16.2.1
CCP PIN CONFIGURATION
In Capture mode, the appropriate CCPx pin should be configured as an input by setting the corresponding TRIS direction bit. Note: If RB3/CCP2 or RC1/CCP2 is configured as an output, a write to the port can cause a capture condition.
EXAMPLE 16-1:
CHANGING BETWEEN CAPTURE PRESCALERS (CCP2 SHOWN)
; ; ; ; ; ; Turn CCP module off Load WREG with the new prescaler mode value and CCP ON Load CCP2CON with this value
16.2.2
TIMER1/TIMER3 MODE SELECTION
The timers that are to be used with the capture feature (Timer1 and/or Timer3) must be running in Timer mode or Synchronized Counter mode. In Asynchronous Counter mode, the capture operation will not work. The timer to be used with each CCP module is selected in the T3CON register (see Section 16.1.1 "CCP Modules and Timer Resources").
CLRF MOVLW
CCP2CON NEW_CAPT_PS
MOVWF
CCP2CON
FIGURE 16-1:
CAPTURE MODE OPERATION BLOCK DIAGRAM
Set CCP1IF T3CCP2 TMR3H TMR3 Enable CCPR1H TMR1 Enable TMR1H Set CCP2IF TMR3H TMR3 Enable CCPR2H TMR1 Enable T3CCP2 T3CCP1 TMR1H TMR1L CCPR2L TMR3L TMR1L CCPR1L TMR3L
CCP1 pin Prescaler / 1, 4, 16 and Edge Detect T3CCP2 CCP1CON<3:0> Q1:Q4 CCP2CON<3:0> 4 4 4 T3CCP1 T3CCP2
CCP2 pin Prescaler / 1, 4, 16 and Edge Detect
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16.3 Compare Mode
16.3.2 TIMER1/TIMER3 MODE SELECTION
In Compare mode, the 16-bit CCPRx register value is constantly compared against either the TMR1 or TMR3 register pair value. When a match occurs, the CCPx pin can be: * * * * driven high driven low toggled (high-to-low or low-to-high) remain unchanged (that is, reflects the state of the I/O latch) Timer1 and/or Timer3 must be running in Timer mode or Synchronized Counter mode if the CCP module is using the compare feature. In Asynchronous Counter mode, the compare operation may not work.
16.3.3
SOFTWARE INTERRUPT MODE
When the Generate Software Interrupt mode is chosen (CCPxM<3:0> = 1010), the corresponding CCPx pin is not affected. Only a CCP interrupt is generated, if enabled and the CCPxIE bit is set.
The action on the pin is based on the value of the mode select bits (CCPxM<3:0>). At the same time, the interrupt flag bit, CCPxIF, is set.
16.3.4
SPECIAL EVENT TRIGGER
16.3.1
CCP PIN CONFIGURATION
The user must configure the CCPx pin as an output by clearing the appropriate TRIS bit. Note: Clearing the CCP2CON register will force the RB3 or RC1 compare output latch (depending on device configuration) to the default low level. This is not the PORTB or PORTC I/O data latch.
Both CCP modules are equipped with a Special Event Trigger. This is an internal hardware signal generated in Compare mode to trigger actions by other modules. The Special Event Trigger is enabled by selecting the Compare Special Event Trigger mode (CCPxM<3:0> = 1011). For either CCP module, the Special Event Trigger resets the Timer register pair for whichever timer resource is currently assigned as the module's time base. This allows the CCPRx registers to serve as a programmable period register for either timer. The Special Event Trigger for CCP2 can also start an A/D conversion. In order to do this, the A/D converter must already be enabled.
FIGURE 16-2:
COMPARE MODE OPERATION BLOCK DIAGRAM
Set CCP1IF Special Event Trigger (Timer1/Timer3 Reset) CCP1 pin Comparator Compare Match Output Logic 4 CCP1CON<3:0> S R TRIS Output Enable Q
CCPR1H
CCPR1L
0
TMR1H
TMR1L
0 Special Event Trigger (Timer1/Timer3 Reset, A/D Trigger) T3CCP2 Set CCP2IF CCP2 pin Output Logic 4 CCP2CON<3:0> S R TRIS Output Enable Q
1
TMR3H T3CCP1
TMR3L
1
Comparator
Compare Match
CCPR2H
CCPR2L
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TABLE 16-3:
Name INTCON RCON PIR1 PIE1 IPR1 PIR2 PIE2 IPR2 TRISB TRISC TMR1L TMR1H T1CON TMR3H TMR3L T3CON CCPR1L CCPR1H CCP1CON CCPR2L CCPR2H CCP2CON
REGISTERS ASSOCIATED WITH CAPTURE, COMPARE, TIMER1 AND TIMER3
Bit 7 Bit 6 Bit 5 TMR0IE -- RCIF RCIE RCIP -- -- -- Bit 4 INT0IE RI TXIF TXIE TXIP EEIF EEIE EEIP Bit 3 RBIE TO SSPIF SSPIE SSPIP BCLIF BCLIE BCLIP Bit 2 TMR0IF PD CCP1IF CCP1IE CCP1IP HLVDIF HLVDIE HLVDIP Bit 1 INT0IF POR TMR2IF TMR2IE TMR2IP TMR3IF TMR3IE TMR3IP Bit 0 RBIF BOR TMR1IF TMR1IE TMR1IP CCP2IF CCP2IE CCP2IP Reset Values on page 55 54 58 58 58 58 58 58 58 58 56 56 TMR1CS TMR1ON 56 57 57 T3CCP1 T3SYNC TMR3CS TMR3ON 57 57 57 CCP1M3 CCP1M2 CCP1M1 CCP1M0 57 57 57 CCP2M3 CCP2M2 CCP2M1 CCP2M0 57
GIE/GIEH PEIE/GIEL IPEN PSPIF(2) PSPIE
(2)
SBOREN ADIF ADIE ADIP CMIF CMIE CMIP
(1)
PSPIP(2) OSCFIF OSCFIE OSCFIP
PORTB Data Direction Register PORTC Data Direction Register Timer1 Register Low Byte Timer1 Register High Byte RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC Timer3 Register High Byte Timer3 Register Low Byte RD16 T3CCP2 T3CKPS1 T3CKPS0 Capture/Compare/PWM Register 1 Low Byte Capture/Compare/PWM Register 1 High Byte P1M1(2) P1M0(2) DC1B1 DC1B0 Capture/Compare/PWM Register 2 Low Byte Capture/Compare/PWM Register 2 High Byte -- -- DC2B1 DC2B0
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by Capture/Compare, Timer1 or Timer3. Note 1: The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 5.4 "Brown-out Reset (BOR)". 2: These bits are unimplemented on 28-pin devices and read as `0'.
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16.4 PWM Mode
16.4.1 PWM PERIOD
In Pulse-Width Modulation (PWM) mode, the CCPx pin produces up to a 10-bit resolution PWM output. Since the CCP2 pin is multiplexed with a PORTB or PORTC data latch, the appropriate TRIS bit must be cleared to make the CCP2 pin an output. Note: Clearing the CCP2CON register will force the RB3 or RC1 output latch (depending on device configuration) to the default low level. This is not the PORTB or PORTC I/O data latch. The PWM period is specified by writing to the PR2 register. The PWM period can be calculated using the following formula:
EQUATION 16-1:
PWM Period = [(PR2) + 1] * 4 * TOSC * (TMR2 Prescale Value) PWM frequency is defined as 1/[PWM period]. When TMR2 is equal to PR2, the following three events occur on the next increment cycle: * TMR2 is cleared * The CCPx pin is set (exception: if PWM duty cycle = 0%, the CCPx pin will not be set) * The PWM duty cycle is latched from CCPRxL into CCPRxH Note: The Timer2 postscalers (see Section 14.0 "Timer2 Module") are not used in the determination of the PWM frequency. The postscaler could be used to have a servo update rate at a different frequency than the PWM output.
Figure 16-3 shows a simplified block diagram of the CCP module in PWM mode. For a step-by-step procedure on how to set up the CCP module for PWM operation, see Section 16.4.4 "Setup for PWM Operation".
FIGURE 16-3:
Duty Cycle Registers CCPRxL
SIMPLIFIED PWM BLOCK DIAGRAM
CCPxCON<5:4>
CCPRxH (Slave) CCPx Output Comparator (Note 1) S Comparator Corresponding TRIS bit R Q
16.4.2
PWM DUTY CYCLE
TMR2
The PWM duty cycle is specified by writing to the CCPRxL register and to the CCPxCON<5:4> bits. Up to 10-bit resolution is available. The CCPRxL contains the eight MSbs and the CCPxCON<5:4> contains the two LSbs. This 10-bit value is represented by CCPRxL:CCPxCON<5:4>. The following equation is used to calculate the PWM duty cycle in time:
PR2
Clear Timer, CCPx pin and latch D.C.
EQUATION 16-2:
PWM Duty Cycle = (CCPRXL:CCPXCON<5:4>) * TOSC * (TMR2 Prescale Value) CCPRxL and CCPxCON<5:4> can be written to at any time, but the duty cycle value is not latched into CCPRxH until after a match between PR2 and TMR2 occurs (i.e., the period is complete). In PWM mode, CCPRxH is a read-only register.
Note 1: The 8-bit TMR2 value is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit time base.
A PWM output (Figure 16-4) has a time base (period) and a time that the output stays high (duty cycle). The frequency of the PWM is the inverse of the period (1/period).
FIGURE 16-4:
Period
PWM OUTPUT
Duty Cycle TMR2 = PR2 TMR2 = Duty Cycle TMR2 = PR2
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The CCPRxH register and a 2-bit internal latch are used to double-buffer the PWM duty cycle. This double-buffering is essential for glitchless PWM operation. When the CCPRxH and 2-bit latch match TMR2, concatenated with an internal 2-bit Q clock or 2 bits of the TMR2 prescaler, the CCPx pin is cleared. The maximum PWM resolution (bits) for a given PWM frequency is given by the equation:
EQUATION 16-3:
FOSC log --------------- FPWM PWM Resolution (max) = -----------------------------bits log ( 2 ) Note: If the PWM duty cycle value is longer than the PWM period, the CCPx pin will not be cleared.
TABLE 16-4:
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
2.44 kHz 16 FFh 10 9.77 kHz 4 FFh 10 39.06 kHz 1 FFh 10 156.25 kHz 1 3Fh 8 312.50 kHz 1 1Fh 7 416.67 kHz 1 17h 6.58
PWM Frequency Timer Prescaler (1, 4, 16) PR2 Value Maximum Resolution (bits)
16.4.3
PWM AUTO-SHUTDOWN (CCP1 ONLY)
16.4.4
SETUP FOR PWM OPERATION
The PWM auto-shutdown features of the Enhanced CCP module are also available to CCP1 in 28-pin devices. The operation of this feature is discussed in detail in Section 17.4.7 "Enhanced PWM Auto-Shutdown". Auto-shutdown features are not available for CCP2.
The following steps should be taken when configuring the CCP module for PWM operation: 1. 2. 3. 4. 5. Set the PWM period by writing to the PR2 register. Set the PWM duty cycle by writing to the CCPRxL register and CCPxCON<5:4> bits. Make the CCPx pin an output by clearing the appropriate TRIS bit. Set the TMR2 prescale value, then enable Timer2 by writing to T2CON. Configure the CCPx module for PWM operation.
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TABLE 16-5:
Name INTCON RCON PIR1 PIE1 IPR1 TRISB TRISC TMR2 PR2 T2CON CCPR1L CCPR1H CCP1CON CCPR2L CCPR2H CCP2CON ECCP1AS ECCP1DEL
REGISTERS ASSOCIATED WITH PWM AND TIMER2
Bit 7 Bit 6 Bit 5 TMR0IE -- RCIF RCIE RCIP Bit 4 INT0IE RI TXIF TXIE TXIP Bit 3 RBIE TO SSPIF SSPIE SSPIP Bit 2 TMR0IF PD CCP1IF CCP1IE CCP1IP Bit 1 INT0IF POR TMR2IF TMR2IE TMR2IP Bit 0 RBIF BOR TMR1IF TMR1IE TMR1IP Reset Values on page 55 54 58 58 58 58 58 56 56 56 57 57 CCP1M3 CCP1M2 CCP1M1 CCP1M0 57 57 57 CCP2M3 PSSAC1 PDC3(2) CCP2M2 PDC2(2) CCP2M1 PDC1(2) CCP2M0 PDC0(2) 57 57 57 PSSAC0 PSSBD1(2) PSSBD0(2)
GIE/GIEH PEIE/GIEL IPEN PSPIF(2) PSPIE
(2)
SBOREN ADIF ADIE ADIP
(1)
PSPIP(2)
PORTB Data Direction Register PORTC Data Direction Register Timer2 Register Timer2 Period Register -- T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 Capture/Compare/PWM Register 1 Low Byte Capture/Compare/PWM Register 1 High Byte P1M1(2) P1M0(2) DC1B1 DC1B0 Capture/Compare/PWM Register 2 Low Byte Capture/Compare/PWM Register 2 High Byte -- PRSEN -- PDC6(2) DC2B1 ECCPAS1 PDC5(2) DC2B0 ECCPAS0 PDC4(2) ECCPASE ECCPAS2
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PWM or Timer2. Note 1: The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 5.4 "Brown-out Reset (BOR)". 2: These bits are unimplemented on 28-pin devices and read as `0'.
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17.0 ENHANCED CAPTURE/ COMPARE/PWM (ECCP) MODULE
The ECCP module is implemented only in 40/44-pin devices. Enhanced features are discussed in detail in Section 17.4 "Enhanced PWM Mode". Capture, Compare and single-output PWM functions of the ECCP module are the same as described for the standard CCP module. The control register for the Enhanced CCP module is shown in Register 17-1. It differs from the CCPxCON registers in PIC18F2221/2321 devices in that the two Most Significant bits are implemented to control PWM functionality.
Note:
In PIC18F4221/4321 devices, CCP1 is implemented as a standard CCP module with Enhanced PWM capabilities. These include the provision for 2 or 4 output channels, user-selectable polarity, dead-band control and automatic shutdown and restart. The
REGISTER 17-1:
CCP1CON REGISTER (ECCP1 MODULE, 40/44-PIN DEVICES)
R/W-0 P1M1 bit 7 R/W-0 P1M0 R/W-0 DC1B1 R/W-0 DC1B0 R/W-0 CCP1M3 R/W-0 CCP1M2 R/W-0 CCP1M1 R/W-0 CCP1M0 bit 0
bit 7-6
P1M<1:0>: Enhanced PWM Output Configuration bits If CCP1M<3:2> = 00, 01, 10: xx = P1A assigned as Capture/Compare input/output; P1B, P1C, P1D assigned as port pins If CCP1M<3:2> = 11: 00 = Single output: P1A modulated; P1B, P1C, P1D assigned as port pins 01 = Full-bridge output forward: P1D modulated; P1A active; P1B, P1C inactive 10 = Half-bridge output: P1A, P1B modulated with dead-band control; P1C, P1D assigned as port pins 11 = Full-bridge output reverse: P1B modulated; P1C active; P1A, P1D inactive DC1B<1:0>: PWM Duty Cycle bit 1 and bit 0 Capture mode: Unused. Compare mode: Unused. PWM mode: These bits are the two LSbs of the 10-bit PWM duty cycle. The eight MSbs of the duty cycle are found in CCPR1L. CCP1M<3:0>: Enhanced CCP Mode Select bits 0000 = Capture/Compare/PWM off (resets ECCP module) 0001 = Reserved 0010 = Compare mode, toggle output on match 0011 = Capture mode 0100 = Capture mode, every falling edge 0101 = Capture mode, every rising edge 0110 = Capture mode, every 4th rising edge 0111 = Capture mode, every 16th rising edge 1000 = Compare mode, initialize CCP1 pin low, set output on compare match (set CCP1IF) 1001 = Compare mode, initialize CCP1 pin high, clear output on compare match (set CCP1IF) 1010 = Compare mode, generate software interrupt only, CCP1 pin reverts to I/O state 1011 = Compare mode, trigger special event (ECCP resets TMR1 or TMR3, sets CC1IF bit) 1100 = PWM mode; P1A, P1C active-high; P1B, P1D active-high 1101 = PWM mode; P1A, P1C active-high; P1B, P1D active-low 1110 = PWM mode; P1A, P1C active-low; P1B, P1D active-high 1111 = PWM mode; P1A, P1C active-low; P1B, P1D active-low Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 5-4
bit 3-0
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In addition to the expanded range of modes available through the CCP1CON and ECCP1AS registers, the ECCP module has an additional register associated with Enhanced PWM operation and auto-shutdown features; it is: * ECCP1DEL (PWM Dead-Band Delay)
17.2
Capture and Compare Modes
17.1
ECCP Outputs and Configuration
Except for the operation of the Special Event Trigger discussed below, the Capture and Compare modes of the ECCP module are identical in operation to that of CCP2. These are discussed in detail in Section 16.2 "Capture Mode" and Section 16.3 "Compare Mode". No changes are required when moving between 28-pin and 40/44-pin devices.
The Enhanced CCP module may have up to four PWM outputs, depending on the selected operating mode. These outputs, designated P1A through P1D, are multiplexed with I/O pins on PORTC and PORTD. The outputs that are active depend on the CCP operating mode selected. The pin assignments are summarized in Table 17-1. To configure the I/O pins as PWM outputs, the proper PWM mode must be selected by setting the P1M<1:0> and CCP1M<3:0> bits. The appropriate TRISC and TRISD direction bits for the port pins must also be set as outputs.
17.2.1
SPECIAL EVENT TRIGGER
The Special Event Trigger output of ECCP1 resets the TMR1 or TMR3 register pair, depending on which timer resource is currently selected. This allows the CCPR1 register to effectively be a 16-bit programmable period register for Timer1 or Timer3.
17.3
Standard PWM Mode
17.1.1
ECCP MODULES AND TIMER RESOURCES
When configured in Single Output mode, the ECCP module functions identically to the standard CCP module in PWM mode, as described in Section 16.4 "PWM Mode". This is also sometimes referred to as "Compatible CCP" mode, as in Table 17-1. Note: When setting up single output PWM operations, users are free to use either of the processes described in Section 16.4.4 "Setup for PWM Operation" or Section 17.4.9 "Setup for PWM Operation". The latter is more generic and will work for either single or multi-output PWM.
Like the standard CCP modules, the ECCP module can utilize Timers 1, 2 or 3, depending on the mode selected. Timer1 and Timer3 are available for modules in Capture or Compare modes, while Timer2 is available for modules in PWM mode. Interactions between the standard and Enhanced CCP modules are identical to those described for standard CCP modules. Additional details on timer resources are provided in Section 16.1.1 "CCP Modules and Timer Resources".
TABLE 17-1:
ECCP Mode
PIN ASSIGNMENTS FOR VARIOUS ECCP1 MODES
CCP1CON Configuration 00xx 11xx 10xx 11xx x1xx 11xx RC2 All 40/44-pin devices: RD5 RD6 RD7
Compatible CCP Dual PWM Quad PWM
CCP1 P1A P1A
RD5/PSP5 P1B P1B
RD6/PSP6 RD6/PSP6 P1C
RD7/PSP7 RD7/PSP7 P1D
Legend: x = Don't care. Shaded cells indicate pin assignments not used by ECCP1 in a given mode.
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17.4 Enhanced PWM Mode
17.4.1 PWM PERIOD
The Enhanced PWM mode provides additional PWM output options for a broader range of control applications. The module is a backward compatible version of the standard CCP module and offers up to four outputs, designated P1A through P1D. Users are also able to select the polarity of the signal (either active-high or active-low). The module's output mode and polarity are configured by setting the P1M<1:0> and CCP1M<3:0> bits of the CCP1CON register. Figure 17-1 shows a simplified block diagram of PWM operation. All control registers are double-buffered and are loaded at the beginning of a new PWM cycle (the period boundary when Timer2 resets) in order to prevent glitches on any of the outputs. The exception is the PWM Dead-Band Delay register, ECCP1DEL, which is loaded at either the duty cycle boundary or the period boundary (whichever comes first). Because of the buffering, the module waits until the assigned timer resets, instead of starting immediately. This means that Enhanced PWM waveforms do not exactly match the standard PWM waveforms, but are instead offset by one full instruction cycle (4 TOSC). As before, the user must manually configure the appropriate TRIS bits for output. The PWM period is specified by writing to the PR2 register. The PWM period can be calculated using the following equation.
EQUATION 17-1:
PWM Period = [(PR2) + 1] * 4 * TOSC * (TMR2 Prescale Value)
PWM frequency is defined as 1/[PWM period]. When TMR2 is equal to PR2, the following three events occur on the next increment cycle: * TMR2 is cleared * The CCP1 pin is set (if PWM duty cycle = 0%, the CCP1 pin will not be set) * The PWM duty cycle is copied from CCPR1L into CCPR1H Note: The Timer2 postscaler (see Section 14.0 "Timer2 Module") is not used in the determination of the PWM frequency. The postscaler could be used to have a servo update rate at a different frequency than the PWM output.
FIGURE 17-1:
SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODULE
CCP1CON<5:4> P1M1<1:0> 2 CCP1M<3:0> 4 CCP1/P1A TRISx
Duty Cycle Registers CCPR1L
CCP1/P1A
CCPR1H (Slave) R Q
P1B Output Controller P1C TRISx
P1B
Comparator (Note 1)
TMR2
P1C TRISx
S P1D
Comparator
P1D TRISx
PR2
Clear Timer, set CCP1 pin and latch D.C. ECCP1DEL
Note: The 8-bit TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit time base.
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17.4.2 PWM DUTY CYCLE EQUATION 17-3:
log FOSC FPWM PWM Resolution (max) = log(2) The PWM duty cycle is specified by writing to the CCPR1L register and to the CCP1CON<5:4> bits. Up to 10-bit resolution is available. The CCPR1L contains the eight MSbs and the CCP1CON<5:4> contains the two LSbs. This 10-bit value is represented by CCPR1L:CCP1CON<5:4>. The PWM duty cycle is calculated by the following equation.
(
) bits
Note:
EQUATION 17-2:
PWM Duty Cycle = (CCPR1L:CCP1CON<5:4>) * TOSC * (TMR2 Prescale Value) CCPR1L and CCP1CON<5:4> can be written to at any time, but the duty cycle value is not copied into CCPR1H until a match between PR2 and TMR2 occurs (i.e., the period is complete). In PWM mode, CCPR1H is a read-only register. The CCPR1H register and a 2-bit internal latch are used to double-buffer the PWM duty cycle. This double-buffering is essential for glitchless PWM operation. When the CCPR1H and 2-bit latch match TMR2, concatenated with an internal 2-bit Q clock or two bits of the TMR2 prescaler, the CCP1 pin is cleared. The maximum PWM resolution (bits) for a given PWM frequency is given by the following equation.
If the PWM duty cycle value is longer than the PWM period, the CCP1 pin will not be cleared.
17.4.3
PWM OUTPUT CONFIGURATIONS
The P1M<1:0> bits in the CCP1CON register allow one of four configurations: * * * * Single Output Half-Bridge Output Full-Bridge Output, Forward mode Full-Bridge Output, Reverse mode
The Single Output mode is the standard PWM mode discussed in Section 17.4 "Enhanced PWM Mode". The Half-Bridge and Full-Bridge Output modes are covered in detail in the sections that follow. The general relationship of the outputs in all configurations is summarized in Figure 17-2.
TABLE 17-2:
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
2.44 kHz 16 FFh 10 9.77 kHz 4 FFh 10 39.06 kHz 1 FFh 10 156.25 kHz 1 3Fh 8 312.50 kHz 1 1Fh 7 416.67 kHz 1 17h 6.58
PWM Frequency Timer Prescaler (1, 4, 16) PR2 Value Maximum Resolution (bits)
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FIGURE 17-2: PWM OUTPUT RELATIONSHIPS (ACTIVE-HIGH STATE)
SIGNAL 0 Duty Cycle PR2 + 1 Period Delay(1) CCP1CON <7:6> 00 (Single Output)
P1A Modulated P1A Modulated
Delay(1)
10
(Half-Bridge)
P1B Modulated P1A Active
01
(Full-Bridge, Forward)
P1B Inactive P1C Inactive P1D Modulated P1A Inactive
11
(Full-Bridge, Reverse)
P1B Modulated P1C Active P1D Inactive
FIGURE 17-3:
PWM OUTPUT RELATIONSHIPS (ACTIVE-LOW STATE)
SIGNAL 0 Duty Cycle PR2 + 1 Period
CCP1CON <7:6>
00
(Single Output)
P1A Modulated P1A Modulated
10
(Half-Bridge)
Delay(1) P1B Modulated P1A Active
Delay(1)
01
(Full-Bridge, Forward)
P1B Inactive P1C Inactive P1D Modulated P1A Inactive
11
(Full-Bridge, Reverse)
P1B Modulated P1C Active P1D Inactive
Relationships: * Period = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value) * Duty Cycle = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale Value) * Delay = 4 * TOSC * (ECCP1DEL<6:0>) Note 1: Dead-band delay is programmed using the ECCP1DEL register (see Section 17.4.6 "Programmable Dead-Band Delay").
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17.4.4 HALF-BRIDGE MODE FIGURE 17-4:
Period Duty Cycle P1A(2) td P1B(2)
(1)
In the Half-Bridge Output mode, two pins are used as outputs to drive push-pull loads. The PWM output signal is output on the P1A pin, while the complementary PWM output signal is output on the P1B pin (Figure 17-4). This mode can be used for half-bridge applications, as shown in Figure 17-5, or for full-bridge applications where four power switches are being modulated with two PWM signals. In Half-Bridge Output mode, the programmable deadband delay can be used to prevent shoot-through current in half-bridge power devices. The value of bits, PDC<6:0>, sets the number of instruction cycles before the output is driven active. If the value is greater than the duty cycle, the corresponding output remains inactive during the entire cycle. See Section 17.4.6 "Programmable Dead-Band Delay" for more details of the dead-band delay operations. Since the P1A and P1B outputs are multiplexed with the PORTC<2> and PORTD<5> data latches, the TRISC<2> and TRISD<5> bits must be cleared to configure P1A and P1B as outputs.
HALF-BRIDGE PWM OUTPUT
Period
td
(1)
(1)
td = Dead-Band Delay Note 1: At this time, the TMR2 register is equal to the PR2 register. 2: Output signals are shown as active-high.
FIGURE 17-5:
EXAMPLES OF HALF-BRIDGE OUTPUT MODE APPLICATIONS
V+
Standard Half-Bridge Circuit ("Push-Pull")
PIC18F4X21 P1A
FET Driver
+ V Load
FET Driver P1B
+ V -
VHalf-Bridge Output Driving a Full-Bridge Circuit V+ PIC18F4X21 P1A Load
FET Driver
FET Driver
FET Driver P1B
FET Driver
V-
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17.4.5 FULL-BRIDGE MODE
In Full-Bridge Output mode, four pins are used as outputs; however, only two outputs are active at a time. In the Forward mode, pin P1A is continuously active and pin P1D is modulated. In the Reverse mode, pin P1C is continuously active and pin P1B is modulated. These are illustrated in Figure 17-6. P1A, P1B, P1C and P1D outputs are multiplexed with the PORTC<2> and PORTD<7:5> data latches. The TRISC<2> and TRISD<7:5> bits must be cleared to make the P1A, P1B, P1C and P1D pins outputs.
FIGURE 17-6:
Forward Mode
FULL-BRIDGE PWM OUTPUT
Period P1A
(2)
Duty Cycle P1B(2)
P1C(2)
P1D(2) (1) Reverse Mode Period Duty Cycle P1A(2) P1B(2) P1C(2) (1)
P1D(2) (1) Note 1: At this time, the TMR2 register is equal to the PR2 register. Note 2: Output signal is shown as active-high. (1)
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FIGURE 17-7: EXAMPLE OF FULL-BRIDGE APPLICATION
V+
PIC18F4X21 P1A
FET Driver
QA
QC
FET Driver
P1B FET Driver
Load FET Driver
P1C
QB
QD
VP1D
17.4.5.1
Direction Change in Full-Bridge Mode
In the Full-Bridge Output mode, the P1M1 bit in the CCP1CON register allows user to control the forward/ reverse direction. When the application firmware changes this direction control bit, the module will assume the new direction on the next PWM cycle. Just before the end of the current PWM period, the modulated outputs (P1B and P1D) are placed in their inactive state, while the unmodulated outputs (P1A and P1C) are switched to drive in the opposite direction. This occurs in a time interval of 4 TOSC * (Timer2 Prescale Value) before the next PWM period begins. The Timer2 prescaler will be either 1, 4 or 16, depending on the value of the T2CKPS<1:0> bits (T2CON<1:0>). During the interval from the switch of the unmodulated outputs to the beginning of the next period, the modulated outputs (P1B and P1D) remain inactive. This relationship is shown in Figure 17-8. Note that in the Full-Bridge Output mode, the ECCP1 module does not provide any dead-band delay. In general, since only one output is modulated at all times, dead-band delay is not required. However, there is a situation where a dead-band delay might be required. This situation occurs when both of the following conditions are true: 1. 2. The direction of the PWM output changes when the duty cycle of the output is at or near 100%. The turn-off time of the power switch, including the power device and driver circuit, is greater than the turn-on time.
Figure 17-9 shows an example where the PWM direction changes from forward to reverse at a near 100% duty cycle. At time t1, the outputs P1A and P1D become inactive, while output P1C becomes active. In this example, since the turn-off time of the power devices is longer than the turn-on time, a shoot-through current may flow through power devices, QC and QD (see Figure 17-7), for the duration of `t'. The same phenomenon will occur to power devices, QA and QB, for PWM direction change from reverse to forward. If changing PWM direction at high duty cycle is required for an application, one of the following requirements must be met: 1. 2. Reduce PWM for a PWM period before changing directions. Use switch drivers that can drive the switches off faster than they can drive them on.
Other options to prevent shoot-through current may exist.
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FIGURE 17-8:
SIGNAL P1A (Active-High) P1B (Active-High) DC P1C (Active-High) P1D (Active-High) DC Note 1: The direction bit in the CCP1 Control register (CCP1CON<7>) is written any time during the PWM cycle. 2: When changing directions, the P1A and P1C signals switch before the end of the current PWM cycle at intervals of 4 TOSC, 16 TOSC or 64 TOSC, depending on the Timer2 prescaler value. The modulated P1B and P1D signals are inactive at this time. (Note 2)
PWM DIRECTION CHANGE
Period(1) Period
FIGURE 17-9:
PWM DIRECTION CHANGE AT NEAR 100% DUTY CYCLE
Forward Period t1 Reverse Period
P1A(1) P1B(1) P1C(1) P1D(1) External Switch C(1) DC
DC tON(2) tOFF(3)
External Switch D(1) Potential Shoot-Through Current(1) Note 1: All signals are shown as active-high. 2: tON is the turn-on delay of power switch QC and its driver. 3: tOFF is the turn-off delay of power switch QD and its driver. t = tOFF - tON(2,3)
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17.4.6
Note:
PROGRAMMABLE DEAD-BAND DELAY
Programmable dead-band delay is not implemented in 28-pin devices with standard CCP modules.
In half-bridge applications, where all power switches are modulated at the PWM frequency at all times, the power switches normally require more time to turn off than to turn on. If both the upper and lower power switches are switched at the same time (one turned on and the other turned off), both switches may be on for a short period of time until one switch completely turns off. During this brief interval, a very high current (shootthrough current) may flow through both power switches, shorting the bridge supply. To avoid this potentially destructive shoot-through current from flowing during switching, turning on either of the power switches is normally delayed to allow the other switch to completely turn off. In the Half-Bridge Output mode, a digitally programmable dead-band delay is available to avoid shoot-through current from destroying the bridge power switches. The delay occurs at the signal transition from the nonactive state to the active state (see Figure 17-4 for illustration). Bits PDC<6:0> of the ECCP1DEL register (Register 17-2) set the delay period in terms of microcontroller instruction cycles (TCY or 4 TOSC). These bits are not available on 28-pin devices as the standard CCP module does not support half-bridge operation.
A shutdown event can be caused by either of the comparator modules, a low level on the Fault input pin (FLT0) or any combination of these three sources. The comparators may be used to monitor a voltage input proportional to a current being monitored in the bridge circuit. If the voltage exceeds a threshold, the comparator switches state and triggers a shutdown. Alternatively, a low digital signal on FLT0 can also trigger a shutdown. The auto-shutdown feature can be disabled by not selecting any auto-shutdown sources. The autoshutdown sources to be used are selected using the ECCPAS<2:0> bits (ECCP1AS<6:4>). When a shutdown occurs, the output pins are asynchronously placed in their shutdown states, specified by the PSSAC<1:0> and PSSBD<1:0> bits (ECCP1AS<3:0>). Each pin pair (P1A/P1C and P1B/ P1D) may be set to drive high, drive low or be tri-stated (not driving). The ECCPASE bit (ECCP1AS<7>) is also set to hold the Enhanced PWM outputs in their shutdown states. The ECCPASE bit is set by hardware when a shutdown event occurs. If automatic restarts are not enabled, the ECCPASE bit is cleared by firmware when the cause of the shutdown clears. If automatic restarts are enabled, the ECCPASE bit is automatically cleared when the cause of the auto-shutdown has cleared. If the ECCPASE bit is set when a PWM period begins, the PWM outputs remain in their shutdown state for that entire PWM period. When the ECCPASE bit is cleared, the PWM outputs will return to normal operation at the beginning of the next PWM period. Note: Writing to the ECCPASE bit is disabled while a shutdown condition is active.
17.4.7
ENHANCED PWM AUTO-SHUTDOWN
When the ECCP1 is programmed for any of the Enhanced PWM modes, the active output pins may be configured for auto-shutdown. Auto-shutdown immediately places the Enhanced PWM output pins into a defined shutdown state when a shutdown event occurs.
REGISTER 17-2:
ECCP1DEL: PWM DEAD-BAND DELAY REGISTER
R/W-0 PRSEN bit 7 R/W-0 PDC6(1) R/W-0 PDC5(1) R/W-0 PDC4(1) R/W-0 PDC3(1) R/W-0 PDC2(1) R/W-0 PDC1(1) R/W-0 PDC0(1) bit 0
bit 7
PRSEN: PWM Restart Enable bit 1 = Upon auto-shutdown, the ECCPASE bit clears automatically once the shutdown event goes away; the PWM restarts automatically 0 = Upon auto-shutdown, ECCPASE must be cleared in software to restart the PWM PDC<6:0>: PWM Delay Count bits(1) Delay time, in number of FOSC/4 (4 * TOSC) cycles, between the scheduled and actual time for a PWM signal to transition to active. Note 1: Unimplemented on 28-pin devices; bits read `0'. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6-0
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REGISTER 17-3: ECCP1AS: ENHANCED CAPTURE/COMPARE/PWM AUTO-SHUTDOWN CONTROL REGISTER
R/W-0 bit 7 bit 7 ECCPASE: ECCP Auto-Shutdown Event Status bit 1 = A shutdown event has occurred; ECCP outputs are in shutdown state 0 = ECCP outputs are operating ECCPAS<2:0>: ECCP Auto-Shutdown Source Select bits 111 = FLT0 or Comparator 1 or Comparator 2 110 = FLT0 or Comparator 2 101 = FLT0 or Comparator 1 100 = FLT0 011 = Either Comparator 1 or 2 010 = Comparator 2 output 001 = Comparator 1 output 000 = Auto-shutdown is disabled PSSAC<1:0>: Pins A and C Shutdown State Control bits 1x = Pins A and C are tri-state (40/44-pin devices); PWM output is tri-state (28-pin devices) 01 = Drive Pins A and C to `1' 00 = Drive Pins A and C to `0' PSSBD<1:0>: Pins B and D Shutdown State Control bits(1) 1x = Pins B and D tri-state 01 = Drive Pins B and D to `1' 00 = Drive Pins B and D to `0' Note 1: Unimplemented on 28-pin devices; bits read as `0'. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 bit 0 ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(1) PSSBD0(1)
bit 6-4
bit 3-2
bit 1-0
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17.4.7.1 Auto-Shutdown and Automatic Restart 17.4.8 START-UP CONSIDERATIONS
The auto-shutdown feature can be configured to allow automatic restarts of the module following a shutdown event. This is enabled by setting the PRSEN bit of the ECCP1DEL register (ECCP1DEL<7>). In Shutdown mode with PRSEN = 1 (Figure 17-10), the ECCPASE bit will remain set for as long as the cause of the shutdown continues. When the shutdown condition clears, the ECCP1ASE bit is cleared. If PRSEN = 0 (Figure 17-11), once a shutdown condition occurs, the ECCPASE bit will remain set until it is cleared by firmware. Once ECCPASE is cleared, the Enhanced PWM will resume at the beginning of the next PWM period. Note: Writing to the ECCPASE bit is disabled while a shutdown condition is active. When the ECCP module is used in the PWM mode, the application hardware must use the proper external pullup and/or pull-down resistors on the PWM output pins. When the microcontroller is released from Reset, all of the I/O pins are in the high-impedance state. The external circuits must keep the power switch devices in the OFF state until the microcontroller drives the I/O pins with the proper signal levels, or activates the PWM output(s). The CCP1M<1:0> bits (CCP1CON<1:0>) allow the user to choose whether the PWM output signals are active-high or active-low for each pair of PWM output pins (P1A/P1C and P1B/P1D). The PWM output polarities must be selected before the PWM pins are configured as outputs. Changing the polarity configuration while the PWM pins are configured as outputs is not recommended, since it may result in damage to the application circuits. The P1A, P1B, P1C and P1D output latches may not be in the proper states when the PWM module is initialized. Enabling the PWM pins for output at the same time as the ECCP module may cause damage to the application circuit. The ECCP module must be enabled in the proper output mode and complete a full PWM cycle before configuring the PWM pins as outputs. The completion of a full PWM cycle is indicated by the TMR2IF bit being set as the second PWM period begins.
Independent of the PRSEN bit setting, if the autoshutdown source is one of the comparators, the shutdown condition is a level. The ECCPASE bit cannot be cleared as long as the cause of the shutdown persists. The Auto-Shutdown mode can be forced by writing a `1' to the ECCPASE bit.
FIGURE 17-10:
PWM AUTO-SHUTDOWN (PRSEN = 1, AUTO-RESTART ENABLED)
PWM Period PWM Period PWM Period
PWM Activity
Dead Time Duty Cycle
Dead Time Duty Cycle
Dead Time Duty Cycle
Shutdown Event ECCPASE bit
FIGURE 17-11:
PWM AUTO-SHUTDOWN (PRSEN = 0, AUTO-RESTART DISABLED)
PWM Period PWM Period PWM Period
PWM Activity
Dead Time Duty Cycle
Dead Time Duty Cycle
Dead Time Duty Cycle
Shutdown Event
ECCPASE bit ECCPASE Cleared by Firmware
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17.4.9 SETUP FOR PWM OPERATION 17.4.10
The following steps should be taken when configuring the ECCP module for PWM operation: Configure the PWM pins, P1A and P1B (and P1C and P1D, if used), as inputs by setting the corresponding TRIS bits. 2. Set the PWM period by loading the PR2 register. 3. If auto-shutdown is required, do the following: * Disable auto-shutdown (ECCPASE = 0) * Configure source (FLT0, Comparator 1 or Comparator 2) * Wait for non-shutdown condition 4. Configure the ECCP module for the desired PWM mode and configuration by loading the CCP1CON register with the appropriate values: * Select one of the available output configurations and direction with the P1M<1:0 bits. * Select the polarities of the PWM output signals with the CCP1M<3:0> bits. 5. Set the PWM duty cycle by loading the CCPR1L register and CCP1CON<5:4> bits. 6. For Half-Bridge Output mode, set the deadband delay by loading ECCP1DEL<6:0> with the appropriate value. 7. If auto-shutdown operation is required, load the ECCP1AS register: * Select the auto-shutdown sources using the ECCPAS<2:0> bits. * Select the shutdown states of the PWM output pins using the PSSAC<1:0> and PSSBD<1:0> bits. * Set the ECCPASE bit (ECCP1AS<7>). * Configure the comparators using the CMCON register. * Configure the comparator inputs as analog inputs. 8. If auto-restart operation is required, set the PRSEN bit (ECCP1DEL<7>). 9. Configure and start TMR2: * Clear the TMR2 interrupt flag bit by clearing the TMR2IF bit (PIR1<1>). * Set the TMR2 prescale value by loading the T2CKPS bits (T2CON<1:0>). * Enable Timer2 by setting the TMR2ON bit (T2CON<2>). 10. Enable PWM outputs after a new PWM cycle has started: * Wait until TMRx overflows (TMRxIF bit is set). * Enable the CCP1/P1A, P1B, P1C and/or P1D pin outputs by clearing the respective TRIS bits. * Clear the ECCPASE bit (ECCP1AS<7>). 1.
OPERATION IN POWER-MANAGED MODES
In Sleep mode, all clock sources are disabled. Timer2 will not increment and the state of the module will not change. If the ECCP pin is driving a value, it will continue to drive that value. When the device wakes up, it will continue from this state. If Two-Speed Start-ups are enabled, the initial start-up frequency from INTOSC and the postscaler may not be stable immediately. In PRI_IDLE mode, the primary clock will continue to clock the ECCP module without change. In all other power-managed modes, the selected power-managed mode clock will clock Timer2. Other power-managed mode clocks will most likely be different than the primary clock frequency.
17.4.10.1
Operation with Fail-Safe Clock Monitor
If the Fail-Safe Clock Monitor is enabled, a clock failure will force the device into the power-managed RC_RUN mode and the OSCFIF bit (PIR2<7>) will be set. The ECCP will then be clocked from the internal oscillator clock source, which may have a different clock frequency than the primary clock. See the previous section for additional details.
17.4.11
EFFECTS OF A RESET
Both Power-on Reset and subsequent Resets will force all ports to Input mode and the CCP registers to their Reset states. This forces the Enhanced CCP module to reset to a state compatible with the standard CCP module.
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TABLE 17-3:
Name INTCON RCON PIR1 PIE1 IPR1 PIR2 PIE2 IPR2 TRISB TRISC TRISD
(2)
REGISTERS ASSOCIATED WITH ECCP1 MODULE AND TIMER1 TO TIMER3
Bit 7 Bit 6 Bit 5 TMR0IE -- RCIF RCIE RCIP -- -- -- Bit 4 INT0IE RI TXIF TXIE TXIP EEIF EEIE EEIP Bit 3 RBIE TO SSPIF SSPIE SSPIP BCLIF BCLIE BCLIP Bit 2 TMR0IF PD CCP1IF CCP1IE CCP1IP HLVDIF HLVDIE HLVDIP Bit 1 INT0IF POR TMR2IF TMR2IE TMR2IP TMR3IF TMR3IE TMR3IP Bit 0 RBIF BOR TMR1IF TMR1IE TMR1IP CCP2IF CCP2IE CCP2IP Reset Values on page 55 54 58 58 58 58 58 58 58 58 58 56 56 T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 56 56 56 56 57 57 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON 57 57 57 CCP1M3 PSSAC1 PDC3(2) CCP1M2 PSSAC0 PDC2(2) CCP1M1 PDC1(2) CCP1M0 PDC0(2) 57 57 57 PSSBD1(2) PSSBD0(2)
GIE/GIEH PEIE/GIEL IPEN PSPIF(2) PSPIE(2) PSPIP(2) OSCFIF OSCFIE OSCFIP SBOREN(1) ADIF ADIE ADIP CMIF CMIE CMIP
PORTB Data Direction Register PORTC Data Direction Register PORTD Data Direction Register Timer1 Register Low Byte Timer1 Register High Byte RD16 -- T1RUN Timer2 Register T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 Timer2 Period Register Timer3 Register Low Byte Timer3 Register High Byte RD16 T3CCP2 Capture/Compare/PWM Register 1 Low Byte Capture/Compare/PWM Register 1 High Byte P1M1
(2)
TMR1L TMR1H T1CON TMR2 T2CON PR2 TMR3L TMR3H T3CON CCPR1L CCPR1H CCP1CON ECCP1AS ECCP1DEL Legend: Note 1: 2:
P1M0(2) PDC6(2)
DC1B1 ECCPAS1 PDC5(2)
DC1B0 ECCPAS0 PDC4(2)
ECCPASE ECCPAS2 PRSEN
-- = unimplemented, read as `0'. Shaded cells are not used during ECCP operation. The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 5.4 "Brown-out Reset (BOR)". These registers and/or bits are unimplemented on 28-pin devices; always maintain these bits clear.
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18.0 MASTER SYNCHRONOUS SERIAL PORT (MSSP) MODULE
Master SSP (MSSP) Module Overview 18.3 SPI Mode
The SPI mode allows 8 bits of data to be synchronously transmitted and received simultaneously. All four SPI modes are supported. To accomplish communication, typically three pins are used: * Serial Data Out (SDO) - SDO * Serial Data In (SDI) - SDI/SDA * Serial Clock (SCK) - SCK/SCL Additionally, a fourth pin may be used when in a Slave mode of operation: * Slave Select (SS) Figure 18-1 shows the block diagram of the MSSP module when operating in SPI mode.
18.1
The Master Synchronous Serial Port (MSSP) module is a serial interface, useful for communicating with other peripheral or microcontroller devices. These peripheral devices may be serial EEPROMs, shift registers, display drivers, A/D converters, etc. The MSSP module can operate in one of two modes: * Serial Peripheral Interface (SPI) * Inter-Integrated Circuit (I2CTM) - Full Master mode - Slave mode (with address masking for both 10-bit and 7-bit addressing) The I2C interface supports the following modes in hardware: * Master mode * Multi-Master mode * Slave mode
FIGURE 18-1:
MSSP BLOCK DIAGRAM (SPI MODE)
Internal Data Bus Read SSPBUF reg Write
18.2
Control Registers
SDI/SDA SSPSR reg SDO bit 0 Shift Clock
The MSSP module has three associated registers. These include a status register (SSPSTAT) and two control registers (SSPCON1 and SSPCON2). The use of these registers and their individual Configuration bits differ significantly depending on whether the MSSP module is operated in SPI or I2C mode. Additional details are provided under the individual sections.
SS
SS Control Enable Edge Select 2 Clock Select SSPM<3:0> SMP:CKE 4 TMR2 Output 2 2 Edge Select Prescaler TOSC 4, 16, 64
SCK/SCL
(
)
Data to TX/RX in SSPSR TRIS bit
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18.3.1 REGISTERS
The MSSP module has four registers for SPI mode operation. These are: * MSSP Control Register 1 (SSPCON1) * MSSP Status Register (SSPSTAT) * Serial Receive/Transmit Buffer Register (SSPBUF) * MSSP Shift Register (SSPSR) - Not directly accessible SSPCON1 and SSPSTAT are the control and status registers in SPI mode operation. The SSPCON1 register is readable and writable. The lower 6 bits of the SSPSTAT are read-only. The upper two bits of the SSPSTAT are read/write. SSPSR is the shift register used for shifting data in or out. SSPBUF is the buffer register to which data bytes are written to or read from. In receive operations, SSPSR and SSPBUF together create a double-buffered receiver. When SSPSR receives a complete byte, it is transferred to SSPBUF and the SSPIF interrupt is set. During transmission, the SSPBUF is not doublebuffered. A write to SSPBUF will write to both SSPBUF and SSPSR.
REGISTER 18-1:
SSPSTAT: MSSP STATUS REGISTER (SPI MODE)
R/W-0 SMP bit 7 R/W-0 CKE R-0 D/A R-0 P R-0 S R-0 R/W R-0 UA R-0 BF bit 0
bit 7
SMP: Sample bit SPI Master mode: 1 = Input data sampled at end of data output time 0 = Input data sampled at middle of data output time SPI Slave mode: SMP must be cleared when SPI is used in Slave mode. CKE: SPI Clock Select bit 1 = Transmit occurs on transition from active to Idle clock state 0 = Transmit occurs on transition from Idle to active clock state Note: Polarity of clock state is set by the CKP bit (SSPCON1<4>). D/A: Data/Address bit Used in I2CTM mode only. P: Stop bit Used in I2C mode only. This bit is cleared when the MSSP module is disabled, SSPEN is cleared. S: Start bit Used in I2C mode only. R/W: Read/Write Information bit Used in I2C mode only. UA: Update Address bit Used in I2C mode only. BF: Buffer Full Status bit (Receive mode only) 1 = Receive complete, SSPBUF is full 0 = Receive not complete, SSPBUF is empty Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5 bit 4
bit 3 bit 2 bit 1 bit 0
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REGISTER 18-2: SSPCON1: MSSP CONTROL REGISTER 1 (SPI MODE)
R/W-0 WCOL bit 7 bit 7 WCOL: Write Collision Detect bit (Transmit mode only) 1 = The SSPBUF register is written while it is still transmitting the previous word (must be cleared in software) 0 = No collision SSPOV: Receive Overflow Indicator bit SPI Slave mode: 1 = A new byte is received while the SSPBUF register is still holding the previous data. In case of overflow, the data in SSPSR is lost. Overflow can only occur in Slave mode. The user must read the SSPBUF, even if only transmitting data, to avoid setting overflow (must be cleared in software). 0 = No overflow Note: bit 5 In Master mode, the overflow bit is not set since each new reception (and transmission) is initiated by writing to the SSPBUF register. R/W-0 SSPOV R/W-0 SSPEN R/W-0 CKP R/W-0 SSPM3 R/W-0 SSPM2 R/W-0 SSPM1 R/W-0 SSPM0 bit 0
bit 6
SSPEN: Synchronous Serial Port Enable bit 1 = Enables serial port and configures SCK, SDO, SDI and SS as serial port pins 0 = Disables serial port and configures these pins as I/O port pins Note: When enabled, these pins must be properly configured as input or output. CKP: Clock Polarity Select bit 1 = Idle state for clock is a high level 0 = Idle state for clock is a low level SSPM<3:0>: Synchronous Serial Port Mode Select bits 0101 = SPI Slave mode, clock = SCK pin, SS pin control disabled, SS can be used as I/O pin 0100 = SPI Slave mode, clock = SCK pin, SS pin control enabled 0011 = SPI Master mode, clock = TMR2 output/2 0010 = SPI Master mode, clock = FOSC/64 0001 = SPI Master mode, clock = FOSC/16 0000 = SPI Master mode, clock = FOSC/4 Note: Bit combinations not specifically listed here are either reserved or implemented in I2CTM mode only.
bit 4
bit 3-0
Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
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18.3.2 OPERATION
When initializing the SPI, several options need to be specified. This is done by programming the appropriate control bits (SSPCON1<5:0> and SSPSTAT<7:6>). These control bits allow the following to be specified: * * * * Master mode (SCK is the clock output) Slave mode (SCK is the clock input) Clock Polarity (Idle state of SCK) Data Input Sample Phase (middle or end of data output time) * Clock Edge (output data on rising/falling edge of SCK) * Clock Rate (Master mode only) * Slave Select mode (Slave mode only) The MSSP consists of a transmit/receive shift register (SSPSR) and a buffer register (SSPBUF). The SSPSR shifts the data in and out of the device, MSb first. The SSPBUF holds the data that was written to the SSPSR until the received data is ready. Once the 8 bits of data have been received, that byte is moved to the SSPBUF register. Then, the Buffer Full detect bit, BF (SSPSTAT<0>), and the interrupt flag bit, SSPIF, are set. This double-buffering of the received data (SSPBUF) allows the next byte to start reception before reading the data that was just received. Any write to the SSPBUF register during transmission/reception of data will be ignored and the write collision detect bit, WCOL (SSPCON1<7>), will be set. User software must clear the WCOL bit so that it can be determined if the following write(s) to the SSPBUF register completed successfully. When the application software is expecting to receive valid data, the SSPBUF should be read before the next byte of data to transfer is written to the SSPBUF. The Buffer Full bit, BF (SSPSTAT<0>), indicates when SSPBUF has been loaded with the received data (transmission is complete). When the SSPBUF is read, the BF bit is cleared. This data may be irrelevant if the SPI is only a transmitter. Generally, the MSSP interrupt is used to determine when the transmission/reception has completed. The SSPBUF must be read and/or written. If the interrupt method is not going to be used, then software polling can be done to ensure that a write collision does not occur. Example 18-1 shows the loading of the SSPBUF (SSPSR) for data transmission. The SSPSR is not directly readable or writable and can only be accessed by addressing the SSPBUF register. Additionally, the MSSP Status register (SSPSTAT) indicates the various status conditions. Note: To avoid lost data in Master mode, a read of the SSPBUF must be performed to clear the Buffer Full (BF) detect bit (SSPSTAT<0>) between each transmission. The SSPBUF register cannot be used with read-modify-write instructions, such as BCF, BTFSC and COMF, etc.
Note:
EXAMPLE 18-1:
LOOP BTFSS BRA MOVF MOVWF MOVF MOVWF
LOADING THE SSPBUF (SSPSR) REGISTER
SSPSTAT, BF LOOP SSPBUF, W RXDATA TXDATA, W SSPBUF ;Has data been received (transmit complete)? ;No ;WREG reg = contents of SSPBUF ;Save in user RAM, if data is meaningful ;W reg = contents of TXDATA ;New data to xmit
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18.3.3 ENABLING SPI I/O
To enable the serial port, MSSP Enable bit, SSPEN (SSPCON1<5>), must be set. To reset or reconfigure SPI mode, clear the SSPEN bit, reinitialize the SSPCON registers and then set the SSPEN bit. This configures the SDI, SDO, SCK and SS pins as serial port pins. For the pins to behave as the serial port function, some must have their data direction bits (in the TRIS register) appropriately programmed as follows: * SDI is automatically controlled by the SPI module * SDO must have TRISC<5> bit cleared * SCK (Master mode) must have TRISC<3> bit cleared * SCK (Slave mode) must have TRISC<3> bit set * SS must have TRISA<5> bit set Any serial port function that is not desired may be overridden by programming the corresponding data direction (TRIS) register to the opposite value.
18.3.4
TYPICAL CONNECTION
Figure 18-2 shows a typical connection between two microcontrollers. The master controller (Processor 1) initiates the data transfer by sending the SCK signal. Data is shifted out of both shift registers on their programmed clock edge and latched on the opposite edge of the clock. Both processors should be programmed to the same Clock Polarity (CKP), then both controllers would send and receive data at the same time. Whether the data is meaningful (or dummy data) depends on the application software. This leads to three scenarios for data transmission: * Master sends data - Slave sends dummy data * Master sends data - Slave sends data * Master sends dummy data - Slave sends data
FIGURE 18-2:
SPI MASTER/SLAVE CONNECTION
SPI Master SSPM<3:0> = 00xxb SDO SDI
SPI Slave SSPM<3:0> = 010xb
Serial Input Buffer (SSPBUF)
Serial Input Buffer (SSPBUF)
Shift Register (SSPSR) MSb LSb
SDI
SDO
Shift Register (SSPSR) MSb LSb
SCK PROCESSOR 1
Serial Clock
SCK PROCESSOR 2
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18.3.5 MASTER MODE
The master can initiate the data transfer at any time because it controls the SCK. The master determines when the slave (Processor 2, Figure 18-2) is to broadcast data by the software protocol. In Master mode, the data is transmitted/received as soon as the SSPBUF register is written to. If the SPI operation is only going to receive, the SDO output could be disabled (programmed as an input). The SSPSR register will continue to shift in the signal present on the SDI pin at the programmed clock rate. As each byte is received, it will be loaded into the SSPBUF register as if a normal received byte (interrupts and status bits appropriately set). This could be useful in receiver applications as a "Line Activity Monitor" mode. The clock polarity is selected by appropriately programming the CKP bit (SSPCON1<4>). This then, would give waveforms for SPI communication as shown in Figure 18-3, Figure 18-5 and Figure 18-6, where the MSB is transmitted first. In Master mode, the SPI clock rate (bit rate) is user-programmable to be one of the following: * * * * FOSC/4 (or TCY) FOSC/16 (or 4 * TCY) FOSC/64 (or 16 * TCY) Timer2 output/2
This allows a maximum data rate (at 40 MHz) of 10.00 Mbps. Figure 18-3 shows the waveforms for Master mode. When the CKE bit is set, the SDO data is valid before there is a clock edge on SCK. The change of the input sample is shown based on the state of the SMP bit. The time when the SSPBUF is loaded with the received data is shown.
FIGURE 18-3:
Write to SSPBUF SCK (CKP = 0 CKE = 0) SCK (CKP = 1 CKE = 0) SCK (CKP = 0 CKE = 1) SCK (CKP = 1 CKE = 1) SDO (CKE = 0) SDO (CKE = 1) SDI (SMP = 0) Input Sample (SMP = 0) SDI (SMP = 1) Input Sample (SMP = 1) SSPIF SSPSR to SSPBUF
SPI MODE WAVEFORM (MASTER MODE)
4 Clock Modes
bit 7 bit 7
bit 6 bit 6
bit 5 bit 5
bit 4 bit 4
bit 3 bit 3
bit 2 bit 2
bit 1 bit 1
bit 0 bit 0
bit 7
bit 0
bit 7
bit 0
Next Q4 Cycle after Q2
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18.3.6 SLAVE MODE
In Slave mode, the data is transmitted and received as the external clock pulses appear on SCK. When the last bit is latched, the SSPIF interrupt flag bit is set. Before enabling the module in SPI Slave mode, the clock line must match the proper Idle state. The clock line can be observed by reading the SCK pin. The Idle state is determined by the CKP bit (SSPCON1<4>). While in Slave mode, the external clock is supplied by the external clock source on the SCK pin. This external clock must meet the minimum high and low times as specified in the electrical specifications. While in Sleep mode, the slave can transmit/receive data. When a byte is received, the device will wake-up from Sleep. SDO pin is driven. When the SS pin goes high, the SDO pin is no longer driven, even if in the middle of a transmitted byte and becomes a floating output. External pull-up/pull-down resistors may be desirable depending on the application. Note 1: When the SPI interface is in Slave mode with SS pin control enabled (SSPCON1<3:0> = 0100), the SPI module will reset if the SS pin is set to VDD. 2: If the SPI interface is used in Slave mode with CKE set, then the SS pin control must be enabled. When the SPI module resets, the bit counter is forced to `0'. This can be done by either forcing the SS pin to a high level or clearing the SSPEN bit. To emulate two-wire communication, the SDO pin can be connected to the SDI pin. When the SPI needs to operate as a receiver, the SDO pin can be configured as an input. This disables transmissions from the SDO. The SDI can always be left as an input (SDI function) since it cannot create a bus conflict.
18.3.7
SLAVE SELECT SYNCHRONIZATION
The SS pin allows a Synchronous Slave mode. The SPI operation must be in Slave mode with the SS pin control enabled (SSPCON1<3:0> = 04h). When the SS pin is low, transmission and reception are enabled and the
FIGURE 18-4:
SS
SLAVE SYNCHRONIZATION WAVEFORM
SCK (CKP = 0 CKE = 0) SCK (CKP = 1 CKE = 0)
Write to SSPBUF
SDO
bit 7
bit 6
bit 7
bit 0
SDI (SMP = 0) Input Sample (SMP = 0) SSPIF Interrupt Flag SSPSR to SSPBUF
bit 0 bit 7 bit 7
Next Q4 Cycle after Q2
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FIGURE 18-5:
SS Optional SCK (CKP = 0 CKE = 0) SCK (CKP = 1 CKE = 0) Write to SSPBUF SDO SDI (SMP = 0) Input Sample (SMP = 0) SSPIF Interrupt Flag SSPSR to SSPBUF bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 0)
bit 7
bit 0
Next Q4 Cycle after Q2
FIGURE 18-6:
SS Not Optional SCK (CKP = 0 CKE = 1) SCK (CKP = 1 CKE = 1) Write to SSPBUF SDO SDI (SMP = 0) Input Sample (SMP = 0) SSPIF Interrupt Flag SSPSR to SSPBUF
SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 1)
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
bit 7
bit 0
Next Q4 Cycle after Q2
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18.3.8 OPERATION IN POWER-MANAGED MODES 18.3.9 EFFECTS OF A RESET
In SPI Master mode, module clocks may be operating at a different speed than when in full power mode. In the case of Sleep mode, all clocks are halted. In Idle modes, a clock is provided to the peripherals. That clock should be from the primary clock source, the secondary clock (Timer1 oscillator at 32.768 kHz) or the INTOSC source. See Section 3.7 "Clock Sources and Oscillator Switching" for additional information. In most cases, the speed that the master clocks SPI data is not important; however, this should be evaluated for each system. If MSSP interrupts are enabled, they can wake the controller from Sleep mode, or one of the Idle modes, when the master completes sending data. If an exit from Sleep or Idle mode is not desired, MSSP interrupts should be disabled. If the Sleep mode is selected, all module clocks are halted and the transmission/reception will remain in that state until the devices wakes. After the device returns to Run mode, the module will resume transmitting and receiving data. In SPI Slave mode, the SPI Transmit/Receive Shift register operates asynchronously to the device. This allows the device to be placed in any power-managed mode and data to be shifted into the SPI Transmit/ Receive Shift register. When all 8 bits have been received, the MSSP interrupt flag bit will be set and if enabled, will wake the device. A Reset disables the MSSP module and terminates the current transfer.
18.3.10
BUS MODE COMPATIBILITY
Table 18-1 shows the compatibility between the standard SPI modes and the states of the CKP and CKE control bits.
TABLE 18-1:
SPI BUS MODES
Control Bits State CKP 0 0 1 1 CKE 1 0 1 0
Standard SPI Mode Terminology 0, 0 0, 1 1, 0 1, 1
There is also an SMP bit which controls when the data is sampled.
TABLE 18-2:
Name INTCON PIR1 PIE1 IPR1 TRISA TRISC SSPBUF SSPCON1 SSPSTAT
REGISTERS ASSOCIATED WITH SPI OPERATION
Bit 7 Bit 6 Bit 5 Bit 4 INT0IE TXIF TXIE TXIP Bit 3 RBIE SSPIF SSPIE SSPIP Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP Bit 1 INT0IF TMR2IF TMR2IE TMR2IP Bit 0 RBIF TMR1IF TMR1IE TMR1IP Reset Values on page 55 58 58 58 58 58 56 SSPM3 S SSPM2 R/W SSPM1 UA SSPM0 BF 56 56
GIE/GIEH PEIE/GIEL TMR0IE PSPIF
(1)
ADIF ADIE ADIP
RCIF RCIE RCIP
PSPIE(1) PSPIP(1)
TRISA7(2) TRISA6(2) PORTA Data Direction Control Register PORTC Data Direction Control Register MSSP Receive Buffer/Transmit Register WCOL SMP SSPOV CKE SSPEN D/A CKP P
Legend: Shaded cells are not used by the MSSP in SPI mode. Note 1: These bits are unimplemented on 28-pin devices and read as `0'. 2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'.
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18.4 I2C Mode
18.4.1 REGISTERS
The MSSP module in I 2C mode fully implements all master and slave functions (including general call support) and provides interrupts on Start and Stop bits in hardware to determine a free bus (multi-master function). The MSSP module implements the standard mode specifications, as well as 7-bit and 10-bit addressing. Two pins are used for data transfer: * Serial clock (SCL) - RC3/SCK/SCL * Serial data (SDA) - RC4/SDI/SDA The user must configure these pins as inputs or outputs through the TRISC<4:3> bits. The MSSP module has six registers for I2C operation. These are: * * * * MSSP Control Register 1 (SSPCON1) MSSP Control Register 2 (SSPCON2) MSSP Status Register (SSPSTAT) Serial Receive/Transmit Buffer Register (SSPBUF) * MSSP Shift Register (SSPSR) - Not directly accessible * MSSP Address Register (SSPADD) SSPCON1, SSPCON2 and SSPSTAT are the control and status registers in I2C mode operation. The SSPCON1 and SSPCON2 registers are readable and writable. The lower 6 bits of the SSPSTAT are read-only. The upper two bits of the SSPSTAT are read/write. SSPSR is the shift register used for shifting data in or out. SSPBUF is the buffer register to which data bytes are written to or read from. SSPADD register holds the slave device address when the MSSP is configured in I2C Slave mode. When the MSSP is configured in Master mode, the lower seven bits of SSPADD act as the Baud Rate Generator reload value. In receive operations, SSPSR and SSPBUF together create a double-buffered receiver. When SSPSR receives a complete byte, it is transferred to SSPBUF and the SSPIF interrupt is set.
Addr Match
FIGURE 18-7:
MSSP BLOCK DIAGRAM (I2CTM MODE)
Internal Data Bus Read SSPBUF reg Shift Clock SSPSR reg Write
RC3/SCK/SCL
RC4/SDI/ SDA
MSb
LSb
Match Detect
SSPADD reg Start and Stop bit Detect Set, Reset S, P bits (SSPSTAT reg)
During transmission, the SSPBUF is not doublebuffered. A write to SSPBUF will write to both SSPBUF and SSPSR.
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REGISTER 18-3: SSPSTAT: MSSP STATUS REGISTER (I2CTM MODE)
R/W-0 SMP bit 7 bit 7 SMP: Slew Rate Control bit In Master or Slave mode: 1 = Slew rate control disabled for Standard Speed mode (100 kHz and 1 MHz) 0 = Slew rate control enabled for High-Speed mode (400 kHz) CKE: SMBus Select bit In Master or Slave mode: 1 = Enable SMBus specific inputs 0 = Disable SMBus specific inputs D/A: Data/Address bit In Master mode: Reserved. In Slave mode: 1 = Indicates that the last byte received or transmitted was data 0 = Indicates that the last byte received or transmitted was address P: Stop bit 1 = Indicates that a Stop bit has been detected last 0 = Stop bit was not detected last Note: bit 3 This bit is cleared on Reset and when SSPEN is cleared. S: Start bit 1 = Indicates that a Start bit has been detected last 0 = Start bit was not detected last Note: bit 2 This bit is cleared on Reset and when SSPEN is cleared. R/W: Read/Write Information bit (I2CTM mode only) In Slave mode: 1 = Read 0 = Write Note: This bit holds the R/W bit information following the last address match. This bit is only valid from the address match to the next Start bit, Stop bit or not ACK bit. R/W-0 CKE R-0 D/A R-0 P R-0 S R-0 R/W R-0 UA R-0 BF bit 0
bit 6
bit 5
bit 4
In Master mode: 1 = Transmit is in progress 0 = Transmit is not in progress Note: bit 1 ORing this bit with SEN, RSEN, PEN, RCEN or ACKEN will indicate if the MSSP is in Active mode.
UA: Update Address bit (10-bit Slave mode only) 1 = Indicates that the user needs to update the address in the SSPADD register 0 = Address does not need to be updated BF: Buffer Full Status bit In Transmit mode: 1 = SSPBUF is full 0 = SSPBUF is empty In Receive mode: 1 = SSPBUF is full (does not include the ACK and Stop bits) 0 = SSPBUF is empty (does not include the ACK and Stop bits) Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 0
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REGISTER 18-4: SSPCON1: MSSP CONTROL REGISTER 1 (I2CTM MODE)
R/W-0 WCOL bit 7 bit 7 R/W-0 SSPOV R/W-0 SSPEN R/W-0 CKP R/W-0 SSPM3 R/W-0 SSPM2 R/W-0 SSPM1 R/W-0 SSPM0 bit 0
WCOL: Write Collision Detect bit In Master Transmit mode: 1 = A write to the SSPBUF register was attempted while the I2CTM conditions were not valid for a transmission to be started (must be cleared in software) 0 = No collision In Slave Transmit mode: 1 = The SSPBUF register is written while it is still transmitting the previous word (must be cleared in software) 0 = No collision In Receive mode (Master or Slave modes): This is a "don't care" bit. SSPOV: Receive Overflow Indicator bit In Receive mode: 1 = A byte is received while the SSPBUF register is still holding the previous byte (must be cleared in software) 0 = No overflow In Transmit mode: This is a "don't care" bit in Transmit mode. SSPEN: Master Synchronous Serial Port Enable bit 1 = Enables the serial port and configures the SDA and SCL pins as the serial port pins 0 = Disables serial port and configures these pins as I/O port pins Note: When enabled, the SDA and SCL pins must be properly configured as inputs. CKP: SCK Release Control bit In Slave mode: 1 = Release clock 0 = Holds clock low (clock stretch), used to ensure data setup time In Master mode: Unused in this mode. SSPM<3:0>: Master Synchronous Serial Port Mode Select bits 1111 = I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled 1110 = I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled 1011 = I2C Firmware Controlled Master mode (slave Idle) 1000 = I2C Master mode, clock = FOSC/(4 * (SSPADD + 1)) 0111 = I2C Slave mode, 10-bit address 0110 = I2C Slave mode, 7-bit address Bit combinations not specifically listed here are either reserved or implemented in SPI mode only. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5
bit 4
bit 3-0
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REGISTER 18-5: SSPCON2: MSSP CONTROL REGISTER 2 (I2CTM MODE)
R/W-0 GCEN bit 7 bit 7 GCEN: General Call Enable bit (Slave mode only) 1 = Enable interrupt when a general call address (0000h) is received in the SSPSR 0 = General call address disabled ACKSTAT: Acknowledge Status bit (Master Transmit mode only) 1 = Acknowledge was not received from slave 0 = Acknowledge was received from slave ACKDT/ADMSK5: Acknowledge Data bit In Master Receive mode: 1 = Not Acknowledge 0 = Acknowledge Note: Value that will be transmitted when the user initiates an Acknowledge sequence at the end of a receive. R/W-0 ACKSTAT R/W-0 ACKDT/ ADMSK5 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 SEN(1) bit 0 ACKEN(1)/ RCEN(1)/ PEN(1)/ RSEN(1)/ ADMSK4 ADMSK3 ADMSK2 ADMSK1
bit 6
bit 5
In Slave mode: 1 = Address masking of ADD5 enabled 0 = Address masking of ADD5 disabled bit 4 ACKEN/ADMSK4: Acknowledge Sequence Enable bit In Master Receive mode:(1) 1 = Initiate Acknowledge sequence on SDA and SCL pins and transmit ACKDT data bit. Automatically cleared by hardware. 0 = Acknowledge sequence Idle In Slave mode: 1 = Address masking of ADD4 enabled 0 = Address masking of ADD4 disabled bit 3 RCEN/ADMSK3: Receive Enable bit In Master Receive mode:(1) 1 = Enables Receive mode for I2C 0 = Receive Idle In Slave mode: 1 = Address masking of ADD3 enabled 0 = Address masking of ADD3 disabled bit 2 PEN/ADMSK2: Stop Condition Enable bit In Master mode:(1) 1 = Initiate Stop condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Stop condition Idle In Slave mode: 1 = Address masking of ADD2 enabled 0 = Address masking of ADD2 disabled bit 1 RSEN/ADMSK1: Repeated Start Condition Enable bit In Master mode:(1) 1 = Initiate Repeated Start condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Repeated Start condition Idle In Slave mode (7-Bit Addressing mode): 1 = Address masking of ADD1 enabled 0 = Address masking of ADD1 disabled In Slave mode (10-Bit Addressing mode): 1 = Address masking of ADD1 and ADD0 enabled 0 = Address masking of ADD1 and ADD0 disabled
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REGISTER 18-5: SSPCON2: MSSP CONTROL REGISTER 2 (I2CTM MODE) - CONTINUED
R/W-0 GCEN bit 7 bit 0 R/W-0 ACKSTAT R/W-0 ACKDT/ ADMSK5 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 SEN(1) bit 0 ACKEN(1)/ RCEN(1)/ PEN(1)/ RSEN(1)/ ADMSK4 ADMSK3 ADMSK2 ADMSK1
SEN: Start Condition Enable/Stretch Enable bit(1) In Master mode: 1 = Initiate Start condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Start condition Idle In Slave mode: 1 = Clock stretching is enabled for both slave transmit and slave receive (stretch enabled) 0 = Clock stretching is disabled Note 1: For bits ACKEN, RCEN, PEN, RSEN, SEN: If the I2C module is active, these bits may not be set (no spooling) and the SSPBUF may not be written (or writes to the SSPBUF are disabled). Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
REGISTER 18-6:
SSPADD: MSSP ADDRESS REGISTER(1)
R/W-0 ADD7 bit 7 R/W-0 ADD6 R/W-0 ADD5 R/W-0 ADD4 R/W-0 ADD3 R/W-0 ADD2 R/W-0 ADD1 R/W-0 ADD0 bit 0
bit 7-0
ADD<7:0>: MSSP Address bits Note 1: MSSP Address register in I2C Slave mode. MSSP Baud Rate register in I2C Master mode. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
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18.4.2 OPERATION 18.4.3.1 Addressing
The MSSP module functions are enabled by setting MSSP Enable bit, SSPEN (SSPCON1<5>). The SSPCON1 register allows control of the I 2C operation. Four mode selection bits (SSPCON1<3:0>) allow one of the following I 2C modes to be selected: * * * * I2C Master mode clock I 2C Slave mode (7-bit address) I 2C Slave mode (10-bit address) I 2C Slave mode (7-bit address) with Start and Stop bit interrupts enabled * I 2C Slave mode (10-bit address) with Start and Stop bit interrupts enabled * I2C Firmware Controlled Master mode, slave is Idle Once the MSSP module has been enabled, it waits for a Start condition to occur. Following the Start condition, the 8 bits are shifted into the SSPSR register. All incoming bits are sampled with the rising edge of the clock (SCL) line. The value of register SSPSR<7:1> is compared to the value of the SSPADD register. The address is compared on the falling edge of the eighth clock (SCL) pulse. If the addresses match and the BF and SSPOV bits are clear, the following events occur: 1. 2. 3. 4. The SSPSR register value is loaded into the SSPBUF register. The Buffer Full bit, BF, is set. An ACK pulse is generated. MSSP Interrupt Flag bit, SSPIF (PIR1<3>), is set (interrupt is generated, if enabled) on the falling edge of the ninth SCL pulse.
Selection of any I 2C mode with the SSPEN bit set, forces the SCL and SDA pins to be open-drain, provided these pins are programmed to inputs by setting the appropriate TRISC bits. To ensure proper operation of the module, pull-up resistors must be provided externally to the SCL and SDA pins.
18.4.3
SLAVE MODE
In Slave mode, the SCL and SDA pins must be configured as inputs (TRISC<4:3> set). The MSSP module will override the input state with the output data when required (slave-transmitter). The I 2C Slave mode hardware will always generate an interrupt on an address match. Address masking will allow the hardware to generate an interrupt for more than one address (up to 31 in 7-Bit Addressing mode and up to 63 in 10-Bit Addressing mode). Through the mode select bits, the user can also choose to interrupt on Start and Stop bits When an address is matched, or the data transfer after an address match is received, the hardware automatically will generate the Acknowledge (ACK) pulse and load the SSPBUF register with the received value currently in the SSPSR register. Any combination of the following conditions will cause the MSSP module not to give this ACK pulse: * The Buffer Full bit, BF (SSPSTAT<0>), was set before the transfer was received. * The overflow bit, SSPOV (SSPCON1<6>), was set before the transfer was received. In this case, the SSPSR register value is not loaded into the SSPBUF, but bit SSPIF (PIR1<3>) is set. The BF bit is cleared by reading the SSPBUF register, while bit SSPOV is cleared through software. The SCL clock input must have a minimum high and low for proper operation. The high and low times of the I2C specification, as well as the requirement of the MSSP module, are shown in timing parameter 100 and parameter 101.
In 10-Bit Addressing mode, two address bytes need to be received by the slave. The five Most Significant bits (MSbs) of the first address byte specify if this is a 10-bit address. Bit R/W (SSPSTAT<2>) must specify a write so the slave device will receive the second address byte. For a 10-bit address, the first byte would equal `11110 A9 A8 0', where `A9' and `A8' are the two MSbs of the address. The sequence of events for 10-bit address is as follows, with steps 7 through 9 for the slave-transmitter: 1. 2. Receive first (high) byte of address (bits SSPIF, BF and UA (SSPSTAT<1>) are set). Update the SSPADD register with second (low) byte of address (clears bit UA and releases the SCL line). Read the SSPBUF register (clears bit BF) and clear flag bit, SSPIF. Receive second (low) byte of address (bits SSPIF, BF and UA are set). Update the SSPADD register with the first (high) byte of address. If match releases SCL line, this will clear bit UA. Read the SSPBUF register (clears bit BF) and clear flag bit, SSPIF. Receive Repeated Start condition. Receive first (high) byte of address (bits SSPIF and BF are set). Read the SSPBUF register (clears bit BF) and clear flag bit, SSPIF.
3. 4. 5.
6. 7. 8. 9.
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18.4.3.2 Address Masking
* 10-Bit Addressing mode Address mask bits, ADMSK<5:2>, mask the corresponding address bits in the SSPADD register. In addition, ADMSK<1> simultaneously masks the two LSBs of the address, ADD<1:0>. For any ADMSK bits that are active (ADMSK = 1), the corresponding address bit is ignored (ADD = x). Also note that although in 10-Bit Addressing mode, the upper address bits reuse part of the SSPADD register bits, the address mask bits do not interact with those bits. They only affect the lower address bits. Note 1: ADMSK<1> masks the two Significant bits of the address. Least Masking an address bit causes that bit to become a "don't care". When one address bit is masked, two addresses will be Acknowledged and cause an interrupt. It is possible to mask more than one address bit at a time, which makes it possible to Acknowledge up to 31 addresses in 7-Bit Addressing mode and up to 63 addresses in 10-Bit Addressing mode (see Example 18-2). The I2C slave behaves the same way whether address masking is used or not. However, when address masking is used, the I2C slave can Acknowledge multiple addresses and cause interrupts. When this occurs, it is necessary to determine which address caused the interrupt by checking the SSPBUF register. * 7-Bit Addressing mode Address mask bits, ADMSK<5:1>, mask the corresponding address bits in the SSPADD register. For any ADMSK bits that are active (ADMSK = 1), the corresponding address bit is ignored (ADD = x). For the module to issue an address Acknowledge, it is sufficient to match only on addresses that do not have an active address mask.
2: The two Most Significant bits of the address are not affected by address masking.
EXAMPLE 18-2:
ADDRESS MASKING
7-Bit Addressing mode: SSPADD<7:1> = 1010 0000 ADMSK<5:1> = 00 111 Addresses Acknowledged = 0xA0, 0xA2, 0xA4, 0xA6, 0xA8, 0xAA, 0xAC, 0xAE 10-Bit Addressing mode: SSPADD<7:0> = 1010 0000 (The two MSbs are ignored in this example since they are not affected) ADMSK<5:1> = 00 111 Addresses Acknowledged = 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF The upper two bits are not affected by the address masking.
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18.4.3.3 Reception 18.4.3.4 Transmission
When the R/W bit of the address byte is clear and an address match occurs, the R/W bit of the SSPSTAT register is cleared. The received address is loaded into the SSPBUF register and the SDA line is held low (ACK). When the address byte overflow condition exists, then the no Acknowledge (ACK) pulse is given. An overflow condition is defined as either bit BF (SSPSTAT<0>) is set, or bit SSPOV (SSPCON1<6>) is set. An MSSP interrupt is generated for each data transfer byte. Flag bit, SSPIF (PIR1<3>), must be cleared in software. The SSPSTAT register is used to determine the status of the byte. If SEN is enabled (SSPCON2<0> = 1), RC3/SCK/SCL will be held low (clock stretch) following each data transfer. The clock must be released by setting bit, CKP (SSPCON1<4>). See Section 18.4.4 "Clock Stretching" for more detail. When the R/W bit of the incoming address byte is set and an address match occurs, the R/W bit of the SSPSTAT register is set. The received address is loaded into the SSPBUF register. The ACK pulse will be sent on the ninth bit and pin RC3/SCK/SCL is held low regardless of SEN (see Section 18.4.4 "Clock Stretching" for more detail). By stretching the clock, the master will be unable to assert another clock pulse until the slave is done preparing the transmit data. The transmit data must be loaded into the SSPBUF register which also loads the SSPSR register. Then pin RC3/ SCK/SCL should be enabled by setting bit, CKP (SSPCON1<4>). The eight data bits are shifted out on the falling edge of the SCL input. This ensures that the SDA signal is valid during the SCL high time (Figure 18-10). The ACK pulse from the master-receiver is latched on the rising edge of the ninth SCL input pulse. If the SDA line is high (not ACK), then the data transfer is complete. In this case, when the ACK is latched by the slave, the slave logic is reset and the slave monitors for another occurrence of the Start bit. If the SDA line was low (ACK), the next transmit data must be loaded into the SSPBUF register. Again, pin RC3/SCK/SCL must be enabled by setting bit CKP. An MSSP interrupt is generated for each data transfer byte. The SSPIF bit must be cleared in software and the SSPSTAT register is used to determine the status of the byte. The SSPIF bit is set on the falling edge of the ninth clock pulse.
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DS39689F-page 183
FIGURE 18-8:
DS39689F-page 184
Receiving Address A5 A4 A3 A2 A1 ACK D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 R/W = 0 Receiving Data ACK Receiving Data D1 D0 ACK 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 P Bus master terminates transfer Cleared in software SSPBUF is read SSPOV is set because SSPBUF is still full. ACK is not sent.
SDA
A7
A6
SCL
S
1
2
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
SSPOV (SSPCON1<6>)
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I2CTM SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 7-BIT ADDRESSING)
(c) 2009 Microchip Technology Inc.
CKP
(CKP does not reset to `0' when SEN = 0)
FIGURE 18-9:
(c) 2009 Microchip Technology Inc.
Receiving Address A5 X A3 X X ACK D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 R/W = 0 Receiving Data ACK Receiving Data D2 D1 D0 ACK 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 P Bus master terminates transfer Cleared in software SSPBUF is read SSPOV is set because SSPBUF is still full. ACK is not sent.
SDA
A7
A6
SCL
S
1
2
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
SSPOV (SSPCON1<6>)
CKP
(CKP does not reset to `0' when SEN = 0)
Note
1:
x = Don't care (i.e., address bit can be either a `1' or a `0').
I2CTM SLAVE MODE TIMING WITH SEN = 0 AND ADMSK<5:1> = 01011 (RECEPTION, 7-BIT ADDRESSING)
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DS39689F-page 185
2:
In this example, an address equal to A7.A6.A5.X.A3.X.X will be Acknowledged and cause an interrupt.
FIGURE 18-10:
DS39689F-page 186
R/W = 1 ACK D1 D0 D4 D3 D2 D5 D7 D6 D1 Transmitting Data D0 A1 D3 D2 ACK D5 D4 D7 D6 Transmitting Data ACK A4 A2 A3 4 SCL held low while CPU responds to SSPIF 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 P Cleared in software SSPBUF is written in software Clear by reading From SSPIF ISR Cleared in software SSPBUF is written in software From SSPIF ISR
Receiving Address
SDA
A7
A6
A5
SCL
S
1
2
3
Data in sampled
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
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CKP
I2CTM SLAVE MODE TIMING (TRANSMISSION, 7-BIT ADDRESSING)
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CKP is set in software
CKP is set in software
FIGURE 18-11:
Clock is held low until update of SSPADD has taken place R/W = 0 A8 D3 D2 ACK A7 A6 A5 X A3 A2 X X D7 D6 D5 D4 D3 D2 D1 D0 ACK D7 D6 D5 D4 ACK Receive Second Byte of Address Receive Data Byte Receive Data Byte D1 D0 ACK
Clock is held low until update of SSPADD has taken place
Receive First Byte of Address
(c) 2009 Microchip Technology Inc.
6 1 2 3 4 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 5 6 7 8 9 P Bus master terminates transfer Cleared in software Cleared in software Cleared in software Dummy read of SSPBUF to clear BF flag SSPOV is set because SSPBUF is still full. ACK is not sent. Cleared by hardware when SSPADD is updated with low byte of address UA is set indicating that SSPADD needs to be updated Cleared by hardware when SSPADD is updated with high byte of address
SDA
1
1
1
1
0
A9
SCL
S
1
2
3
4
5
SSPIF (PIR1<3>)
Cleared in software
BF (SSPSTAT<0>)
SSPBUF is written with contents of SSPSR
SSPOV (SSPCON1<6>)
UA (SSPSTAT<1>)
UA is set indicating that the SSPADD needs to be updated
CKP
I2CTM SLAVE MODE TIMING WITH SEN = 0 AND ADMSK = 01001 (RECEPTION, 10-BIT ADDRESSING)
(CKP does not reset to `0' when SEN = 0)
Note
1:
x = Don't care (i.e., address bit can be either a `1' or a `0').
2:
In this example, an address equal to A9.A8.A7.A6.A5.X.A3.A2.X.X will be Acknowledged and cause an interrupt.
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DS39689F-page 187
3:
Note that the Most Significant bits of the address are not affected by the bit masking.
FIGURE 18-12:
DS39689F-page 188
Clock is held low until update of SSPADD has taken place R/W = 0 A8 D3 D2 ACK A7 A6 A5 A4 A3 A2 A1 D7 D6 D5 D4 D3 D2 D1 D0 ACK D7 D6 D5 D4 A0 ACK D1 D0 Receive Second Byte of Address Receive Data Byte Receive Data Byte ACK Clock is held low until update of SSPADD has taken place 0 A9 5 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 6 7 8 9 P Bus master terminates transfer Cleared in software Cleared in software Cleared in software Dummy read of SSPBUF to clear BF flag SSPOV is set because SSPBUF is still full. ACK is not sent. Cleared by hardware when SSPADD is updated with low byte of address UA is set indicating that SSPADD needs to be updated Cleared by hardware when SSPADD is updated with high byte of address
Receive First Byte of Address
SDA
1
1
1
1
SCL
S
1
2
3
4
SSPIF (PIR1<3>)
Cleared in software
BF (SSPSTAT<0>)
SSPBUF is written with contents of SSPSR
SSPOV (SSPCON1<6>)
UA (SSPSTAT<1>)
UA is set indicating that the SSPADD needs to be updated
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I2CTM SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 10-BIT ADDRESSING)
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CKP
(CKP does not reset to `0' when SEN = 0)
FIGURE 18-13:
Bus master terminates transfer Clock is held low until CKP is set to `1' R/W=1 ACK Transmitting Data Byte D7 D6 D5 D4 D3 D2 D1 D0 ACK
(c) 2009 Microchip Technology Inc.
Clock is held low until update of SSPADD has taken place R/W = 0 Receive Second Byte of Address Receive First Byte of Address ACK 1 1 1 1 0 A9 A8 ACK A7 A6 A5 A4 A3 A2 A1 A0 Clock is held low until update of SSPADD has taken place 1 0 A9 A8 4 Sr 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 P Cleared in software Cleared in software Cleared in software Dummy read of SSPBUF to clear BF flag Dummy read of SSPBUF to clear BF flag Write of SSPBUF BF flag is clear initiates transmit at the end of the third address sequence Completion of data transmission clears BF flag Cleared by hardware when SSPADD is updated with low byte of address UA is set indicating that SSPADD needs to be updated Cleared by hardware when SSPADD is updated with high byte of address. CKP is set in software CKP is automatically cleared in hardware, holding SCL low
Receive First Byte of Address
SDA
1
1
1
SCL
S
1
2
3
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
SSPBUF is written with contents of SSPSR
UA (SSPSTAT<1>)
UA is set indicating that the SSPADD needs to be updated
I2CTM SLAVE MODE TIMING (TRANSMISSION, 10-BIT ADDRESSING)
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CKP (SSPCON1<4>)
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18.4.4 CLOCK STRETCHING 18.4.4.3
Both 7-Bit and 10-Bit Slave modes implement automatic clock stretching during a transmit sequence. The SEN bit (SSPCON2<0>) allows clock stretching to be enabled during receives. Setting SEN will cause the SCL pin to be held low at the end of each data receive sequence.
Clock Stretching for 7-Bit Slave Transmit Mode
7-Bit Slave Transmit mode implements clock stretching by clearing the CKP bit after the falling edge of the ninth clock if the BF bit is clear. This occurs regardless of the state of the SEN bit. The user's ISR must set the CKP bit before transmission is allowed to continue. By holding the SCL line low, the user has time to service the ISR and load the contents of the SSPBUF before the master device can initiate another transmit sequence (see Figure 18-10). Note 1: If the user loads the contents of SSPBUF, setting the BF bit before the falling edge of the ninth clock, the CKP bit will not be cleared and clock stretching will not occur. 2: The CKP bit can be set in software regardless of the state of the BF bit.
18.4.4.1
Clock Stretching for 7-Bit Slave Receive Mode (SEN = 1)
In 7-Bit Slave Receive mode, on the falling edge of the ninth clock at the end of the ACK sequence if the BF bit is set, the CKP bit in the SSPCON1 register is automatically cleared, forcing the SCL output to be held low. The CKP bit being cleared to `0' will assert the SCL line low. The CKP bit must be set in the user's ISR before reception is allowed to continue. By holding the SCL line low, the user has time to service the ISR and read the contents of the SSPBUF before the master device can initiate another receive sequence. This will prevent buffer overruns from occurring (see Figure 18-15). Note 1: If the user reads the contents of the SSPBUF before the falling edge of the ninth clock, thus clearing the BF bit, the CKP bit will not be cleared and clock stretching will not occur. 2: The CKP bit can be set in software regardless of the state of the BF bit. The user should be careful to clear the BF bit in the ISR before the next receive sequence in order to prevent an overflow condition.
18.4.4.4
Clock Stretching for 10-Bit Slave Transmit Mode
In 10-Bit Slave Transmit mode, clock stretching is controlled during the first two address sequences by the state of the UA bit, just as it is in 10-Bit Slave Receive mode. The first two addresses are followed by a third address sequence which contains the highorder bits of the 10-bit address and the R/W bit set to `1'. After the third address sequence is performed, the UA bit is not set, the module is now configured in Transmit mode and clock stretching is controlled by the BF flag as in 7-Bit Slave Transmit mode (see Figure 18-13).
18.4.4.2
Clock Stretching for 10-Bit Slave Receive Mode (SEN = 1)
In 10-Bit Slave Receive mode during the address sequence, clock stretching automatically takes place but CKP is not cleared. During this time, if the UA bit is set after the ninth clock, clock stretching is initiated. The UA bit is set after receiving the upper byte of the 10-bit address and following the receive of the second byte of the 10-bit address with the R/W bit cleared to `0'. The release of the clock line occurs upon updating SSPADD. Clock stretching will occur on each data receive sequence as described in 7-bit mode. Note: If the user polls the UA bit and clears it by updating the SSPADD register before the falling edge of the ninth clock occurs and if the user hasn't cleared the BF bit by reading the SSPBUF register before that time, then the CKP bit will still NOT be asserted low. Clock stretching on the basis of the state of the BF bit only occurs during a data sequence, not an address sequence.
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18.4.4.5 Clock Synchronization and the CKP bit
When the CKP bit is cleared, the SCL output is forced to `0'. However, clearing the CKP bit will not assert the SCL output low until the SCL output is already sampled low. Therefore, the CKP bit will not assert the SCL line until an external I2C master device has already asserted the SCL line. The SCL output will remain low until the CKP bit is set and all other devices on the I2C bus have deasserted SCL. This ensures that a write to the CKP bit will not violate the minimum high time requirement for SCL (see Figure 18-14).
FIGURE 18-14:
CLOCK SYNCHRONIZATION TIMING
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
SDA
DX
DX - 1
SCL Master device asserts clock Master device deasserts clock WR SSPCON
CKP
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FIGURE 18-15:
DS39689F-page 192
Clock is not held low because buffer full bit is clear prior to falling edge of 9th clock Clock is held low until CKP is set to `1' ACK Receiving Data D7 D6 D5 D4 D3 D2 D1 D0 D2 D1 D0 Receiving Address A5 A4 A3 A2 A1 ACK D7 D6 D5 D4 D3 R/W = 0 Receiving Data Clock is not held low because ACK = 1 ACK 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 P Bus master terminates transfer Cleared in software SSPBUF is read SSPOV is set because SSPBUF is still full. ACK is not sent.
SDA
A7
A6
SCL
S
1
2
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
SSPOV (SSPCON1<6>)
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CKP CKP written to `1' in software BF is set after falling edge of the 9th clock, CKP is reset to `0' and clock stretching occurs
I2CTM SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 7-BIT ADDRESSING)
(c) 2009 Microchip Technology Inc.
If BF is cleared prior to the falling edge of the 9th clock, CKP will not be reset to `0' and no clock stretching will occur
FIGURE 18-16:
Clock is held low until update of SSPADD has taken place Clock is held low until CKP is set to `1' Receive Data Byte D1 D0 D7 D6 D5 D4 ACK D3 D2 D1 D0 R/W = 0 ACK A7 A6 A5 A4 A3 A2 A1 A0 ACK D7 D6 D5 D4 D3 D2 Receive Second Byte of Address Receive Data Byte
Clock is held low until update of SSPADD has taken place
Clock is not held low because ACK = 1 ACK
Receive First Byte of Address A9 A8
(c) 2009 Microchip Technology Inc.
6 1 2 3 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 4 5 6 7 8 9 P Cleared in software Cleared in software Cleared in software Bus master terminates transfer Dummy read of SSPBUF to clear BF flag Dummy read of SSPBUF to clear BF flag SSPOV is set because SSPBUF is still full. ACK is not sent. Cleared by hardware when SSPADD is updated with low byte of address after falling edge of ninth clock UA is set indicating that SSPADD needs to be updated Cleared by hardware when SSPADD is updated with high byte of address after falling edge of ninth clock Note: An update of the SSPADD register before the falling edge of the ninth clock will have no effect on UA and UA will remain set. Note: An update of the SSPADD register before the falling edge of the ninth clock will have no effect on UA and UA will remain set. CKP written to `1' in software
SDA
1
1
1
1
0
SCL
S
1
2
3
4
5
SSPIF (PIR1<3>)
Cleared in software
BF (SSPSTAT<0>)
SSPBUF is written with contents of SSPSR
SSPOV (SSPCON1<6>)
UA (SSPSTAT<1>)
UA is set indicating that the SSPADD needs to be updated
I2CTM SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 10-BIT ADDRESSING)
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CKP
DS39689F-page 193
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18.4.5 GENERAL CALL ADDRESS SUPPORT
The addressing procedure for the I2C bus is such that the first byte after the Start condition usually determines which device will be the slave addressed by the master. The exception is the general call address which can address all devices. When this address is used, all devices should, in theory, respond with an Acknowledge. The general call address is one of eight addresses reserved for specific purposes by the I2C protocol. It consists of all `0's with R/W = 0. The general call address is recognized when the General Call Enable bit, GCEN, is enabled (SSPCON2<7> is set). Following a Start bit detect, 8 bits are shifted into the SSPSR and the address is compared against the SSPADD. It is also compared to the general call address and fixed in hardware. If the general call address matches, the SSPSR is transferred to the SSPBUF, the BF flag bit is set (eighth bit) and on the falling edge of the ninth bit (ACK bit), the SSPIF interrupt flag bit is set. When the interrupt is serviced, the source for the interrupt can be checked by reading the contents of the SSPBUF. The value can be used to determine if the address was device specific or a general call address. In 10-bit mode, the SSPADD is required to be updated for the second half of the address to match and the UA bit (SSPSTAT<1>) is set. If the general call address is sampled when the GCEN bit is set, while the slave is configured in 10-Bit Addressing mode, then the second half of the address is not necessary, the UA bit will not be set and the slave will begin receiving data after the Acknowledge (Figure 18-17).
FIGURE 18-17:
SLAVE MODE GENERAL CALL ADDRESS SEQUENCE (7 OR 10-BIT ADDRESSING MODE)
Address is compared to General Call Address after ACK, set interrupt R/W = 0 ACK D7 D6 Receiving Data D5 D4 D3 D2 D1 D0 ACK
SDA SCL S SSPIF BF (SSPSTAT<0>)
General Call Address
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
Cleared in software SSPBUF is read SSPOV (SSPCON1<6>) GCEN (SSPCON2<7>) `1' `0'
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18.4.6 MASTER MODE
Note: Master mode is enabled by setting and clearing the appropriate SSPM bits in SSPCON1 and by setting the SSPEN bit. In Master mode, the SCL and SDA lines are manipulated by the MSSP hardware. Master mode of operation is supported by interrupt generation on the detection of the Start and Stop conditions. The Stop (P) and Start (S) bits are cleared from a Reset or when the MSSP module is disabled. Control of the I 2C bus may be taken when the P bit is set, or the bus is Idle, with both the S and P bits clear. In Firmware Controlled Master mode, user code conducts all I 2C bus operations based on Start and Stop bit conditions. Once Master mode is enabled, the user has six options. 1. 2. 3. 4. 5. 6. Assert a Start condition on SDA and SCL. Assert a Repeated Start condition on SDA and SCL. Write to the SSPBUF register initiating transmission of data/address. Configure the I2C port to receive data. Generate an Acknowledge condition at the end of a received byte of data. Generate a Stop condition on SDA and SCL. The MSSP module, when configured in I2C Master mode, does not allow queueing of events. For instance, the user is not allowed to initiate a Start condition and immediately write the SSPBUF register to initiate transmission before the Start condition is complete. In this case, the SSPBUF will not be written to and the WCOL bit will be set, indicating that a write to the SSPBUF did not occur.
The following events will cause the MSSP Interrupt Flag bit, SSPIF, to be set (MSSP interrupt, if enabled): * * * * * Start condition Stop condition Data transfer byte transmitted/received Acknowledge transmit Repeated Start
FIGURE 18-18:
MSSP BLOCK DIAGRAM (I2CTM MASTER MODE)
Internal Data Bus Read SSPBUF Write Baud Rate Generator Clock Arbitrate/WCOL Detect (hold off clock source) DS39689F-page 195 Shift Clock SSPSR Receive Enable MSb LSb SSPM<3:0> SSPADD<6:0>
SDA
SDA In
SCL
SCL In Bus Collision
Start bit Detect Stop bit Detect Write Collision Detect Clock Arbitration State Counter for end of XMIT/RCV
Set/Reset, S, P, WCOL (SSPSTAT); Set SSPIF, BCLIF; Reset ACKSTAT, PEN (SSPCON2)
(c) 2009 Microchip Technology Inc.
Clock Cntl
Start bit, Stop bit, Acknowledge Generate
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18.4.6.1 I2C Master Mode Operation
A typical transmit sequence would go as follows: 1. The user generates a Start condition by setting the Start Enable bit, SEN (SSPCON2<0>). 2. SSPIF is set. The MSSP module will wait the required start time before any other operation takes place. 3. The user loads the SSPBUF with the slave address to transmit. 4. Address is shifted out the SDA pin until all 8 bits are transmitted. 5. The MSSP module shifts in the ACK bit from the slave device and writes its value into the SSPCON2 register. 6. The MSSP module generates an interrupt at the end of the ninth clock cycle by setting the SSPIF bit. 7. The user loads the SSPBUF with eight bits of data. 8. Data is shifted out the SDA pin until all 8 bits are transmitted. 9. The MSSP module shifts in the ACK bit from the slave device and writes its value into the SSPCON2 register. 10. The MSSP module generates an interrupt at the end of the ninth clock cycle by setting the SSPIF bit. 11. The user generates a Stop condition by setting the Stop Enable bit, PEN (SSPCON2<2>). 12. Interrupt is generated once the Stop condition is complete. The master device generates all of the serial clock pulses and the Start and Stop conditions. A transfer is ended with a Stop condition or with a Repeated Start condition. Since the Repeated Start condition is also the beginning of the next serial transfer, the I2C bus will not be released. In Master Transmitter mode, serial data is output through SDA, while SCL outputs the serial clock. The first byte transmitted contains the slave address of the receiving device (7 bits) and the Read/Write (R/W) bit. In this case, the R/W bit will be logic `0'. Serial data is transmitted 8 bits at a time. After each byte is transmitted, an Acknowledge bit is received. Start and Stop conditions are output to indicate the beginning and the end of a serial transfer. In Master Receive mode, the first byte transmitted contains the slave address of the transmitting device (7 bits) and the R/W bit. In this case, the R/W bit will be logic `1'. Thus, the first byte transmitted is a 7-bit slave address followed by a `1' to indicate the receive bit. Serial data is received via SDA, while SCL outputs the serial clock. Serial data is received 8 bits at a time. After each byte is received, an Acknowledge bit is transmitted. Start and Stop conditions indicate the beginning and end of transmission. The Baud Rate Generator used for the SPI mode operation is used to set the SCL clock frequency for either 100 kHz, 400 kHz or 1 MHz I2C operation. See Section 18.4.7 "Baud Rate" for more detail.
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18.4.7
2
BAUD RATE
In I C Master mode, the Baud Rate Generator (BRG) reload value is placed in the lower 7 bits of the SSPADD register (Figure 18-19). When a write occurs to SSPBUF, the Baud Rate Generator will automatically begin counting. The BRG counts down to 0 and stops until another reload has taken place. The BRG count is decremented twice per instruction cycle (TCY) on the Q2 and Q4 clocks. In I2C Master mode, the BRG is reloaded automatically.
Once the given operation is complete (i.e., transmission of the last data bit is followed by ACK), the internal clock will automatically stop counting and the SCL pin will remain in its last state. Table 18-3 demonstrates clock rates based on instruction cycles and the BRG value loaded into SSPADD.
FIGURE 18-19:
BAUD RATE GENERATOR BLOCK DIAGRAM
SSPM<3:0> SSPADD<6:0>
SSPM<3:0> SCL
Reload Control CLKO
Reload
BRG Down Counter
FOSC/4
TABLE 18-3:
Fosc 40 MHz 40 MHz 40 MHz 16 MHz 16 MHz 16 MHz 4 MHz 4 MHz 4 MHz
I2CTM CLOCK RATE W/BRG
FCY 10 MHz 10 MHz 10 MHz 4 MHz 4 MHz 4 MHz 1 MHz 1 MHz 1 MHz FCY * 2 20 MHz 20 MHz 20 MHz 8 MHz 8 MHz 8 MHz 2 MHz 2 MHz 2 MHz BRG Value 18h 1Fh 63h 09h 0Ch 27h 02h 09h 00h FSCL (2 Rollovers of BRG) 400 kHz 312.5 kHz 100 kHz 400 kHz 308 kHz 100 kHz 333 kHz 100 kHz 1 MHz
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18.4.7.1 Clock Arbitration
Clock arbitration occurs when the master, during any receive, transmit or Repeated Start/Stop condition, deasserts the SCL pin (SCL allowed to float high). When the SCL pin is allowed to float high, the Baud Rate Generator (BRG) is suspended from counting until the SCL pin is actually sampled high. When the SCL pin is sampled high, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and begins counting. This ensures that the SCL high time will always be at least one BRG rollover count in the event that the clock is held low by an external device (Figure 18-20).
FIGURE 18-20:
SDA
BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION
DX DX - 1 SCL allowed to transition high
SCL deasserted but slave holds SCL low (clock arbitration) SCL BRG decrements on Q2 and Q4 cycles BRG Value 03h 02h 01h 00h (hold off)
03h
02h
SCL is sampled high, reload takes place and BRG starts its count BRG Reload
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18.4.8 I2C MASTER MODE START CONDITION TIMING
Note: To initiate a Start condition, the user sets the Start Enable bit, SEN (SSPCON2<0>). If the SDA and SCL pins are sampled high, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and starts its count. If SCL and SDA are both sampled high when the Baud Rate Generator times out (TBRG), the SDA pin is driven low. The action of the SDA being driven low while SCL is high is the Start condition and causes the S bit (SSPSTAT<3>) to be set. Following this, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and resumes its count. When the Baud Rate Generator times out (TBRG), the SEN bit (SSPCON2<0>) will be automatically cleared by hardware; the Baud Rate Generator is suspended, leaving the SDA line held low and the Start condition is complete. If at the beginning of the Start condition, the SDA and SCL pins are already sampled low, or if during the Start condition, the SCL line is sampled low before the SDA line is driven low, a bus collision occurs, the Bus Collision Interrupt Flag, BCLIF, is set, the Start condition is aborted and the I2C module is reset into its Idle state.
18.4.8.1
WCOL Status Flag
If the user writes the SSPBUF when a Start sequence is in progress, the WCOL is set and the contents of the buffer are unchanged (the write doesn't occur). Note: Because queueing of events is not allowed, writing to the lower 5 bits of SSPCON2 is disabled until the Start condition is complete.
FIGURE 18-21:
FIRST START BIT TIMING
Write to SEN bit occurs here SDA = 1, SCL = 1 TBRG TBRG Set S bit (SSPSTAT<3>) At completion of Start bit, hardware clears SEN bit and sets SSPIF bit Write to SSPBUF occurs here 1st bit TBRG TBRG S 2nd bit
SDA
SCL
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18.4.9 I2C MASTER MODE REPEATED START CONDITION TIMING
Note 1: If RSEN is programmed while any other event is in progress, it will not take effect. 2: A bus collision during the Repeated Start condition occurs if: * SDA is sampled low when SCL goes from low-to-high. * SCL goes low before SDA is asserted low. This may indicate that another master is attempting to transmit a data `1'. Immediately following the SSPIF bit getting set, the user may write the SSPBUF with the 7-bit address in 7-bit mode, or the default first address in 10-bit mode. After the first eight bits are transmitted and an ACK is received, the user may then transmit an additional eight bits of address (10-bit mode) or eight bits of data (7-bit mode). A Repeated Start condition occurs when the RSEN bit (SSPCON2<1>) is programmed high and the I2C logic module is in the Idle state. When the RSEN bit is set, the SCL pin is asserted low. When the SCL pin is sampled low, the Baud Rate Generator is loaded with the contents of SSPADD<5:0> and begins counting. The SDA pin is released (brought high) for one Baud Rate Generator count (TBRG). When the Baud Rate Generator times out, if SDA is sampled high, the SCL pin will be deasserted (brought high). When SCL is sampled high, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and begins counting. SDA and SCL must be sampled high for one TBRG. This action is then followed by assertion of the SDA pin (SDA = 0) for one TBRG while SCL is high. Following this, the RSEN bit (SSPCON2<1>) will be automatically cleared and the Baud Rate Generator will not be reloaded, leaving the SDA pin held low. As soon as a Start condition is detected on the SDA and SCL pins, the S bit (SSPSTAT<3>) will be set. The SSPIF bit will not be set until the Baud Rate Generator has timed out.
18.4.9.1
WCOL Status Flag
If the user writes the SSPBUF when a Repeated Start sequence is in progress, the WCOL is set and the contents of the buffer are unchanged (the write doesn't occur). Note: Because queueing of events is not allowed, writing of the lower 5 bits of SSPCON2 is disabled until the Repeated Start condition is complete.
FIGURE 18-22:
REPEATED START CONDITION WAVEFORM
Write to SSPCON2 occurs here. SDA = 1, SCL (no change). S bit set by hardware SDA = 1, SCL = 1 At completion of Start bit, hardware clears RSEN bit and sets SSPIF TBRG 1st bit
TBRG SDA RSEN bit set by hardware on falling edge of ninth clock, end of Xmit SCL
TBRG
Write to SSPBUF occurs here TBRG TBRG Sr = Repeated Start
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18.4.10 I2C MASTER MODE TRANSMISSION 18.4.10.3 ACKSTAT Status Flag
Transmission of a data byte, a 7-bit address or the other half of a 10-bit address is accomplished by simply writing a value to the SSPBUF register. This action will set the Buffer Full flag bit, BF and allow the Baud Rate Generator to begin counting and start the next transmission. Each bit of address/data will be shifted out onto the SDA pin after the falling edge of SCL is asserted (see data hold time specification parameter 106). SCL is held low for one Baud Rate Generator rollover count (TBRG). Data should be valid before SCL is released high (see data setup time specification parameter 107). When the SCL pin is released high, it is held that way for TBRG. The data on the SDA pin must remain stable for that duration and some hold time after the next falling edge of SCL. After the eighth bit is shifted out (the falling edge of the eighth clock), the BF flag is cleared and the master releases SDA. This allows the slave device being addressed to respond with an ACK bit during the ninth bit time if an address match occurred, or if data was received properly. The status of ACK is written into the ACKDT bit on the falling edge of the ninth clock. If the master receives an Acknowledge, the Acknowledge Status bit, ACKSTAT, is cleared. If not, the bit is set. After the ninth clock, the SSPIF bit is set and the master clock (Baud Rate Generator) is suspended until the next data byte is loaded into the SSPBUF, leaving SCL low and SDA unchanged (Figure 18-23). After the write to the SSPBUF, each bit of the address will be shifted out on the falling edge of SCL until all seven address bits and the R/W bit are completed. On the falling edge of the eighth clock, the master will deassert the SDA pin, allowing the slave to respond with an Acknowledge. On the falling edge of the ninth clock, the master will sample the SDA pin to see if the address was recognized by a slave. The status of the ACK bit is loaded into the ACKSTAT status bit (SSPCON2<6>). Following the falling edge of the ninth clock transmission of the address, the SSPIF is set, the BF flag is cleared and the Baud Rate Generator is turned off until another write to the SSPBUF takes place, holding SCL low and allowing SDA to float. In Transmit mode, the ACKSTAT bit (SSPCON2<6>) is cleared when the slave has sent an Acknowledge (ACK = 0) and is set when the slave does not Acknowledge (ACK = 1). A slave sends an Acknowledge when it has recognized its address (including a general call), or when the slave has properly received its data.
18.4.11
I2C MASTER MODE RECEPTION
Master mode reception is enabled by programming the Receive Enable bit, RCEN (SSPCON2<3>). Note: The MSSP module must be in an Idle state before the RCEN bit is set or the RCEN bit will be disregarded.
The Baud Rate Generator begins counting and on each rollover, the state of the SCL pin changes (high-to-low/ low-to-high) and data is shifted into the SSPSR. After the falling edge of the eighth clock, the receive enable flag is automatically cleared, the contents of the SSPSR are loaded into the SSPBUF, the BF flag bit is set, the SSPIF flag bit is set and the Baud Rate Generator is suspended from counting, holding SCL low. The MSSP is now in Idle state awaiting the next command. When the buffer is read by the CPU, the BF flag bit is automatically cleared. The user can then send an Acknowledge bit at the end of reception by setting the Acknowledge Sequence Enable bit, ACKEN (SSPCON2<4>).
18.4.11.1
BF Status Flag
In receive operation, the BF bit is set when an address or data byte is loaded into SSPBUF from SSPSR. It is cleared when the SSPBUF register is read.
18.4.11.2
SSPOV Status Flag
In receive operation, the SSPOV bit is set when 8 bits are received into the SSPSR and the BF flag bit is already set from a previous reception.
18.4.11.3
WCOL Status Flag
18.4.10.1
BF Status Flag
In Transmit mode, the BF bit (SSPSTAT<0>) is set when the CPU writes to SSPBUF and is cleared when all 8 bits are shifted out.
If the user writes the SSPBUF when a receive is already in progress (i.e., SSPSR is still shifting in a data byte), the WCOL bit is set and the contents of the buffer are unchanged (the write doesn't occur).
18.4.10.2
WCOL Status Flag
If the user writes the SSPBUF when a transmit is already in progress (i.e., SSPSR is still shifting out a data byte), the WCOL flag is set and the contents of the buffer are unchanged (the write doesn't occur) after 2 TCY after the SSPBUF write. If SSPBUF is rewritten within 2 TCY, the WCOL bit is set and SSPBUF is updated. This may result in a corrupted transfer. The user should verify that the WCOL flag is clear after each write to SSPBUF to ensure the transfer is correct.
(c) 2009 Microchip Technology Inc. DS39689F-page 201
FIGURE 18-23:
DS39689F-page 202
Write SSPCON2<0> SEN = 1 Start condition begins From slave, clear ACKSTAT bit SSPCON2<6>
R/W = 0
ACKSTAT in SSPCON2 = 1
SEN = 0 Transmit Address to Slave SDA A7 SSPBUF written with 7-bit address and R/W, start transmit SCL S 1 2 3 4 5 6 7 8 9 1 SCL held low while CPU responds to SSPIF 2 3 4 5 6 7 8 9 P A6 A5 A4 A3 A2 A1 ACK = `0' D7 D6 D5 D4 D3 D2 D1 Transmitting Data or Second Half of 10-bit Address D0 ACK
SSPIF Cleared in software Cleared in software service routine from MSSP interrupt Cleared in software
BF (SSPSTAT<0>) SSPBUF written SEN After Start condition, SEN cleared by hardware SSPBUF is written in software
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PEN
I 2CTM MASTER MODE WAVEFORM (TRANSMISSION, 7 OR 10-BIT ADDRESSING)
(c) 2009 Microchip Technology Inc.
R/W
FIGURE 18-24:
(c) 2009 Microchip Technology Inc.
Write to SSPCON2<4> to start Acknowledge sequence SDA = ACKDT (SSPCON2<5>) = 0 Master configured as a receiver by programming SSPCON2<3> (RCEN = 1) ACK from Slave R/W = 1 Receiving Data from Slave ACK Receiving Data from Slave RCEN cleared automatically RCEN = 1, start next receive RCEN cleared automatically ACK ACK from Master SDA = ACKDT = 0 Set ACKEN, start Acknowledge sequence SDA = ACKDT = 1 PEN bit = 1 written here
Write to SSPCON2<0> (SEN = 1), begin Start condition
SEN = 0 Write to SSPBUF occurs here, start XMIT
Transmit Address to Slave
SDA D0
A7 A1 D7 D6 D5 D4 D3 D2 D1 D7 D6 D5 D4 D3 D2 D1
A6 A5 A4 A3 A2
D0
ACK ACK is not sent Bus master terminates transfer
SCL
Set SSPIF interrupt at end of receive
S
1 5 1 2 3 4 5 1 2 3 4
2
3 4 8 6 7 8 9
6
7 9
5
6
7
8
9
Set SSPIF at end of receive
P
Set SSPIF interrupt at end of Acknowledge sequence
Data shifted in on falling edge of CLK
SSPIF
Cleared in software Cleared in software
Set SSPIF interrupt at end of Acknowledge sequence Cleared in software Cleared in software
SDA = 0, SCL = 1 while CPU responds to SSPIF
Cleared in software
Set P bit (SSPSTAT<4>) and SSPIF
BF (SSPSTAT<0>)
Last bit is shifted into SSPSR and contents are unloaded into SSPBUF
SSPOV
SSPOV is set because SSPBUF is still full
I 2CTM MASTER MODE WAVEFORM (RECEPTION, 7-BIT ADDRESSING)
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ACKEN
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18.4.12 ACKNOWLEDGE SEQUENCE TIMING 18.4.13 STOP CONDITION TIMING
An Acknowledge sequence is enabled by setting the Acknowledge Sequence Enable bit, ACKEN (SSPCON2<4>). When this bit is set, the SCL pin is pulled low and the contents of the Acknowledge data bit are presented on the SDA pin. If the user wishes to generate an Acknowledge, then the ACKDT bit should be cleared. If not, the user should set the ACKDT bit before starting an Acknowledge sequence. The Baud Rate Generator then counts for one rollover period (TBRG) and the SCL pin is deasserted (pulled high). When the SCL pin is sampled high (clock arbitration), the Baud Rate Generator counts for TBRG. The SCL pin is then pulled low. Following this, the ACKEN bit is automatically cleared, the Baud Rate Generator is turned off and the MSSP module then goes into Idle mode (Figure 18-25). A Stop bit is asserted on the SDA pin at the end of a receive/transmit by setting the Stop Sequence Enable bit, PEN (SSPCON2<2>). At the end of a receive/ transmit, the SCL line is held low after the falling edge of the ninth clock. When the PEN bit is set, the master will assert the SDA line low. When the SDA line is sampled low, the Baud Rate Generator is reloaded and counts down to 0. When the Baud Rate Generator times out, the SCL pin will be brought high and one TBRG (Baud Rate Generator rollover count) later, the SDA pin will be deasserted. When the SDA pin is sampled high while SCL is high, the P bit (SSPSTAT<4>) is set. A TBRG later, the PEN bit is cleared and the SSPIF bit is set (Figure 18-26).
18.4.13.1
WCOL Status Flag
18.4.12.1
WCOL Status Flag
If the user writes the SSPBUF when an Acknowledge sequence is in progress, then WCOL is set and the contents of the buffer are unchanged (the write doesn't occur).
If the user writes the SSPBUF when a Stop sequence is in progress, then the WCOL bit is set and the contents of the buffer are unchanged (the write doesn't occur).
FIGURE 18-25:
ACKNOWLEDGE SEQUENCE WAVEFORM
Acknowledge sequence starts here, write to SSPCON2 ACKEN = 1, ACKDT = 0 TBRG SDA SCL D0 8 ACK TBRG ACKEN automatically cleared
9
SSPIF SSPIF set at the end of receive Note: TBRG = one Baud Rate Generator period. Cleared in software SSPIF set at the end of Acknowledge sequence
Cleared in software
FIGURE 18-26:
STOP CONDITION RECEIVE OR TRANSMIT MODE
Write to SSPCON2, set PEN Falling edge of 9th clock SCL = 1 for TBRG, followed by SDA = 1 for TBRG after SDA sampled high. P bit (SSPSTAT<4>) is set. PEN bit (SSPCON2<2>) is cleared by hardware and the SSPIF bit is set TBRG
SCL
SDA
ACK P TBRG TBRG TBRG SCL brought high after TBRG SDA asserted low before rising edge of clock to setup Stop condition
Note: TBRG = one Baud Rate Generator period.
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18.4.14 SLEEP OPERATION
2
18.4.17
While in Sleep mode, the I C module can receive addresses or data and when an address match or complete byte transfer occurs, wake the processor from Sleep (if the MSSP interrupt is enabled).
MULTI -MASTER COMMUNICATION, BUS COLLISION AND BUS ARBITRATION
18.4.15
EFFECTS OF A RESET
A Reset disables the MSSP module and terminates the current transfer.
18.4.16
MULTI-MASTER MODE
In Multi-Master mode, the interrupt generation on the detection of the Start and Stop conditions allows the determination of when the bus is free. The Stop (P) and Start (S) bits are cleared from a Reset or when the MSSP module is disabled. Control of the I 2C bus may be taken when the P bit (SSPSTAT<4>) is set, or the bus is Idle, with both the S and P bits clear. When the bus is busy, enabling the MSSP interrupt will generate the interrupt when the Stop condition occurs. In multi-master operation, the SDA line must be monitored for arbitration to see if the signal level is the expected output level. This check is performed in hardware with the result placed in the BCLIF bit. The states where arbitration can be lost are: * * * * * Address Transfer Data Transfer A Start Condition A Repeated Start Condition An Acknowledge Condition
Multi-Master mode support is achieved by bus arbitration. When the master outputs address/data bits onto the SDA pin, arbitration takes place when the master outputs a `1' on SDA, by letting SDA float high and another master asserts a `0'. When the SCL pin floats high, data should be stable. If the expected data on SDA is a `1' and the data sampled on the SDA pin = 0, then a bus collision has taken place. The master will set the Bus Collision Interrupt Flag, BCLIF and reset the I2C port to its Idle state (Figure 18-27). If a transmit was in progress when the bus collision occurred, the transmission is halted, the BF flag is cleared, the SDA and SCL lines are deasserted and the SSPBUF can be written to. When the user services the bus collision Interrupt Service Routine and if the I2C bus is free, the user can resume communication by asserting a Start condition. If a Start, Repeated Start, Stop or Acknowledge condition was in progress when the bus collision occurred, the condition is aborted, the SDA and SCL lines are deasserted and the respective control bits in the SSPCON2 register are cleared. When the user services the bus collision Interrupt Service Routine and if the I2C bus is free, the user can resume communication by asserting a Start condition. The master will continue to monitor the SDA and SCL pins. If a Stop condition occurs, the SSPIF bit will be set. A write to the SSPBUF will start the transmission of data at the first data bit, regardless of where the transmitter left off when the bus collision occurred. In Multi-Master mode, the interrupt generation on the detection of Start and Stop conditions allows the determination of when the bus is free. Control of the I2C bus can be taken when the P bit is set in the SSPSTAT register, or the bus is Idle and the S and P bits are cleared.
FIGURE 18-27:
BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE
Data changes while SCL = 0 SDA line pulled low by another source SDA released by master Sample SDA. While SCL is high, data doesn't match what is driven by the master. Bus collision has occurred.
SDA
SCL
Set bus collision interrupt (BCLIF)
BCLIF
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18.4.17.1 Bus Collision During a Start Condition
During a Start condition, a bus collision occurs if: a) b) SDA or SCL are sampled low at the beginning of the Start condition (Figure 18-28). SCL is sampled low before SDA is asserted low (Figure 18-29). If the SDA pin is sampled low during this count, the BRG is reset and the SDA line is asserted early (Figure 18-30). If, however, a `1' is sampled on the SDA pin, the SDA pin is asserted low at the end of the BRG count. The Baud Rate Generator is then reloaded and counts down to 0; if the SCL pin is sampled as `0' during this time, a bus collision does not occur. At the end of the BRG count, the SCL pin is asserted low. Note: The reason that bus collision is not a factor during a Start condition is that no two bus masters can assert a Start condition at the exact same time. Therefore, one master will always assert SDA before the other. This condition does not cause a bus collision because the two masters must be allowed to arbitrate the first address following the Start condition. If the address is the same, arbitration must be allowed to continue into the data portion, Repeated Start or Stop conditions.
During a Start condition, both the SDA and the SCL pins are monitored. If the SDA pin is already low, or the SCL pin is already low, then all of the following occur: * the Start condition is aborted, * the BCLIF flag is set and * the MSSP module is reset to its Idle state (Figure 18-28). The Start condition begins with the SDA and SCL pins deasserted. When the SDA pin is sampled high, the Baud Rate Generator is loaded from SSPADD<6:0> and counts down to 0. If the SCL pin is sampled low while SDA is high, a bus collision occurs because it is assumed that another master is attempting to drive a data `1' during the Start condition.
FIGURE 18-28:
BUS COLLISION DURING START CONDITION (SDA ONLY)
SDA goes low before the SEN bit is set. Set BCLIF, S bit and SSPIF set because SDA = 0, SCL = 1.
SDA
SCL Set SEN, enable Start condition if SDA = 1, SCL = 1 SEN SDA sampled low before Start condition. Set BCLIF. S bit and SSPIF set because SDA = 0, SCL = 1. SSPIF and BCLIF are cleared in software S SEN cleared automatically because of bus collision. MSSP module reset into Idle state.
BCLIF
SSPIF SSPIF and BCLIF are cleared in software
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FIGURE 18-29: BUS COLLISION DURING START CONDITION (SCL = 0)
SDA = 0, SCL = 1
TBRG TBRG
SDA Set SEN, enable Start sequence if SDA = 1, SCL = 1 SCL = 0 before SDA = 0, bus collision occurs. Set BCLIF. SCL = 0 before BRG time-out, bus collision occurs. Set BCLIF. BCLIF Interrupt cleared in software S SSPIF `0' `0' `0' `0'
SCL
SEN
FIGURE 18-30:
BRG RESET DUE TO SDA ARBITRATION DURING START CONDITION
SDA = 0, SCL = 1 Set S Less than TBRG
TBRG
Set SSPIF
SDA
SDA pulled low by other master. Reset BRG and assert SDA.
SCL
S
SCL pulled low after BRG time-out Set SEN, enable Start sequence if SDA = 1, SCL = 1
SEN
BCLIF
`0'
S
SSPIF SDA = 0, SCL = 1, set SSPIF Interrupts cleared in software
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18.4.17.2 Bus Collision During a Repeated Start Condition
During a Repeated Start condition, a bus collision occurs if: a) b) A low level is sampled on SDA when SCL goes from low level to high level. SCL goes low before SDA is asserted low, indicating that another master is attempting to transmit a data `1'. If SDA is low, a bus collision has occurred (i.e., another master is attempting to transmit a data `0', Figure 18-31). If SDA is sampled high, the BRG is reloaded and begins counting. If SDA goes from high-to-low before the BRG times out, no bus collision occurs because no two masters can assert SDA at exactly the same time. If SCL goes from high-to-low before the BRG times out and SDA has not already been asserted, a bus collision occurs. In this case, another master is attempting to transmit a data `1' during the Repeated Start condition, see Figure 18-32. If, at the end of the BRG time-out, both SCL and SDA are still high, the SDA pin is driven low and the BRG is reloaded and begins counting. At the end of the count, regardless of the status of the SCL pin, the SCL pin is driven low and the Repeated Start condition is complete.
When the user deasserts SDA and the pin is allowed to float high, the BRG is loaded with SSPADD<6:0> and counts down to 0. The SCL pin is then deasserted and when sampled high, the SDA pin is sampled.
FIGURE 18-31:
SDA
BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)
SCL Sample SDA when SCL goes high. If SDA = 0, set BCLIF and release SDA and SCL. RSEN
BCLIF Cleared in software `0' `0'
S SSPIF
FIGURE 18-32:
BUS COLLISION DURING REPEATED START CONDITION (CASE 2)
TBRG TBRG
SDA SCL SCL goes low before SDA, set BCLIF. Release SDA and SCL. Interrupt cleared in software RSEN S SSPIF `0'
BCLIF
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18.4.17.3 Bus Collision During a Stop Condition
Bus collision occurs during a Stop condition if: a) After the SDA pin has been deasserted and allowed to float high, SDA is sampled low after the BRG has timed out. After the SCL pin is deasserted, SCL is sampled low before SDA goes high. The Stop condition begins with SDA asserted low. When SDA is sampled low, the SCL pin is allowed to float. When the pin is sampled high (clock arbitration), the Baud Rate Generator is loaded with SSPADD<6:0> and counts down to 0. After the BRG times out, SDA is sampled. If SDA is sampled low, a bus collision has occurred. This is due to another master attempting to drive a data `0' (Figure 18-33). If the SCL pin is sampled low before SDA is allowed to float high, a bus collision occurs. This is another case of another master attempting to drive a data `0' (Figure 18-34).
b)
FIGURE 18-33:
BUS COLLISION DURING A STOP CONDITION (CASE 1)
TBRG TBRG TBRG SDA sampled low after TBRG, set BCLIF
SDA SDA asserted low SCL PEN BCLIF P SSPIF
`0' `0'
FIGURE 18-34:
BUS COLLISION DURING A STOP CONDITION (CASE 2)
TBRG TBRG TBRG
SDA Assert SDA SCL PEN BCLIF P SSPIF `0' `0' SCL goes low before SDA goes high, set BCLIF
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TABLE 18-4:
Name INTCON PIR1 PIE1 IPR1 PIR2 PIE2 IPR2 TRISC TRISD SSPBUF SSPADD TMR2 PR2 SSPCON1 SSPCON2 SSPSTAT
REGISTERS ASSOCIATED WITH I2CTM OPERATION
Bit 7 Bit 6 Bit 5 Bit 4 INT0IE TXIF TXIE TXIP EEIF EEIE EEIP TRISC4 TRISD4 ADD4 Bit 3 RBIE SSPIF SSPIE SSPIP BCLIF BCLIE BCLIP TRISC3 TRISD3 ADD3 Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP HLVDIF HLVDIE HLVDIP TRISC2 TRISD2 ADD2 Bit 1 INT0IF TMR2IF TMR2IE TMR2IP TMR3IF TMR3IE TMR3IP TRISC1 TRISD1 ADD1 Bit 0 RBIF TMR1IF TMR1IE TMR1IP CCP2IF CCP2IE CCP2IP TRISC0 TRISD0 ADD0 Reset Values on page 55 58 58 58 58 58 58 58 58 56 56 56 56 SSPEN ACKDT/ ADMSK5 D/A CKP ACKEN/ ADMSK5 P SSPM3 RCEN/ ADMSK5 S SSPM2 PEN/ ADMSK5 R/W SSPM1 RSEN/ ADMSK5 UA SSPM0 SEN BF 56 56 56
GIE/GIEH PEIE/GIEL TMR0IE PSPIF PSPIE PSPIP OSCFIF OSCFIE OSCFIP TRISC7 TRISD7 ADD7 ADIF ADIE ADIP CMIF CMIE CMIP TRISC6 TRISD6 ADD6 RCIF RCIE RCIP -- -- -- TRISC5 TRISD5 ADD5
MSSP Receive Buffer/Transmit Register Timer2 Register Timer2 Period Register WCOL GCEN SMP SSPOV ACKSTAT CKE
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the MSSP module in I2C mode.
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19.0 ENHANCED UNIVERSAL SYNCHRONOUS ASYNCHRONOUS RECEIVER TRANSMITTER (EUSART)
The pins of the Enhanced USART are multiplexed with PORTC. In order to configure RC6/TX/CK and RC7/RX/DT as an EUSART: * bit SPEN (RCSTA<7>) must be set (= 1) * bit TRISC<7> must be set (= 1) * bit TRISC<6> must be set (= 1) Note: The EUSART control will automatically reconfigure the pin from input to output as needed.
The Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) module is one of the two serial I/O modules. (Generically, the USART is also known as a Serial Communications Interface or SCI.) The EUSART can be configured as a full-duplex asynchronous system that can communicate with peripheral devices, such as CRT terminals and personal computers. It can also be configured as a halfduplex synchronous system that can communicate with peripheral devices, such as A/D or D/A integrated circuits, serial EEPROMs, etc. The Enhanced USART module implements additional features, including automatic baud rate detection and calibration, automatic wake-up on Sync Break reception and 12-bit Break character transmit. These make it ideally suited for use in Local Interconnect Network bus (LIN/J2602 bus) systems. The EUSART can be configured in the following modes: * Asynchronous (full duplex) with: - Auto-wake-up on Break signal - Auto-baud calibration - 12-bit Break character transmission * Synchronous - Master (half duplex) with selectable clock polarity * Synchronous - Slave (half duplex) with selectable clock polarity
The operation of the Enhanced USART module is controlled through three registers: * Transmit Status and Control (TXSTA) * Receive Status and Control (RCSTA) * Baud Rate Control (BAUDCON) These are detailed on the following pages in Register 19-1, Register 19-2 and Register 19-3, respectively.
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REGISTER 19-1: TXSTA: TRANSMIT STATUS AND CONTROL REGISTER
R/W-0 CSRC bit 7 bit 7 CSRC: Clock Source Select bit Asynchronous mode: Don't care. Synchronous mode: 1 = Master mode (clock generated internally from BRG) 0 = Slave mode (clock from external source) TX9: 9-bit Transmit Enable bit 1 = Selects 9-bit transmission 0 = Selects 8-bit transmission TXEN: Transmit Enable bit 1 = Transmit enabled 0 = Transmit disabled Note: bit 4 SREN/CREN overrides TXEN in Sync mode. SYNC: EUSART Mode Select bit 1 = Synchronous mode 0 = Asynchronous mode SENDB: Send Break Character bit Asynchronous mode: 1 = Send Sync Break on next transmission (cleared by hardware upon completion) 0 = Sync Break transmission completed Synchronous mode: Don't care. BRGH: High Baud Rate Select bit Asynchronous mode: 1 = High speed 0 = Low speed Synchronous mode: Unused in this mode. TRMT: Transmit Shift Register Status bit 1 = TSR empty 0 = TSR full TX9D: 9th bit of Transmit Data Can be address/data bit or a parity bit. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-0 TX9 R/W-0 TXEN R/W-0 SYNC R/W-0 SENDB R/W-0 BRGH R-1 TRMT R/W-0 TX9D bit 0
bit 6
bit 5
bit 3
bit 2
bit 1
bit 0
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REGISTER 19-2: RCSTA: RECEIVE STATUS AND CONTROL REGISTER
R/W-0 SPEN bit 7 bit 7 SPEN: Serial Port Enable bit 1 = Serial port enabled (configures RX/DT and TX/CK pins as serial port pins) 0 = Serial port disabled (held in Reset) RX9: 9-bit Receive Enable bit 1 = Selects 9-bit reception 0 = Selects 8-bit reception SREN: Single Receive Enable bit Asynchronous mode: Don't care. Synchronous mode - Master: 1 = Enables single receive 0 = Disables single receive This bit is cleared after reception is complete. Synchronous mode - Slave: Don't care. CREN: Continuous Receive Enable bit Asynchronous mode: 1 = Enables receiver 0 = Disables receiver Synchronous mode: 1 = Enables continuous receive until enable bit CREN is cleared (CREN overrides SREN) 0 = Disables continuous receive ADDEN: Address Detect Enable bit Asynchronous mode 9-bit (RX9 = 1): 1 = Enables address detection, enables interrupt and loads the receive buffer when RSR<8> is set 0 = Disables address detection, all bytes are received and ninth bit can be used as parity bit Asynchronous mode 9-bit (RX9 = 0): Don't care. FERR: Framing Error bit 1 = Framing error (can be updated by reading RCREG register and receiving next valid byte) 0 = No framing error OERR: Overrun Error bit 1 = Overrun error (can be cleared by clearing bit CREN) 0 = No overrun error RX9D: 9th bit of Received Data This can be address/data bit or a parity bit and must be calculated by user firmware. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R/W-0 RX9 R/W-0 SREN R/W-0 CREN R/W-0 ADDEN R-0 FERR R-0 OERR R-x RX9D bit 0
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
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REGISTER 19-3: BAUDCON: BAUD RATE CONTROL REGISTER
R/W-0 ABDOVF bit 7 bit 7 ABDOVF: Auto-Baud Acquisition Rollover Status bit 1 = A BRG rollover has occurred during Auto-Baud Rate Detect mode (must be cleared in software) 0 = No BRG rollover has occurred RCIDL: Receive Operation Idle Status bit 1 = Receive operation is Idle 0 = Receive operation is active RXDTP: Received Data Polarity Select bit Asynchronous mode: 1 = Receive data (RX) is inverted (active-low) 0 = Receive data (RX) is not inverted (active-high) Synchronous mode: No affect. TXCKP: Clock and Data Polarity Select bit Asynchronous mode: 1 = Idle state for transmit (TX) is a low level 0 = Idle state for transmit (TX) is a high level Synchronous mode: 1 = Idle state for clock (CK) is a high level 0 = Idle state for clock (CK) is a low level BRG16: 16-bit Baud Rate Register Enable bit 1 = 16-bit Baud Rate Generator - SPBRGH and SPBRG 0 = 8-bit Baud Rate Generator - SPBRG only (Compatible mode), SPBRGH value ignored Unimplemented: Read as `0' WUE: Wake-up Enable bit Asynchronous mode: 1 = EUSART will continue to sample the RX pin - interrupt generated on falling edge; bit cleared in hardware on following rising edge 0 = RX pin not monitored or rising edge detected Synchronous mode: Unused in this mode. ABDEN: Auto-Baud Detect Enable bit Asynchronous mode: 1 = Enable baud rate measurement on the next character. Requires reception of a Sync field (55h); cleared in hardware upon completion 0 = Baud rate measurement disabled or completed Synchronous mode: Unused in this mode. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown R-1 RCIDL R/W-0 RXDTP R/W-0 TXCKP R/W-0 BRG16 U-0 -- R/W-0 WUE R/W-0 ABDEN bit 0
bit 6
bit 5
bit 4
bit 3
bit 2 bit 1
bit 0
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19.1 Baud Rate Generator (BRG)
The BRG is a dedicated 8-bit or 16-bit generator that supports both the Asynchronous and Synchronous modes of the EUSART. By default, the BRG operates in 8-bit mode; setting the BRG16 bit (BAUDCON<3>) selects 16-bit mode. The SPBRGH:SPBRG register pair controls the period of a free running timer. In Asynchronous mode, bits BRGH (TXSTA<2>) and BRG16 (BAUDCON<3>) also control the baud rate. In Synchronous mode, BRGH is ignored. Table 19-1 shows the formula for computation of the baud rate for different EUSART modes which only apply in Master mode (internally generated clock). Given the desired baud rate and FOSC, the nearest integer value for the SPBRGH:SPBRG registers can be calculated using the formulas in Table 19-1. From this, the error in baud rate can be determined. An example calculation is shown in Example 19-1. Typical baud rates and error values for the various Asynchronous modes are shown in Table 19-2. It may be advantageous to use the high baud rate (BRGH = 1) or the 16-bit BRG to reduce the baud rate error, or achieve a slow baud rate for a fast oscillator frequency. Writing a new value to the SPBRGH:SPBRG registers causes the BRG timer to be reset (or cleared). This ensures the BRG does not wait for a timer overflow before outputting the new baud rate. Note: A BRG value of 0 is not supported.
19.1.1
OPERATION IN POWER-MANAGED MODES
The device clock is used to generate the desired baud rate. When one of the power-managed modes is entered, the new clock source may be operating at a different frequency. This may require an adjustment to the value in the SPBRG register pair.
19.1.2
SAMPLING
The data on the RX pin is sampled three times by a majority detect circuit to determine if a high or a low level is present at the RX pin when SYNC is clear or when BRG16 and BRGH are both not set. The data on the RX pin is sampled once when SYNC is set or when BRGH16 and BRGH are both set.
TABLE 19-1:
SYNC 0 0 0 0 1 1
BAUD RATE FORMULAS
BRG16 0 0 1 1 0 1 BRGH 0 1 0 1 x x BRG/EUSART Mode 8-bit/Asynchronous 8-bit/Asynchronous 16-bit/Asynchronous 16-bit/Asynchronous 8-bit/Synchronous 16-bit/Synchronous FOSC/[4 (n + 1)] Baud Rate Formula FOSC/[64 (n + 1)] FOSC/[16 (n + 1)]
Configuration Bits
Legend: x = Don't care, n = value of SPBRGH:SPBRG register pair
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EXAMPLE 19-1: CALCULATING BAUD RATE ERROR
For a device with FOSC of 16 MHz, desired baud rate of 9600, Asynchronous mode, 8-bit BRG: Desired Baud Rate = FOSC/(64 ([SPBRGH:SPBRG] + 1)) Solving for SPBRGH:SPBRG: X = ((FOSC/Desired Baud Rate)/64) - 1 = ((16000000/9600)/64) - 1 = [25.042] = 25 Calculated Baud Rate = 16000000/(64 (25 + 1)) = 9615 Error = (Calculated Baud Rate - Desired Baud Rate)/Desired Baud Rate = (9615 - 9600)/9600 = 0.16%
TABLE 19-2:
Name TXSTA RCSTA SPBRGH SPBRG
REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Bit 7 CSRC SPEN Bit 6 TX9 RX9 RCIDL Bit 5 TXEN SREN RXDTP Bit 4 SYNC CREN TXCKP Bit 3 SENDB ADDEN BRG16 Bit 2 BRGH FERR -- Bit 1 TRMT OERR WUE Bit 0 TX9D RX9D ABDEN Reset Values on page 57 57 57 57 57
BAUDCON ABDOVF
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the BRG.
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TABLE 19-3:
BAUD RATE (K)
BAUD RATES FOR ASYNCHRONOUS MODES
SYNC = 0, BRGH = 0, BRG16 = 0 FOSC = 20.000 MHz Actual Rate (K) -- 1.221 2.404 9.766 19.531 62.500 104.167 % Error -- 1.73 0.16 1.73 1.73 8.51 -9.58 SPBRG value
(decimal)
FOSC = 40.000 MHz Actual Rate (K) -- -- 2.441 9.615 19.531 56.818 125.000 % Error -- -- 1.73 0.16 1.73 -1.36 8.51 SPBRG value
(decimal)
FOSC = 10.000 MHz Actual Rate (K) -- 1.202 2.404 9.766 19.531 52.083 78.125 % Error -- 0.16 0.16 1.73 1.73 -9.58 -32.18 SPBRG value
(decimal)
FOSC = 8.000 MHz Actual Rate (K) -- 1.201 2.403 9.615 -- -- -- % Error -- -0.16 -0.16 -0.16 -- -- -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
-- -- 255 64 31 10 4
-- 255 129 31 15 4 2
-- 129 64 15 7 2 1
-- 103 51 12 -- -- --
SYNC = 0, BRGH = 0, BRG16 = 0 BAUD RATE (K) FOSC = 4.000 MHz Actual Rate (K) 0.300 1.202 2.404 8.929 20.833 62.500 62.500 % Error 0.16 0.16 0.16 -6.99 8.51 8.51 -45.75 SPBRG value
(decimal)
FOSC = 2.000 MHz Actual Rate (K) 0.300 1.201 2.403 -- -- -- -- % Error -0.16 -0.16 -0.16 -- -- -- -- SPBRG value
(decimal)
FOSC = 1.000 MHz Actual Rate (K) 0.300 1.201 -- -- -- -- -- % Error -0.16 -0.16 -- -- -- -- -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
207 51 25 6 2 0 0
103 25 12 -- -- -- --
51 12 -- -- -- -- --
SYNC = 0, BRGH = 1, BRG16 = 0 BAUD RATE (K) FOSC = 40.000 MHz Actual Rate (K) -- -- -- 9.766 19.231 58.140 113.636 % Error -- -- -- 1.73 0.16 0.94 -1.36 SPBRG value
(decimal)
FOSC = 20.000 MHz Actual Rate (K) -- -- -- 9.615 19.231 56.818 113.636 % Error -- -- -- 0.16 0.16 -1.36 -1.36 SPBRG value
(decimal)
FOSC = 10.000 MHz Actual Rate (K) -- -- 2.441 9.615 19.531 56.818 125.000 % Error -- -- 1.73 0.16 1.73 -1.36 8.51 SPBRG value
(decimal)
FOSC = 8.000 MHz Actual Rate (K) -- -- 2.403 9.615 19.230 55.555 -- % Error -- -- -0.16 -0.16 -0.16 3.55 -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
-- -- -- 255 129 42 21
-- -- -- 129 64 21 10
-- -- 255 64 31 10 4
-- -- 207 51 25 8 --
SYNC = 0, BRGH = 1, BRG16 = 0 BAUD RATE (K) FOSC = 4.000 MHz Actual Rate (K) -- 1.202 2.404 9.615 19.231 62.500 125.000 % Error -- 0.16 0.16 0.16 0.16 8.51 8.51 SPBRG value
(decimal)
FOSC = 2.000 MHz Actual Rate (K) -- 1.201 2.403 9.615 -- -- -- % Error -- -0.16 -0.16 -0.16 -- -- -- SPBRG value
(decimal)
FOSC = 1.000 MHz Actual Rate (K) 0.300 1.201 2.403 -- -- -- -- % Error -0.16 -0.16 -0.16 -- -- -- -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
-- 207 103 25 12 3 1
-- 103 51 12 -- -- --
207 51 25 -- -- -- --
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TABLE 19-3:
BAUD RATE (K)
BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 0, BRG16 = 1 FOSC = 20.000 MHz Actual Rate (K) 0.300 1.200 2.399 9.615 19.231 56.818 113.636 % Error 0.02 -0.03 -0.03 0.16 0.16 -1.36 -1.36 SPBRG value
(decimal)
FOSC = 40.000 MHz Actual Rate (K) 0.300 1.200 2.402 9.615 19.231 58.140 113.636 % Error 0.00 0.02 0.06 0.16 0.16 0.94 -1.36 SPBRG value
(decimal)
FOSC = 10.000 MHz Actual Rate (K) 0.300 1.200 2.404 9.615 19.531 56.818 125.000 % Error 0.02 -0.03 0.16 0.16 1.73 -1.36 8.51 SPBRG value
(decimal)
FOSC = 8.000 MHz Actual Rate (K) 0.300 1.201 2.403 9.615 19.230 55.555 -- % Error -0.04 -0.16 -0.16 -0.16 -0.16 3.55 -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
8332 2082 1040 259 129 42 21
4165 1041 520 129 64 21 10
2082 520 259 64 31 10 4
1665 415 207 51 25 8 --
SYNC = 0, BRGH = 0, BRG16 = 1 BAUD RATE (K) FOSC = 4.000 MHz Actual Rate (K) 0.300 1.202 2.404 9.615 19.231 62.500 125.000 % Error 0.04 0.16 0.16 0.16 0.16 8.51 8.51 SPBRG value
(decimal)
FOSC = 2.000 MHz Actual Rate (K) 0.300 1.201 2.403 9.615 -- -- -- % Error -0.16 -0.16 -0.16 -0.16 -- -- -- SPBRG value
(decimal)
FOSC = 1.000 MHz Actual Rate (K) 0.300 1.201 2.403 -- -- -- -- % Error -0.16 -0.16 -0.16 -- -- -- -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
832 207 103 25 12 3 1
415 103 51 12 -- -- --
207 51 25 -- -- -- --
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1 BAUD RATE (K) FOSC = 40.000 MHz Actual Rate (K) 0.300 1.200 2.400 9.606 19.193 57.803 114.943 % Error 0.00 0.00 0.02 0.06 -0.03 0.35 -0.22 SPBRG value
(decimal)
FOSC = 20.000 MHz Actual Rate (K) 0.300 1.200 2.400 9.596 19.231 57.471 116.279 % Error 0.00 0.02 0.02 -0.03 0.16 -0.22 0.94 SPBRG value
(decimal)
FOSC = 10.000 MHz Actual Rate (K) 0.300 1.200 2.402 9.615 19.231 58.140 113.636 % Error 0.00 0.02 0.06 0.16 0.16 0.94 -1.36 SPBRG value
(decimal)
FOSC = 8.000 MHz Actual Rate (K) 0.300 1.200 2.400 9.615 19.230 57.142 117.647 % Error -0.01 -0.04 -0.04 -0.16 -0.16 0.79 -2.12 SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
33332 8332 4165 1040 520 172 86
16665 4165 2082 520 259 86 42
8332 2082 1040 259 129 42 21
6665 1665 832 207 103 34 16
SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1 BAUD RATE (K) FOSC = 4.000 MHz Actual Rate (K) 0.300 1.200 2.404 9.615 19.231 58.824 111.111 % Error 0.01 0.04 0.16 0.16 0.16 2.12 -3.55 SPBRG value
(decimal)
FOSC = 2.000 MHz Actual Rate (K) 0.300 1.201 2.403 9.615 19.230 55.555 -- % Error -0.04 -0.16 -0.16 -0.16 -0.16 3.55 -- SPBRG value
(decimal)
FOSC = 1.000 MHz Actual Rate (K) 0.300 1.201 2.403 9.615 19.230 -- -- % Error -0.04 -0.16 -0.16 -0.16 -0.16 -- -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
3332 832 415 103 51 16 8
1665 415 207 51 25 8 --
832 207 103 25 12 -- --
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19.1.3 AUTO-BAUD RATE DETECT
The Enhanced USART module supports the automatic detection and calibration of baud rate. This feature is active only in Asynchronous mode and while the WUE bit is clear. The automatic baud rate measurement sequence (Figure 19-1) begins whenever a Start bit is received and the ABDEN bit is set. The calculation is self-averaging. In the Auto-Baud Rate Detect (ABD) mode, the clock to the BRG is reversed. Rather than the BRG clocking the incoming RX signal, the RX signal is timing the BRG. In ABD mode, the internal Baud Rate Generator is used as a counter to time the bit period of the incoming serial byte stream. Once the ABDEN bit is set, the state machine will clear the BRG and look for a Start bit. The Auto-Baud Rate Detect must receive a byte with the value 55h (ASCII "U", which is also the LIN/J2602 bus Sync character) in order to calculate the proper bit rate. The measurement is taken over both a low and a high bit time in order to minimize any effects caused by asymmetry of the incoming signal. After a Start bit, the SPBRG begins counting up, using the preselected clock source on the first rising edge of RX. After eight bits on the RX pin, or the fifth rising edge, an accumulated value totalling the proper BRG period is left in the SPBRGH:SPBRG register pair. Once the 5th edge is seen (this should correspond to the Stop bit), the ABDEN bit is automatically cleared. If a rollover of the BRG occurs (an overflow from FFFFh to 0000h), the event is trapped by the ABDOVF status bit (BAUDCON<7>). It is set in hardware by BRG rollovers and can be set or cleared by the user in software. ABD mode remains active after rollover events and the ABDEN bit remains set (Figure 19-2). While calibrating the baud rate period, the BRG registers are clocked at 1/8th the preconfigured clock rate. Note that the BRG clock can be configured by the BRG16 and BRGH bits. The BRG16 bit must be set to use both SPBRG1 and SPBRGH1 as a 16-bit counter This allows the user to verify that no carry occurred for 8-bit modes by checking for 00h in the SPBRGH register. Refer to Table 19-4 for counter clock rates to the BRG. While the ABD sequence takes place, the EUSART state machine is held in Idle. The RCIF interrupt is set once the fifth rising edge on RX is detected. The value in the RCREG needs to be read to clear the RCIF interrupt. The contents of RCREG should be discarded. Note 1: If the WUE bit is set with the ABDEN bit, Auto-Baud Rate Detection will occur on the byte following the Break character. 2: It is up to the user to determine that the incoming character baud rate is within the range of the selected BRG clock source. Some combinations of oscillator frequency and EUSART baud rates are not possible due to bit error rates. Overall system timing and communication baud rates must be taken into consideration when using the Auto-Baud Rate Detection feature. 3: To maximize the baud rate range, it is recommended to set the BRG16 bit if the auto-baud feature is used.
TABLE 19-4:
BRG16 0 0 1 1 BRGH 0 1 0 1
BRG COUNTER CLOCK RATES
BRG Counter Clock FOSC/512 FOSC/128 FOSC/128 FOSC/32
19.1.3.1
ABD and EUSART Transmission
Since the BRG clock is reversed during ABD acquisition, the EUSART transmitter cannot be used during ABD. This means that whenever the ABDEN bit is set, TXREG cannot be written to. Users should also ensure that ABDEN does not become set during a transmit sequence. Failing to do this may result in unpredictable EUSART operation.
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FIGURE 19-1:
BRG Value RX pin
AUTOMATIC BAUD RATE CALCULATION
XXXXh 0000h Start Edge #1 Bit 1 Bit 0 Edge #2 Bit 3 Bit 2 Edge #3 Bit 5 Bit 4 Edge #4 Bit 7 Bit 6 001Ch Edge #5 Stop Bit
BRG Clock Set by User ABDEN bit RCIF bit (Interrupt) Read RCREG SPBRG SPBRGH XXXXh XXXXh 1Ch 00h Auto-Cleared
Note: The ABD sequence requires the EUSART module to be configured in Asynchronous mode and WUE = 0.
FIGURE 19-2:
BRG Clock ABDEN bit RX pin ABDOVF bit
BRG OVERFLOW SEQUENCE
Start
Bit 0
FFFFh BRG Value XXXXh 0000h 0000h
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19.2 EUSART Asynchronous Mode
The Asynchronous mode of operation is selected by clearing the SYNC bit (TXSTA<4>). In this mode, the EUSART uses standard Non-Return-to-Zero (NRZ) format (one Start bit, eight or nine data bits and one Stop bit). The most common data format is 8 bits. An on-chip dedicated 8-bit/16-bit Baud Rate Generator can be used to derive standard baud rate frequencies from the oscillator. The EUSART transmits and receives the LSb first. The EUSART's transmitter and receiver are functionally independent but use the same data format and baud rate. The Baud Rate Generator produces a clock, either x16 or x64 of the bit shift rate depending on the BRGH and BRG16 bits (TXSTA<2> and BAUDCON<3>). Parity is not supported by the hardware but can be implemented in software and stored as the 9th data bit. The TXCKP (BAUDCON<4>) and RXDTP (BAUDCON<5>) bits allow the TX and RX signals to be inverted (polarity reversed). Devices that buffer signals between TTL and RS-232 levels also invert the signal. Setting the TXCKP and RXDTP bits allows for the use of circuits that provide buffering without inverting the signal. In Asynchronous mode, clock polarity is selected with the TXCKP bit (BAUDCON<4>). Setting TXCKP sets the Idle state on CK as high, while clearing the bit sets the Idle state as low. Data polarity is selected with the RXDTP bit (BAUDCON<5>). Setting RXDTP inverts data on RX, while clearing the bit has no affect on received data. When operating in Asynchronous mode, the EUSART module consists of the following important elements: * * * * * * * * Baud Rate Generator Sampling Circuit Asynchronous Transmitter Asynchronous Receiver Auto-Wake-up on Break signal 12-bit Break Character Transmit Auto-Baud Rate Detection Pin State Polarity 2. 3. 4. 5. 6. 7. 8. 9. Once the TXREG register transfers the data to the TSR register (occurs in one TCY), the TXREG register is empty and the TXIF flag bit (PIR1<4>) is set. This interrupt can be enabled or disabled by setting or clearing the interrupt enable bit, TXIE (PIE1<4>). TXIF will be set regardless of the state of TXIE; it cannot be cleared in software. TXIF is also not cleared immediately upon loading TXREG, but becomes valid in the second instruction cycle following the load instruction. Polling TXIF immediately following a load of TXREG will return invalid results. While TXIF indicates the status of the TXREG register, another bit, TRMT (TXSTA<1>), shows the status of the TSR register. TRMT is a read-only bit which is set when the TSR register is empty. No interrupt logic is tied to this bit so the user has to poll this bit in order to determine if the TSR register is empty. The TXCKP bit (BAUDCON<4>) allows the TX signal to be inverted (polarity reversed). Devices that buffer signals from TTL to RS-232 levels also invert the signal (when TTL = 1, RS-232 = negative). Inverting the polarity of the TX pin data by setting the TXCKP bit allows for use of circuits that provide buffering without inverting the signal. Note 1: The TSR register is not mapped in data memory so it is not available to the user. 2: Flag bit TXIF is set when enable bit TXEN is set. To set up an Asynchronous Transmission: 1. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRGH and BRG16 bits, as required, to achieve the desired baud rate. Enable the asynchronous serial port by clearing bit, SYNC, and setting bit, SPEN. If the signal from the TX pin is to be inverted, set the TXCKP bit. If interrupts are desired, set enable bit, TXIE. If 9-bit transmission is desired, set transmit bit, TX9; can be used as address/data bit. Enable the transmission by setting bit, TXEN, which will also set bit, TXIF. If 9-bit transmission is selected, the ninth bit should be loaded in bit, TX9D. Load data to the TXREG register (starts transmission). If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set.
19.2.1
EUSART ASYNCHRONOUS TRANSMITTER
The EUSART transmitter block diagram is shown in Figure 19-3. The heart of the transmitter is the Transmit (Serial) Shift Register (TSR). The Shift register obtains its data from the Read/Write Transmit Buffer register, TXREG. The TXREG register is loaded with data in software. The TSR register is not loaded until the Stop bit has been transmitted from the previous load. As soon as the Stop bit is transmitted, the TSR is loaded with new data from the TXREG register (if available).
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FIGURE 19-3: EUSART TRANSMIT BLOCK DIAGRAM
Data Bus TXIF TXIE MSb (8) Interrupt TXEN Baud Rate CLK TRMT BRG16 SPBRGH SPBRG TX9 TX9D SPEN *** TSR Register TXREG Register 8 LSb 0 Pin Buffer and Control TX pin TXCKP
Baud Rate Generator
FIGURE 19-4:
Write to TXREG BRG Output (Shift Clock) TX (pin) TXIF bit (Transmit Buffer Reg. Empty Flag)
ASYNCHRONOUS TRANSMISSION, TXCKP = 0 (TX NOT INVERTED)
Word 1
Start bit 1 TCY
bit 0
bit 1 Word 1
bit 7/8
Stop bit
TRMT bit (Transmit Shift Reg. Empty Flag)
Word 1 Transmit Shift Reg
FIGURE 19-5:
ASYNCHRONOUS TRANSMISSION (BACK TO BACK), TXCKP = 0 (TX NOT INVERTED)
Word 1 Word 2
Write to TXREG BRG Output (Shift Clock) TX (pin) TXIF bit (Interrupt Reg. Flag) 1 TCY 1 TCY Word 1 Transmit Shift Reg. Word 2 Transmit Shift Reg. Start bit bit 0 bit 1 Word 1 bit 7/8 Stop bit Start bit Word 2 bit 0
TRMT bit (Transmit Shift Reg. Empty Flag)
Note: This timing diagram shows two consecutive transmissions.
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TABLE 19-5:
Name INTCON PIR1 PIE1 IPR1 RCSTA TXREG TXSTA BAUDCON SPBRGH SPBRG
REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Bit 7 Bit 6 Bit 5 TMR0IE RCIF RCIE RCIP SREN TXEN RXDTP Bit 4 INT0IE TXIF TXIE TXIP CREN SYNC TXCKP Bit 3 RBIE SSPIF SSPIE SSPIP ADDEN SENDB BRG16 Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP FERR BRGH -- Bit 1 INT0IF TMR2IF TMR2IE TMR2IP OERR TRMT WUE Bit 0 RBIF TMR1IF TMR1IE TMR1IP RX9D TX9D ABDEN Reset Values on page 55 58 58 58 57 57 57 57 57 57
GIE/GIEH PEIE/GIEL PSPIF(1) PSPIE PSPIP
(1) (1)
ADIF ADIE ADIP RX9 TX9 RCIDL
SPEN CSRC ABDOVF
EUSART Transmit Register
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte
Legend: -- = unimplemented locations read as `0'. Shaded cells are not used for asynchronous transmission. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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19.2.2 EUSART ASYNCHRONOUS RECEIVER 19.2.3 SETTING UP 9-BIT MODE WITH ADDRESS DETECT
The receiver block diagram is shown in Figure 19-6. The data is received on the RX pin and drives the data recovery block. The data recovery block is actually a high-speed shifter operating at x16 times the baud rate, whereas the main receive serial shifter operates at the bit rate or at FOSC. This mode would typically be used in RS-232 systems. The RXDTP bit (BAUDCON<5>) allows the RX signal to be inverted (polarity reversed). Devices that buffer signals from RS-232 to TTL levels also perform an inversion of the signal (when RS-232 = positive, TTL = 0). Inverting the polarity of the RX pin data by setting the RXDTP bit allows for the use of circuits that provide buffering without inverting the signal. To set up an Asynchronous Reception: Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRGH and BRG16 bits, as required, to achieve the desired baud rate. 2. Enable the asynchronous serial port by clearing bit, SYNC, and setting bit, SPEN. 3. If the signal at the RX pin is to be inverted, set the RXDTP bit. 4. If interrupts are desired, set enable bit, RCIE. 5. If 9-bit reception is desired, set bit, RX9. 6. Enable the reception by setting bit, CREN. 7. Flag bit, RCIF, will be set when reception is complete and an interrupt will be generated if enable bit, RCIE, was set. 8. Read the RCSTA register to get the 9th bit (if enabled) and determine if any error occurred during reception. 9. Read the 8-bit received data by reading the RCREG register. 10. If any error occurred, clear the error by clearing enable bit, CREN. 11. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. 1. This mode would typically be used in RS-485 systems. To set up an Asynchronous Reception with Address Detect Enable: 1. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRGH and BRG16 bits, as required, to achieve the desired baud rate. 2. Enable the asynchronous serial port by clearing the SYNC bit and setting the SPEN bit. 3. If the signal at the RX pin is to be inverted, set the RXDTP bit. If the signal from the TX pin is to be inverted, set the TXCKP bit. 4. If interrupts are required, set the RCEN bit and select the desired priority level with the RCIP bit. 5. Set the RX9 bit to enable 9-bit reception. 6. Set the ADDEN bit to enable address detect. 7. Enable reception by setting the CREN bit. 8. The RCIF bit will be set when reception is complete. The interrupt will be Acknowledged if the RCIE and GIE bits are set. 9. Read the RCSTA register to determine if any error occurred during reception, as well as read bit 9 of data (if applicable). 10. Read RCREG to determine if the device is being addressed. 11. If any error occurred, clear the CREN bit. 12. If the device has been addressed, clear the ADDEN bit to allow all received data into the receive buffer and interrupt the CPU.
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FIGURE 19-6: EUSART RECEIVE BLOCK DIAGRAM
CREN x64 Baud Rate CLK BRG16 SPBRGH SPBRG / 64 or / 16 or /4 MSb Stop (8) 7 RSR Register *** 1 0 LSb Start OERR FERR
Baud Rate Generator
RX9 Pin Buffer and Control RX Data Recovery RX9D RCREG Register FIFO
RXDTP
SPEN Interrupt RCIF RCIE
8 Data Bus
FIGURE 19-7:
RX (pin) Rcv Shift Reg Rcv Buffer Reg Read Rcv Buffer Reg RCREG RCIF (Interrupt Flag) OERR bit CREN Note:
ASYNCHRONOUS RECEPTION, TXCKP = 0 (TX NOT INVERTED)
Start bit bit 0 bit 1 bit 7/8 Stop bit Start bit bit 0 bit 7/8 Stop bit Start bit bit 7/8 Stop bit
Word 1 RCREG
Word 2 RCREG
This timing diagram shows three words appearing on the RX input. The RCREG (receive buffer) is read after the third word causing the OERR (overrun) bit to be set.
TABLE 19-6:
Name INTCON PIR1 PIE1 IPR1 RCSTA RCREG TXSTA BAUDCON SPBRGH SPBRG
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Bit 7 Bit 6 Bit 5 TMR0IE RCIF RCIE RCIP SREN TXEN RXDTP Bit 4 INT0IE TXIF TXIE TXIP CREN SYNC TXCKP Bit 3 RBIE SSPIF SSPIE SSPIP ADDEN SENDB BRG16 Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP FERR BRGH -- Bit 1 INT0IF TMR2IF TMR2IE TMR2IP OERR TRMT WUE Bit 0 RBIF TMR1IF TMR1IE TMR1IP RX9D TX9D ABDEN Reset Values on page 55 58 58 58 57 57 57 57 57 57
GIE/GIEH PEIE/GIEL PSPIF(1) PSPIE(1) PSPIP(1) SPEN CSRC ABDOVF ADIF ADIE ADIP RX9 TX9 RCIDL
EUSART Receive Register
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte
Legend: -- = unimplemented locations read as `0'. Shaded cells are not used for asynchronous reception. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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19.2.4 AUTO-WAKE-UP ON SYNC BREAK CHARACTER
During Sleep mode, all clocks to the EUSART are suspended. Because of this, the Baud Rate Generator is inactive and a proper byte reception cannot be performed. The auto-wake-up feature allows the controller to wake-up due to activity on the RX/DT line while the EUSART is operating in Asynchronous mode. The auto-wake-up feature is enabled by setting the WUE bit (BAUDCON<1>). Once set, the typical receive sequence on RX/DT is disabled and the EUSART remains in an Idle state, monitoring for a wake-up event independent of the CPU mode. A wake-up event consists of a high-to-low transition on the RX/DT line. (This coincides with the start of a Sync Break or a Wake-up Signal character for the LIN/J2602 protocol.) Following a wake-up event, the module generates an RCIF interrupt. The interrupt is generated synchronously to the Q clocks in normal operating modes (Figure 19-8) and asynchronously, if the device is in Sleep mode (Figure 19-9). The interrupt condition is cleared by reading the RCREG register. The WUE bit is automatically cleared once a low-tohigh transition is observed on the RX line following the wake-up event. At this point, the EUSART module is in Idle mode and returns to normal operation. This signals to the user that the Sync Break event is over. and cause data or framing errors. To work properly, therefore, the initial character in the transmission must be all `0's. This can be 00h (8 bytes) for standard RS-232 devices or 000h (12 bits) for the LIN/J2602 bus. Oscillator start-up time must also be considered, especially in applications using oscillators with longer start-up intervals (i.e., XT or HS mode). The Sync Break (or Wake-up Signal) character must be of sufficient length and be followed by a sufficient interval to allow enough time for the selected oscillator to start and provide proper initialization of the EUSART.
19.2.4.2
Special Considerations Using the WUE Bit
The timing of WUE and RCIF events may cause some confusion when it comes to determining the validity of received data. As noted, setting the WUE bit places the EUSART in an Idle mode. The wake-up event causes a receive interrupt by setting the RCIF bit. The WUE bit is cleared after this when a rising edge is seen on RX/DT. The interrupt condition is then cleared by reading the RCREG register. Ordinarily, the data in RCREG will be dummy data and should be discarded. The fact that the WUE bit has been cleared (or is still set) and the RCIF flag is set should not be used as an indicator of the integrity of the data in RCREG. Users should consider implementing a parallel method in firmware to verify received data integrity. To assure that no actual data is lost, check the RCIDL bit to verify that a receive operation is not in process. If a receive operation is not occurring, the WUE bit may then be set just prior to entering the Sleep mode.
19.2.4.1
Special Considerations Using Auto-Wake-up
Since auto-wake-up functions by sensing rising edge transitions on RX/DT, information with any state changes before the Stop bit may signal a false end-of-character
FIGURE 19-8:
OSC1 WUE bit(1) RX/DT Line RCIF Note 1:
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING NORMAL OPERATION
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Bit set by user
Auto-Cleared
Cleared due to user read of RCREG
The EUSART remains in Idle while the WUE bit is set.
FIGURE 19-9:
OSC1 WUE bit(2) RX/DT Line RCIF
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Bit set by user
Auto-Cleared
Note 1 Sleep Ends Cleared due to user read of RCREG
Sleep Command Executed Note 1: 2:
If the wake-up event requires long oscillator warm-up time, the auto-clear of the WUE bit can occur before the oscillator is ready. This sequence should not depend on the presence of Q clocks. The EUSART remains in Idle while the WUE bit is set.
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19.2.5 BREAK CHARACTER SEQUENCE
The EUSART module has the capability of sending the special Break character sequences that are required by the LIN/J2602 bus standard. The Break character transmit consists of a Start bit, followed by twelve `0' bits and a Stop bit. The Frame Break character is sent whenever the SENDB and TXEN bits (TXSTA<3> and TXSTA<5>) are set while the Transmit Shift register is loaded with data. Note that the value of data written to TXREG will be ignored and all `0's will be transmitted. The SENDB bit is automatically reset by hardware after the corresponding Stop bit is sent. This allows the user to preload the transmit FIFO with the next transmit byte following the Break character (typically, the Sync character in the LIN/J2602 specification). Note that the data value written to the TXREG for the Break character is ignored. The write simply serves the purpose of initiating the proper sequence. The TRMT bit indicates when the transmit operation is active or Idle, just as it does during normal transmission. See Figure 19-10 for the timing of the Break character sequence. 1. 2. 3. 4. 5. Configure the EUSART for the desired mode. Set the TXEN and SENDB bits to set up the Break character. Load the TXREG with a dummy character to initiate transmission (the value is ignored). Write `55h' to TXREG to load the Sync character into the transmit FIFO buffer. After the Break has been sent, the SENDB bit is reset by hardware. The Sync character now transmits in the preconfigured mode.
When the TXREG becomes empty, as indicated by the TXIF, the next data byte can be written to TXREG.
19.2.6
RECEIVING A BREAK CHARACTER
The Enhanced USART module can receive a Break character in two ways. The first method forces configuration of the baud rate at a frequency of 9/13 the typical speed. This allows for the Stop bit transition to be at the correct sampling location (13 bits for Break versus Start bit and 8 data bits for typical data). The second method uses the auto-wake-up feature described in Section 19.2.4 "Auto-Wake-up on Sync Break Character". By enabling this feature, the EUSART will sample the next two transitions on RX/DT, cause an RCIF interrupt and receive the next data byte followed by another interrupt. Note that following a Break character, the user will typically want to enable the Auto-Baud Rate Detect feature. For both methods, the user can set the ABD bit once the TXIF interrupt is observed.
19.2.5.1
Break and Sync Transmit Sequence
The following sequence will send a message frame header made up of a Break, followed by an Auto-Baud Sync byte. This sequence is typical of a LIN/J2602 bus master.
FIGURE 19-10:
Write to TXREG BRG Output (Shift Clock) TX (pin)
SEND BREAK CHARACTER SEQUENCE
Dummy Write
Start Bit
Bit 0
Bit 1 Break
Bit 11
Stop Bit
TXIF bit (Transmit Buffer Reg. Empty Flag) TRMT bit (Transmit Shift Reg. Empty Flag) SENDB sampled here SENDB (Transmit Shift Reg. Empty Flag) Auto-Cleared
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19.3 EUSART Synchronous Master Mode
Once the TXREG register transfers the data to the TSR register (occurs in one TCY), the TXREG is empty and the TXIF flag bit (PIR1<4>) is set. The interrupt can be enabled or disabled by setting or clearing the interrupt enable bit, TXIE (PIE1<4>). TXIF is set regardless of the state of enable bit TXIE; it cannot be cleared in software. It will reset only when new data is loaded into the TXREG register. While flag bit TXIF indicates the status of the TXREG register, another bit, TRMT (TXSTA<1>), shows the status of the TSR register. TRMT is a read-only bit which is set when the TSR is empty. No interrupt logic is tied to this bit so the user has to poll this bit in order to determine if the TSR register is empty. The TSR is not mapped in data memory so it is not available to the user. To set up a Synchronous Master Transmission: 1. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRG16 bit, as required, to achieve the desired baud rate. Enable the synchronous master serial port by setting bits, SYNC, SPEN and CSRC. If the signal from the CK pin is to be inverted, set the TXCKP bit. If interrupts are desired, set enable bit, TXIE. If 9-bit transmission is desired, set bit, TX9. Enable the transmission by setting bit, TXEN. If 9-bit transmission is selected, the ninth bit should be loaded in bit, TX9D. Start transmission by loading data to the TXREG register. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set.
The Master mode indicates that the processor transmits the master clock on the CK line. The Synchronous Master mode is entered by setting the CSRC bit (TXSTA<7>). In this mode, the data is transmitted in a half-duplex manner (i.e., transmission and reception do not occur at the same time). When transmitting data, the reception is inhibited and vice versa. Synchronous mode is entered by setting bit SYNC (TXSTA<4>). In addition, enable bit SPEN (RCSTA<7>) is set in order to configure the TX and RX pins to CK (clock) and DT (data) lines, respectively. The Master mode indicates that the processor transmits the master clock on the CK line. Clock polarity (CK) is selected with the TXCKP bit (BAUDCON<4>). Setting TXCKP sets the Idle state on CK as high, while clearing the bit sets the Idle state as low.
2. 3. 4. 5. 6. 7. 8. 9.
19.3.1
EUSART SYNCHRONOUS MASTER TRANSMISSION
The EUSART transmitter block diagram is shown in Figure 19-3. The heart of the transmitter is the Transmit (Serial) Shift Register (TSR). The Shift register obtains its data from the Read/Write Transmit Buffer register, TXREG. The TXREG register is loaded with data in software. The TSR register is not loaded until the last bit has been transmitted from the previous load. As soon as the last bit is transmitted, the TSR is loaded with new data from the TXREG (if available).
FIGURE 19-11:
SYNCHRONOUS TRANSMISSION
Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 bit 7 bit 0 bit 1 bit 7
Q1 Q2 Q3Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1Q2 Q3 Q4
RC7/RX/DT RC6/TX/CK pin (TXCKP = 0) RC6/TX/CK pin (TXCKP = 1) Write to TXREG Reg TXIF bit (Interrupt Flag) TRMT bit TXEN bit `1' Note:
bit 0
bit 1
bit 2
Word 1
Word 2
Write Word 1
Write Word 2
`1'
Sync Master mode, SPBRG = 0, continuous transmission of two 8-bit words.
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FIGURE 19-12: SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
bit 0 bit 1 bit 2 bit 6 bit 7 RC7/RX/DT pin
RC6/TX/CK pin Write to TXREG reg
TXIF bit
TRMT bit
TXEN bit
TABLE 19-7:
Name INTCON PIR1 PIE1 IPR1 RCSTA TXREG TXSTA BAUDCON SPBRGH SPBRG
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
Bit 7 Bit 6 Bit 5 Bit 4 INT0IE TXIF TXIE TXIP CREN SYNC TXCKP Bit 3 RBIE SSPIF SSPIE SSPIP ADDEN SENDB BRG16 Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP FERR BRGH -- Bit 1 INT0IF TMR2IF TMR2IE TMR2IP OERR TRMT WUE Bit 0 RBIF TMR1IF TMR1IE TMR1IP RX9D TX9D ABDEN Reset Values on page 55 58 58 58 57 57 57 57 57 57
GIE/GIEH PEIE/GIEL TMR0IE PSPIF(1) PSPIE(1) PSPIP(1) SPEN CSRC ABDOVF ADIF ADIE ADIP RX9 TX9 RCIDL RCIF RCIE RCIP SREN TXEN RXDTP
EUSART Transmit Register
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte
Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous master transmission. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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19.3.2 EUSART SYNCHRONOUS MASTER RECEPTION
4. Once Synchronous mode is selected, reception is enabled by setting either the Single Receive Enable bit, SREN (RCSTA<5>), or the Continuous Receive Enable bit, CREN (RCSTA<4>). Data is sampled on the RX pin on the falling edge of the clock. If enable bit SREN is set, only a single word is received. If enable bit CREN is set, the reception is continuous until CREN is cleared. If both bits are set, then CREN takes precedence. To set up a Synchronous Master Reception: 1. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRG16 bit, as required, to achieve the desired baud rate. Enable the synchronous master serial port by setting bits, SYNC, SPEN and CSRC. Ensure bits, CREN and SREN, are clear. If the signal from the CK pin is to be inverted, set the TXCKP bit. 5. If interrupts are desired, set enable bit, RCIE. 6. If 9-bit reception is desired, set bit, RX9. 7. If a single reception is required, set bit, SREN. For continuous reception, set bit, CREN. 8. Interrupt flag bit, RCIF, will be set when reception is complete and an interrupt will be generated if the enable bit, RCIE, was set. 9. Read the RCSTA register to get the 9th bit (if enabled) and determine if any error occurred during reception. 10. Read the 8-bit received data by reading the RCREG register. 11. If any error occurred, clear the error by clearing bit, CREN. 12. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set.
2. 3.
FIGURE 19-13:
RC7/RX/DT pin RC6/TX/CK pin (TXCKP = 0) RC6/TX/CK pin (TXCKP = 1) Write to bit SREN SREN bit CREN bit `0' RCIF bit (Interrupt) Read RXREG Note:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
`0'
Timing diagram demonstrates Sync Master mode with bit SREN = 1 and bit BRGH = 0.
TABLE 19-8:
Name INTCON PIR1 PIE1 IPR1 RCSTA RCREG TXSTA SPBRGH SPBRG
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
Bit 7 Bit 6 Bit 5 Bit 4 INT0IE TXIF TXIE TXIP CREN SYNC TXCKP Bit 3 RBIE SSPIF SSPIE SSPIP ADDEN SENDB BRG16 Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP FERR BRGH -- Bit 1 INT0IF TMR2IF TMR2IE TMR2IP OERR TRMT WUE Bit 0 RBIF TMR1IF TMR1IE TMR1IP RX9D TX9D ABDEN Reset Values on page 55 58 58 58 57 57 57 57 57 57
GIE/GIEH PEIE/GIEL TMR0IE PSPIF(1) PSPIE(1) PSPIP(1) SPEN CSRC ADIF ADIE ADIP RX9 TX9 RCIDL RCIF RCIE RCIP SREN TXEN RXDTP
EUSART Receive Register
BAUDCON ABDOVF
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte
Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous master reception. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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19.4 EUSART Synchronous Slave Mode
To set up a Synchronous Slave Transmission: 1. Enable the synchronous slave serial port by setting bits, SYNC and SPEN, and clearing bit, CSRC. Clear bits, CREN and SREN. If interrupts are desired, set enable bit, TXIE. If the signal from the CK pin is to be inverted, set the TXCKP bit. If 9-bit transmission is desired, set bit, TX9. Enable the transmission by setting enable bit, TXEN. If 9-bit transmission is selected, the ninth bit should be loaded in bit TX9D. Start transmission by loading data to the TXREGx register. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set.
Synchronous Slave mode is entered by clearing bit, CSRC (TXSTA<7>). This mode differs from the Synchronous Master mode in that the shift clock is supplied externally at the CK pin (instead of being supplied internally in Master mode). This allows the device to transfer or receive data while in any power-managed mode.
2. 3. 4. 5. 6. 7. 8. 9.
19.4.1
EUSART SYNCHRONOUS SLAVE TRANSMISSION
The operation of the Synchronous Master and Slave modes are identical, except in the case of the Sleep mode. If two words are written to the TXREG and then the SLEEP instruction is executed, the following will occur: a) b) c) d) The first word will immediately transfer to the TSR register and transmit. The second word will remain in the TXREG register. Flag bit, TXIF, will not be set. When the first word has been shifted out of TSR, the TXREG register will transfer the second word to the TSR and flag bit, TXIF, will now be set. If enable bit, TXIE, is set, the interrupt will wake the chip from Sleep. If the global interrupt is enabled, the program will branch to the interrupt vector.
e)
TABLE 19-9:
Name INTCON PIR1 PIE1 IPR1 RCSTA TXREG TXSTA BAUDCON SPBRGH SPBRG
REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
Bit 7 Bit 6 Bit 5 Bit 4 INT0IE TXIF TXIE TXIP CREN SYNC TXCKP Bit 3 RBIE SSPIF SSPIE SSPIP ADDEN SENDB BRG16 Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP FERR BRGH -- Bit 1 INT0IF TMR2IF TMR2IE TMR2IP OERR TRMT WUE Bit 0 RBIF TMR1IF TMR1IE TMR1IP RX9D TX9D ABDEN Reset Values on page 55 58 58 58 57 57 57 57 57 57
GIE/GIEH PEIE/GIEL TMR0IE PSPIF
(1)
ADIF ADIE ADIP RX9 TX9 RCIDL
RCIF RCIE RCIP SREN TXEN RXDTP
PSPIE(1) PSPIP(1) SPEN CSRC ABDOVF
EUSART Transmit Register
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte
Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous slave transmission. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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19.4.2 EUSART SYNCHRONOUS SLAVE RECEPTION
To set up a Synchronous Slave Reception: 1. Enable the synchronous master serial port by setting bits, SYNC and SPEN, and clearing bit, CSRC. 2. If interrupts are desired, set enable bit RCIE. 3. If the signal from the CK pin is to be inverted, set the TXCKP bit. 4. If 9-bit reception is desired, set bit, RX9. 5. To enable reception, set enable bit, CREN. 6. Flag bit, RCIF, will be set when reception is complete. An interrupt will be generated if enable bit, RCIE, was set. 7. Read the RCSTA register to get the 9th bit (if enabled) and determine if any error occurred during reception. 8. Read the 8-bit received data by reading the RCREG register. 9. If any error occurred, clear the error by clearing bit, CREN. 10. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. The operation of the Synchronous Master and Slave modes is identical, except in the case of Sleep, or any Idle mode and bit SREN, which is a "don't care" in Slave mode. If receive is enabled by setting the CREN bit prior to entering Sleep or any Idle mode, then a word may be received while in this low-power mode. Once the word is received, the RSR register will transfer the data to the RCREG register; if the RCIE enable bit is set, the interrupt generated will wake the chip from the lowpower mode. If the global interrupt is enabled, the program will branch to the interrupt vector.
TABLE 19-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Name INTCON PIR1 PIE1 IPR1 RCSTA RCREG TXSTA BAUDCON SPBRGH SPBRG Bit 7 Bit 6 Bit 5 Bit 4 INT0IE TXIF TXIE TXIP CREN SYNC TXCKP Bit 3 RBIE SSPIF SSPIE SSPIP ADDEN SENDB BRG16 Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP FERR BRGH -- Bit 1 INT0IF TMR2IF TMR2IE TMR2IP OERR TRMT WUE Bit 0 RBIF TMR1IF TMR1IE TMR1IP RX9D TX9D ABDEN Reset Values on page 55 58 58 58 57 57 57 57 57 57
GIE/GIEH PEIE/GIEL TMR0IE PSPIF(1) PSPIE(1) PSPIP(1) SPEN CSRC ABDOVF ADIF ADIE ADIP RX9 TX9 RCIDL RCIF RCIE RCIP SREN TXEN RXDTP
EUSART Receive Register
EUSART Baud Rate Generator Register High Byte EUSART Baud Rate Generator Register Low Byte
Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous slave reception. Note 1: These bits are unimplemented on 28-pin devices and read as `0'.
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20.0 10-BIT ANALOG-TO-DIGITAL CONVERTER (A/D) MODULE
The ADCON0 register, shown in Register 20-1, controls the operation of the A/D module. The ADCON1 register, shown in Register 20-2, configures the functions of the port pins. The ADCON2 register, shown in Register 20-3, configures the A/D clock source, programmed acquisition time and justification.
The Analog-to-Digital (A/D) converter module has 10 inputs for the 28-pin devices and 13 for the 40/44-pin devices. This module allows conversion of an analog input signal to a corresponding 10-bit digital number. The module has five registers: * * * * * A/D Result High Register (ADRESH) A/D Result Low Register (ADRESL) A/D Control Register 0 (ADCON0) A/D Control Register 1 (ADCON1) A/D Control Register 2 (ADCON2)
REGISTER 20-1:
ADCON0: A/D CONTROL REGISTER 0
U-0 -- bit 7 U-0 -- R/W-0 CHS3 R/W-0 CHS2 R/W-0 CHS1 R/W-0 CHS0 R/W-0 GO/DONE R/W-0 ADON bit 0
bit 7-6 bit 5-2
Unimplemented: Read as `0' CHS<3:0>: Analog Channel Select bits 0000 = Channel 0 (AN0) 0001 = Channel 1 (AN1) 0010 = Channel 2 (AN2) 0011 = Channel 3 (AN3) 0100 = Channel 4 (AN4) 0101 = Channel 5 (AN5)(1,2) 0110 = Channel 6 (AN6)(1,2) 0111 = Channel 7 (AN7)(1,2) 1000 = Channel 8 (AN8) 1001 = Channel 9 (AN9) 1010 = Channel 10 (AN10) 1011 = Channel 11 (AN11) 1100 = Channel 12 (AN12 1101 = Unimplemented(2) 1110 = Unimplemented(2) 1111 = Unimplemented(2) Note 1: These channels are not implemented on 28-pin devices. 2: Performing a conversion on unimplemented channels will return a floating input measurement.
bit 1
GO/DONE: A/D Conversion Status bit When ADON = 1: 1 = A/D conversion in progress 0 = A/D Idle ADON: A/D On bit 1 = A/D converter module is enabled 0 = A/D converter module is disabled Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 0
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REGISTER 20-2: ADCON1: A/D CONTROL REGISTER 1
U-0 -- bit 7 bit 7-6 bit 5 Unimplemented: Read as `0' VCFG1: Voltage Reference Configuration bit (VREF- source) 1 = VREF- (AN2) 0 = VSS VCFG0: Voltage Reference Configuration bit (VREF+ source) 1 = VREF+ (AN3) 0 = VDD PCFG<3:0>: A/D Port Configuration Control bits AN7(2) AN6(2) AN5(2) AN12 AN10 AN11 AN9 AN8 AN4 AN3 AN2 AN1 A A A A A A A A A A A A A A D D PCFG<3:0> 0000(1) 0001 0010 0011 0100 0101 0110 0111(1) 1000 1001 1010 1011 1100 1101 1110 1111 AN0 A A A A A A A A A A A A A A A D U-0 -- R/W-0 VCFG1 R/W-0 VCFG0 R/W-0(1) PCFG3 R/W(1) PCFG2 R/W(1) PCFG1 R/W(1) PCFG0 bit 0
bit 4
bit 3-0
A A A D D D D D D D D D D D D D
A A A A D D D D D D D D D D D D
A A A A A D D D D D D D D D D D
A A A A A A D D D D D D D D D D
A A A A A A A D D D D D D D D D
A A A A A A A A D D D D D D D D
A A A A A A A A A D D D D D D D
A A A A A A A A A A D D D D D D
A A A A A A A A A A A D D D D D
A A A A A A A A A A A A D D D D
A A A A A A A A A A A A A D D D
A = Analog input
D = Digital I/O
Note 1: The POR value of the PCFG bits depends on the value of the PBADEN Configuration bit. When PBADEN = 1, PCFG<3:0> = 0000; when PBADEN = 0, PCFG<3:0> = 0111. 2: AN5 through AN7 are available only on 40/44-pin devices. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
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REGISTER 20-3: ADCON2: A/D CONTROL REGISTER 2
R/W-0 ADFM bit 7 bit 7 ADFM: A/D Result Format Select bit 1 = Right justified 0 = Left justified Unimplemented: Read as `0' ACQT<2:0>: A/D Acquisition Time Select bits 111 = 20 TAD 110 = 16 TAD 101 = 12 TAD 100 = 8 TAD 011 = 6 TAD 010 = 4 TAD 001 = 2 TAD 000 = 0 TAD(1) ADCS<2:0>: A/D Conversion Clock Select bits 111 = FRC (clock derived from A/D RC oscillator)(1) 110 = FOSC/64 101 = FOSC/16 100 = FOSC/4 011 = FRC (clock derived from A/D RC oscillator)(1) 010 = FOSC/32 001 = FOSC/8 000 = FOSC/2 Note 1: If the A/D FRC clock source is selected, a delay of one TCY (instruction cycle) is added before the A/D clock starts. This allows the SLEEP instruction to be executed before starting a conversion. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown U-0 -- R/W-0 ACQT2 R/W-0 ACQT1 R/W-0 ACQT0 R/W-0 ADCS2 R/W-0 ADCS1 R/W-0 ADCS0 bit 0
bit 6 bit 5-3
bit 2-0
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The analog reference voltage is software selectable to either the device's positive and negative supply voltage (VDD and VSS), or the voltage level on the RA3/AN3/ VREF+ and RA2/AN2/VREF-/CVREF pins. The A/D converter has a unique feature of being able to operate while the device is in Sleep mode. To operate in Sleep, the A/D conversion clock must be derived from the A/D's internal RC oscillator. The output of the sample and hold is the input into the converter, which generates the result via successive approximation. A device Reset forces all registers to their Reset state. This forces the A/D module to be turned off and any conversion in progress is aborted. Each port pin associated with the A/D converter can be configured as an analog input, or as a digital I/O. The ADRESH and ADRESL registers contain the result of the A/D conversion. When the A/D conversion is complete, the result is loaded into the ADRESH:ADRESL register pair, the GO/DONE bit (ADCON0 register) is cleared and A/D Interrupt Flag bit, ADIF, is set. The block diagram of the A/D module is shown in Figure 20-1.
FIGURE 20-1:
A/D BLOCK DIAGRAM
CHS<3:0> 1100 1011 1010 1001 1000 0111 0110 0101 0100 VAIN AN12 AN11 AN10 AN9 AN8 AN7(1) AN6(1) AN5(1) AN4 AN3 AN2 AN1 AN0
10-Bit A/D Converter
(Input Voltage)
0011 0010
VCFG<1:0> VDD Reference Voltage VREF+ VREFX0 X1
0001 0000
1X 0X VSS
Note 1: 2:
Channels AN5 through AN7 are not available on 28-pin devices. I/O pins have diode protection to VDD and VSS.
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The value in the ADRESH:ADRESL registers is not modified for a Power-on Reset. The ADRESH:ADRESL registers will contain unknown data after a Power-on Reset. After the A/D module has been configured as desired, the selected channel must be acquired before the conversion is started. The analog input channels must have their corresponding TRIS bits selected as an input. To determine acquisition time, see Section 20.1 "A/D Acquisition Requirements". After this acquisition time has elapsed, the A/D conversion can be started. An acquisition time can be programmed to occur between setting the GO/DONE bit and the actual start of the conversion. The following steps should be followed to perform an A/D conversion:
Digital Code Output
5.
Wait for A/D conversion to complete, by either: * Polling for the GO/DONE bit to be cleared OR * Waiting for the A/D interrupt Read A/D Result registers (ADRESH:ADRESL); clear bit ADIF, if required. For next conversion, go to step 1 or step 2, as required. The A/D conversion time per bit is defined as TAD. A minimum wait of 2 TAD is required before the next acquisition starts.
6. 7.
FIGURE 20-2:
3FFh 3FEh
A/D TRANSFER FUNCTION
1.
2.
3. 4.
Configure the A/D module: * Configure analog pins, voltage reference and digital I/O (ADCON1) * Select A/D input channel (ADCON0) * Select A/D acquisition time (ADCON2) * Select A/D conversion clock (ADCON2) * Turn on A/D module (ADCON0) Configure A/D interrupt (if desired): * Clear ADIF bit * Set ADIE bit * Set GIE bit Wait the required acquisition time (if required). Start conversion: * Set GO/DONE bit (ADCON0 register)
003h 002h 001h 000h 1022 LSB 1022.5 LSB 1023 LSB 1 LSB 2 LSB 3 LSB 1023.5 LSB 0.5 LSB 1.5 LSB 2.5 LSB
Analog Input Voltage
FIGURE 20-3:
ANALOG INPUT MODEL
VDD VT = 0.6V RIC 1k Sampling Switch SS RSS
Rs
ANx
VAIN
CPIN 5 pF VT = 0.6V
ILEAKAGE 100 nA
CHOLD = 25 pF
VSS
Legend: CPIN = Input Capacitance VT = Threshold Voltage ILEAKAGE = Leakage Current at the pin due to various junctions = Interconnect Resistance RIC = Sampling Switch SS = Sample/Hold Capacitance (from DAC) CHOLD RSS = Sampling Switch Resistance
VDD
6V 5V 4V 3V 2V 1 2 3 4
Sampling Switch (k)
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20.1 A/D Acquisition Requirements
For the A/D converter to meet its specified accuracy, the charge holding capacitor (CHOLD) must be allowed to fully charge to the input channel voltage level. The analog input model is shown in Figure 20-3. The source impedance (RS) and the internal sampling switch (RSS) impedance directly affect the time required to charge the capacitor CHOLD. The sampling switch (RSS) impedance varies over the device voltage (VDD). The source impedance affects the offset voltage at the analog input (due to pin leakage current). The maximum recommended impedance for analog sources is 2.5 k. After the analog input channel is selected (changed), the channel must be sampled for at least the minimum acquisition time before starting a conversion. Note: When the conversion is started, the holding capacitor is disconnected from the input pin. To calculate the minimum acquisition time, Equation 20-1 may be used. This equation assumes that 1/2 LSb error is used (1024 steps for the A/D). The 1/2 LSb error is the maximum error allowed for the A/D to meet its specified resolution. Example 20-3 shows the calculation of the minimum required acquisition time TACQ. This calculation is based on the following application system assumptions: CHOLD Rs Conversion Error VDD Temperature = = = = 25 pF 2.5 k 1/2 LSb 5V Rss = 2 k 85C (system max.)
EQUATION 20-1:
TACQ = =
ACQUISITION TIME
Amplifier Settling Time + Holding Capacitor Charging Time + Temperature Coefficient TAMP + TC + TCOFF
EQUATION 20-2:
VHOLD or TC = =
A/D MINIMUM CHARGING TIME
(VREF - (VREF/2048)) * (1 - e(-TC/CHOLD(RIC + RSS + RS))) -(CHOLD)(RIC + RSS + RS) ln(1/2048)
EQUATION 20-3:
TACQ TAMP TCOFF = = = 0.2 s
CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME
TAMP + TC + TCOFF (Temp - 25C)(0.02 s/C) (85C - 25C)(0.02 s/C) 1.2 s -(CHOLD)(RIC + RSS + RS) ln(1/2047) -(25 pF) (1 k + 2 k + 2.5 k) ln(0.0004883) 1.05 s 0.2 s + 1 s + 1.2 s 2.4 s
Temperature coefficient is only required for temperatures > 25C. Below 25C, TCOFF = 0 ms. TC =
TACQ
=
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20.2 Selecting and Configuring Acquisition Time 20.3 Selecting the A/D Conversion Clock
The ADCON2 register allows the user to select an acquisition time that occurs each time the GO/DONE bit is set. It also gives users the option to use an automatically determined acquisition time. Acquisition time may be set with the ACQT<2:0> bits (ADCON2<5:3>), which provides a range of 2 to 20 TAD. When the GO/DONE bit is set, the A/D module continues to sample the input for the selected acquisition time, then automatically begins a conversion. Since the acquisition time is programmed, there may be no need to wait for an acquisition time between selecting a channel and setting the GO/DONE bit. Manual acquisition is selected when ACQT<2:0> = 000. When the GO/DONE bit is set, sampling is stopped and a conversion begins. The user is responsible for ensuring the required acquisition time has passed between selecting the desired input channel and setting the GO/DONE bit. This option is also the default Reset state of the ACQT<2:0> bits and is compatible with devices that do not offer programmable acquisition times. In either case, when the conversion is completed, the GO/DONE bit is cleared, the ADIF flag is set and the A/D begins sampling the currently selected channel again. If an acquisition time is programmed, there is nothing to indicate if the acquisition time has ended or if the conversion has begun.
The A/D conversion time per bit is defined as TAD. The A/D conversion requires 11 TAD per 10-bit conversion. The source of the A/D conversion clock is software selectable. There are seven possible options for TAD: * * * * * * * 2 TOSC 4 TOSC 8 TOSC 16 TOSC 32 TOSC 64 TOSC Internal RC Oscillator
For correct A/D conversions, the A/D conversion clock (TAD) must be as short as possible, but greater than the minimum TAD (see parameter 130 for more information). Table 20-1 shows the resultant TAD times derived from the device operating frequencies and the A/D clock source selected.
TABLE 20-1:
TAD vs. DEVICE OPERATING FREQUENCIES
AD Clock Source (TAD) Maximum Device Frequency PIC18F2X21/4X21 2.86 MHz 5.71 MHz 11.43 MHz 22.86 MHz 40.0 MHz 40.0 MHz 1.00 MHz(1) PIC18LF2X21/4X21(4) 1.43 kHz 2.86 MHz 5.72 MHz 11.43 MHz 22.86 MHz 22.86 MHz 1.00 MHz(2) ADCS<2:0> 000 100 001 101 010 110 x11
Operation 2 TOSC 4 TOSC 8 TOSC 16 TOSC 32 TOSC 64 TOSC RC(3) Note 1: 2: 3: 4:
The RC source has a typical TAD time of 1.2 s. The RC source has a typical TAD time of 2.5 s. For device frequencies above 1 MHz, the device must be in Sleep for the entire conversion or the A/D accuracy may be out of specification. Low-power (PIC18LFXXXX) devices only.
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20.4 Operation in Power-Managed Modes 20.5 Configuring Analog Port Pins
The ADCON1, TRISA, TRISB and TRISE registers all configure the A/D port pins. The port pins needed as analog inputs must have their corresponding TRIS bits set (input). If the TRIS bit is cleared (output), the digital output level (VOH or VOL) will be converted. The A/D operation is independent of the state of the CHS<3:0> bits and the TRIS bits. Note 1: When reading the Port register, all pins configured as analog input channels will read as cleared (a low level). Pins configured as digital inputs will convert as analog inputs. Analog levels on a digitally configured input will be accurately converted. 2: Analog levels on any pin defined as a digital input may cause the digital input buffer to consume current out of the device's specification limits. 3: The PBADEN bit in Configuration Register 3H configures PORTB pins to reset as analog or digital pins by controlling how the PCFG<3:0> bits in ADCON1 are reset.
The selection of the automatic acquisition time and A/D conversion clock is determined in part by the clock source and frequency while in a power-managed mode. If the A/D is expected to operate while the device is in a power-managed mode, the ACQT<2:0> and ADCS<2:0> bits in ADCON2 should be updated in accordance with the clock source to be used in that mode. After entering the mode, an A/D acquisition or conversion may be started. Once started, the device should continue to be clocked by the same clock source until the conversion has been completed. If desired, the device may be placed into the corresponding Idle mode during the conversion. If the device clock frequency is less than 1 MHz, the A/D RC clock source should be selected. Operation in Sleep mode requires the A/D FRC clock to be selected. If bits ACQT<2:0> are set to `000' and a conversion is started, the conversion will be delayed one instruction cycle to allow execution of the SLEEP instruction and entry to Sleep mode. The IDLEN bit (OSCCON<7>) must have already been cleared prior to starting the conversion.
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20.6 A/D Conversions
Figure 20-4 shows the operation of the A/D converter after the GO/DONE bit has been set and the ACQT<2:0> bits are cleared. A conversion is started after the following instruction to allow entry into Sleep mode before the conversion begins. Figure 20-5 shows the operation of the A/D converter after the GO/DONE bit has been set and the ACQT<2:0> bits are set to `010' and selecting a 4 TAD acquisition time before the conversion starts. Clearing the GO/DONE bit during a conversion will abort the current conversion. The A/D Result register pair will NOT be updated with the partially completed A/D conversion sample. This means the ADRESH:ADRESL registers will continue to contain the value of the last completed conversion (or the last value written to the ADRESH:ADRESL registers). After the A/D conversion is completed or aborted, a 2 TAD wait is required before the next acquisition can be started. After this wait, acquisition on the selected channel is automatically started. Note: The GO/DONE bit should NOT be set in the same instruction that turns on the A/D.
20.7
Discharge
The discharge phase is used to initialize the value of the capacitor array. The array is discharged before every sample. This feature helps to optimize the unitygain amplifier, as the circuit always needs to charge the capacitor array, rather than charge/discharge based on previous measure values.
FIGURE 20-4:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)
TCY - TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11 TAD1 b4 b1 b0 b6 b7 b2 b9 b8 b3 b5 Conversion starts Holding capacitor is disconnected from analog input (typically 100 ns) Set GO/DONE bit On the following cycle: ADRESH:ADRESL is loaded, GO/DONE bit is cleared, ADIF bit is set, holding capacitor is connected to analog input. Discharge
FIGURE 20-5:
A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)
TAD Cycles 4 1 2 b9 3 b8 4 b7 5 b6 6 b5 7 b4 8 b3 9 b2 10 b1 11 b0 Discharge TAD1
TACQT Cycles 1 2 3
Automatic Acquisition Time
Conversion starts (Holding capacitor is disconnected)
Set GO/DONE bit (Holding capacitor continues acquiring input)
On the following cycle: ADRESH:ADRESL is loaded, GO/DONE bit is cleared, ADIF bit is set, holding capacitor is connected to analog input.
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20.8 Use of the CCP2 Trigger
An A/D conversion can be started by the Special Event Trigger of the CCP2 module. This requires that the CCP2M<3:0> bits (CCP2CON<3:0>) be programmed as `1011' and that the A/D module is enabled (ADON bit is set). When the trigger occurs, the GO/DONE bit will be set, starting the A/D acquisition and conversion and the Timer1 (or Timer3) counter will be reset to zero. Timer1 (or Timer3) is reset to automatically repeat the A/D acquisition period with minimal software overhead (moving ADRESH:ADRESL to the desired location). The appropriate analog input channel must be selected and the minimum acquisition period is either timed by the user, or an appropriate TACQ time selected before the Special Event Trigger sets the GO/DONE bit (starts a conversion). If the A/D module is not enabled (ADON is cleared), the Special Event Trigger will be ignored by the A/D module but will still reset the Timer1 (or Timer3) counter.
TABLE 20-2:
Name INTCON PIR1 PIE1 IPR1 PIR2 PIE2 IPR2 ADRESH ADRESL ADCON0 ADCON1 ADCON2 PORTA TRISA PORTB TRISB LATB PORTE TRISE
(1)
REGISTERS ASSOCIATED WITH A/D OPERATION
Bit 7 Bit 6 Bit 5 TMR0IE RCIF RCIE RCIP -- -- -- Bit 4 INT0IE TXIF TXIE TXIP EEIF EEIE EEIP Bit 3 RBIE SSPIF SSPIE SSPIP BCLIF BCLIE BCLIP Bit 2 TMR0IF CCP1IF CCP1IE CCP1IP HLVDIF HLVDIE HLVDIP Bit 1 INT0IF TMR2IF TMR2IE TMR2IP TMR3IF TMR3IE TMR3IP Bit 0 RBIF TMR1IF TMR1IE TMR1IP CCP2IF CCP2IE CCP2IP Reset Values on page 55 58 58 58 58 58 58 57 57 CHS2 VCFG0 ACQT1 RA4 RB4 CHS1 PCFG3 ACQT0 RA3 RB3 CHS0 PCFG2 ADCS2 RA2 RB2 GO/DONE PCFG1 ADCS1 RA1 RB1 ADON PCFG0 ADCS0 RA0 RB0 57 57 57 58 58 58 58 58 RE2(1) TRISE2 RE1(1) TRISE1 RE0(1) TRISE0 58 58 58 -- PSPMODE -- RE3(3) -- --
GIE/GIEH PEIE/GIEL PSPIF(1) PSPIE(1) PSPIP(1) OSCFIF OSCFIE OSCFIP ADIF ADIE ADIP CMIF CMIE CMIP
A/D Result Register High Byte A/D Result Register Low Byte -- -- ADFM RA7(2) RB7 -- -- -- RA6(2) RB6 CHS3 VCFG1 ACQT2 RA5 RB5
TRISA7(2) TRISA6(2) PORTA Data Direction Control Register PORTB Data Direction Control Register PORTB Data Latch Register (Read and Write to Data Latch) -- IBF -- -- OBF -- -- IBOV --
LATE(1)
PORTE Data Latch Register
Legend: -- = unimplemented, read as `0'. Shaded cells are not used for A/D conversion. Note 1: These registers and/or bits are unimplemented on 28-pin devices and are read as `0'. 2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. 3: RE3 port bit is available only as an input pin when the MCLRE Configuration bit is `0'.
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21.0 COMPARATOR MODULE
The analog comparator module contains two comparators that can be configured in a variety of ways. The inputs can be selected from the analog inputs multiplexed with pins RA0 through RA5, as well as the on-chip voltage reference (see Section 22.0 "Comparator Voltage Reference Module"). The digital outputs (normal or inverted) are available at the pin level and can also be read through the control register. The CMCON register (Register 21-1) selects the comparator input and output configuration. Block diagrams of the various comparator configurations are shown in Figure 21-1.
REGISTER 21-1:
CMCON: COMPARATOR CONTROL REGISTER
R-0 C2OUT bit 7 R-0 C1OUT R/W-0 C2INV R/W-0 C1INV R/W-0 CIS R/W-1 CM2 R/W-1 CM1 R/W-1 CM0 bit 0
bit 7
C2OUT: Comparator 2 Output bit When C2INV = 0: 1 = C2 VIN+ > C2 VIN0 = C2 VIN+ < C2 VINWhen C2INV = 1: 1 = C2 VIN+ < C2 VIN0 = C2 VIN+ > C2 VINC1OUT: Comparator 1 Output bit When C1INV = 0: 1 = C1 VIN+ > C1 VIN0 = C1 VIN+ < C1 VINWhen C1INV = 1: 1 = C1 VIN+ < C1 VIN0 = C1 VIN+ > C1 VINC2INV: Comparator 2 Output Inversion bit 1 = C2 output inverted 0 = C2 output not inverted C1INV: Comparator 1 Output Inversion bit 1 = C1 output inverted 0 = C1 output not inverted CIS: Comparator Input Switch bit When CM<2:0> = 110: 1 = C1 VIN- connects to RA3/AN3/VREF+ C2 VIN- connects to RA2/AN2/VREF-/CVREF 0 = C1 VIN- connects to RA0/AN0 C2 VIN- connects to RA1/AN1 CM<2:0>: Comparator Mode bits Figure 21-1 shows the Comparator modes and the CM<2:0> bit settings. Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5
bit 4
bit 3
bit 2-0
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21.1 Comparator Configuration
There are eight modes of operation for the comparators, shown in Figure 21-1. Bits CM<2:0> of the CMCON register are used to select these modes. The TRISA register controls the data direction of the comparator pins for each mode. If the Comparator mode is changed, the comparator output level may not be valid for the specified mode change delay shown in Section 27.0 "Electrical Characteristics". Note: Comparator interrupts should be disabled during a Comparator mode change; otherwise, a false interrupt may occur.
FIGURE 21-1:
Comparators Reset CM<2:0> = 000 RA0/AN0
A
COMPARATOR I/O OPERATING MODES
Comparators Off (POR Default Value) CM<2:0> = 111
VINVIN+
RA0/AN0 C1 Off (Read as `0') RA3/AN3/ VREF+ RA1/AN1 C2 Off (Read as `0')
D D
VINVIN+
RA3/AN3/ A VREF+ RA1/AN1
A
C1
Off (Read as `0')
VINVIN+
D
VINVIN+
RA2/AN2/ A VREF-/CVREF
D RA2/AN2/ VREF-/CVREF
C2
Off (Read as `0')
Two Independent Comparators CM<2:0> = 010 RA0/AN0
A VINVIN+
Two Independent Comparators with Outputs CM<2:0> = 011 C1OUT RA0/AN0 RA3/AN3/ VREF+
A A VINVIN+
RA3/AN3/ A VREF+ RA1/AN1
A
C1
C1
C1OUT
RA4/T0CKI/C1OUT*
VINVIN+
RA2/AN2/ A VREF-/CVREF
C2
C2OUT
RA1/AN1
A
VINVIN+
RA2/AN2/ A VREF-/CVREF
C2
C2OUT
RA5/AN4/SS/HLVDIN/C2OUT* Two Common Reference Comparators CM<2:0> = 100 RA0/AN0
A VINVIN+
Two Common Reference Comparators with Outputs CM<2:0> = 101 C1OUT RA0/AN0 RA3/AN3/ VREF+
A A VINVIN+
RA3/AN3/ A VREF+ RA1/AN1
A
C1
C1
C1OUT
RA4/T0CKI/C1OUT*
VINVIN+
RA2/AN2/ D VREF-/CVREF
C2
C2OUT
RA1/AN1
A
VINVIN+
RA2/AN2/ D VREF-/CVREF
C2
C2OUT
RA5/AN4/SS/HLVDIN/C2OUT* One Independent Comparator with Output CM<2:0> = 001 RA0/AN0
A VINVIN+
Four Inputs Multiplexed to Two Comparators CM<2:0> = 110 RA0/AN0
A A CIS = 0 CIS = 1 VINVIN+
RA3/AN3/ A VREF+
C1
C1OUT
RA3/AN3/ VREF+ RA1/AN1
C1
C1OUT
RA4/T0CKI/C1OUT* RA1/AN1
D VINVIN+
A CIS = 0 CIS = 1 VINVIN+
A RA2/AN2/ VREF-/CVREF
C2
C2OUT
RA2/AN2/ D VREF-/CVREF
C2
Off (Read as `0')
CVREF
From VREF Module
A = Analog Input, port reads zeros always D = Digital Input CIS (CMCON<3>) is the Comparator Input Switch * Setting the TRISA<5:4> bits will disable the comparator outputs by configuring the pins as inputs.
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21.2 Comparator Operation
21.3.2 INTERNAL REFERENCE SIGNAL
A single comparator is shown in Figure 21-2, along with the relationship between the analog input levels and the digital output. When the analog input at VIN+ is less than the analog input VIN-, the output of the comparator is a digital low level. When the analog input at VIN+ is greater than the analog input VIN-, the output of the comparator is a digital high level. The shaded areas of the output of the comparator in Figure 21-2 represent the uncertainty, due to input offsets and response time. The comparator module also allows the selection of an internally generated voltage reference from the comparator voltage reference module. This module is described in more detail in Section 22.0 "Comparator Voltage Reference Module". The internal reference is only available in the mode where four inputs are multiplexed to two comparators (CM<2:0> = 110). In this mode, the internal voltage reference is applied to the VIN+ pin of both comparators.
21.3
Comparator Reference
21.4
Comparator Response Time
Depending on the comparator operating mode, either an external or internal voltage reference may be used. The analog signal present at VIN- is compared to the signal at VIN+ and the digital output of the comparator is adjusted accordingly (Figure 21-2).
FIGURE 21-2:
SINGLE COMPARATOR
Response time is the minimum time, after selecting a new reference voltage or input source, before the comparator output has a valid level. If the internal reference is changed, the maximum delay of the internal voltage reference must be considered when using the comparator outputs. Otherwise, the maximum delay of the comparators should be used (see Section 27.0 "Electrical Characteristics").
VIN+ VIN-
+ -
21.5
Output
Comparator Outputs
VINVIN+
The comparator outputs are read through the CMCON register. These bits are read-only. The comparator outputs may also be directly output to the RA4 and RA5 I/O pins. When enabled, multiplexors in the output path of the RA4 and RA5 pins will switch and the output of each pin will be the unsynchronized output of the comparator. The uncertainty of each of the comparators is related to the input offset voltage and the response time given in the specifications. Figure 21-3 shows the comparator output block diagram. The TRISA bits will still function as an output enable/ disable for the RA4 and RA5 pins while in this mode. The polarity of the comparator outputs can be changed using the C2INV and C1INV bits (CMCON<5:4>).
Output
21.3.1
EXTERNAL REFERENCE SIGNAL
When external voltage references are used, the comparator module can be configured to have the comparators operate from the same or different reference sources. However, threshold detector applications may require the same reference. The reference signal must be between VSS and VDD and can be applied to either pin of the comparator(s).
Note 1: When reading the Port register, all pins configured as analog inputs will read as a `0'. Pins configured as digital inputs will convert an analog input according to the Schmitt Trigger input specification. 2: Analog levels on any pin defined as a digital input may cause the input buffer to consume more current than is specified.
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FIGURE 21-3: COMPARATOR OUTPUT BLOCK DIAGRAM
MULTIPLEX
Port Pins
+
To RA4 or RA5 pin D CxINV EN Q Bus Data
Read CMCON
-
D EN Reset
Q CL From Other Comparator
Set CMIF bit
21.6
Comparator Interrupts
21.7
The comparator interrupt flag is set whenever there is a change in the output value of either comparator. Software will need to maintain information about the status of the output bits, as read from CMCON<7:6>, to determine the actual change that occurred. The CMIF bit (PIR2<6>) is the Comparator Interrupt Flag. The CMIF bit must be reset by clearing it. Since it is also possible to write a `1' to this register, a simulated interrupt may be initiated. Both the CMIE bit (PIE2<6>) and the PEIE bit (INTCON<6>) must be set to enable the interrupt. In addition, the GIE bit (INTCON<7>) must also be set. If any of these bits are clear, the interrupt is not enabled, though the CMIF bit will still be set if an interrupt condition occurs. Note: If a change in the CMCON register (C1OUT or C2OUT) should occur when a read operation is being executed (start of the Q2 cycle), then the CMIF (PIR2 register) interrupt flag may not get set.
Comparator Operation During Sleep
When a comparator is active and the device is placed in Sleep mode, the comparator remains active and the interrupt is functional if enabled. This interrupt will wake-up the device from Sleep mode, when enabled. Each operational comparator will consume additional current, as shown in the comparator specifications. To minimize power consumption while in Sleep mode, turn off the comparators (CM<2:0> = 111) before entering Sleep. If the device wakes up from Sleep, the contents of the CMCON register are not affected.
21.8
Effects of a Reset
The user, in the Interrupt Service Routine, can clear the interrupt in the following manner: a) b) Any read or write of CMCON will end the mismatch condition. Clear flag bit CMIF.
A device Reset forces the CMCON register to its Reset state, causing the comparator modules to be turned off (CM<2:0> = 111). However, the input pins (RA0 through RA3) are configured as analog inputs by default on device Reset. The I/O configuration for these pins is determined by the setting of the PCFG<3:0> bits (ADCON1<3:0>). Therefore, device current is minimized when analog inputs are present at Reset time.
A mismatch condition will continue to set flag bit CMIF. Reading CMCON will end the mismatch condition and allow flag bit CMIF to be cleared.
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21.9 Analog Input Connection Considerations
range by more than 0.6V in either direction, one of the diodes is forward biased and a latch-up condition may occur. A maximum source impedance of 10 k is recommended for the analog sources. Any external component connected to an analog input pin, such as a capacitor or a Zener diode, should have very little leakage current.
A simplified circuit for an analog input is shown in Figure 21-4. Since the analog pins are connected to a digital output, they have reverse biased diodes to VDD and VSS. The analog input, therefore, must be between VSS and VDD. If the input voltage deviates from this
FIGURE 21-4:
COMPARATOR ANALOG INPUT MODEL
VDD RS < 10k AIN VT = 0.6V RIC Comparator Input CPIN 5 pF VT = 0.6V ILEAKAGE 100 nA
VA
VSS Legend: CPIN VT ILEAKAGE RIC RS VA = = = = = = Input Capacitance Threshold Voltage Leakage Current at the pin due to various junctions Interconnect Resistance Source Impedance Analog Voltage
TABLE 21-1:
Name CMCON CVRCON INTCON PIR2 PIE2 IPR2 PORTA LATA TRISA
REGISTERS ASSOCIATED WITH COMPARATOR MODULE
Bit 7 C2OUT CVREN OSCFIF OSCFIE OSCFIP RA7(1) LATA7(1) Bit 6 C1OUT CVROE CMIF CMIE CMIP RA6(1) LATA6(1) Bit 5 C2INV CVRR TMR0IE -- -- -- RA5 Bit 4 C1INV CVRSS INT0IE EEIF EEIE EEIP RA4 Bit 3 CIS CVR3 RBIE BCLIF BCLIE BCLIP RA3 Bit 2 CM2 CVR2 TMR0IF HLVDIF HLVDIE HLVDIP RA2 Bit 1 CM1 CVR1 INT0IF TMR3IF TMR3IE TMR3IP RA1 Bit 0 CM0 CVR0 RBIF CCP2IF CCP2IE CCP2IP RA0 Reset Values on page 57 57 58 58 58 58 58 58 58
GIE/GIEH PEIE/GIEL
PORTA Data Latch Register (Read and Write to Data Latch)
TRISA7
(1)
TRISA6(1) PORTA Data Direction Control Register
Legend: -- = unimplemented, read as `0'. Shaded cells are unused by the comparator module. Note 1: PORTA<7:6> and their direction and latch bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'.
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NOTES:
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22.0 COMPARATOR VOLTAGE REFERENCE MODULE
used is selected by the CVRR bit (CVRCON<5>). The primary difference between the ranges is the size of the steps selected by the CVREF selection bits (CVR<3:0>), with one range offering finer resolution. The equations used to calculate the output of the comparator voltage reference are as follows: If CVRR = 1: CVREF = ((CVR<3:0>)/24) x CVRSRC If CVRR = 0: CVREF = (CVRSRC x 1/4) + (((CVR<3:0>)/32) x CVRSRC) The comparator reference supply voltage can come from either VDD and VSS, or the external VREF+ and VREF- that are multiplexed with RA2 and RA3. The voltage source is selected by the CVRSS bit (CVRCON<4>). The settling time of the comparator voltage reference must be considered when changing the CVREF output (see Table 27-3 in Section 27.0 "Electrical Characteristics").
The comparator voltage reference is a 16-tap resistor ladder network that provides a selectable reference voltage. Although its primary purpose is to provide a reference for the analog comparators, it may also be used independently of them. A block diagram of the module is shown in Figure 22-1. The resistor ladder is segmented to provide two ranges of CVREF values and has a power-down function to conserve power when the reference is not being used. The module's supply reference can be provided from either device VDD/VSS or an external voltage reference.
22.1
Configuring the Comparator Voltage Reference
The voltage reference module is controlled through the CVRCON register (Register 22-1). The comparator voltage reference provides two ranges of output voltage, each with 16 distinct levels. The range to be
REGISTER 22-1:
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
R/W-0 CVREN bit 7 R/W-0 CVROE(1) R/W-0 CVRR R/W-0 CVRSS R/W-0 CVR3 R/W-0 CVR2 R/W-0 CVR1 R/W-0 CVR0 bit 0
bit 7
CVREN: Comparator Voltage Reference Enable bit 1 = CVREF circuit powered on 0 = CVREF circuit powered down CVROE: Comparator VREF Output Enable bit(1) 1 = CVREF voltage level is also output on the RA2/AN2/VREF-/CVREF pin 0 = CVREF voltage is disconnected from the RA2/AN2/VREF-/CVREF pin Note 1: CVROE overrides the TRISA<2> bit setting. CVRR: Comparator VREF Range Selection bit 1 = 0.00 CVRSRC to 0.667 CVRSRC, with CVRSRC/24 step size (low range) 0 = 0.25 CVRSRC to 0.75 CVRSRC, with CVRSRC/32 step size (high range) CVRSS: Comparator VREF Source Selection bit 1 = Comparator reference source, CVRSRC = (VREF+) - (VREF-) 0 = Comparator reference source, CVRSRC = VDD - VSS CVR<3:0>: Comparator VREF Value Selection bits (0 (CVR<3:0>) 15) When CVRR = 1: CVREF = ((CVR<3:0>)/24) * (CVRSRC) When CVRR = 0: CVREF = (CVRSRC/4) + ((CVR<3:0>)/32) * (CVRSRC) Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown
bit 6
bit 5
bit 4
bit 3-0
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FIGURE 22-1: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM
VREF+ VDD CVRSS = 1
CVRSS = 0
8R R R R
CVR<3:0>
CVREN
16 Steps
16-to-1 MUX
R
CVREF
R R R CVRR VREFCVRSS = 1
8R
CVRSS = 0
22.2
Voltage Reference Accuracy/Error
22.4
Effects of a Reset
The full range of voltage reference cannot be realized due to the construction of the module. The transistors on the top and bottom of the resistor ladder network (Figure 22-1) keep CVREF from approaching the reference source rails. The voltage reference is derived from the reference source; therefore, the CVREF output changes with fluctuations in that source. The tested absolute accuracy of the voltage reference can be found in Section 27.0 "Electrical Characteristics".
A device Reset disables the voltage reference by clearing bit, CVREN (CVRCON<7>). This Reset also disconnects the reference from the RA2 pin by clearing bit, CVROE (CVRCON<6>) and selects the high-voltage range by clearing bit, CVRR (CVRCON<5>). The CVR value select bits are also cleared.
22.5
Connection Considerations
22.3
Operation During Sleep
When the device wakes up from Sleep through an interrupt or a Watchdog Timer time-out, the contents of the CVRCON register are not affected. To minimize current consumption in Sleep mode, the voltage reference should be disabled.
The voltage reference module operates independently of the comparator module. The output of the reference generator may be connected to the RA2 pin if the CVROE bit is set. Enabling the voltage reference output onto RA2 when it is configured as a digital input will increase current consumption. Connecting RA2 as a digital output with CVRSS enabled will also increase current consumption. The RA2 pin can be used as a simple D/A output with limited drive capability. Due to the limited current drive capability, a buffer must be used on the voltage reference output for external connections to VREF. Figure 22-2 shows an example buffering technique.
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FIGURE 22-2: COMPARATOR VOLTAGE REFERENCE OUTPUT BUFFER EXAMPLE
PIC18FXXXX
CVREF Module R(1) Voltage Reference Output Impedance RA2
+ -
CVREF Output
Note 1:
R is dependent upon the voltage reference configuration bits, CVRCON<3:0> and CVRCON<5>.
TABLE 22-1:
Name CVRCON CMCON TRISA
REGISTERS ASSOCIATED WITH COMPARATOR VOLTAGE REFERENCE
Bit 7 CVREN C2OUT TRISA7
(1)
Bit 6 CVROE C1OUT TRISA6(1)
Bit 5 CVRR C2INV
Bit 4 CVRSS C1INV
Bit 3 CVR3 CIS
Bit 2 CVR2 CM2
Bit 1 CVR1 CM1
Bit 0 CVR0 CM0
Reset Values on page 57 57 58
PORTA Data Direction Control Register
Legend: Shaded cells are not used with the comparator voltage reference. Note 1: PORTA pins are enabled based on oscillator configuration.
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NOTES:
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23.0 HIGH/LOW-VOLTAGE DETECT (HLVD)
The High/Low-Voltage Detect Control register (Register 23-1) completely controls the operation of the HLVD module. This allows the circuitry to be "turned off" by the user under software control, which minimizes the current consumption for the device. The block diagram for the HLVD module is shown in Figure 23-1.
PIC18F2221/2321/4221/4321 family devices have a High/Low-Voltage Detect module (HLVD). This is a programmable circuit that allows the user to specify both a device voltage trip point and the direction of change from that point. If the device experiences an excursion past the trip point in that direction, an interrupt flag is set. If the interrupt is enabled, the program execution will branch to the interrupt vector address and the software can then respond to the interrupt.
REGISTER 23-1:
HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER
R/W-0 VDIRMAG bit 7 U-0 -- R-0 IRVST R/W-0 HLVDEN R/W-0 HLVDL3 R/W-1 HLVDL2 R/W-0 HLVDL1 R/W-1 HLVDL0 bit 0
bit 7
VDIRMAG: Voltage Direction Magnitude Select bit 1 = Event occurs when voltage equals or exceeds trip point (HLVDL<3:0>) 0 = Event occurs when voltage equals or falls below trip point (HLVDL<3:0>) Unimplemented: Read as `0' IRVST: Internal Reference Voltage Stable Flag bit 1 = Indicates that the voltage detect logic will generate the interrupt flag at the specified voltage range 0 = Indicates that the voltage detect logic will not generate the interrupt flag at the specified voltage range and the HLVD interrupt should not be enabled HLVDEN: High/Low-Voltage Detect Power Enable bit 1 = HLVD enabled 0 = HLVD disabled HLVDL<3:0>: Voltage Detection Limit bits 1111 = External analog input is used (input comes from the HLVDIN pin) 1110 = Maximum setting . . . 0000 = Minimum setting Note: Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown See Table 27-4 in Section 27.0 "Electrical Characteristics" for the specifications.
bit 6 bit 5
bit 4
bit 3-0
The module is enabled by setting the HLVDEN bit. Each time that the HLVD module is enabled, the circuitry requires some time to stabilize. The IRVST bit is a read-only bit and is used to indicate when the circuit is stable. The module can only generate an interrupt after the circuit is stable and IRVST is set.
The VDIRMAG bit determines the overall operation of the module. When VDIRMAG is cleared, the module monitors for drops in VDD below a predetermined set point. When the bit is set, the module monitors for rises in VDD above the set point.
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23.1 Operation
When the HLVD module is enabled, a comparator uses an internally generated reference voltage as the set point. The set point is compared with the trip point, where each node in the resistor divider represents a trip point voltage. The "trip point" voltage is the voltage level at which the device detects a high or low-voltage event, depending on the configuration of the module. When the supply voltage is equal to the trip point, the voltage tapped off of the resistor array is equal to the internal reference voltage generated by the voltage reference module. The comparator then generates an interrupt signal by setting the HLVDIF bit. The trip point voltage is software programmable to any one of 16 values. The trip point is selected by programming the HLVDL<3:0> bits (HLVDCON<3:0>). The HLVD module has an additional feature that allows the user to supply the trip voltage to the module from an external source. This mode is enabled when bits HLVDL<3:0> are set to `1111'. In this state, the comparator input is multiplexed from the external input pin, HLVDIN. This gives users flexibility because it allows them to configure the High/Low-Voltage Detect interrupt to occur at any voltage in the valid operating range.
FIGURE 23-1:
HLVD MODULE BLOCK DIAGRAM (WITH EXTERNAL INPUT)
VDD
Externally Generated Trip Point VDD
HLVDL<3:0>
HLVDCON Register HLVDEN VDIRMAG
HLVDIN
HLVDIN
16-to-1 MUX
Set HLVDIF
HLVDEN
BOREN
Internal Voltage Reference
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23.2 HLVD Setup
The following steps are needed to set up the HLVD module: 1. 2. 3. 4. 5. 6. Disable the module by clearing the HLVDEN bit (HLVDCON<4>). Write the value to the HLVDL<3:0> bits that selects the desired HLVD trip point. Set the VDIRMAG bit to detect high voltage (VDIRMAG = 1) or low voltage (VDIRMAG = 0). Enable the HLVD module by setting the HLVDEN bit. Clear the HLVD interrupt flag (PIR2<2>), which may have been set from a previous interrupt. Enable the HLVD interrupt if interrupts are desired by setting the HLVDIE and GIE bits (PIE<2> and INTCON<7>). An interrupt will not be generated until the IRVST bit is set. Depending on the application, the HLVD module does not need to be operating constantly. To decrease the current requirements, the HLVD circuitry may only need to be enabled for short periods where the voltage is checked. After doing the check, the HLVD module may be disabled.
23.4
HLVD Start-up Time
The internal reference voltage of the HLVD module, specified in electrical specification parameter D420, may be used by other internal circuitry, such as the Programmable Brown-out Reset. If the HLVD or other circuits using the voltage reference are disabled to lower the device's current consumption, the reference voltage circuit will require time to become stable before a low or high-voltage condition can be reliably detected. This start-up time, TIRVST, is an interval that is independent of device clock speed. It is specified in electrical specification parameter 36. The HLVD interrupt flag is not enabled until TIRVST has expired and a stable reference voltage is reached. For this reason, brief excursions beyond the set point may not be detected during this interval. Refer to Figure 23-2 or Figure 23-3.
23.3
Current Consumption
When the module is enabled, the HLVD comparator and voltage divider are enabled and will consume static current. The total current consumption, when enabled, is specified in electrical specification parameter D022B.
FIGURE 23-2:
CASE 1: VDD
LOW-VOLTAGE DETECT OPERATION (VDIRMAG = 0)
HLVDIF may not be set
VLVD HLVDIF Enable HLVD IRVST TIRVST Internal Reference is stable CASE 2: VDD VLVD HLVDIF Enable HLVD IRVST Internal Reference is stable HLVDIF cleared in software HLVDIF cleared in software, HLVDIF remains set since HLVD condition still exists TIRVST HLVDIF cleared in software
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FIGURE 23-3:
CASE 1:
HIGH-VOLTAGE DETECT OPERATION (VDIRMAG = 1)
HLVDIF may not be set VLVD VDD
HLVDIF Enable HLVD IRVST TIRVST HLVDIF cleared in software Internal Reference is stable CASE 2: VLVD VDD HLVDIF Enable HLVD IRVST Internal Reference is stable HLVDIF cleared in software HLVDIF cleared in software, HLVDIF remains set since HLVD condition still exists TIRVST
23.5
Applications
FIGURE 23-4:
For general battery applications, Figure 23-4 shows a possible voltage curve. Over time, the device voltage decreases. When the device voltage reaches voltage VA, the HLVD logic generates an interrupt at time TA. The interrupt could cause the execution of an ISR, which would allow the application to perform "housekeeping tasks" and perform a controlled shutdown before the device voltage exits the valid operating range at TB. The HLVD, thus, would give the application a time window, represented by the difference between TA and TB, to safely exit.
Voltage
In many applications, the ability to detect a drop below or rise above a particular threshold is desirable. For example, the HLVD module could be periodically enabled to detect a Universal Serial Bus (USB) attach or detach. This assumes the device is powered by a lower voltage source than the USB when detached. An attach would indicate a high-voltage detect from, for example, 3.3V to 5V (the voltage on USB) and vice versa for a detach. This feature could save a design a few extra components and an attach signal (input pin).
TYPICAL LOW-VOLTAGE DETECT APPLICATION
VA VB
Time
TA
TB
Legend: VA = HLVD trip point VB = Minimum valid device operating voltage
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23.6 Operation During Sleep 23.7 Effects of a Reset
When enabled, the HLVD circuitry continues to operate during Sleep. If the device voltage crosses the trip point, the HLVDIF bit will be set and the device will wake-up from Sleep. Device execution will continue from the interrupt vector address if interrupts have been globally enabled. A device Reset forces all registers to their Reset state. This forces the HLVD module to be turned off.
TABLE 23-1:
Name HLVDCON INTCON PIR2 PIE2 IPR2
REGISTERS ASSOCIATED WITH HIGH/LOW-VOLTAGE DETECT MODULE
Bit 7 Bit 6 -- CMIF CMIE CMIP Bit 5 IRVST TMR0IE -- -- -- Bit 4 HLVDEN INT0IE EEIF EEIE EEIP Bit 3 HLVDL3 RBIE BCLIF BCLIE BCLIP Bit 2 HLVDL2 TMR0IF HLVDIF HLVDIE HLVDIP Bit 1 HLVDL1 INT0IF TMR3IF TMR3IE TMR3IP Bit 0 HLVDL0 RBIF CCP2IF CCP2IE CCP2IP Reset Values on Page 56 55 58 58 58
VDIRMAG OSCFIF OSCFIE OSCFIP
GIE/GIEH PEIE/GIEL
Legend: -- = unimplemented, read as `0'. Shaded cells are unused by the HLVD module.
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NOTES:
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24.0 SPECIAL FEATURES OF THE CPU
The inclusion of an internal RC oscillator also provides the additional benefits of a Fail-Safe Clock Monitor (FSCM) and Two-Speed Start-up. FSCM provides for background monitoring of the peripheral clock and automatic switchover in the event of its failure. TwoSpeed Start-up enables code to be executed almost immediately on start-up, while the primary clock source completes its start-up delays. All of these features are enabled and configured by setting the appropriate Configuration register bits.
PIC18F2221/2321/4221/4321 family devices include several features intended to maximize reliability and minimize cost through elimination of external components. These are: * Oscillator Selection * Resets: - Power-on Reset (POR) - Power-up Timer (PWRT) - Oscillator Start-up Timer (OST) - Brown-out Reset (BOR) * Interrupts * Watchdog Timer (WDT) * Fail-Safe Clock Monitor * Two-Speed Start-up * Code Protection * ID Locations * In-Circuit Serial Programming The oscillator can be configured for the application depending on frequency, power, accuracy and cost. All of the options are discussed in detail in Section 3.0 "Oscillator Configurations". A complete discussion of device Resets and interrupts is available in previous sections of this data sheet. In addition to their Power-up and Oscillator Start-up Timers provided for Resets, PIC18F2221/2321/4221/ 4321 family devices have a Watchdog Timer, which is either permanently enabled via the Configuration bits or software controlled (if configured as disabled).
24.1
Configuration Bits
The Configuration bits can be programmed (read as `0') or left unprogrammed (read as `1') to select various device configurations. These bits are mapped starting at program memory location 300000h. The user will note that address 300000h is beyond the user program memory space. In fact, it belongs to the configuration memory space (300000h-3FFFFFh), which can only be accessed using table reads and table writes. Programming the Configuration registers is done in a manner similar to programming the Flash memory. The WR bit in the EECON1 register starts a self-timed write to the Configuration register. In normal operation mode, a TBLWT instruction with the TBLPTR pointing to the Configuration register sets up the address and the data for the Configuration register write. Setting the WR bit starts a long write to the Configuration register. The Configuration registers are written a byte at a time. To write or erase a configuration cell, a TBLWT instruction can write a `1' or a `0' into the cell. For additional details on Flash programming, refer to Section 7.5 "Writing to Flash Program Memory".
TABLE 24-1:
File Name 300001h 300002h 300003h 300005h 300006h 300008h 300009h 30000Ah 30000Bh 30000Ch 30000Dh 3FFFFFh Legend: Note 1: 2:
CONFIGURATION BITS AND DEVICE IDs
Bit 7 IESO -- -- MCLRE DEBUG -- CPD -- WRTD -- -- DEV2 DEV10 Bit 6 FCMEN -- -- -- XINST -- CPB -- WRTB -- EBTRB DEV1 DEV9 Bit 5 -- -- -- -- BBSIZ1 -- -- -- WRTC -- -- DEV0 DEV8 Bit 4 -- BORV1 -- BBSIZ0 -- -- -- -- -- -- REV4 DEV7 Bit 3 FOSC3 BORV0 -- r -- -- -- -- -- -- REV3 DEV6 Bit 2 FOSC2 BOREN1 Bit 1 FOSC1 Bit 0 FOSC0 WDTEN CCP2MX STVREN CP0 -- WRT0 -- EBTR0 -- REV0 DEV3 Default/ Unprogrammed Value 00-- 0111 ---1 1111 ---1 1111 1--- -011 1000 01-1 ---- --11 11-- ------- --11 111- ------- --11 -1-- ---xxxx xxxx(2) 0000 1100
CONFIG1H CONFIG2L CONFIG2H CONFIG3H CONFIG4L CONFIG5L CONFIG5H CONFIG6L CONFIG6H CONFIG7L CONFIG7H DEVID2(1)
BOREN0 PWRTEN
WDTPS3 WDTPS2 WDTPS1 WDTPS0 LPT1OSC PBADEN LVP -- -- -- -- -- -- REV2 DEV5 -- CP1 -- WRT1 -- EBTR1 -- REV1 DEV4
3FFFFEh DEVID1(1)
x = unknown, u = unchanged, - = unimplemented, q = value depends on condition, r = reserved, maintain as `0'. Shaded cells are unimplemented, read as `0'. Unimplemented in PIC18F2221/4221 devices; maintain these bits set. See Register 24-14 for DEVID1 values. DEVID registers are read-only and cannot be programmed by the user.
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REGISTER 24-1: CONFIG1H: CONFIGURATION REGISTER 1 HIGH (BYTE ADDRESS 300001h)
R/P-0 IESO bit 7 bit 7 IESO: Internal/External Oscillator Switchover bit 1 = Oscillator Switchover mode enabled 0 = Oscillator Switchover mode disabled FCMEN: Fail-Safe Clock Monitor Enable bit 1 = Fail-Safe Clock Monitor enabled 0 = Fail-Safe Clock Monitor disabled Unimplemented: Read as `0' FOSC<3:0>: Oscillator Selection bits 11xx = External RC oscillator, CLKO function on RA6 101x = External RC oscillator, CLKO function on RA6 1001 = Internal oscillator block, CLKO function on RA6, port function on RA7 1000 = Internal oscillator block, port function on RA6 and RA7 0111 = External RC oscillator, port function on RA6 0110 = HS oscillator, PLL enabled (Clock Frequency = 4 x FOSC1) 0101 = EC oscillator, port function on RA6 0100 = EC oscillator, CLKO function on RA6 0011 = External RC oscillator, CLKO function on RA6 0010 = HS oscillator 0001 = XT oscillator 0000 = LP oscillator Legend: R = Readable bit P = Programmable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed R/P-0 FCMEN U-0 -- U-0 -- R/P-0 FOSC3 R/P-1 FOSC2 R/P-1 FOSC1 R/P-1 FOSC0 bit 0
bit 6
bit 5-4 bit 3-0
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REGISTER 24-2: CONFIG2L: CONFIGURATION REGISTER 2 LOW (BYTE ADDRESS 300002h)
U-0 -- bit 7 bit 7-5 bit 4-3 Unimplemented: Read as `0' BORV<1:0>: Brown-out Reset Voltage bits(1) 11 = Minimum setting . . . 00 = Maximum setting BOREN<1:0>: Brown-out Reset Enable bits(2) 11 = Brown-out Reset enabled in hardware only (SBOREN is disabled) 10 = Brown-out Reset enabled in hardware only and disabled in Sleep mode (SBOREN is disabled) 01 = Brown-out Reset enabled and controlled by software (SBOREN is enabled) 00 = Brown-out Reset disabled in hardware and software PWRTEN: Power-up Timer Enable bit(2) 1 = PWRT disabled 0 = PWRT enabled Note 1: See Section 27.1 "DC Characteristics" for the specifications. 2: The Power-up Timer is decoupled from Brown-out Reset, allowing these features to be independently controlled. Legend: R = Readable bit P = Programmable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed U-0 -- U-0 -- R/P-1 BORV1
(1)
R/P-1 BORV0
(1)
R/P-1 BOREN1
(2)
R/P-1 BOREN0
(2)
R/P-1 PWRTEN(2) bit 0
bit 2-1
bit 0
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REGISTER 24-3: CONFIG2H: CONFIGURATION REGISTER 2 HIGH (BYTE ADDRESS 300003h)
U-0 -- bit 7 bit 7-5 bit 4-1 Unimplemented: Read as `0' WDTPS<3:0>: Watchdog Timer Postscale Select bits 1111 = 1:32,768 1110 = 1:16,384 1101 = 1:8,192 1100 = 1:4,096 1011 = 1:2,048 1010 = 1:1,024 1001 = 1:512 1000 = 1:256 0111 = 1:128 0110 = 1:64 0101 = 1:32 0100 = 1:16 0011 = 1:8 0010 = 1:4 0001 = 1:2 0000 = 1:1 WDTEN: Watchdog Timer Enable bit 1 = WDT enabled 0 = WDT disabled (control is placed on the SWDTEN bit) Legend: R = Readable bit P = Programmable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed U-0 -- U-0 -- R/P-1 WDTPS3 R/P-1 WDTPS2 R/P-1 WDTPS1 R/P-1 WDTPS0 R/P-1 WDTEN bit 0
bit 0
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REGISTER 24-4: CONFIG3H: CONFIGURATION REGISTER 3 HIGH (BYTE ADDRESS 300005h)
R/P-1 MCLRE bit 7 bit 7 MCLRE: MCLR Pin Enable bit 1 = MCLR pin enabled; RE3 input pin disabled 0 = RE3 input pin enabled; MCLR disabled Unimplemented: Read as `0' LPT1OSC: Low-Power Timer1 Oscillator Enable bit 1 = Timer1 configured for low-power operation 0 = Timer1 configured for higher power operation PBADEN: PORTB A/D Enable bit (Affects ADCON1 Reset state. ADCON1 controls PORTB<4:0> pin configuration.) 1 = PORTB<4:0> pins are configured as analog input channels on Reset 0 = PORTB<4:0> pins are configured as digital I/O on Reset CCP2MX: CCP2 MUX bit 1 = CCP2 input/output is multiplexed with RC1 0 = CCP2 input/output is multiplexed with RB3 Legend: R = Readable bit P = Programmable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed U-0 -- U-0 -- U-0 -- U-0 -- R/P-0 LPT1OSC R/P-1 PBADEN R/P-1 CCP2MX bit 0
bit 6-3 bit 2
bit 1
bit 0
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REGISTER 24-5: CONFIG4L: CONFIGURATION REGISTER 4 LOW (BYTE ADDRESS 300006h)
R/P-1 DEBUG bit 7 bit 7 DEBUG: Background Debugger Enable bit 1 = Background debugger disabled, RB6 and RB7 configured as general purpose I/O pins 0 = Background debugger enabled, RB6 and RB7 are dedicated to in-circuit debug XINST: Extended Instruction Set Enable bit 1 = Instruction set extension and Indexed Addressing mode enabled 0 = Instruction set extension and Indexed Addressing mode disabled (Legacy mode) PIC18F4221/4321 Devices: 1x = 1024 Words 01 = 512 Words 00 = 256 Words PIC18F2221/2321 Devices: 1x = 512 Words x1 = 512 Words 00 = 256 Words bit 3 bit 2 Reserved: Maintain as `0' LVP: Single-Supply ICSPTM Enable bit 1 = Single-Supply ICSP enabled 0 = Single-Supply ICSP disabled Unimplemented: Read as `0' STVREN: Stack Full/Underflow Reset Enable bit 1 = Stack full/underflow will cause Reset 0 = Stack full/underflow will not cause Reset Legend: R = Readable bit r = Reserved bit, program as `0' C = Clearable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state R/P-0 XINST U-0 BBSIZ1 U-0 BBSIZ0 r-0 -- R/P-1 LVP U-0 -- R/P-1 STVREN bit 0
bit 6
bit 5-4 BBSIZ<1:0>: Boot Block Size Select bits
bit 1 bit 0
-n = Value when device is unprogrammed
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REGISTER 24-6: CONFIG5L: CONFIGURATION REGISTER 5 LOW (BYTE ADDRESS 300008h)
U-0 -- bit 7 bit 7-2 bit 1 Unimplemented: Read as `0' CP1: Code Protection bit 1 = Block 1 not code-protected(1) 0 = Block 1 code-protected(1) CP0: Code Protection bit 1 = Block 0 not code-protected(1) 0 = Block 0 code-protected(1) Note 1: See Figure 24-5 for variable block boundaries. Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- R/C-1 CP1 R/C-1 CP0 bit 0
bit 0
REGISTER 24-7:
CONFIG5H: CONFIGURATION REGISTER 5 HIGH (BYTE ADDRESS 300009h)
R/C-1 CPD bit 7 R/C-1 CPB U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- bit 0
bit 7
CPD: Data EEPROM Code Protection bit 1 = Data EEPROM not code-protected 0 = Data EEPROM code-protected CPB: Boot Block Code Protection bit 1 = Boot block not code-protected(1) 0 = Boot block code-protected(1) Unimplemented: Read as `0' Note 1: See Figure 24-5 for variable block boundaries. Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed
bit 6
bit 5-0
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REGISTER 24-8: CONFIG6L: CONFIGURATION REGISTER 6 LOW (BYTE ADDRESS 30000Ah)
U-0 -- bit 7 bit 7-2 bit 1 Unimplemented: Read as `0' WRT1: Write Protection bit 1 = Block 1 not write-protected(1) 0 = Block 1 write-protected(1) WRT0: Write Protection bit 1 = Block 0 not write-protected(1) 0 = Block 0 write-protected(1) Note 1: See Figure 24-5 for variable block boundaries. Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- R/C-1 WRT1 R/C-1 WRT0 bit 0
bit 0
REGISTER 24-9:
CONFIG6H: CONFIGURATION REGISTER 6 HIGH (BYTE ADDRESS 30000Bh)
R/C-1 WRTD bit 7 R/C-1 WRTB R-1 WRTC(1) U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- bit 0
bit 7
WRTD: Data EEPROM Write Protection bit 1 = Data EEPROM not write-protected 0 = Data EEPROM write-protected WRTB: Boot Block Write Protection bit 1 = Boot block not write-protected(2) 0 = Boot block write-protected(2) WRTC: Configuration Register Write Protection bit(1) 1 = Configuration registers (300000-3000FFh) not write-protected 0 = Configuration registers (300000-3000FFh) write-protected Unimplemented: Read as `0' Note 1: This bit is read-only in normal execution mode; it can be written only in Program mode. 2: See Figure 24-5 for block boundaries. Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed
bit 6
bit 5
bit 4-0
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REGISTER 24-10: CONFIG7L: CONFIGURATION REGISTER 7 LOW (BYTE ADDRESS 30000Ch)
U-0 -- bit 7 bit 7-2 bit 1 Unimplemented: Read as `0' EBTR1: Table Read Protection bit 1 = Block 1 not protected from table reads executed in other blocks(1) 0 = Block 1 protected from table reads executed in other blocks(1) EBTR0: Table Read Protection bit 1 = Block 0 not protected from table reads executed in other blocks(1) 0 = Block 0 protected from table reads executed in other blocks(1) Note 1: See Figure 24-5 for variable block boundaries. Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- R/C-1 EBTR1 R/C-1 EBTR0 bit 0
bit 0
REGISTER 24-11: CONFIG7H: CONFIGURATION REGISTER 7 HIGH (BYTE ADDRESS 30000Dh)
U-0 -- bit 7 bit 7 bit 6 Unimplemented: Read as `0' EBTRB: Boot Block Table Read Protection bit 1 = Boot block not protected from table reads executed in other blocks(1) 0 = Boot block protected from table reads executed in other blocks(1) Unimplemented: Read as `0' Note 1: See Figure 24-5 for variable block boundaries. Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed R/C-1 EBTRB U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- bit 0
bit 5-0
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REGISTER 24-12: DEVID1: DEVICE ID REGISTER 1 FOR PIC18F2221/2321/4221/4321 DEVICES
R DEV2 bit 7 bit 7-5 DEV<2:0>: Device ID bits 000 = PIC18F4321 010 = PIC18F4221 001 = PIC18F2321 011 = PIC18F2221 REV<4:0>: Revision ID bits These bits are used to indicate the device revision. Legend: R = Read-only bit P = Programmable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed R DEV1 R DEV0 R REV4 R REV3 R REV2 R REV1 R REV0 bit 0
bit 4-0
REGISTER 24-13: DEVID2: DEVICE ID REGISTER 2 FOR PIC18F2221/2321/4221/4321 DEVICES
R DEV10 bit 7 bit 7-0 DEV<10:3>: Device ID bits These bits are used with the DEV<2:0> bits in the Device ID Register 1 to identify the part number. 0010 0001 = PIC18F2221/2321/4221/4321 devices Note: These values for DEV<10:3> may be shared with other devices. The specific device is always identified by using the entire DEV<10:0> bit sequence. R DEV9 R DEV8 R DEV7 R DEV6 R DEV5 R DEV4 R DEV3 bit 0
Legend: R = Read-only bit P = Programmable bit U = Unimplemented bit, read as `0' u = Unchanged from programmed state -n = Value when device is unprogrammed
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24.2 Watchdog Timer (WDT)
For PIC18F2221/2321/4221/4321 family devices, the WDT is driven by the INTRC source. When the WDT is enabled, the clock source is also enabled. The nominal WDT period is 4 ms and has the same stability as the INTRC oscillator. The 4 ms period of the WDT is multiplied by a 16-bit postscaler. Any output of the WDT postscaler is selected by a multiplexer, controlled by bits in Configuration Register 2H. Available periods range from 4 ms to 131.072 seconds (2.18 minutes). The WDT and postscaler are cleared when any of the following events occur: a SLEEP or CLRWDT instruction is executed, the IRCF bits (OSCCON<6:4>) are changed or a clock failure has occurred. Note 1: The CLRWDT and SLEEP instructions clear the WDT and postscaler counts when executed. 2: Changing the setting of the IRCF bits (OSCCON<6:4>) clears the WDT and postscaler counts. 3: When a CLRWDT instruction is executed, the postscaler count will be cleared.
24.2.1
CONTROL REGISTER
Register 24-14 shows the WDTCON register. This is a readable and writable register which contains a control bit that allows software to override the WDT enable Configuration bit, but only if the Configuration bit has disabled the WDT.
FIGURE 24-1:
SWDTEN WDTEN INTRC Source Change on IRCF bits CLRWDT All Device Resets WDTPS<3:0> Sleep
WDT BLOCK DIAGRAM
Enable WDT WDT Counter /128 Wake-up from Power-Managed Modes Programmable Postscaler 1:1 to 1:32,768 4 Reset WDT Reset
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REGISTER 24-14: WDTCON: WATCHDOG TIMER CONTROL REGISTER
U-0 -- bit 7 bit 7-1 bit 0 Unimplemented: Read as `0' SWDTEN: Software Controlled Watchdog Timer Enable bit(1) 1 = Watchdog Timer is on 0 = Watchdog Timer is off Note 1: This bit has no effect if the Configuration bit, WDTEN, is enabled. Legend: R = Readable bit U = Unimplemented bit, read as `0' W = Writable bit -n = Value at POR U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- U-0 -- R/W-0 SWDTEN(1) bit 0
TABLE 24-2:
Name RCON WDTCON
SUMMARY OF WATCHDOG TIMER REGISTERS
Bit 7 IPEN -- Bit 6 SBOREN(1) -- Bit 5 -- -- Bit 4 RI -- Bit 3 TO -- Bit 2 PD -- Bit 1 POR -- Bit 0 BOR SWDTEN Reset Values on page 56 56
Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the Watchdog Timer. Note 1: The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 5.4 "Brown-out Reset (BOR)".
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24.3 Two-Speed Start-up
The Two-Speed Start-up feature helps to minimize the latency period from oscillator start-up to code execution by allowing the microcontroller to use the INTOSC oscillator as a clock source until the primary clock source is available. It is enabled by setting the IESO Configuration bit. Two-Speed Start-up should be enabled only if the primary oscillator mode is LP, XT, HS or HSPLL (crystal-based modes). Other sources do not require an OST start-up delay; for these, Two-Speed Start-up should be disabled. When enabled, Resets and wake-ups from Sleep mode cause the device to configure itself to run from the internal oscillator block as the clock source, following the time-out of the Power-up Timer after a Power-on Reset is enabled. This allows almost immediate code execution while the primary oscillator starts and the OST is running. Once the OST times out, the device automatically switches to PRI_RUN mode. To use a higher clock speed on wake-up, the INTOSC or postscaler clock sources can be selected to provide a higher clock speed by setting bits, IRCF<2:0>, immediately after Reset. For wake-ups from Sleep, the INTOSC or postscaler clock sources can be selected by setting the IRCF<2:0> bits prior to entering Sleep mode. In all other power-managed modes, Two-Speed Startup is not used. The device will be clocked by the currently selected clock source until the primary clock source becomes available. The setting of the IESO bit is ignored.
24.3.1
SPECIAL CONSIDERATIONS FOR USING TWO-SPEED START-UP
While using the INTOSC oscillator in Two-Speed Startup, the device still obeys the normal command sequences for entering power-managed modes, including multiple SLEEP instructions (refer to Section 4.1.4 "Multiple Sleep Commands"). In practice, this means that user code can change the SCS<1:0> bit settings or issue SLEEP instructions before the OST times out. This would allow an application to briefly wake-up, perform routine "housekeeping" tasks and return to Sleep before the device starts to operate from the primary oscillator. User code can also check if the primary clock source is currently providing the device clocking by checking the status of the OSTS bit (OSCCON<3>). If the bit is set, the primary oscillator is providing the clock. Otherwise, the internal oscillator block is providing the clock during wake-up from Reset or Sleep mode.
FIGURE 24-2:
INTOSC Multiplexer OSC1
TIMING TRANSITION FOR TWO-SPEED START-UP (INTOSC TO HSPLL)
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3
TOST(1) PLL Clock Output CPU Clock Peripheral Clock Program Counter PC
TPLL(1) 1 2 n-1 n
Clock Transition(2)
PC + 2 OSTS bit Set
PC + 4
PC + 6
Wake from Interrupt Event
Note 1: 2:
TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale. Clock transition typically occurs within 2-4 TOSC.
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24.4 Fail-Safe Clock Monitor
The Fail-Safe Clock Monitor (FSCM) allows the microcontroller to continue operation in the event of an external oscillator failure by automatically switching the device clock to the internal oscillator block. The FSCM function is enabled by setting the FCMEN Configuration bit. When FSCM is enabled, the INTRC oscillator runs at all times to monitor clocks to peripherals and provide a backup clock in the event of a clock failure. Clock monitoring (shown in Figure 24-3) is accomplished by creating a sample clock signal, which is the INTRC output divided by 64. This allows ample time between FSCM sample clocks for a peripheral clock edge to occur. The peripheral device clock and the sample clock are presented as inputs to the Clock Monitor latch (CM). The CM is set on the falling edge of the device clock source, but cleared on the rising edge of the sample clock. To use a higher clock speed on wake-up, the INTOSC or postscaler clock sources can be selected to provide a higher clock speed by setting bits, IRCF<2:0>, immediately after Reset. For wake-ups from Sleep, the INTOSC or postscaler clock sources can be selected by setting the IRCF<2:0> bits prior to entering Sleep mode. The FSCM will detect failures of the primary or secondary clock sources only. If the internal oscillator block fails, no failure would be detected, nor would any action be possible.
24.4.1
FSCM AND THE WATCHDOG TIMER
Both the FSCM and the WDT are clocked by the INTRC oscillator. Since the WDT operates with a separate divider and counter, disabling the WDT has no effect on the operation of the INTRC oscillator when the FSCM is enabled. As already noted, the clock source is switched to the INTOSC clock when a clock failure is detected. Depending on the frequency selected by the IRCF<2:0> bits, this may mean a substantial change in the speed of code execution. If the WDT is enabled with a small prescale value, a decrease in clock speed allows a WDT time-out to occur and a subsequent device Reset. For this reason, fail-safe clock events also reset the WDT and postscaler, allowing it to start timing from when execution speed was changed and decreasing the likelihood of an erroneous time-out.
FIGURE 24-3:
FSCM BLOCK DIAGRAM
Clock Monitor Latch (CM) (edge-triggered)
Peripheral Clock
S
Q
INTRC Source (32 s)
/ 64 488 Hz (2.048 ms)
C
Q
24.4.2
EXITING FAIL-SAFE OPERATION
Clock Failure Detected
Clock failure is tested for on the falling edge of the sample clock. If a sample clock falling edge occurs while CM is still set, a clock failure has been detected (Figure 24-4). This causes the following: * the FSCM generates an oscillator fail interrupt by setting bit, OSCFIF (PIR2<7>); * the device clock source is switched to the internal oscillator block (OSCCON is not updated to show the current clock source - this is the fail-safe condition); and * the WDT is reset. During switchover, the postscaler frequency from the internal oscillator block may not be sufficiently stable for timing sensitive applications. In these cases, it may be desirable to select another clock configuration and enter an alternate power-managed mode. This can be done to attempt a partial recovery or execute a controlled shutdown. See Section 4.1.4 "Multiple Sleep Commands" and Section 24.3.1 "Special Considerations for Using Two-Speed Start-up" for more details.
The fail-safe condition is terminated by either a device Reset or by entering a power-managed mode. On Reset, the controller starts the primary clock source specified in Configuration Register 1H (with any required start-up delays that are required for the oscillator mode, such as OST or PLL timer). The INTOSC multiplexer provides the device clock until the primary clock source becomes ready (similar to a TwoSpeed Start-up). The clock source is then switched to the primary clock (indicated by the OSTS bit in the OSCCON register becoming set). The Fail-Safe Clock Monitor then resumes monitoring the peripheral clock. The primary clock source may never become ready during start-up. In this case, operation is clocked by the INTOSC multiplexer. The OSCCON register will remain in its Reset state until a power-managed mode is entered.
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FIGURE 24-4:
Sample Clock Device Clock Output CM Output (Q) OSCFIF Oscillator Failure
FSCM TIMING DIAGRAM
Failure Detected
CM Test Note:
CM Test
CM Test
The device clock is normally at a much higher frequency than the sample clock. The relative frequencies in this example have been chosen for clarity.
24.4.3
FSCM INTERRUPTS IN POWER-MANAGED MODES
24.4.4
POR OR WAKE FROM SLEEP
By entering a power-managed mode, the clock multiplexer selects the clock source selected by the OSCCON register. Fail-Safe Monitoring of the powermanaged clock source resumes in the power-managed mode. If an oscillator failure occurs during power-managed operation, the subsequent events depend on whether or not the oscillator failure interrupt is enabled. If enabled (OSCFIF = 1), code execution will be clocked by the INTOSC multiplexer. An automatic transition back to the failed clock source will not occur. If the interrupt is disabled, subsequent interrupts while in Idle mode will cause the CPU to begin executing instructions while being clocked by the INTOSC source.
The FSCM is designed to detect oscillator failure at any point after the device has exited Power-on Reset (POR) or low-power Sleep mode. When the primary device clock is EC, RC or INTRC modes, monitoring can begin immediately following these events. For oscillator modes involving a crystal or resonator (HS, HSPLL, LP or XT), the situation is somewhat different. Since the oscillator may require a start-up time considerably longer than the FCSM sample clock time, a false clock failure may be detected. To prevent this, the internal oscillator block is automatically configured as the device clock and functions until the primary clock is stable (the OST and PLL timers have timed out). This is identical to Two-Speed Start-up mode. Once the primary clock is stable, the INTRC returns to its role as the FSCM source. Note: The same logic that prevents false oscillator failure interrupts on POR, or wake from Sleep, will also prevent the detection of the oscillator's failure to start at all following these events. This can be avoided by monitoring the OSTS bit and using a timing routine to determine if the oscillator is taking too long to start. Even so, no oscillator failure interrupt will be flagged.
As noted in Section 24.3.1 "Special Considerations for Using Two-Speed Start-up", it is also possible to select another clock configuration and enter an alternate power-managed mode while waiting for the primary clock to become stable. When the new powermanaged mode is selected, the primary clock is disabled.
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24.5 Program Verification and Code Protection
Each of the three blocks has three code protection bits associated with them. They are: * Code-Protect bit (CPn) * Write-Protect bit (WRTn) * External Block Table Read bit (EBTRn) Figure 24-5 shows the program memory organization for 4 and 8-Kbyte devices and the specific code protection bit associated with each block. The actual locations of the bits are summarized in Table 24-3.
The overall structure of the code protection on the PIC18 Flash devices differs significantly from other PIC(R) devices. The user program memory is divided into three blocks. One of these is a boot block of variable size. The remainder of the memory is divided into two blocks on binary boundaries.
FIGURE 24-5:
CODE-PROTECTED PROGRAM MEMORY FOR PIC18F2221/2321/4221/4321 FAMILY DEVICES
MEMORY SIZE/DEVICE 8 Kbytes (PIC18FX321) BBSIZ<1:0> 4 Kbytes (PIC18FX221) Address Range Block Code Protection Controlled By:
11/10
01
Boot Block 512 words
00
Boot Block 256 words
11/10/01
Boot Block 512 words
00
Boot Block 256 words 000000h CPB, WRTB, EBTRB 0001FFh 000200h 0003FFh 000400h
Boot Block 1K word Block 0 0.5K words Block 0 1.75K words Block 1 1K word
Block 0 0.75K words
0007FFh 000800h
CP0, WRT0, EBTR0
Block 0 1.5K words Block 0 1K word
Block 1 1K word
000FFFh 001000h
CP1, WRT1, EBTR1
Block 1 2K words
Block 1 2K words
Block 1 2K words
Unimplemented Reads all `0's
Unimplemented Reads all `0's
001FFFh 002000h 1FFFFFh
(Unimplemented Memory Space)
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TABLE 24-3:
File Name 300008h 300009h 30000Ah 30000Bh 30000Ch 30000Dh CONFIG5L CONFIG5H CONFIG6L CONFIG6H CONFIG7L CONFIG7H
SUMMARY OF CODE PROTECTION REGISTERS
Bit 7 -- CPD -- WRTD -- -- Bit 6 -- CPB -- WRTB -- EBTRB Bit 5 -- -- -- WRTC -- -- Bit 4 -- -- -- -- -- -- Bit 3 -- -- -- -- -- -- Bit 2 -- -- -- -- -- -- Bit 1 CP1 -- WRT1 -- EBTR1 -- Bit 0 CP0 -- WRT0 -- EBTR0 --
Legend: Shaded cells are unimplemented.
24.5.1
PROGRAM MEMORY CODE PROTECTION
The program memory may be read to or written from any location using the table read and table write instructions. The device ID may be read with table reads. The Configuration registers may be read and written with the table read and table write instructions. In normal execution mode, the CPn bits have no direct effect. CPn bits inhibit external reads and writes. A block of user memory may be protected from table writes if the WRTn Configuration bit is `0'. The EBTRn bits control table reads. For a block of user memory with the EBTRn bit set to `0', a table read instruction that executes from within that block is allowed to read.
A table read instruction that executes from a location outside of that block is not allowed to read and will result in reading `0's. Figures 24-6 through 24-8 illustrate table write and table read protection. Note: Code protection bits may only be written to a `0' from a `1' state. It is not possible to write a `1' to a bit in the `0' state. Code protection bits are only set to `1' by a full chip erase or block erase function. The full chip erase and block erase functions can only be initiated via ICSP operation or an external programmer.
FIGURE 24-6:
TABLE WRITE (WRTn) DISALLOWED
Program Memory(1) Boot Block Configuration Bit Settings WRTB, EBTRB = 11
Register Values
TBLPTR = 0008FFh PC = 003FFEh
Block 0 TBLWT* Block 1
WRT0, EBTR0 = 01
PC = 00BFFEh
WRT1, EBTR1 = 11
TBLWT*
Results: All table writes disabled to Blockn whenever WRTn = 0. Note 1: See Figure 24-5 for block boundaries.
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FIGURE 24-7: EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
Program Memory(1) Boot Block Configuration Bit Settings WRTB, EBTRB = 11 Register Values
TBLPTR = 0008FFh
Block 0
WRT0, EBTR0 = 10
PC = 007FFEh
Block 1 TBLRD*
WRT1, EBTR1 = 11
Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0. TABLAT register returns a value of `0'. Note 1: See Figure 24-5 for block boundaries.
FIGURE 24-8:
EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
Program Memory(1) Boot Block Configuration Bit Settings WRTB, EBTRB = 11
Register Values
TBLPTR = 0008FFh PC = 003FFEh
Block 0 TBLRD* Block 1
WRT0, EBTR0 = 10
WRT1, EBTR1 = 11
Results: Table reads permitted within Blockn, even when EBTRBn = 0. TABLAT register returns the value of the data at the location TBLPTR. Note 1: See Figure 24-5 for block boundaries.
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24.5.2 DATA EEPROM CODE PROTECTION
The entire data EEPROM is protected from external reads and writes by two bits: CPD and WRTD. CPD inhibits external reads and writes of data EEPROM. WRTD inhibits internal and external writes to data EEPROM. The CPU can always read data EEPROM under normal operation, regardless of the protection bit settings. To use the In-Circuit Debugger function of the microcontroller, the design must implement In-Circuit Serial Programming connections to MCLR/VPP/RE3, VDD, VSS, RB7 and RB6. This will interface to the In-Circuit Debugger module available from Microchip or one of the third party development tool companies.
24.9
Single-Supply ICSP Programming
24.5.3
CONFIGURATION REGISTER PROTECTION
The Configuration registers can be write-protected. The WRTC bit controls protection of the Configuration registers. In normal execution mode, the WRTC bit is readable only. WRTC can only be written via ICSP operation or an external programmer.
The LVP Configuration bit enables Single-Supply ICSP Programming (formerly known as Low-Voltage ICSP Programming or LVP). When Single-Supply Programming is enabled, the microcontroller can be programmed without requiring high voltage being applied to the MCLR/VPP/RE3 pin, but the RB5/KBI1/PGM pin is then dedicated to controlling Program mode entry and is not available as a general purpose I/O pin. While programming, using Single-Supply Programming, VDD is applied to the MCLR/VPP/RE3 pin as in normal execution mode. To enter Programming mode, VDD is applied to the PGM pin. Note 1: High-voltage programming is always available, regardless of the state of the LVP bit or the PGM pin, by applying VIHH to the MCLR pin. 2: By default, Single-Supply ICSP Programming is enabled in unprogrammed devices (as supplied from Microchip) and erased devices. 3: When Single-Supply ICSP Programming is enabled, the RB5 pin can no longer be used as a general purpose I/O pin. 4: When LVP is enabled, externally pull the PGM pin to VSS to allow normal program execution. If Single-Supply ICSP Programming mode will not be used, the LVP bit can be cleared. RB5/KBI1/PGM then becomes available as the digital I/O pin, RB5. The LVP bit may be set or cleared only when using standard high-voltage programming (VIHH applied to the MCLR/ VPP/RE3 pin). Once LVP has been disabled, only the standard high-voltage programming is available and must be used to program the device. Memory that is not code-protected can be erased using either a block erase, or erased row by row, then written at any specified VDD. If code-protected memory is to be erased, a block erase is required. If a block erase is to be performed when using Low-Voltage ICSP Programming, the device must be supplied with VDD of 4.5V to 5.5V.
24.6
ID Locations
Eight memory locations (200000h-200007h) are designated as ID locations, where the user can store checksum or other code identification numbers. These locations are both readable and writable during normal execution through the TBLRD and TBLWT instructions or during program/verify. The ID locations can be read when the device is code-protected.
24.7
In-Circuit Serial Programming
PIC18F2221/2321/4221/4321 family microcontrollers can be serially programmed while in the end application circuit. This is simply done with two lines for clock and data and three other lines for power, ground and the programming voltage. This allows customers to manufacture boards with unprogrammed devices and then program the microcontroller just before shipping the product. This also allows the most recent firmware or a custom firmware to be programmed.
24.8
In-Circuit Debugger
When the DEBUG Configuration bit is programmed to a `0', the In-Circuit Debugger functionality is enabled. This function allows simple debugging functions when used with MPLAB(R) IDE. When the microcontroller has this feature enabled, some resources are not available for general use. Table 24-4 shows which resources are required by the background debugger.
TABLE 24-4:
I/O Pins: Stack:
DEBUGGER RESOURCES
RB6, RB7 2 levels 512 bytes 10 bytes
Program Memory: Data Memory:
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NOTES:
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25.0 INSTRUCTION SET SUMMARY
PIC18F2221/2321/4221/4321 family devices incorporate the standard set of 75 PIC18 core instructions, as well as an extended set of 8 new instructions for the optimization of code that is recursive or that utilizes a software stack. The extended set is discussed later in this section. The literal instructions may use some of the following operands: * A literal value to be loaded into a file register (specified by `k') * The desired FSR register to load the literal value into (specified by `f') * No operand required (specified by `--') The control instructions may use some of the following operands: * A program memory address (specified by `n') * The mode of the CALL or RETURN instructions (specified by `s') * The mode of the table read and table write instructions (specified by `m') * No operand required (specified by `--') All instructions are a single word, except for four double-word instructions. These instructions were made double-word to contain the required information in 32 bits. In the second word, the 4 MSbs are `1's. If this second word is executed as an instruction (by itself), it will execute as a NOP. All single-word instructions are executed in a single instruction cycle, unless a conditional test is true or the program counter is changed as a result of the instruction. In these cases, the execution takes two instruction cycles, with the additional instruction cycle(s) executed as a NOP. The double-word instructions execute in two instruction cycles. One instruction cycle consists of four oscillator periods. Thus, for an oscillator frequency of 4 MHz, the normal instruction execution time is 1 s. If a conditional test is true, or the program counter is changed as a result of an instruction, the instruction execution time is 2 s. Two-word branch instructions (if true) would take 3 s. Figure 25-1 shows the general formats that the instructions can have. All examples use the convention `nnh' to represent a hexadecimal number. The Instruction Set Summary, shown in Table 25-2, lists the standard instructions recognized by the Microchip MPASMTM Assembler. Section 25.1.1 "Standard Instruction Set" provides a description of each instruction.
25.1
Standard Instruction Set
The standard PIC18 instruction set adds many enhancements to the previous PIC(R) MCU instruction sets, while maintaining an easy migration from these PIC MCU instruction sets. Most instructions are a single program memory word (16 bits), but there are four instructions that require two program memory locations. Each single-word instruction is a 16-bit word divided into an opcode, which specifies the instruction type and one or more operands, which further specify the operation of the instruction. The instruction set is highly orthogonal and is grouped into four basic categories: * * * * Byte-oriented operations Bit-oriented operations Literal operations Control operations
The PIC18 instruction set summary in Table 25-2 lists byte-oriented, bit-oriented, literal and control operations. Table 25-1 shows the opcode field descriptions. Most byte-oriented instructions have three operands: 1. 2. 3. The file register (specified by `f') The destination of the result (specified by `d') The accessed memory (specified by `a')
The file register designator `f' specifies which file register is to be used by the instruction. The destination designator `d' specifies where the result of the operation is to be placed. If `d' is zero, the result is placed in the WREG register. If `d' is one, the result is placed in the file register specified in the instruction. All bit-oriented instructions have three operands: 1. 2. 3. The file register (specified by `f') The bit in the file register (specified by `b') The accessed memory (specified by `a')
The bit field designator `b' selects the number of the bit affected by the operation, while the file register designator `f' represents the number of the file in which the bit is located.
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TABLE 25-1:
Field a
OPCODE FIELD DESCRIPTIONS
Description RAM access bit a = 0: RAM location in Access RAM (BSR register is ignored) a = 1: RAM bank is specified by BSR register Bit address within an 8-bit file register (0 to 7). Bank Select Register. Used to select the current RAM bank. ALU Status bits: Carry, Digit Carry, Zero, Overflow, Negative. Destination select bit d = 0: store result in WREG d = 1: store result in file register f Destination: either the WREG register or the specified register file location. 8-bit Register file address (00h to FFh) or 2-bit FSR designator (0h to 3h). 12-bit Register file address (000h to FFFh). This is the source address. 12-bit Register file address (000h to FFFh). This is the destination address. Global Interrupt Enable bit. Literal field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value). Label name. The mode of the TBLPTR register for the table read and table write instructions. Only used with table read and table write instructions: No change to register (such as TBLPTR with table reads and writes) Post-Increment register (such as TBLPTR with table reads and writes) Post-Decrement register (such as TBLPTR with table reads and writes) Pre-Increment register (such as TBLPTR with table reads and writes) The relative address (2's complement number) for relative branch instructions or the direct address for Call/Branch and Return instructions. Program Counter. Program Counter Low Byte. Program Counter High Byte. Program Counter High Byte Latch. Program Counter Upper Byte Latch. Power-Down bit. Product of Multiply High Byte. Product of Multiply Low Byte. Fast Call/Return mode select bit s = 0: do not update into/from shadow registers s = 1: certain registers loaded into/from shadow registers (Fast mode) 21-bit Table Pointer (points to a program memory location). 8-bit Table Latch. Time-out bit. Top-of-Stack. Unused or unchanged. Watchdog Timer. Working register (accumulator). Don't care (`0' or `1'). The assembler will generate code with x = 0. It is the recommended form of use for compatibility with all Microchip software tools. 7-bit offset value for indirect addressing of register files (source). 7-bit offset value for indirect addressing of register files (destination).
bbb BSR C, DC, Z, OV, N d
dest f fs fd GIE k label mm * *+ *+* n PC PCL PCH PCLATH PCLATU PD PRODH PRODL s
TBLPTR TABLAT TO TOS u WDT WREG x zs zd { } [text] (text) [expr] <> italics
Optional argument. Indicates an indexed address. The contents of text. Specifies bit n of the register indicated by the pointer expr. Assigned to. Register bit field. In the set of. User-defined term (font is Courier New).
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FIGURE 25-1: GENERAL FORMAT FOR INSTRUCTIONS
Byte-oriented file register operations 15 10 OPCODE d 9 87 a f (FILE #) 0 ADDWF MYREG, W, B Example Instruction
d = 0 for result destination to be WREG register d = 1 for result destination to be file register (f) a = 0 to force Access Bank a = 1 for BSR to select bank f = 8-bit file register address Byte to Byte move operations (2-word) 15 15 1111 12 11 f (Source FILE #) 0 f (Destination FILE #) 12 11 0 MOVFF MYREG1, MYREG2 OPCODE
f = 12-bit file register address Bit-oriented file register operations 15 12 11 98 7 f (FILE #) 0 BSF MYREG, bit, B OPCODE b (BIT #) a
b = 3-bit position of bit in file register (f) a = 0 to force Access Bank a = 1 for BSR to select bank f = 8-bit file register address Literal operations 15 OPCODE k = 8-bit immediate value Control operations CALL, GOTO and Branch operations 15 OPCODE 15 1111 12 11 n<19:8> (literal) 87 n<7:0> (literal) 0 0 GOTO Label 8 7 k (literal) 0 MOVLW 7Fh
n = 20-bit immediate value 15 OPCODE 15 1111 S = Fast bit 15 OPCODE 15 OPCODE 87 n<7:0> (literal) 11 10 n<10:0> (literal) 0 BC MYFUNC 0 BRA MYFUNC 12 11 n<19:8> (literal) 87 S n<7:0> (literal) 0 0 CALL MYFUNC
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TABLE 25-2:
Mnemonic, Operands
PIC18FXXXX INSTRUCTION SET
Description Cycles 16-Bit Instruction Word MSb LSb Status Affected Notes
BYTE-ORIENTED OPERATIONS ADDWF ADDWFC ANDWF CLRF COMF CPFSEQ CPFSGT CPFSLT DECF DECFSZ DCFSNZ INCF INCFSZ INFSNZ IORWF MOVF MOVFF MOVWF MULWF NEGF RLCF RLNCF RRCF RRNCF SETF SUBFWB SUBWF SUBWFB SWAPF TSTFSZ XORWF Note 1: f, d, a f, d, a f, d, a f, a f, d, a f, a f, a f, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a fs, fd f, a f, a f, a f, d, a f, d, a f, d, a f, d, a f, a f, d, a f, d, a f, d, a f, d, a f, a f, d, a Add WREG and f Add WREG and Carry bit to f AND WREG with f Clear f Complement f Compare f with WREG, Skip = Compare f with WREG, Skip > Compare f with WREG, Skip < Decrement f Decrement f, Skip if 0 Decrement f, Skip if Not 0 Increment f Increment f, Skip if 0 Increment f, Skip if Not 0 Inclusive OR WREG with f Move f Move fs (source) to 1st Word fd (destination) 2nd Word Move WREG to f Multiply WREG with f Negate f Rotate Left f through Carry Rotate Left f (No Carry) Rotate Right f through Carry Rotate Right f (No Carry) Set f Subtract f from WREG with Borrow Subtract WREG from f Subtract WREG from f with Borrow Swap Nibbles in f Test f, Skip if 0 Exclusive OR WREG with f 1 1 1 1 1 1 (2 or 3) 1 (2 or 3) 1 (2 or 3) 1 1 (2 or 3) 1 (2 or 3) 1 1 (2 or 3) 1 (2 or 3) 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 (2 or 3) 1 0010 01da0 0010 0da 0001 01da 0110 101a 0001 11da 0110 001a 0110 010a 0110 000a 0000 01da 0010 11da 0100 11da 0010 10da 0011 11da 0100 10da 0001 00da 0101 00da 1100 ffff 1111 ffff 0110 111a 0000 001a 0110 110a 0011 01da 0100 01da 0011 00da 0100 00da 0110 100a 0101 01da 0101 0101 0011 0110 0001 11da 10da 10da 011a 10da ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff C, DC, Z, OV, N C, DC, Z, OV, N Z, N Z Z, N None None None C, DC, Z, OV, N None None C, DC, Z, OV, N None None Z, N Z, N None None None C, DC, Z, OV, N C, Z, N Z, N C, Z, N Z, N None C, DC, Z, OV, N 1, 2 1, 2 1,2 2 1, 2 4 4 1, 2 1, 2, 3, 4 1, 2, 3, 4 1, 2 1, 2, 3, 4 4 1, 2 1, 2 1
1, 2 1, 2
1, 2
ffff C, DC, Z, OV, N ffff C, DC, Z, OV, N ffff None ffff None ffff Z, N
1, 2
4 1, 2
2: 3: 4:
When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value present on the pins themselves. For example, if the data latch is `1' for a pin configured as input and is driven low by an external device, the data will be written back with a `0'. If this instruction is executed on the TMR0 register (and where applicable, `d' = 1), the prescaler will be cleared if assigned. If the Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is executed as a NOP. Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory locations have a valid instruction.
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TABLE 25-2:
Mnemonic, Operands BIT-ORIENTED OPERATIONS BCF BSF BTFSC BTFSS BTG BC BN BNC BNN BNOV BNZ BOV BRA BZ CALL CLRWDT DAW GOTO NOP NOP POP PUSH RCALL RESET RETFIE RETLW RETURN SLEEP Note 1: f, b, a f, b, a f, b, a f, b, a f, d, a n n n n n n n n n n, s -- -- n -- -- -- -- n s k s -- Bit Clear f Bit Set f Bit Test f, Skip if Clear Bit Test f, Skip if Set Bit Toggle f Branch if Carry Branch if Negative Branch if Not Carry Branch if Not Negative Branch if Not Overflow Branch if Not Zero Branch if Overflow Branch Unconditionally Branch if Zero Call Subroutine 1st Word 2nd Word Clear Watchdog Timer Decimal Adjust WREG Go to Address 1st Word 2nd Word No Operation No Operation Pop Top of Return Stack (TOS) Push Top of Return Stack (TOS) Relative Call Software Device Reset Return from Interrupt Enable Return with Literal in WREG Return from Subroutine Go into Standby mode 1 1 1 (2 or 3) 1 (2 or 3) 1 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 2 1 (2) 2 1 1 2 1 1 1 1 2 1 2 2 2 1 1001 1000 1011 1010 0111 1110 1110 1110 1110 1110 1110 1110 1101 1110 1110 1111 0000 0000 1110 1111 0000 1111 0000 0000 1101 0000 0000 0000 0000 0000 bbba bbba bbba bbba bbba 0010 0110 0011 0111 0101 0001 0100 0nnn 0000 110s kkkk 0000 0000 1111 kkkk 0000 xxxx 0000 0000 1nnn 0000 0000 1100 0000 0000 ffff ffff ffff ffff ffff nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn kkkk kkkk 0000 0000 kkkk kkkk 0000 xxxx 0000 0000 nnnn 1111 0001 kkkk 0001 0000 ffff ffff ffff ffff ffff nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn kkkk kkkk 0100 0111 kkkk kkkk 0000 xxxx 0110 0101 nnnn 1111 000s None None None None None None None None None None None None None None None TO, PD C None 1, 2 1, 2 3, 4 3, 4 1, 2
PIC18FXXXX INSTRUCTION SET (CONTINUED)
Description Cycles 16-Bit Instruction Word MSb LSb Status Affected Notes
CONTROL OPERATIONS
None None None None None All GIE/GIEH, PEIE/GIEL kkkk None 001s None 0011 TO, PD
4
2: 3: 4:
When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value present on the pins themselves. For example, if the data latch is `1' for a pin configured as input and is driven low by an external device, the data will be written back with a `0'. If this instruction is executed on the TMR0 register (and where applicable, `d' = 1), the prescaler will be cleared if assigned. If the Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is executed as a NOP. Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory locations have a valid instruction.
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TABLE 25-2:
Mnemonic, Operands LITERAL OPERATIONS ADDLW ANDLW IORLW LFSR MOVLB MOVLW MULLW RETLW SUBLW XORLW TBLRD* TBLRD*+ TBLRD*TBLRD+* TBLWT* TBLWT*+ TBLWT*TBLWT+* Note 1: k k k f, k k k k k k k Add Literal and WREG AND Literal with WREG Inclusive OR Literal with WREG Move Literal (12-bit) 2nd Word to FSR(f) 1st Word Move Literal to BSR<3:0> Move Literal to WREG Multiply Literal with WREG Return with Literal in WREG Subtract WREG from Literal Exclusive OR Literal with WREG Table Read Table Read with Post-Increment Table Read with Post-Decrement Table Read with Pre-Increment Table Write Table Write with Post-Increment Table Write with Post-Decrement Table Write with Pre-Increment 1 1 1 2 1 1 1 2 1 1 2 0000 0000 0000 1110 1111 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 1111 1011 1001 1110 0000 0001 1110 1101 1100 1000 1010 0000 0000 0000 0000 0000 0000 0000 0000 kkkk kkkk kkkk 00ff kkkk 0000 kkkk kkkk kkkk kkkk kkkk 0000 0000 0000 0000 0000 0000 0000 0000 kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk 1000 1001 1010 1011 1100 1101 1110 1111 C, DC, Z, OV, N Z, N Z, N None None None None None C, DC, Z, OV, N Z, N None None None None None None None None
PIC18FXXXX INSTRUCTION SET (CONTINUED)
Description Cycles 16-Bit Instruction Word MSb LSb Status Affected Notes
DATA MEMORY PROGRAM MEMORY OPERATIONS
2
2: 3: 4:
When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value present on the pins themselves. For example, if the data latch is `1' for a pin configured as input and is driven low by an external device, the data will be written back with a `0'. If this instruction is executed on the TMR0 register (and where applicable, `d' = 1), the prescaler will be cleared if assigned. If the Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second cycle is executed as a NOP. Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory locations have a valid instruction.
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25.1.1
ADDLW
Syntax: Operands: Operation: Status Affected: Encoding: Description:
STANDARD INSTRUCTION SET
ADD Literal to W
ADDLW 0 k 255 (W) + k W N, OV, C, DC, Z 0000 1111 kkkk kkkk The contents of W are added to the 8-bit literal `k' and the result is placed in W. 1 1 Q1 Q2 Read literal `k' Q3 Process Data Q4 Write to W Operation: Status Affected: Encoding: Description: k
ADDWF
Syntax: Operands:
ADD W to f
ADDWF 0 f 255 d [0,1] a [0,1] (W) + (f) dest N, OV, C, DC, Z 0010 01da ffff ffff Add W to register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 f {,d {,a}}
Words: Cycles: Q Cycle Activity: Decode
Example:
ADDLW
15h
Before Instruction W = 10h After Instruction W = 25h Words: Cycles:
Q Cycle Activity: Q1 Decode Q2 Read register `f' Q3 Process Data Q4 Write to destination
Example: W = REG = After Instruction W REG = =
ADDWF 17h 0C2h 0D9h 0C2h
REG, 0, 0
Before Instruction
Note:
All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in symbolic addressing. If a label is used, the instruction format then becomes: {label} instruction argument(s).
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ADDWFC
Syntax: Operands:
ADD W and Carry bit to f
ADDWFC 0 f 255 d [0,1] a [0,1] (W) + (f) + (C) dest N,OV, C, DC, Z 0010 00da ffff ffff Add W, the Carry flag and data memory location `f'. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed in data memory location `f'. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 f {,d {,a}}
ANDLW
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode
AND Literal with W
ANDLW 0 k 255 (W) .AND. k W N, Z 0000 1011 kkkk kkkk The contents of W are ANDed with the 8-bit literal `k'. The result is placed in W. 1 1 Q2 Read literal `k' ANDLW A3h 03h Q3 Process Data 05Fh Q4 Write to W k
Operation: Status Affected: Encoding: Description:
Example: W = After Instruction W =
Before Instruction
Words: Cycles: Q Cycle Activity: Q1 Decode
Q2 Read register `f' ADDWFC 1 02h 4Dh 0 02h 50h
Q3 Process Data REG, 0, 1
Q4 Write to destination
Example:
Before Instruction Carry bit = REG = W = After Instruction Carry bit = REG = W =
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ANDWF
Syntax: Operands:
AND W with f
ANDWF 0 f 255 d [0,1] a [0,1] (W) .AND. (f) dest N, Z 0001 01da ffff ffff The contents of W are ANDed with register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Q2 Read register `f' ANDWF 17h C2h 02h C2h Q3 Process Data REG, 0, 0 Q4 Write to destination f {,d {,a}}
BC
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Carry
BC n -128 n 127 If Carry bit is `1', (PC) + 2 + 2n PC None 1110 0010 nnnn nnnn If the Carry bit is `1', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: If Jump: Q1 Decode No operation If No Jump: Q1 Decode
Q2 Read literal `n' No operation Q2 Read literal `n' HERE = = = = =
Q3 Process Data No operation Q3 Process Data BC 5
Q4 Write to PC No operation Q4 No operation
Words: Cycles: Q Cycle Activity: Decode
Example: W = REG = After Instruction W REG = =
Before Instruction
Example:
Before Instruction PC After Instruction If Carry PC If Carry PC
address (HERE) 1; address (HERE + 12) 0; address (HERE + 2)
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BCF
Syntax: Operands:
Bit Clear f
BCF f, b {,a} 0 f 255 0b7 a [0,1] 0 f None 1001 bbba ffff ffff Bit `b' in register `f' is cleared. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' BCF = = Q3 Process Data FLAG_REG, C7h 47h Q4 Write register `f' 7, 0
BN
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Negative
BN n -128 n 127 If Negative bit is `1', (PC) + 2 + 2n PC None 1110 0110 nnnn nnnn If the Negative bit is `1', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: If Jump: Q1 Decode No operation If No Jump: Q1
Words: Cycles: Q Cycle Activity:
Q2 Read literal `n' No operation Q2 Read literal `n' HERE = = = = =
Q3 Process Data No operation Q3 Process Data BN Jump
Q4 Write to PC No operation Q4 No operation
Example:
Decode
Before Instruction FLAG_REG After Instruction FLAG_REG
Example:
Before Instruction PC After Instruction If Negative PC If Negative PC
address (HERE) 1; address (Jump) 0; address (HERE + 2)
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BNC
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Not Carry
BNC n -128 n 127 If Carry bit is `0', (PC) + 2 + 2n PC None 1110 0011 nnnn nnnn If the Carry bit is `0', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
BNN
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Not Negative
BNN n -128 n 127 If Negative bit is `0', (PC) + 2 + 2n PC None 1110 0111 nnnn nnnn If the Negative bit is `0', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
Words: Cycles: Q Cycle Activity: If Jump: Q1 Decode No operation If No Jump: Q1 Decode
Words: Cycles: Q Cycle Activity: If Jump: Q2 Q3 Process Data No operation Q3 Process Data BNC Jump Q4 Write to PC No operation Q4 No operation Q1 Decode No operation If No Jump: Q2 Q1 Decode
Q2 Read literal `n' No operation Q2 Read literal `n' HERE = = = = =
Q3 Process Data No operation Q3 Process Data BNN Jump
Q4 Write to PC No operation Q4 No operation
Read literal `n' No operation
Read literal `n' HERE = = = = =
Example:
Example:
Before Instruction PC After Instruction If Carry PC If Carry PC
address (HERE) 0; address (Jump) 1; address (HERE + 2)
Before Instruction PC After Instruction If Negative PC If Negative PC
address (HERE) 0; address (Jump) 1; address (HERE + 2)
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BNOV
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Not Overflow
BNOV n -128 n 127 If Overflow bit is `0', (PC) + 2 + 2n PC None 1110 0101 nnnn nnnn If the Overflow bit is `0', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
BNZ
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Not Zero
BNZ n -128 n 127 If Zero bit is `0', (PC) + 2 + 2n PC None 1110 0001 nnnn nnnn If the Zero bit is `0', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
Words: Cycles: Q Cycle Activity: If Jump: Q1 Decode No operation If No Jump: Q1 Decode
Words: Cycles: Q Cycle Activity: If Jump: Q2 Q3 Process Data No operation Q3 Process Data BNOV Jump address (HERE) 0; address (Jump) 1; address (HERE + 2) Q4 Write to PC No operation Q4 No operation Q1 Decode No operation If No Jump: Q2 Q1 Decode
Q2 Read literal `n' No operation Q2 Read literal `n' HERE = = = = =
Q3 Process Data No operation Q3 Process Data BNZ Jump
Q4 Write to PC No operation Q4 No operation
Read literal `n' No operation
Read literal `n' HERE = = = = =
Example:
Example:
Before Instruction PC After Instruction If Overflow PC If Overflow PC
Before Instruction PC After Instruction If Zero PC If Zero PC
address (HERE) 0; address (Jump) 1; address (HERE + 2)
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BRA
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Unconditional Branch
BRA n -1024 n 1023 (PC) + 2 + 2n PC None 1101 0nnn nnnn nnnn Add the 2's complement number `2n' to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is a two-cycle instruction. 1 2 Q1 Decode No operation Q2 Read literal `n' No operation Q3 Process Data No operation Q4 Write to PC No operation
BSF
Syntax: Operands:
Bit Set f
BSF f, b {,a} 0 f 255 0b7 a [0,1] 1 f None 1000 bbba ffff ffff Bit `b' in register `f' is set. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' BSF = = Q3 Process Data Q4 Write register `f'
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity:
Words: Cycles: Q Cycle Activity:
Example:
HERE = =
BRA
Jump
Before Instruction PC After Instruction PC
address (HERE) address (Jump)
Example:
FLAG_REG, 7, 1 0Ah 8Ah
Before Instruction FLAG_REG After Instruction FLAG_REG
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BTFSC
Syntax: Operands:
Bit Test File, Skip if Clear
BTFSC f, b {,a} 0 f 255 0b7 a [0,1] skip if (f) = 0 None 1011 bbba ffff ffff If bit `b' in register `f' is `0', then the next instruction is skipped. If bit `b' is `0', then the next instruction fetched during the current instruction execution is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q1 Decode Q2 Read register `f' Q2 No operation Q2 No operation No operation HERE FALSE TRUE = = = = = Q3 Process Data Q3 No operation Q3 No operation No operation BTFSC : : Q4 No operation
BTFSS
Syntax: Operands:
Bit Test File, Skip if Set
BTFSS f, b {,a} 0 f 255 0b<7 a [0,1] skip if (f) = 1 None 1010 bbba ffff ffff If bit `b' in register `f' is `1', then the next instruction is skipped. If bit `b' is `1', then the next instruction fetched during the current instruction execution is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q3 Process Data Q3 No operation Q3 No operation No operation BTFSS : : Q4 No operation Q4 No operation Q4 No operation No operation
Operation: Status Affected: Encoding: Description:
Operation: Status Affected: Encoding: Description:
Words: Cycles:
Words: Cycles:
Q Cycle Activity:
Q Cycle Activity: Q1 Decode If skip: Q2 Read register `f' Q2 No operation Q2 No operation No operation HERE FALSE TRUE = = = = =
If skip: Q1 No operation Q1 No operation No operation Example: Q4 No operation Q4 No operation No operation
Q1 No operation Q1 No operation No operation Example:
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
FLAG, 1, 0
FLAG, 1, 0
Before Instruction PC After Instruction If FLAG<1> PC If FLAG<1> PC
address (HERE) 0; address (TRUE) 1; address (FALSE)
Before Instruction PC After Instruction If FLAG<1> PC If FLAG<1> PC
address (HERE) 0; address (FALSE) 1; address (TRUE)
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BTG
Syntax: Operands:
Bit Toggle f
BTG f, b {,a} 0 f 255 0b<7 a [0,1] (f) f None 0111 bbba ffff ffff Bit `b' in data memory location `f' is inverted. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' BTG Q3 Process Data PORTC, 4, 0 Q4 Write register `f'
BOV
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Overflow
BOV n -128 n 127 If Overflow bit is `1', (PC) + 2 + 2n PC None 1110 0100 nnnn nnnn If the Overflow bit is `1', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: If Jump: Q1 Decode No operation If No Jump: Q1 Decode
Words: Cycles: Q Cycle Activity:
Q2 Read literal `n' No operation Q2 Read literal `n' HERE = = = = =
Q3 Process Data No operation Q3 Process Data BOV Jump
Q4 Write to PC No operation Q4 No operation
Example:
Before Instruction: PORTC = 0111 0101 [75h] After Instruction: PORTC = 0110 0101 [65h]
Example:
Before Instruction PC After Instruction If Overflow PC If Overflow PC
address (HERE) 1; address (Jump) 0; address (HERE + 2)
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BZ
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Branch if Zero
BZ n -128 n 127 If Zero bit is `1', (PC) + 2 + 2n PC None 1110 0000 nnnn nnnn If the Zero bit is `1', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. 1 1(2)
CALL
Syntax: Operands: Operation:
Subroutine Call
CALL k {,s} 0 k 1048575 s [0,1] (PC) + 4 TOS, k PC<20:1>; if s = 1, (W) WS, (STATUS) STATUSS, (BSR) BSRS None 1110 1111 110s k19kkk k7kkk kkkk kkkk0 kkkk8
Status Affected: Encoding: 1st word (k<7:0>) 2nd word(k<19:8>) Description:
Words: Cycles: Q Cycle Activity: If Jump: Q1 Decode No operation If No Jump: Q1 Decode
Q2 Read literal `n' No operation Q2 Read literal `n' HERE = = = = =
Q3 Process Data No operation Q3 Process Data BZ Jump
Q4 Write to PC No operation Q4 No operation Words: Cycles: Q Cycle Activity: Q1 Decode
Subroutine call of entire 2-Mbyte memory range. First, return address (PC + 4) is pushed onto the return stack. If `s' = 1, the W, STATUS and BSR registers are also pushed into their respective shadow registers, WS, STATUSS and BSRS. If `s' = 0, no update occurs (default). Then, the 20-bit value `k' is loaded into PC<20:1>. CALL is a two-cycle instruction. 2 2 Q2 Q3 Q4 Read literal `k'<19:8>, Write to PC No operation
Read literal PUSH PC to `k'<7:0>, stack No operation HERE No operation CALL
Example:
Before Instruction PC After Instruction If Zero PC If Zero PC
address (HERE) 1; address (Jump) 0; address (HERE + 2)
No operation Example:
THERE, 1
Before Instruction PC = After Instruction PC = TOS = WS = BSRS = STATUSS =
address (HERE) address (THERE) address (HERE + 4) W BSR STATUS
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CLRF
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Clear f
CLRF f {,a} 0 f 255 a [0,1] 000h f, 1Z Z 0110 101a ffff ffff
CLRWDT
Syntax: Operands: Operation:
Clear Watchdog Timer
CLRWDT None 000h WDT, 000h WDT postscaler, 1 TO, 1 PD TO, PD 0000 0000 0000 0100
Status Affected: Encoding: Description:
Clears the contents of the specified register. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1
CLRWDT instruction resets the Watchdog Timer. It also resets the postscaler of the WDT. Status bits, TO and PD, are set.
1 1
Words: Cycles: Q Cycle Activity: Q1 Decode
Q2 No operation CLRWDT = = = = = ?
Q3 Process Data
Q4 No operation
Words: Cycles: Q Cycle Activity: Q1 Decode
Example: Q2 Q3 Process Data FLAG_REG, 1 5Ah 00h Q4 Write register `f'
Read register `f' CLRF = =
Example:
Before Instruction WDT Counter After Instruction WDT Counter WDT Postscaler TO PD
00h 0 1 1
Before Instruction FLAG_REG After Instruction FLAG_REG
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COMF
Syntax: Operands:
Complement f
COMF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f) dest N, Z 0001 11da ffff ffff The contents of register `f' are complemented. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1
CPFSEQ
Syntax: Operands: Operation:
Compare f with W, Skip if f = W
CPFSEQ 0 f 255 a [0,1] (f) - (W), skip if (f) = (W) (unsigned comparison) None 0110 001a ffff ffff Compares the contents of data memory location `f' to the contents of W by performing an unsigned subtraction. If `f' = W, then the fetched instruction is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q1 Q2 Read register `f' Q3 Process Data Q4 No operation Q4 No operation Q4 No operation No operation f {,a}
Operation: Status Affected: Encoding: Description:
Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: Q1 Decode
Words: Q2 Read register `f' COMF 13h If skip: 13h ECh Q3 Process Data REG, 0, 0 Q4 Write to destination Cycles:
Q Cycle Activity: Example: Before Instruction REG = After Instruction REG = W = Decode
Q1 Q2 Q3 No No No operation operation operation If skip and followed by 2-word instruction: Q1 Q2 Q3 No No No operation operation operation No No No operation operation operation Example: HERE NEQUAL EQUAL = = = = = =
CPFSEQ REG, 0 : : HERE ? ? W; Address (EQUAL) W; Address (NEQUAL)
Before Instruction PC Address W REG After Instruction If REG PC If REG PC
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CPFSGT
Syntax: Operands: Operation:
Compare f with W, Skip if f > W
CPFSGT 0 f 255 a [0,1] (f) - (W), skip if (f) > (W) (unsigned comparison) None 0110 010a ffff ffff Compares the contents of data memory location `f' to the contents of the W by performing an unsigned subtraction. If the contents of `f' are greater than the contents of WREG, then the fetched instruction is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. f {,a}
CPFSLT
Syntax: Operands: Operation:
Compare f with W, Skip if f < W
CPFSLT 0 f 255 a [0,1] (f) - (W), skip if (f) < (W) (unsigned comparison) None 0110 000a ffff ffff Compares the contents of data memory location `f' to the contents of W by performing an unsigned subtraction. If the contents of `f' are less than the contents of W, then the fetched instruction is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q3 Process Data Q3 No operation Q3 No operation No operation Q4 No operation Q4 No operation Q4 No operation No operation f {,a}
Status Affected: Encoding: Description:
Status Affected: Encoding: Description:
Words: Cycles:
Q Cycle Activity: Q1 Decode If skip: Q1 Q2 No operation Q2 No operation No operation HERE NLESS LESS = = < = = No operation Q1 Q2 Read register `f'
Words: Cycles:
Q Cycle Activity: Q1 Decode If skip: Q1 Q2 Q3 No No No operation operation operation If skip and followed by 2-word instruction: Q1 Q2 Q3 No No No operation operation operation No No No operation operation operation Example: HERE NGREATER GREATER = = > = = Q4 No operation Q4 No operation No operation Q2 Read register `f' Q3 Process Data Q4 No operation
If skip and followed by 2-word instruction: No operation No operation Example:
CPFSLT REG, 1 : : Address (HERE) ? W; Address (LESS) W; Address (NLESS)
CPFSGT REG, 0 : :
Before Instruction PC W After Instruction If REG PC If REG PC
Before Instruction PC W After Instruction If REG PC If REG PC
Address (HERE) ? W; Address (GREATER) W; Address (NGREATER)
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DAW
Syntax: Operands: Operation:
Decimal Adjust W Register
DAW None If [W<3:0> > 9] or [DC = 1] then, (W<3:0>) + 6 W<3:0>; else, (W<3:0>) W<3:0> If [W<7:4> + DC > 9] or [C = 1] then, (W<7:4>) + 6 + DC W<7:4>; else, (W<7:4>) + DC W<7:4>
DECF
Syntax: Operands:
Decrement f
DECF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f) - 1 dest C, DC, N, OV, Z 0000 01da ffff ffff Decrement register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' DECF 01h 0 00h 1 Q3 Process Data CNT, 1, 0 Q4 Write to destination
Operation: Status Affected: Encoding: Description:
Status Affected: Encoding: Description:
C 0000 0000 0000 0111 DAW adjusts the eight-bit value in W resulting from the earlier addition of two variables (each in packed BCD format) and produces a correct packed BCD result. 1 1 Words: Q2 Read register W DAW Q3 Process Data Q4 Write W Cycles: Q Cycle Activity:
Words: Cycles: Q Cycle Activity: Q1 Decode Example 1:
Before Instruction W = C = DC = After Instruction W C DC Example 2: = = = A5h 0 0 05h 1 0 Example:
Before Instruction CNT = Z = After Instruction CNT = Z =
Before Instruction W = C = DC = After Instruction W C DC = = = CEh 0 0 34h 1 0
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DECFSZ
Syntax: Operands:
Decrement f, Skip if 0
DECFSZ f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f) - 1 dest, skip if result = 0 None 0010 11da ffff ffff The contents of register `f' are decremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q1 Q2 Read register `f' Q2 No operation Q2 No operation No operation HERE CONTINUE Q3 Process Data Q3 No operation Q3 No operation No operation DECFSZ GOTO Q4 Write to destination Q4 No operation Q4 No operation No operation CNT, 1, 1 LOOP
DCFSNZ
Syntax: Operands:
Decrement f, Skip if Not 0
DCFSNZ 0 f 255 d [0,1] a [0,1] (f) - 1 dest, skip if result 0 None 0100 11da ffff ffff The contents of register `f' are decremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is not `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q3 Process Data Q3 No operation Q3 No operation No operation DCFSNZ : : = = = = = ? TEMP - 1 0; Address (ZERO) 0; Address (NZERO) Q4 Write to destination Q4 No operation Q4 No operation No operation f {,d {,a}}
Operation: Status Affected: Encoding: Description:
Operation: Status Affected: Encoding: Description:
Words: Cycles:
Words: Cycles:
Q Cycle Activity: Q Cycle Activity: Q1 Decode If skip: Q1 No operation Q1 No operation No operation Example: Q2 Q2 Decode If skip: Q1 No operation Q1 No operation No operation Example:
Read register `f'
If skip and followed by 2-word instruction:
No operation Q2 No operation No operation HERE ZERO NZERO
If skip and followed by 2-word instruction:
TEMP, 1, 0
Before Instruction PC = After Instruction CNT = If CNT = PC = If CNT PC =
Address (HERE) CNT - 1 0; Address (CONTINUE) 0; Address (HERE + 2)
Before Instruction TEMP After Instruction TEMP If TEMP PC If TEMP PC
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GOTO
Syntax: Operands: Operation: Status Affected: Encoding: 1st word (k<7:0>) 2nd word(k<19:8>) Description:
Unconditional Branch
GOTO k 0 k 1048575 k PC<20:1> None 1110 1111 1111 k19kkk k7kkk kkkk kkkk0 kkkk8
INCF
Syntax: Operands:
Increment f
INCF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f) + 1 dest C, DC, N, OV, Z 0010 10da ffff ffff The contents of register `f' are incremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' INCF FFh 0 ? ? 00h 1 1 1 Q3 Process Data CNT, 1, 0 Q4 Write to destination
Operation: Status Affected: Encoding: Description:
GOTO allows an unconditional branch
anywhere within entire 2-Mbyte memory range. The 20-bit value `k' is loaded into PC<20:1>. GOTO is always a two-cycle instruction.
Words: Cycles: Q Cycle Activity: Q1 Decode
2 2 Q2 Read literal `k'<7:0>, No operation GOTO THERE Q3 No operation No operation Q4 Read literal `k'<19:8>, Write to PC No operation
No operation Example:
Words: Cycles: Q Cycle Activity:
After Instruction PC = Address (THERE)
Example:
Before Instruction CNT = Z = C = DC = After Instruction CNT = Z = C = DC =
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INCFSZ
Syntax: Operands:
Increment f, Skip if 0
INCFSZ 0 f 255 d [0,1] a [0,1] (f) + 1 dest, skip if result = 0 None 0011 11da ffff ffff The contents of register `f' are incremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q1 Q2 Read register `f' Q2 No operation Q2 No operation No operation HERE NZERO ZERO Q3 Process Data Q3 No operation Q3 No operation No operation INCFSZ : : Q4 Write to destination f {,d {,a}}
INFSNZ
Syntax: Operands:
Increment f, Skip if Not 0
INFSNZ 0 f 255 d [0,1] a [0,1] (f) + 1 dest, skip if result 0 None 0100 10da ffff ffff The contents of register `f' are incremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is not `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q3 Process Data Q3 No operation Q3 No operation No operation INFSNZ Q4 Write to destination Q4 No operation Q4 No operation No operation f {,d {,a}}
Operation: Status Affected: Encoding: Description:
Operation: Status Affected: Encoding: Description:
Words: Cycles:
Words: Cycles:
Q Cycle Activity: Decode If skip: Q1 No operation Q1 No operation No operation Example: Q4 No operation Q4 No operation No operation
Q Cycle Activity: Q1 Decode If skip: Q1 No operation Q1 No operation No operation Example: Q2 No operation Q2 No operation No operation HERE ZERO NZERO Q2 Read register `f'
If skip and followed by 2-word instruction:
If skip and followed by 2-word instruction:
CNT, 1, 0
REG, 1, 0
Before Instruction PC = After Instruction CNT = If CNT = PC = If CNT PC =
Address (HERE) CNT + 1 0; Address (ZERO) 0; Address (NZERO)
Before Instruction PC = After Instruction REG = If REG PC = If REG = PC =
Address (HERE) REG + 1 0; Address (NZERO) 0; Address (ZERO)
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IORLW
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Inclusive OR Literal with W
IORLW k 0 k 255 (W) .OR. k W N, Z 0000 1001 kkkk kkkk The contents of W are ORed with the eight-bit literal `k'. The result is placed in W. 1 1 Q1 Q2 Read literal `k' IORLW 9Ah BFh Q3 Process Data 35h Q4 Write to W
IORWF
Syntax: Operands:
Inclusive OR W with f
IORWF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (W) .OR. (f) dest N, Z 0001 00da ffff ffff Inclusive OR W with register `f'. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Q2 Read register `f' IORWF 13h 91h 13h 93h Q3 Process Data RESULT, 0, 1 Q4 Write to destination
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: Decode
Example: W = After Instruction W =
Before Instruction Words: Cycles: Q Cycle Activity: Decode
Example:
Before Instruction RESULT = W = After Instruction RESULT = W =
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LFSR
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode Q2 Read literal `k' MSB Q3 Process Data Q4 Write literal `k' MSB to FSRfH Write literal `k' to FSRfL
Load FSR
LFSR f, k 0f2 0 k 4095 k FSRf None 1110 1111 1110 0000 00ff k7kkk k11kkk kkkk
MOVF
Syntax: Operands:
Move f
MOVF f {,d {,a}} 0 f 255 d [0,1] a [0,1] f dest N, Z 0101 00da ffff ffff The contents of register `f' are moved to a destination dependent upon the status of `d'. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). Location `f' can be anywhere in the 256-byte bank. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' MOVF = = = = Q3 Process Data REG, 0, 0 22h FFh 22h 22h Q4 Write W
Operation: Status Affected: Encoding: Description:
The 12-bit literal `k' is loaded into the File Select Register pointed to by `f'. 2 2
Decode
Read literal `k' LSB
Process Data
Example: After Instruction FSR2H FSR2L
LFSR 2, 3ABh = = 03h ABh Words: Cycles: Q Cycle Activity:
Example:
Before Instruction REG W After Instruction REG W
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MOVFF
Syntax: Operands: Operation: Status Affected: Encoding: 1st word (source) 2nd word (destin.) Description:
Move f to f
MOVFF fs,fd 0 fs 4095 0 fd 4095 (fs) fd None 1100 1111 ffff ffff ffff ffff ffffs ffffd
MOVLB
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Move Literal to Low Nibble in BSR
MOVLW k 0 k 255 k BSR None 0000 0001 kkkk kkkk The eight-bit literal `k' is loaded into the Bank Select Register (BSR). The value of BSR<7:4> always remains `0', regardless of the value of k7:k4. 1 1 Q1 Q2 Read literal `k' MOVLB 02h 05h Q3 Process Data 5 Q4 Write literal `k' to BSR
The contents of source register `fs' are moved to destination register `fd'. Location of source `fs' can be anywhere in the 4096-byte data space (000h to FFFh) and location of destination `fd' can also be anywhere from 000h to FFFh. Either source or destination can be W (a useful special situation). MOVFF is particularly useful for transferring a data memory location to a peripheral register (such as the transmit buffer or an I/O port). The MOVFF instruction cannot use the PCL, TOSU, TOSH or TOSL as the destination register. 2 2 (3)
Words: Cycles: Q Cycle Activity: Decode
Example:
Before Instruction BSR Register = After Instruction BSR Register =
Words: Cycles: Q Cycle Activity: Q1 Decode
Q2 Read register `f' (src) No operation No dummy read
Q3 Process Data No operation
Q4 No operation Write register `f' (dest)
Decode
Example:
MOVFF = = = =
REG1, REG2 33h 11h 33h 33h
Before Instruction REG1 REG2 After Instruction REG1 REG2
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MOVLW
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode Q2 Read literal `k' MOVLW W = 5Ah Words: Cycles: Q Cycle Activity: Q1 Decode Q2 Read register `f' MOVWF 4Fh FFh 4Fh 4Fh Q3 Process Data REG, 0 Q4 Write register `f' Q3 Process Data 5Ah Q4 Write to W 1 1
Move Literal to W
MOVLW k 0 k 255 kW None 0000 1110 kkkk kkkk The eight-bit literal `k' is loaded into W.
MOVWF
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Move W to f
MOVWF 0 f 255 a [0,1] (W) f None 0110 111a ffff ffff Move data from W to register `f'. Location `f' can be anywhere in the 256-byte bank. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 f {,a}
Example: After Instruction
Example: W = REG = After Instruction W REG = =
Before Instruction
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MULLW
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Multiply Literal with W
MULLW k 0 k 255 (W) x k PRODH:PRODL None 0000 1101 kkkk kkkk An unsigned multiplication is carried out between the contents of W and the 8-bit literal `k'. The 16-bit result is placed in the PRODH:PRODL register pair. PRODH contains the high byte. W is unchanged. None of the Status flags are affected. Note that neither Overflow nor Carry is possible in this operation. A Zero result is possible but not detected. 1 1 Q1 Q2 Read literal `k' Q3 Process Data Q4 Write registers PRODH: PRODL
MULWF
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Multiply W with f
MULWF 0 f 255 a [0,1] (W) x (f) PRODH:PRODL None 0000 001a ffff ffff An unsigned multiplication is carried out between the contents of W and the register file location `f'. The 16-bit result is stored in the PRODH:PRODL register pair. PRODH contains the high byte. Both W and `f' are unchanged. None of the Status flags are affected. Note that neither Overflow nor Carry is possible in this operation. A Zero result is possible but not detected. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Q2 Read register `f' Q3 Process Data Q4 Write registers PRODH: PRODL f {,a}
Words: Cycles: Q Cycle Activity: Decode
Example: Before Instruction W PRODH PRODL After Instruction W PRODH PRODL
MULLW = = = = = =
0C4h E2h ? ? E2h ADh 08h Words: Cycles: Q Cycle Activity: Decode
Example: Before Instruction W REG PRODH PRODL After Instruction W REG PRODH PRODL
MULWF = = = = = = = =
REG, 1 C4h B5h ? ? C4h B5h 8Ah 94h
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NEGF
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Negate f
NEGF f {,a} 0 f 255 a [0,1] (f) + 1 f N, OV, C, DC, Z 0110 110a ffff ffff Location `f' is negated using two's complement. The result is placed in the data memory location `f'. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' NEGF Q3 Process Data REG, 1 Q4 Write register `f'
NOP
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode
No Operation
NOP None No operation None 0000 1111 1 1 Q2 No operation Q3 No operation Q4 No operation 0000 xxxx 0000 xxxx 0000 xxxx
No operation.
Example: None.
Words: Cycles: Q Cycle Activity:
Example:
Before Instruction REG = After Instruction REG =
0011 1010 [3Ah] 1100 0110 [C6h]
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POP
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Pop Top of Return Stack
POP None (TOS) bit bucket None 0000 0000 0000 0110 The TOS value is pulled off the return stack and is discarded. The TOS value then becomes the previous value that was pushed onto the return stack. This instruction is provided to enable the user to properly manage the return stack to incorporate a software stack. 1 1 Q1 Decode Q2 No operation POP GOTO Q3 POP TOS value Q4 No operation
PUSH
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Push Top of Return Stack
PUSH None (PC + 2) TOS None 0000 0000 0000 0101 The PC + 2 is pushed onto the top of the return stack. The previous TOS value is pushed down on the stack. This instruction allows implementing a software stack by modifying TOS and then pushing it onto the return stack. 1 1 Q1 Decode Q2 PUSH PC + 2 onto return stack PUSH = = = = = 345Ah 0124h 0126h 0126h 345Ah Q3 No operation Q4 No operation
Words: Cycles: Q Cycle Activity:
Words: Cycles: Q Cycle Activity:
Example:
Example: NEW = = = = 0031A2h 014332h 014332h NEW
Before Instruction TOS Stack (1 level down) After Instruction TOS PC
Before Instruction TOS PC After Instruction PC TOS Stack (1 level down)
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RCALL
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Relative Call
RCALL n -1024 n 1023 (PC) + 2 TOS, (PC) + 2 + 2n PC None 1101 1nnn nnnn nnnn Subroutine call with a jump up to 1K from the current location. First, return address (PC + 2) is pushed onto the stack. Then, add the 2's complement number `2n' to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is a two-cycle instruction. 1 2 Q1 Q2 Read literal `n' PUSH PC to stack Q3 Process Data Q4 Write to PC
RESET
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode
Reset
RESET None Reset all registers and flags that are affected by a MCLR Reset. All 0000 0000 1111 1111 This instruction provides a way to execute a MCLR Reset in software. 1 1 Q2 Start Reset RESET Reset Value Reset Value Q3 No operation Q4 No operation
Words: Cycles: Q Cycle Activity: Decode
Example: After Instruction Registers = Flags* =
No operation Example:
No operation HERE
No operation RCALL Jump
No operation
Before Instruction PC = Address (HERE) After Instruction PC = Address (Jump) TOS = Address (HERE + 2)
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RETFIE
Syntax: Operands: Operation:
Return from Interrupt
RETFIE {s} s [0,1] (TOS) PC, 1 GIE/GIEH or PEIE/GIEL; if s = 1, (WS) W, (STATUSS) STATUS, (BSRS) BSR, PCLATU, PCLATH are unchanged GIE/GIEH, PEIE/GIEL 0000 0000 0001 000s Return from interrupt. Stack is popped and Top-of-Stack (TOS) is loaded into the PC. Interrupts are enabled by setting either the high or low-priority global interrupt enable bit. If `s' = 1, the contents of the shadow registers, WS, STATUSS and BSRS, are loaded into their corresponding registers, W, STATUS and BSR. If `s' = 0, no update of these registers occurs (default). 1 2
RETLW
Syntax: Operands: Operation:
Return Literal to W
RETLW k 0 k 255 k W, (TOS) PC, PCLATU, PCLATH are unchanged None 0000 1100 kkkk kkkk W is loaded with the eight-bit literal `k'. The program counter is loaded from the top of the stack (the return address). The high address latch (PCLATH) remains unchanged. 1 2 Q1 Q2 Read literal `k' No operation Q3 Process Data No operation Q4 POP PC from stack, Write to W No operation
Status Affected: Encoding: Description:
Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: Decode
Words: Cycles: Q Cycle Activity: Q1 Decode
No operation Example: Q2 Q3 No operation Q4 POP PC from stack Set GIEH or GIEL
No operation
No operation Example:
No operation RETFIE 1
No operation
No operation
After Interrupt PC W BSR STATUS GIE/GIEH, PEIE/GIEL
= = = = =
TOS WS BSRS STATUSS 1
CALL TABLE ; ; ; ; : TABLE ADDWF PCL ; RETLW k0 ; RETLW k1 ; : : RETLW kn ; Before Instruction W = After Instruction W =
W contains table offset value W now has table value
W = offset Begin table
End of table
07h value of kn
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RETURN
Syntax: Operands: Operation:
Return from Subroutine
RETURN {s} s [0,1] (TOS) PC; if s = 1, (WS) W, (STATUSS) STATUS, (BSRS) BSR, PCLATU, PCLATH are unchanged None 0000 0000 0001 001s Return from subroutine. The stack is popped and the top of the stack (TOS) is loaded into the program counter. If `s'= 1, the contents of the shadow registers, WS, STATUSS and BSRS, are loaded into their corresponding registers, W, STATUS and BSR. If `s' = 0, no update of these registers occurs (default). 1 2 Q1 Q2 No operation No operation Q3 Process Data No operation Q4 POP PC from stack No operation
RLCF
Syntax: Operands:
Rotate Left f through Carry
RLCF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f) dest, (f<7>) C, (C) dest<0> C, N, Z 0011 01da ffff ffff The contents of register `f' are rotated one bit to the left through the Carry flag. If `d' is `0', the result is placed in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. C register f
Operation:
Status Affected: Encoding: Description:
Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: Decode No operation
Words: Cycles: Q Cycle Activity:
1 1 Q1 Decode Q2 Read register `f' RLCF Q3 Process Data Q4 Write to destination
Example:
RETURN
After Instruction: PC = TOS
Example: Before Instruction REG = C = After Instruction REG = W = C =
REG, 0, 0
1110 0110 0 1110 0110 1100 1100 1
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RLNCF
Syntax: Operands:
Rotate Left f (No Carry)
RLNCF 0 f 255 d [0,1] a [0,1] (f) dest, (f<7>) dest<0> N, Z 0100 01da ffff ffff f {,d {,a}}
RRCF
Syntax: Operands:
Rotate Right f through Carry
RRCF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f) dest, (f<0>) C, (C) dest<7> C, N, Z 0011 00da ffff ffff The contents of register `f' are rotated one bit to the right through the Carry flag. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. C register f
Operation: Status Affected: Encoding: Description:
Operation:
Status Affected: Encoding: Description:
The contents of register `f' are rotated one bit to the left. If `d' is `0', the result is placed in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. register f
Words: Cycles: Q Cycle Activity: Q1 Decode
1 1 Q2 Read register `f' RLNCF Q3 Process Data Q4 Write to destination Words: Cycles: Q Cycle Activity: Q1 Decode Q2 1 1
Q3 Process Data REG, 0, 0
Q4 Write to destination
Example: Before Instruction REG = After Instruction REG =
REG, 1, 0 Example:
Read register `f' RRCF
1010 1011 0101 0111
Before Instruction REG = C = After Instruction REG = W = C =
1110 0110 0 1110 0110 0111 0011 0
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RRNCF
Syntax: Operands:
Rotate Right f (No Carry)
RRNCF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f) dest, (f<0>) dest<7> N, Z 0100 00da ffff ffff The contents of register `f' are rotated one bit to the right. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank will be selected, overriding the BSR value. If `a' is `1', then the bank will be selected as per the BSR value (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. register f
SETF
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Set f
SETF f {,a} 0 f 255 a [0,1] FFh f None 0110 100a ffff ffff The contents of the specified register are set to FFh. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Decode Q2 Read register `f' SETF = = 5Ah FFh Q3 Process Data REG, 1 Q4 Write register `f'
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity:
Words: Cycles: Q Cycle Activity: Q1 Decode
1 1 Q2 Read register `f' RRNCF Q3 Process Data REG, 1, 0 Q4 Write to destination Example:
Before Instruction REG After Instruction REG
Example 1:
Before Instruction REG = After Instruction REG = Example 2: W = REG = After Instruction W REG = =
1101 0111 1110 1011 REG, 0, 0
RRNCF
Before Instruction ? 1101 0111 1110 1011 1101 0111
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SLEEP
Syntax: Operands: Operation:
Enter Sleep mode
SLEEP None 00h WDT, 0 WDT postscaler, 1 TO, 0 PD TO, PD 0000 0000 0000 0011 The Power-Down status bit (PD) is cleared. The Time-out status bit (TO) is set. Watchdog Timer and its postscaler are cleared. The processor is put into Sleep mode with the oscillator stopped. 1 1 Q1 Q2 No operation SLEEP Q3 Process Data Q4 Go to Sleep
SUBFWB
Syntax: Operands:
Subtract f from W with Borrow
SUBFWB 0 f 255 d [0,1] a [0,1] (W) - (f) - (C) dest N, OV, C, DC, Z 0101 01da ffff ffff Subtract register `f' and Carry flag (borrow) from W (2's complement method). If `d' is `0', the result is stored in W. If `d' is `1', the result is stored in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 f {,d {,a}}
Operation: Status Affected: Encoding: Description:
Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: Decode
Example: Before Instruction TO = ? PD = ? After Instruction 1 TO = 0 PD =
Words: Cycles: Q Cycle Activity: Q1 Decode
Q2 Read register `f'
Q3 Process Data
Q4 Write to destination
If WDT causes wake-up, this bit is cleared.
Example 1: SUBFWB REG, 1, 0 Before Instruction REG = 3 W = 2 C = 1 After Instruction REG = FF W = 2 C = 0 Z = 0 N = 1 ; result is negative SUBFWB REG, 0, 0 Example 2: Before Instruction REG = 2 W = 5 C = 1 After Instruction REG = 2 W = 3 C = 1 Z = 0 N = 0 ; result is positive SUBFWB REG, 1, 0 Example 3: Before Instruction REG = 1 W = 2 C = 0 After Instruction REG = 0 W = 2 C = 1 Z = 1 ; result is zero N = 0
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SUBLW
Syntax: Operands: Operation: Status Affected: Encoding: Description Words: Cycles: Q Cycle Activity: Q1 Decode Example 1: Before Instruction W = C = After Instruction W = C = Z = N = Example 2: Before Instruction W = C = After Instruction W = C = Z = N = Example 3: Before Instruction W = C = After Instruction W = C = Z = N = Q2 Read literal `k' SUBLW 01h ? 01h 1 ; result is positive 0 0 SUBLW 02h ? 00h 1 ; result is zero 1 0 SUBLW 03h ? FFh ; (2's complement) 0 ; result is negative 0 1 02h 02h Q3 Process Data 02h Q4 Write to W
Subtract W from Literal
SUBLW k 0 k 255 k - (W) W N, OV, C, DC, Z 0000 1000 kkkk kkkk W is subtracted from the eight-bit literal `k'. The result is placed in W. 1 1
SUBWF
Syntax: Operands:
Subtract W from f
SUBWF 0 f 255 d [0,1] a [0,1] (f) - (W) dest N, OV, C, DC, Z 0101 11da ffff ffff Subtract W from register `f' (2's complement method). If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Q2 Read register `f' SUBWF 3 2 ? 1 2 1 0 0 SUBWF 2 2 ? 2 0 1 1 0 SUBWF 1 2 ? FFh 2 0 0 1 ;(2's complement) ; result is negative Q3 Process Data REG, 1, 0 Q4 Write to destination f {,d {,a}}
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: Decode Example 1: Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 2: Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 3: Before Instruction REG = W = C = After Instruction REG = W = C = Z = N =
; result is positive REG, 0, 0
; result is zero
REG, 1, 0
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SUBWFB
Syntax: Operands:
Subtract W from f with Borrow
SUBWFB
0 f 255 d [0,1] a [0,1] (f) - (W) - (C) dest N, OV, C, DC, Z 0101 10da ffff ffff
SWAPF
Syntax: Operands:
Swap f
SWAPF f {,d {,a}} 0 f 255 d [0,1] a [0,1] (f<3:0>) dest<7:4>, (f<7:4>) dest<3:0> None 0011 10da ffff ffff The upper and lower nibbles of register `f' are exchanged. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Q2 Read register `f' SWAPF 53h 35h Q3 Process Data REG, 1, 0 Q4 Write to destination
f {,d {,a}}
Operation: Status Affected: Encoding: Description:
Operation: Status Affected: Encoding: Description:
Subtract W and the Carry flag (borrow) from register `f' (2's complement method). If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1
Words: Cycles: Q Cycle Activity: Q1 Decode Example 1:
Words: Cycles: Q3 Process Data REG, 1, 0 (0001 1001) (0000 1101) (0000 1011) (0000 1101) ; result is positive Example: Q4 Write to destination Q Cycle Activity: Decode
Q2 Read register `f' SUBWFB 19h 0Dh 1 0Ch 0Dh 1 0 0
Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 2: Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 3: Before Instruction REG = W = C = After Instruction REG = W C Z N = = = =
Before Instruction REG = After Instruction REG =
SUBWFB REG, 0, 0 1Bh 1Ah 0 1Bh 00h 1 1 0 SUBWFB 03h 0Eh 1 F5h 0Eh 0 0 1 (0001 1011) (0001 1010) (0001 1011) ; result is zero REG, 1, 0 (0000 0011) (0000 1101) (1111 0100) ; [2's comp] (0000 1101) ; result is negative
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TBLRD
Syntax: Operands: Operation:
Table Read
TBLRD ( *; *+; *-; +*) None if TBLRD *, (Prog Mem (TBLPTR)) TABLAT, TBLPTR - No Change; if TBLRD *+, (Prog Mem (TBLPTR)) TABLAT, (TBLPTR) + 1 TBLPTR; if TBLRD *-, (Prog Mem (TBLPTR)) TABLAT, (TBLPTR) - 1 TBLPTR; if TBLRD +*, (TBLPTR) + 1 TBLPTR, (Prog Mem (TBLPTR)) TABLAT 0000 0000 0000 10nn nn=0 * =1 *+ =2 *=3 +*
TBLRD
Example 1:
Table Read (Continued)
TBLRD *+ ; = = = = = 55h 00A356h 34h 34h 00A357h
Before Instruction TABLAT TBLPTR MEMORY (00A356h) After Instruction TABLAT TBLPTR Example 2: TBLRD Before Instruction TABLAT TBLPTR MEMORY (01A357h) MEMORY (01A358h) After Instruction TABLAT TBLPTR
+* ; = = = = = = AAh 01A357h 12h 34h 34h 01A358h
Status Affected: None Encoding:
Description:
This instruction is used to read the contents of Program Memory (P.M.). To address the program memory, a pointer called Table Pointer (TBLPTR) is used. The TBLPTR (a 21-bit pointer) points to each byte in the program memory. TBLPTR has a 2-Mbyte address range. TBLPTR[0] = 0: Least Significant Byte of Program Memory Word TBLPTR[0] = 1: Most Significant Byte of Program Memory Word The TBLRD instruction can modify the value of TBLPTR as follows: * no change * post-increment * post-decrement * pre-increment 1 2
Words: Cycles: Q1 Decode No operation
Q Cycle Activity: Q2 No operation No operation (Read Program Memory) Q3 No operation No operation Q4 No operation No operation (Write TABLAT)
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TBLWT
Syntax: Operands: Operation:
Table Write
TBLWT ( *; *+; *-; +*) None if TBLWT*, (TABLAT) Holding Register, TBLPTR - No Change; if TBLWT*+, (TABLAT) Holding Register, (TBLPTR) + 1 TBLPTR; if TBLWT*-, (TABLAT) Holding Register, (TBLPTR) - 1 TBLPTR; if TBLWT+*, (TBLPTR) + 1 TBLPTR, (TABLAT) Holding Register None 0000 0000 0000 11nn nn=0 * =1 *+ =2 *=3 +*
TBLWT
Example 1:
Table Write (Continued) TBLWT *+;
Before Instruction TABLAT = 55h TBLPTR = 00A356h HOLDING REGISTER (00A356h) = FFh After Instructions (table write completion) TABLAT = 55h TBLPTR = 00A357h HOLDING REGISTER (00A356h) = 55h Example 2:
TBLWT +*;
Status Affected: Encoding:
Description:
This instruction uses the 3 LSBs of TBLPTR to determine which of the 8 holding registers the TABLAT is written to. The holding registers are used to program the contents of Program Memory (P.M.). (Refer to Section 7.0 "Flash Program Memory" for additional details on programming Flash memory.) The TBLPTR (a 21-bit pointer) points to each byte in the program memory. TBLPTR has a 2-Mbyte address range. The LSb of the TBLPTR selects which byte of the program memory location to access. TBLPTR[0] = 0: Least Significant Byte of Program Memory Word TBLPTR[0] = 1: Most Significant Byte of Program Memory Word The TBLWT instruction can modify the value of TBLPTR as follows: * no change * post-increment * post-decrement * pre-increment 1 2 Q1 Decode Q2 Q3 Q4
Before Instruction TABLAT = 34h TBLPTR = 01389Ah HOLDING REGISTER (01389Ah) = FFh HOLDING REGISTER (01389Bh) = FFh After Instruction (table write completion) TABLAT = 34h TBLPTR = 01389Bh HOLDING REGISTER (01389Ah) = FFh HOLDING REGISTER (01389Bh) = 34h
Words: Cycles: Q Cycle Activity:
No No No operation operation operation
No No No No operation operation operation operation (Read (Write to TABLAT) Holding Register )
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TSTFSZ
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Test f, Skip if 0
TSTFSZ f {,a} 0 f 255 a [0,1] skip if f = 0 None 0110 011a ffff ffff If `f' = 0, the next instruction fetched during the current instruction execution is discarded and a NOP is executed, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q1 Q2 Read register `f' Q2 No operation Q2 No operation No operation HERE NZERO ZERO = = = = Q3 Process Data Q3 No operation Q3 No operation No operation TSTFSZ : : Q4 No operation Q4 No operation Q4 No operation No operation
XORLW
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Exclusive OR Literal with W
XORLW k 0 k 255 (W) .XOR. k W N, Z 0000 1010 kkkk kkkk The contents of W are XORed with the 8-bit literal `k'. The result is placed in W. 1 1 Q1 Q2 Read literal `k' XORLW B5h 1Ah Q3 Process Data 0AFh Q4 Write to W
Words: Cycles: Q Cycle Activity: Decode
Example: Before Instruction W = After Instruction W =
Words: Cycles:
Q Cycle Activity: Decode If skip: Q1 No operation Q1 No operation No operation Example:
If skip and followed by 2-word instruction:
CNT, 1
Before Instruction PC After Instruction If CNT PC If CNT PC
Address (HERE) 00h, Address (ZERO) 00h, Address (NZERO)
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XORWF
Syntax: Operands:
Exclusive OR W with f
XORWF 0 f 255 d [0,1] a [0,1] (W) .XOR. (f) dest N, Z 0001 10da ffff ffff Exclusive OR the contents of W with register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in the register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 25.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 1 1 Q1 Q2 Read register `f' XORWF AFh B5h 1Ah B5h Q3 Process Data REG, 1, 0 Q4 Write to destination f {,d {,a}}
Operation: Status Affected: Encoding: Description:
Words: Cycles: Q Cycle Activity: Decode
Example:
Before Instruction REG = W = After Instruction REG = W =
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25.2 Extended Instruction Set
In addition to the standard 75 instructions of the PIC18 instruction set, PIC18F2221/2321/4221/4321 family devices also provide an optional extension to the core CPU functionality. The added features include eight additional instructions that augment indirect and indexed addressing operations and the implementation of Indexed Literal Offset Addressing mode for many of the standard PIC18 instructions. The additional features of the extended instruction set are disabled by default. To enable them, users must set the XINST Configuration bit. The instructions in the extended set (with the exception of CALLW, MOVSF and MOVSS) can all be classified as literal operations, which either manipulate the File Select Registers, or use them for indexed addressing. Two of the instructions, ADDFSR and SUBFSR, each have an additional special instantiation for using FSR2. These versions (ADDULNK and SUBULNK) allow for automatic return after execution. The extended instructions are specifically implemented to optimize re-entrant program code (that is, code that is recursive or that uses a software stack) written in high-level languages, particularly C. Among other things, they allow users working in high-level languages to perform certain operations on data structures more efficiently. These include: * Dynamic allocation and deallocation of software stack space when entering and leaving subroutines * Function Pointer invocation * Software Stack Pointer manipulation * Manipulation of variables located in a software stack A summary of the instructions in the extended instruction set is provided in Table 25-3. Detailed descriptions are provided in Section 25.2.2 "Extended Instruction Set". The opcode field descriptions in Table 25-1 (page 280) apply to both the standard and extended PIC18 instruction sets. Note: The instruction set extension and the Indexed Literal Offset Addressing mode were designed for optimizing applications written in C; the user may likely never use these instructions directly in the assembler. The syntax for these commands is provided as a reference for users who may be reviewing code that has been generated by a compiler.
25.2.1
EXTENDED INSTRUCTION SYNTAX
Most of the extended instructions use indexed arguments, using one of the File Select Registers and some offset to specify a source or destination register. When an argument for an instruction serves as part of indexed addressing, it is enclosed in square brackets ("[ ]"). This is done to indicate that the argument is used as an index or offset. The MPASMTM Assembler will flag an error if it determines that an index or offset value is not bracketed. When the extended instruction set is enabled, brackets are also used to indicate index arguments in byteoriented and bit-oriented instructions. This is in addition to other changes in their syntax. For more details, see Section 25.2.3.1 "Extended Instruction Syntax with Standard PIC18 Commands". Note: In the past, square brackets have been used to denote optional arguments in the PIC18 and earlier instruction sets. In this text and going forward, optional arguments are denoted by braces ("{ }").
TABLE 25-3:
Mnemonic, Operands ADDFSR ADDULNK CALLW MOVSF MOVSS PUSHL SUBFSR SUBULNK f, k k
EXTENSIONS TO THE PIC18 INSTRUCTION SET
Description Add Literal to FSR Add Literal to FSR2 and Return Call Subroutine using WREG Move zs (source) to 1st Word fd (destination) 2nd Word Move zs (source) to 1st word zd (destination) 2nd Word Store Literal at FSR2, Decrement FSR2 Subtract Literal from FSR Subtract Literal from FSR2 and Return Cycles 1 2 2 2 2 1 1 2 16-Bit Instruction Word MSb 1110 1110 0000 1110 1111 1110 1111 1110 1110 1110 1000 1000 0000 1011 ffff 1011 xxxx 1010 1001 1001 ffkk 11kk 0001 0zzz ffff 1zzz xzzz kkkk ffkk 11kk LSb kkkk kkkk 0100 zzzz ffff zzzz zzzz kkkk kkkk kkkk Status Affected None None None None None None None None
zs, fd zs, zd k f, k k
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25.2.2
ADDFSR
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode Q2 Read literal `k' Q3 Process Data Q4 Write to FSR
EXTENDED INSTRUCTION SET
Add Literal to FSR
ADDFSR f, k 0 k 63 f [ 0, 1, 2 ] FSR(f) + k FSR(f) None 1110 1000 ffkk kkkk The 6-bit literal `k' is added to the contents of the FSR specified by `f'. 1 1 Status Affected: Encoding: Description:
ADDULNK
Syntax: Operands: Operation:
Add Literal to FSR2 and Return
ADDULNK k 0 k 63 FSR2 + k FSR2, (TOS) PC None 1110 1000 11kk kkkk The 6-bit literal `k' is added to the contents of FSR2. A RETURN is then executed by loading the PC with the TOS. The instruction takes two cycles to execute; a NOP is performed during the second cycle. This may be thought of as a special case of the ADDFSR instruction, where f = 3 (binary `11'); it operates only on FSR2. 1 2
Example:
ADDFSR 2, 23h Words: 03FFh 0422h Cycles: Q Cycle Activity: Q1 Decode No Operation Example:
Before Instruction FSR2 = After Instruction FSR2 =
Q2 Read literal `k' No Operation
Q3 Process Data No Operation
Q4 Write to FSR No Operation
ADDULNK 23h 03FFh 0100h 0422h (TOS)
Before Instruction FSR2 = PC = After Instruction FSR2 = PC =
Note:
All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in symbolic addressing. If a label is used, the instruction syntax then becomes: {label} instruction argument(s).
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CALLW
Syntax: Operands: Operation:
Subroutine Call Using WREG
CALLW None (PC + 2) TOS, (W) PCL, (PCLATH) PCH, (PCLATU) PCU None 0000 0000 0001 0100 First, the return address (PC + 2) is pushed onto the return stack. Next, the contents of W are written to PCL; the existing value is discarded. Then, the contents of PCLATH and PCLATU are latched into PCH and PCU, respectively. The second cycle is executed as a NOP instruction while the new next instruction is fetched. Unlike CALL, there is no option to update W, STATUS or BSR. 1 2 Q1 Q2 Read WREG No operation Q3 PUSH PC to stack No operation Q4 No operation No operation
MOVSF
Syntax: Operands: Operation: Status Affected: Encoding: 1st word (source) 2nd word (destin.) Description:
Move Indexed to f
MOVSF [zs], fd 0 zs 127 0 fd 4095 ((FSR2) + zs) fd None 1110 1111 1011 ffff 0zzz ffff zzzzs ffffd
Status Affected: Encoding: Description
Words: Cycles: Q Cycle Activity: Decode No operation
The contents of the source register are moved to destination register `fd'. The actual address of the source register is determined by adding the 7-bit literal offset `zs' in the first word to the value of FSR2. The address of the destination register is specified by the 12-bit literal `fd' in the second word. Both addresses can be anywhere in the 4096-byte data space (000h to FFFh). The MOVSF instruction cannot use the PCL, TOSU, TOSH or TOSL as the destination register. If the resultant source address points to an indirect addressing register, the value returned will be 00h. 2 2
Words: Cycles: Q Cycle Activity: Q1 Decode
Q2
Q3
Q4 Read source reg Write register `f' (dest)
Example:
HERE
CALLW Decode
Determine Determine source addr source addr No operation No dummy read No operation
Before Instruction PC = PCLATH = PCLATU = W = After Instruction PC = TOS = PCLATH = PCLATU = W =
address (HERE) 10h 00h 06h 001006h address (HERE + 2) 10h 00h 06h Example:
MOVSF = = = = = =
[05h], REG2 80h 33h 11h 80h 33h 33h
Before Instruction FSR2 Contents of 85h REG2 After Instruction FSR2 Contents of 85h REG2
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MOVSS
Syntax: Operands: Operation: Status Affected: Encoding: 1st word (source) 2nd word (dest.) Description
Move Indexed to Indexed
MOVSS [zs], [zd] 0 zs 127 0 zd 127 ((FSR2) + zs) ((FSR2) + zd) None 1110 1111 1011 xxxx 1zzz xzzz zzzzs zzzzd
PUSHL
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Store Literal at FSR2, Decrement FSR2
PUSHL k 0 k 255 k (FSR2), FSR2 - 1 FSR2 None 1111 1010 kkkk kkkk The 8-bit literal `k' is written to the data memory address specified by FSR2. FSR2 is decremented by 1 after the operation. This instruction allows users to push values onto a software stack. 1 1 Q1 Q2 Read `k' Q3 Process data Q4 Write to destination
The contents of the source register are moved to the destination register. The addresses of the source and destination registers are determined by adding the 7-bit literal offsets `zs' or `zd', respectively, to the value of FSR2. Both registers can be located anywhere in the 4096-byte data memory space (000h to FFFh). The MOVSS instruction cannot use the PCL, TOSU, TOSH or TOSL as the destination register. If the resultant source address points to an indirect addressing register, the value returned will be 00h. If the resultant destination address points to an indirect addressing register, the instruction will execute as a NOP. 2 2
Words: Cycles: Q Cycle Activity: Decode
Example:
PUSHL 08h = = = = 01ECh 00h 01EBh 08h
Before Instruction FSR2H:FSR2L Memory (01ECh) After Instruction FSR2H:FSR2L Memory (01ECh)
Words: Cycles: Q Cycle Activity: Q1 Decode Decode
Q2
Q3
Q4 Read source reg Write to dest reg
Determine Determine source addr source addr Determine dest addr Determine dest addr
Example:
MOVSS [05h], [06h] = = = = = = 80h 33h 11h 80h 33h 33h
Before Instruction FSR2 Contents of 85h Contents of 86h After Instruction FSR2 Contents of 85h Contents of 86h
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SUBFSR
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Subtract Literal from FSR
SUBFSR f, k 0 k 63 f [ 0, 1, 2 ] FSR(f - k) FSR(f) None 1110 1001 ffkk kkkk The 6-bit literal `k' is subtracted from the contents of the FSR specified by `f'. 1 1 Q1 Q2 Read register `f' Q3 Process Data Q4 Write to destination
SUBULNK
Syntax: Operands: Operation: Status Affected: Encoding: Description:
Subtract Literal from FSR2 and Return
SUBULNK k 0 k 63 FSR2 - k FSR2, (TOS) PC None 1110 1001 11kk kkkk
Words: Cycles: Q Cycle Activity: Decode
The 6-bit literal `k' is subtracted from the contents of the FSR2. A RETURN is then executed by loading the PC with the TOS. The instruction takes two cycles to execute; a NOP is performed during the second cycle. This may be thought of as a special case of the SUBFSR instruction, where f = 3 (binary `11'); it operates only on FSR2. 1 2
Words: Example: Before Instruction FSR2 = After Instruction FSR2 = SUBFSR 2, 23h 03FFh 03DCh Cycles: Q1 Decode
Q Cycle Activity: Q2 Read register `f' No Operation Q3 Process Data No Operation Q4 Write to destination No Operation
No Operation
Example: Before Instruction FSR2 = PC = After Instruction FSR2 = PC =
SUBULNK 23h 03FFh 0100h 03DCh (TOS)
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25.2.3 BYTE-ORIENTED AND BIT-ORIENTED INSTRUCTIONS IN INDEXED LITERAL OFFSET MODE
Enabling the PIC18 instruction set extension may cause legacy applications to behave erratically or fail entirely.
25.2.3.1
Extended Instruction Syntax with Standard PIC18 Commands
Note:
In addition to eight new commands in the extended set, enabling the extended instruction set also enables Indexed Literal Offset Addressing mode (Section 6.5.1 "Indexed Addressing with Literal Offset"). This has a significant impact on the way that many commands of the standard PIC18 instruction set are interpreted. When the extended set is disabled, addresses embedded in opcodes are treated as literal memory locations: either as a location in the Access Bank (`a' = 0) or in a GPR bank designated by the BSR (`a' = 1). When the extended instruction set is enabled and `a' = 0, however, a file register argument of 5Fh or less is interpreted as an offset from the pointer value in FSR2 and not as a literal address. For practical purposes, this means that all instructions that use the Access RAM bit as an argument - that is, all byte-oriented and bitoriented instructions, or almost half of the core PIC18 instructions - may behave differently when the extended instruction set is enabled. When the content of FSR2 is 00h, the boundaries of the Access RAM are essentially remapped to their original values. This may be useful in creating backward compatible code. If this technique is used, it may be necessary to save the value of FSR2 and restore it when moving back and forth between C and assembly routines in order to preserve the Stack Pointer. Users must also keep in mind the syntax requirements of the extended instruction set (see Section 25.2.3.1 "Extended Instruction Syntax with Standard PIC18 Commands"). Although the Indexed Literal Offset Addressing mode can be very useful for dynamic stack and pointer manipulation, it can also be very annoying if a simple arithmetic operation is carried out on the wrong register. Users who are accustomed to the PIC18 programming must keep in mind that, when the extended instruction set is enabled, register addresses of 5Fh or less are used for Indexed Literal Offset Addressing mode. Representative examples of typical byte-oriented and bit-oriented instructions in the Indexed Literal Offset Addressing mode are provided on the following page to show how execution is affected. The operand conditions shown in the examples are applicable to all instructions of these types.
When the extended instruction set is enabled, the file register argument, `f', in the standard byte-oriented and bit-oriented commands is replaced with the literal offset value, `k'. As already noted, this occurs only when `f' is less than or equal to 5Fh. When an offset value is used, it must be indicated by square brackets ("[ ]"). As with the extended instructions, the use of brackets indicates to the compiler that the value is to be interpreted as an index or an offset. Omitting the brackets, or using a value greater than 5Fh within brackets, will generate an error in the MPASM Assembler. If the index argument is properly bracketed for Indexed Literal Offset Addressing mode, the Access RAM argument is never specified; it will automatically be assumed to be `0'. This is in contrast to standard operation (extended instruction set disabled) when `a' is set on the basis of the target address. Declaring the Access RAM bit in this mode will also generate an error in the MPASM Assembler. The destination argument, `d', functions as before. In the latest versions of the MPASM Assembler, language support for the extended instruction set must be explicitly invoked. This is done with either the command line option, /y, or the PE directive in the source listing.
25.2.4
CONSIDERATIONS WHEN ENABLING THE EXTENDED INSTRUCTION SET
It is important to note that the extensions to the instruction set may not be beneficial to all users. In particular, users who are not writing code that uses a software stack may not benefit from using the extensions to the instruction set. Additionally, the Indexed Literal Offset Addressing mode may create issues with legacy applications written to the PIC18 assembler. This is because instructions in the legacy code may attempt to address registers in the Access Bank below 5Fh. Since these addresses are interpreted as literal offsets to FSR2 when the instruction set extension is enabled, the application may read or write to the wrong data addresses. When porting an application to the PIC18F2221/2321/ 4221/4321 family, it is very important to consider the type of code. A large, re-entrant application that is written in `C' and would benefit from efficient compilation will do well when using the instruction set extensions. Legacy applications that heavily use the Access Bank will most likely not benefit from using the extended instruction set.
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ADDWF
Syntax: Operands: Operation: Status Affected: Encoding: Description:
ADD W to Indexed (Indexed Literal Offset mode)
ADDWF 0 k 95 d [0,1] (W) + ((FSR2) + k) dest N, OV, C, DC, Z 0010 01d0 kkkk kkkk The contents of W are added to the contents of the register indicated by FSR2, offset by the value `k'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). 1 1 Q1 Q2 Read `k' Q3 Process Data [OFST] , 0 = = = = = = 17h 2Ch 0A00h 20h 37h 20h Q4 Write to destination [k] {,d}
BSF
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode
Bit Set Indexed (Indexed Literal Offset mode)
BSF [k], b 0 f 95 0b7 1 ((FSR2) + k) None 1000 bbb0 kkkk kkkk Bit `b' of the register indicated by FSR2, offset by the value `k', is set. 1 1 Q2 Read register `f' BSF = = = = Q3 Process Data Q4 Write to destination
Words: Cycles: Q Cycle Activity:
Example:
Decode
[FLAG_OFST], 7 0Ah 0A00h 55h D5h
Example: W OFST FSR2 Contents of 0A2Ch After Instruction W Contents of 0A2Ch
ADDWF
Before Instruction
Before Instruction FLAG_OFST FSR2 Contents of 0A0Ah After Instruction Contents of 0A0Ah
SETF
Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Q Cycle Activity: Q1 Decode
Set Indexed (Indexed Literal Offset mode)
SETF [k] 0 k 95 FFh ((FSR2) + k) None 0110 1000 kkkk kkkk The contents of the register indicated by FSR2, offset by `k', are set to FFh. 1 1 Q2 Read `k' Q3 Process Data [OFST] 2Ch 0A00h 00h FFh Q4 Write register
Example:
SETF = = = =
Before Instruction OFST FSR2 Contents of 0A2Ch After Instruction Contents of 0A2Ch
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25.2.5 SPECIAL CONSIDERATIONS WITH MICROCHIP MPLAB(R) IDE TOOLS
The latest versions of Microchip's software tools have been designed to fully support the extended instruction set of the PIC18F2221/2321/4221/4321 family family of devices. This includes the MPLAB C18 C Compiler, MPASM Assembly language and MPLAB Integrated Development Environment (IDE). When selecting a target device for software development, MPLAB IDE will automatically set default Configuration bits for that device. The default setting for the XINST Configuration bit is `0', disabling the extended instruction set and Indexed Literal Offset Addressing mode. For proper execution of applications developed to take advantage of the extended instruction set, XINST must be set during programming. To develop software for the extended instruction set, the user must enable support for the instructions and the Indexed Addressing mode in their language tool(s). Depending on the environment being used, this may be done in several ways: * A menu option, or dialog box within the environment, that allows the user to configure the language tool and its settings for the project * A command line option * A directive in the source code These options vary between different compilers, assemblers and development environments. Users are encouraged to review the documentation accompanying their development systems for the appropriate information.
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26.0 DEVELOPMENT SUPPORT
26.1
The PIC(R) microcontrollers and dsPIC(R) digital signal controllers are supported with a full range of software and hardware development tools: * Integrated Development Environment - MPLAB(R) IDE Software * Compilers/Assemblers/Linkers - MPLAB C Compiler for Various Device Families - HI-TECH C for Various Device Families - MPASMTM Assembler - MPLINKTM Object Linker/ MPLIBTM Object Librarian - MPLAB Assembler/Linker/Librarian for Various Device Families * Simulators - MPLAB SIM Software Simulator * Emulators - MPLAB REAL ICETM In-Circuit Emulator * In-Circuit Debuggers - MPLAB ICD 3 - PICkitTM 3 Debug Express * Device Programmers - PICkitTM 2 Programmer - MPLAB PM3 Device Programmer * Low-Cost Demonstration/Development Boards, Evaluation Kits, and Starter Kits
MPLAB Integrated Development Environment Software
The MPLAB IDE software brings an ease of software development previously unseen in the 8/16/32-bit microcontroller market. The MPLAB IDE is a Windows(R) operating system-based application that contains: * A single graphical interface to all debugging tools - Simulator - Programmer (sold separately) - In-Circuit Emulator (sold separately) - In-Circuit Debugger (sold separately) * A full-featured editor with color-coded context * A multiple project manager * Customizable data windows with direct edit of contents * High-level source code debugging * Mouse over variable inspection * Drag and drop variables from source to watch windows * Extensive on-line help * Integration of select third party tools, such as IAR C Compilers The MPLAB IDE allows you to: * Edit your source files (either C or assembly) * One-touch compile or assemble, and download to emulator and simulator tools (automatically updates all project information) * Debug using: - Source files (C or assembly) - Mixed C and assembly - Machine code MPLAB IDE supports multiple debugging tools in a single development paradigm, from the cost-effective simulators, through low-cost in-circuit debuggers, to full-featured emulators. This eliminates the learning curve when upgrading to tools with increased flexibility and power.
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26.2 MPLAB C Compilers for Various Device Families 26.5 MPLINK Object Linker/ MPLIB Object Librarian
The MPLAB C Compiler code development systems are complete ANSI C compilers for Microchip's PIC18, PIC24 and PIC32 families of microcontrollers and the dsPIC30 and dsPIC33 families of digital signal controllers. These compilers provide powerful integration capabilities, superior code optimization and ease of use. For easy source level debugging, the compilers provide symbol information that is optimized to the MPLAB IDE debugger.
The MPLINK Object Linker combines relocatable objects created by the MPASM Assembler and the MPLAB C18 C Compiler. It can link relocatable objects from precompiled libraries, using directives from a linker script. The MPLIB Object Librarian manages the creation and modification of library files of precompiled code. When a routine from a library is called from a source file, only the modules that contain that routine will be linked in with the application. This allows large libraries to be used efficiently in many different applications. The object linker/library features include: * Efficient linking of single libraries instead of many smaller files * Enhanced code maintainability by grouping related modules together * Flexible creation of libraries with easy module listing, replacement, deletion and extraction
26.3
HI-TECH C for Various Device Families
The HI-TECH C Compiler code development systems are complete ANSI C compilers for Microchip's PIC family of microcontrollers and the dsPIC family of digital signal controllers. These compilers provide powerful integration capabilities, omniscient code generation and ease of use. For easy source level debugging, the compilers provide symbol information that is optimized to the MPLAB IDE debugger. The compilers include a macro assembler, linker, preprocessor, and one-step driver, and can run on multiple platforms.
26.6
MPLAB Assembler, Linker and Librarian for Various Device Families
26.4
MPASM Assembler
The MPASM Assembler is a full-featured, universal macro assembler for PIC10/12/16/18 MCUs. The MPASM Assembler generates relocatable object files for the MPLINK Object Linker, Intel(R) standard HEX files, MAP files to detail memory usage and symbol reference, absolute LST files that contain source lines and generated machine code and COFF files for debugging. The MPASM Assembler features include: * Integration into MPLAB IDE projects * User-defined macros to streamline assembly code * Conditional assembly for multi-purpose source files * Directives that allow complete control over the assembly process
MPLAB Assembler produces relocatable machine code from symbolic assembly language for PIC24, PIC32 and dsPIC devices. MPLAB C Compiler uses the assembler to produce its object file. The assembler generates relocatable object files that can then be archived or linked with other relocatable object files and archives to create an executable file. Notable features of the assembler include: * * * * * * Support for the entire device instruction set Support for fixed-point and floating-point data Command line interface Rich directive set Flexible macro language MPLAB IDE compatibility
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26.7 MPLAB SIM Software Simulator 26.9
The MPLAB SIM Software Simulator allows code development in a PC-hosted environment by simulating the PIC MCUs and dsPIC(R) DSCs on an instruction level. On any given instruction, the data areas can be examined or modified and stimuli can be applied from a comprehensive stimulus controller. Registers can be logged to files for further run-time analysis. The trace buffer and logic analyzer display extend the power of the simulator to record and track program execution, actions on I/O, most peripherals and internal registers. The MPLAB SIM Software Simulator fully supports symbolic debugging using the MPLAB C Compilers, and the MPASM and MPLAB Assemblers. The software simulator offers the flexibility to develop and debug code outside of the hardware laboratory environment, making it an excellent, economical software development tool.
MPLAB ICD 3 In-Circuit Debugger System
MPLAB ICD 3 In-Circuit Debugger System is Microchip's most cost effective high-speed hardware debugger/programmer for Microchip Flash Digital Signal Controller (DSC) and microcontroller (MCU) devices. It debugs and programs PIC(R) Flash microcontrollers and dsPIC(R) DSCs with the powerful, yet easyto-use graphical user interface of MPLAB Integrated Development Environment (IDE). The MPLAB ICD 3 In-Circuit Debugger probe is connected to the design engineer's PC using a high-speed USB 2.0 interface and is connected to the target with a connector compatible with the MPLAB ICD 2 or MPLAB REAL ICE systems (RJ-11). MPLAB ICD 3 supports all MPLAB ICD 2 headers.
26.8
MPLAB REAL ICE In-Circuit Emulator System
26.10 PICkit 3 In-Circuit Debugger/ Programmer and PICkit 3 Debug Express
The MPLAB PICkit 3 allows debugging and programming of PIC(R) and dsPIC(R) Flash microcontrollers at a most affordable price point using the powerful graphical user interface of the MPLAB Integrated Development Environment (IDE). The MPLAB PICkit 3 is connected to the design engineer's PC using a full speed USB interface and can be connected to the target via an Microchip debug (RJ-11) connector (compatible with MPLAB ICD 3 and MPLAB REAL ICE). The connector uses two device I/O pins and the reset line to implement in-circuit debugging and In-Circuit Serial ProgrammingTM. The PICkit 3 Debug Express include the PICkit 3, demo board and microcontroller, hookup cables and CDROM with user's guide, lessons, tutorial, compiler and MPLAB IDE software.
MPLAB REAL ICE In-Circuit Emulator System is Microchip's next generation high-speed emulator for Microchip Flash DSC and MCU devices. It debugs and programs PIC(R) Flash MCUs and dsPIC(R) Flash DSCs with the easy-to-use, powerful graphical user interface of the MPLAB Integrated Development Environment (IDE), included with each kit. The emulator is connected to the design engineer's PC using a high-speed USB 2.0 interface and is connected to the target with either a connector compatible with incircuit debugger systems (RJ11) or with the new highspeed, noise tolerant, Low-Voltage Differential Signal (LVDS) interconnection (CAT5). The emulator is field upgradable through future firmware downloads in MPLAB IDE. In upcoming releases of MPLAB IDE, new devices will be supported, and new features will be added. MPLAB REAL ICE offers significant advantages over competitive emulators including low-cost, full-speed emulation, run-time variable watches, trace analysis, complex breakpoints, a ruggedized probe interface and long (up to three meters) interconnection cables.
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26.11 PICkit 2 Development Programmer/Debugger and PICkit 2 Debug Express
The PICkitTM 2 Development Programmer/Debugger is a low-cost development tool with an easy to use interface for programming and debugging Microchip's Flash families of microcontrollers. The full featured Windows(R) programming interface supports baseline (PIC10F, PIC12F5xx, PIC16F5xx), midrange (PIC12F6xx, PIC16F), PIC18F, PIC24, dsPIC30, dsPIC33, and PIC32 families of 8-bit, 16-bit, and 32-bit microcontrollers, and many Microchip Serial EEPROM products. With Microchip's powerful MPLAB Integrated Development Environment (IDE) the PICkitTM 2 enables in-circuit debugging on most PIC(R) microcontrollers. In-Circuit-Debugging runs, halts and single steps the program while the PIC microcontroller is embedded in the application. When halted at a breakpoint, the file registers can be examined and modified. The PICkit 2 Debug Express include the PICkit 2, demo board and microcontroller, hookup cables and CDROM with user's guide, lessons, tutorial, compiler and MPLAB IDE software.
26.13 Demonstration/Development Boards, Evaluation Kits, and Starter Kits
A wide variety of demonstration, development and evaluation boards for various PIC MCUs and dsPIC DSCs allows quick application development on fully functional systems. Most boards include prototyping areas for adding custom circuitry and provide application firmware and source code for examination and modification. The boards support a variety of features, including LEDs, temperature sensors, switches, speakers, RS-232 interfaces, LCD displays, potentiometers and additional EEPROM memory. The demonstration and development boards can be used in teaching environments, for prototyping custom circuits and for learning about various microcontroller applications. In addition to the PICDEMTM and dsPICDEMTM demonstration/development board series of circuits, Microchip has a line of evaluation kits and demonstration software for analog filter design, KEELOQ(R) security ICs, CAN, IrDA(R), PowerSmart battery management, SEEVAL(R) evaluation system, Sigma-Delta ADC, flow rate sensing, plus many more. Also available are starter kits that contain everything needed to experience the specified device. This usually includes a single application and debug capability, all on one board. Check the Microchip web page (www.microchip.com) for the complete list of demonstration, development and evaluation kits.
26.12 MPLAB PM3 Device Programmer
The MPLAB PM3 Device Programmer is a universal, CE compliant device programmer with programmable voltage verification at VDDMIN and VDDMAX for maximum reliability. It features a large LCD display (128 x 64) for menus and error messages and a modular, detachable socket assembly to support various package types. The ICSPTM cable assembly is included as a standard item. In Stand-Alone mode, the MPLAB PM3 Device Programmer can read, verify and program PIC devices without a PC connection. It can also set code protection in this mode. The MPLAB PM3 connects to the host PC via an RS-232 or USB cable. The MPLAB PM3 has high-speed communications and optimized algorithms for quick programming of large memory devices and incorporates an MMC card for file storage and data applications.
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27.0 ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings()
Ambient temperature under bias.............................................................................................................-40C to +125C Storage temperature .............................................................................................................................. -65C to +150C Voltage on any pin with respect to VSS (except VDD and MCLR) ................................................... -0.3V to (VDD + 0.3V) Voltage on VDD with respect to VSS ......................................................................................................... -0.3V to +7.5V Voltage on MCLR with respect to VSS (Note 2) ......................................................................................... 0V to +13.25V Total power dissipation (Note 1) ...............................................................................................................................1.0W Maximum current out of VSS pin ...........................................................................................................................300 mA Maximum current into VDD pin ..............................................................................................................................250 mA Input clamp current, IIK (VI < 0 or VI > VDD)...................................................................................................................... 20 mA Output clamp current, IOK (VO < 0 or VO > VDD) .............................................................................................................. 20 mA Maximum output current sunk by any I/O pin..........................................................................................................25 mA Maximum output current sourced by any I/O pin ....................................................................................................25 mA Maximum current sunk by all ports .......................................................................................................................200 mA Maximum current sourced by all ports ..................................................................................................................200 mA Note 1: Power dissipation is calculated as follows: Pdis = VDD x {IDD - IOH} + {(VDD - VOH) x IOH} + (VOL x IOL) 2: Voltage spikes below VSS at the MCLR/VPP/RE3 pin, inducing currents greater than 80 mA, may cause latch-up. Thus, a series resistor of 50-100 should be used when applying a "low" level to the MCLR/VPP/ RE3 pin, rather than pulling this pin directly to VSS.
NOTICE: Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
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FIGURE 27-1: PIC18F2221/2321/4221/4321 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V 5.5V 5.0V 4.5V 4.0V 3.5V 3.0V 2.5V 2.0V
Voltage
4.2V
40 MHz
Frequency
FIGURE 27-2:
PIC18F2221/2321/4221/4321 VOLTAGE-FREQUENCY GRAPH (EXTENDED)
6.0V 5.5V 5.0V 4.5V 4.0V 3.5V 3.0V 2.5V 2.0V
Voltage
4.2V
25 MHz
Frequency
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FIGURE 27-3: PIC18LF2221/2321/4221/4321 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)
6.0V 5.5V 5.0V 4.5V 4.0V 3.5V 3.0V 2.5V 2.0V
Voltage
4.2V
4 MHz
25 MHz
40 MHz
Frequency
FMAX = (9.54 MHz/V) (VDDAPPMIN - 2.0V) + 4 MHz Note: VDDAPPMIN is the minimum voltage of the PIC(R) device in the application.
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27.1 DC Characteristics: Supply Voltage PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Min Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param Symbol No. D001 VDD Characteristic Supply Voltage
PIC18LF2X21/4X21 2.0 -- 5.5 V PIC18F2X21/4X21 4.2 -- 5.5 V D001C AVDD Analog Supply Voltage VDD - 0.3V -- VDD + 0.3V V D001D AVSS Analog Ground Voltage VSS - 0.3V -- VSS + 0.3V V D002 VDR RAM Data Retention 1.5 -- -- V Voltage(1) VDD Start Voltage -- -- 0.7 V See section on Power-on Reset for D003 VPOR to Ensure Internal details Power-on Reset Signal VDD Rise Rate 0.05 -- -- V/ms See section on Power-on Reset for D004 SVDD to Ensure Internal details Power-on Reset Signal VBOR Brown-out Reset Voltage D005 PIC18LF2X21/4X21 BORV<1:0> = 11 2.00 2.11 2.22 V BORV<1:0> = 10 2.65 2.79 2.93 V D005 All devices BORV<1:0> = 01(2) 4.11 4.33 4.55 V BORV<1:0> = 00 4.36 4.59 4.82 V Legend: Shading of rows is to assist in readability of the table. Note 1: This is the limit to which VDD can be lowered in Sleep mode, or during a device Reset, without losing RAM data. 2: With BOR enabled, full-speed operation (FOSC = 40 MHz) is supported until a BOR occurs. This is valid although VDD may be below the minimum voltage for this frequency.
DS39689F-page 336
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device
Power-Down Current (IPD)(1) 0.5 0.7 A -40C VDD = 2.0V 0.5 0.7 A +25C (Sleep mode) 0.5 1.7 A +85C PIC18LF2X21/4X21 0.6 0.9 A -40C VDD = 3.0V 0.6 0.9 A +25C (Sleep mode) 0.6 1.9 A +85C All Devices 0.9 2.0 A -40C 0.9 2.0 A +25C VDD = 5.0V (Sleep mode) 0.9 6.5 A +85C Extended Devices Only 7.5 70 A +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. PIC18LF2X21/4X21
Legend: Note 1:
2:
3: 4: 5:
(c) 2009 Microchip Technology Inc.
DS39689F-page 337
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device Supply Current (IDD)(2) PIC18LF2X21/4X21
PIC18LF2X21/4X21
All Devices
Extended Devices Only PIC18LF2X21/4X21
13 13 13 41 34 27 104 86 67 68 0.31
19 19 17 45 38 30 115 95 75 100 0.35
A A A A A A A A A A mA
-40C +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C
VDD = 2.0V
VDD = 3.0V
FOSC = 31 kHz (RC_RUN mode, INTRC source)
VDD = 5.0V
Legend: Note 1:
2:
3: 4: 5:
VDD = 2.0V 0.31 0.35 mA +25C 0.31 0.35 mA +85C PIC18LF2X21/4X21 0.55 0.60 mA -40C FOSC = 1 MHz 0.51 0.60 mA +25C VDD = 3.0V (RC_RUN mode, 0.47 0.60 mA +85C INTOSC source) All Devices 1.0 1.3 mA -40C 0.94 1.3 mA +25C VDD = 5.0V 0.88 1.2 mA +85C Extended Devices Only 0.88 1.2 mA +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
DS39689F-page 338
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device
Supply Current (IDD)(2) PIC18LF2X21/4X21 0.69
0.9
mA
-40C
Legend: Note 1:
2:
3: 4: 5:
VDD = 2.0V 0.70 0.9 mA +25C 0.71 0.9 mA +85C PIC18LF2X21/4X21 1.17 1.45 mA -40C FOSC = 4 MHz 1.15 1.45 mA +25C VDD = 3.0V (RC_RUN mode, 1.14 1.45 mA +85C INTOSC source) All Devices 2.24 2.9 mA -40C 2.20 2.9 mA +25C VDD = 5.0V 2.16 2.8 mA +85C Extended Devices Only 2.18 2.8 mA +125C PIC18LF2X21/4X21 3 5 A -40C VDD = 2.0V 3 5 A +25C 3 5.6 A +85C PIC18LF2X21/4X21 4 7 A -40C FOSC = 31 kHz 5 7 A +25C VDD = 3.0V (RC_IDLE mode, 5 10 A +85C INTRC source) All Devices 10 12 A -40C 10 12 A +25C VDD = 5.0V 10 16 A +85C Extended Devices Only 17 50 A +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
(c) 2009 Microchip Technology Inc.
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27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device Supply Current (IDD)(2) PIC18LF2X21/4X21
160 170 170
230 230 230 330 330 330 500 500 500 500 440 440 440 750 750 750 1.3 1.3 1.3
A A A A A A A A A A A A A A A A mA mA mA
-40C +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C +25C +85C -40C +25C +85C -40C +25C +85C VDD = 5.0V VDD = 3.0V FOSC = 4 MHz (RC_IDLE mode, INTOSC source) VDD = 2.0V VDD = 5.0V VDD = 3.0V FOSC = 1 MHz (RC_IDLE mode, INTOSC source) VDD = 2.0V
PIC18LF2X21/4X21
220 240 250
All Devices
410 420 430
Extended Devices Only PIC18LF2X21/4X21
450 310 330 340
PIC18LF2X21/4X21
480 500 520
All Devices 0.91 0.93 0.96 Legend: Note 1:
2:
3: 4: 5:
Extended Devices Only 0.98 1.3 mA +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
DS39689F-page 340
(c) 2009 Microchip Technology Inc.
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27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device Supply Current (IDD)(2)
PIC18LF2X21/4X21 0.22 0.22 0.21 PIC18LF2X21/4X21 0.51 0.45 0.39 All Devices 1.14 0.99 0.83 Extended Devices Only 0.80 PIC18LF2X21/4X21 610 610 610 1.16 1.10 1.07 2.35 2.24 2.14 2.14 9 12
0.35 0.35 0.3 0.55 0.50 0.45 1.15 1.1 1.1 1.1 870 870 870 1.83 1.83 1.83 2.85 2.85 2.85 2.85 15 20
mA mA mA mA mA mA mA mA mA mA A A A mA mA mA mA mA mA mA mA mA
-40C +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C +25C +85C -40C +25C +85C -40C +25C +85C +125C +125C +125C
VDD = 2.0V
VDD = 3.0V
FOSC = 1 MHz (PRI_RUN mode, EC oscillator)
VDD = 5.0V
VDD = 2.0V
PIC18LF2X21/4X21
VDD = 3.0V
All Devices
FOSC = 4 MHz (PRI_RUN mode, EC oscillator)
VDD = 5.0V
Extended Devices Only Extended Devices Only
VDD = 4.2V VDD = 5.0V
FOSC = 25 MHz (PRI_RUN mode, EC oscillator)
Legend: Note 1:
2:
3: 4: 5:
16 19 mA -40C VDD = 4.2V 14 19 mA +25C FOSC = 40 MHz 14 19 mA +85C (PRI_RUN mode, All Devices 17 22.7 mA -40C EC oscillator) VDD = 5.0V 17 22.7 mA +25C 17 22.7 mA +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
All Devices
(c) 2009 Microchip Technology Inc.
DS39689F-page 341
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device Supply Current (IDD)(2) All Devices
Legend: Note 1:
2:
3: 4: 5:
FOSC = 4 MHz, 9 12 mA +25C 16 MHz internal VDD = 5.0V 9 12 mA +85C (PRI_RUN HS+PLL) Extended Devices Only 9 12 mA +125C All Devices 17 19 mA -40C FOSC = 10 MHz, VDD = 4.2V 15 19 mA +25C 40 MHz internal (PRI_RUN HS+PLL) 15 19 mA +85C All Devices 18 23 mA -40C FOSC = 10 MHz, 18 23 mA +25C 40 MHz internal VDD = 5.0V (PRI_RUN HS+PLL) 18 23 mA +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
Extended Devices Only All Devices
7 6 6 6 10
10 10 10 10 12
mA mA mA mA mA
-40C +25C +85C +125C -40C
VDD = 4.2V
FOSC = 4 MHz, 16 MHz internal (PRI_RUN HS+PLL)
DS39689F-page 342
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device Supply Current (IDD)(2) PIC18LF2X21/4X21
51 54 60 83 88 93 180 180 180 190 210 220 230 350 360 370 0.69 0.70 0.72 0.74 3.7 4.6 6.0 6.2 6.6 6.8
75 75 75 123 123 123 260 260 260 260 290 290 290 480 480 480 1 1 1 1 4.0 5.0 7.3 7.3 7.3 9.2
A A A A A A A A A A A A A A A A mA mA mA mA mA mA mA mA mA mA
-40C +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C +25C +85C -40C +25C +85C -40C +25C +85C +125C +125C +125C -40C +25C +85C -40C VDD = 2.0V
PIC18LF2X21/4X21
VDD = 3.0V
All Devices
FOSC = 1 MHz (PRI_IDLE mode, EC oscillator)
VDD = 5.0V
Extended Devices Only PIC18LF2X21/4X21
VDD = 2.0V
PIC18LF2X21/4X21
VDD = 3.0V
All Devices
FOSC = 4 MHz (PRI_IDLE mode, EC oscillator)
VDD = 5.0V
Extended Devices Only Extended Devices Only
VDD = 4.2V VDD = 5.0V VDD = 4.2V
FOSC = 25 MHz (PRI_IDLE mode, EC oscillator)
All Devices
All Devices
Legend: Note 1:
2:
3: 4: 5:
VDD = 5.0V 7.0 9.2 mA +25C 7.1 9.2 mA +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
FOSC = 40 MHz (PRI_IDLE mode, EC oscillator)
(c) 2009 Microchip Technology Inc.
DS39689F-page 343
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. Device Supply Current (IDD)(2) PIC18LF2X21/4X21
12 -- 13 13 40 -- 33 27 101 -- 83 65 2.5
19 19 19 19 45 45 45 45 115 110 110 88 5
A A A A A A A A A A A A A
-40C(5) -10C +25C +85C -40C(5) -10C +25C +85C -40C(5) -10C +25C +85C -40C(5) VDD = 2.0V
PIC18LF2X21/4X21
VDD = 3.0V
FOSC = 32 kHz (SEC_RUN mode, Timer1 as clock)(3)
All Devices
VDD = 5.0V
PIC18LF2X21/4X21
Legend: Note 1:
2:
3: 4: 5:
-- 5 A -10C VDD = 2.0V 3.0 5 A +25C 3.5 8 A +85C PIC18LF2X21/4X21 3.9 7 A -40C(5) FOSC = 32 kHz -- 7 A -10C VDD = 3.0V (SEC_IDLE mode, 4.5 7 A +25C Timer1 as clock)(3) 5.2 10.7 A +85C All Devices 7.5 10 A -40C(5) -- 10 A -10C VDD = 5.0V 8.0 10 A +25C 8.6 15 A +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
DS39689F-page 344
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ Max Units Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. D022 (IWDT) Device
Module Differential Currents (IWDT, IBOR, ILVD, IOSCB, IAD) Watchdog Timer 1.6 2.5 A -40C 1.6 2.5 A +25C
D022A (IBOR)
D022B (ILVD)
Legend: Note 1:
2:
3: 4: 5:
VDD = 2.0V 1.5 2.5 A +85C 2.3 3.5 A -40C VDD = 3.0V 2.2 3.5 A +25C 2.1 3 A +85C 3.4 7.4 A -40C 3.9 7.4 A +25C VDD = 5.0V 4.4 7.4 A +85C 4.5 7.4 A +125C 45 A -40C to +85C VDD = 3.0V Brown-out Reset(4) 34 40 62.6 A -40C to +85C VDD = 5.0V 42 62.6 A -40C to +125C 0 2 A -40C to +85C VDD = 3.0V Sleep mode, BOREN<1:0> = 10 0 5 A -40C to +125C VDD = 5.0V High/Low-Voltage 23 35 A -40C to +85C VDD = 2.0V Detect(4) 23 35 A -40C to +85C VDD = 3.0V 28 35 A -40C to +85C VDD = 5.0V 30 40 A -40C to +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0.
(c) 2009 Microchip Technology Inc.
DS39689F-page 345
PIC18F2221/2321/4221/4321 FAMILY
27.2 DC Characteristics: Power-Down and Supply Current PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Typ 2.1 -- 1.8 2.1 2.2 -- 2.6 2.9 3.0 -- 3.2 3.4 Max 4.5 4.5 4.5 4.5 6.0 6 6.0 6.0 8.0 8 8.0 8.0 Units A A A A A A A A A A A A -40C(5) -10C +25C +85C -40C(5) -10C +25C +85C -40C(5) -10C +25C +85C Conditions
PIC18LF2221/2321/4221/4321 (Industrial) PIC18F2221/2321/4221/4321 (Industrial, Extended) Param No. D025 (IOSCB) Device Timer1 Oscillator
VDD = 2.0V
VDD = 3.0V
32 kHz Tuning Fork, Crystal on Timer1 Oscillator(3)
VDD = 5.0V
D026 (IAD)
Legend: Note 1:
2:
3: 4: 5:
1.0 2.0 A -40C to +85C VDD = 2.0V 1.0 2.0 A -40C to +85C VDD = 3.0V A/D on, Not Converting 1.0 2.0 A -40C to +85C VDD = 5.0V 2.0 8.0 A -40C to +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS, and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. Low-power, Timer1 oscillator is selected unless otherwise indicated, where LPT1OSC (CONFIG3H<2>) = 1. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. A/D Converter
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27.3 DC Characteristics: PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Characteristic Input Low Voltage I/O Ports: D030 D030A D031 D031A D031B D032 D033 D033A D033B D034 VIH D040 D040A D041 D041A D041B D042 D043 D043A D043B D043C D044 IIL D060 MCLR OSC1 OSC1 OSC1 OSC1 T13CKI Input Leakage Current(2,3) I/O Ports -- 200 nA VDD < 5.5V, VSS VPIN VDD, Pin at High-Impedance VDD < 3V, VSS VPIN VDD, Pin at High-Impedance Vss VPIN VDD Vss VPIN VDD with Schmitt Trigger Buffer RC3 and RC4 MCLR OSC1 OSC1 OSC1 T13CKI Input High Voltage I/O Ports: with TTL Buffer 0.25 VDD + 0.8V 2.0 0.8 VDD 0.7 VDD 2.1 0.8 VDD 0.7 VDD 0.8 VDD 0.9 VDD 1.6 1.6 VDD VDD VDD VDD VDD VDD VDD VDD VDD VDD VDD V V V V V V V V V V V HS, HSPLL modes EC mode RC mode(1) XT, LP modes I2CTM enabled SMBus enabled, VSS 3V VDD < 4.5V 4.5V VDD 5.5V with Schmitt Trigger Buffer RC3 and RC4 with TTL Buffer VSS -- VSS VSS VSS VSS VSS VSS VSS VSS 0.15 VDD 0.8 0.2 VDD 0.3 VDD 0.8 0.2 VDD 0.3 VDD 0.2 VDD 0.3 0.3 V V V V V V V V V V HS, HSPLL modes RC, EC modes(1) XT, LP modes I2CTM enabled SMBus enabled VDD < 4.5V 4.5V VDD 5.5V Min Max Units Conditions
DC CHARACTERISTICS Param Symbol No. VIL
--
50
nA
D061 D063 Note 1: 2:
MCLR OSC1
-- --
1 1
A A
3:
In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the PIC(R) device be driven with an external clock while in RC mode. The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified levels represent normal operating conditions. Higher leakage current may be measured at different input voltages. Negative current is defined as current sourced by the pin.
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27.3 DC Characteristics: PIC18F2221/2321/4221/4321 (Industrial) PIC18LF2221/2321/4221/4321 (Industrial) (Continued)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Characteristic Weak Pull-up Current PORTB Weak Pull-up Current Output Low Voltage I/O Ports OSC2/CLKO (RC, RCIO, EC, ECIO modes) VOH D090 D092 Output High Voltage(3) I/O Ports OSC2/CLKO (RC, RCIO, EC, ECIO modes) Capacitive Loading Specs on Output Pins D100 COSC2 OSC2 Pin -- 15 pF In XT, HS and LP modes when external clock is used to drive OSC1 Maximum that allows the AC Timing Specifications to be met Maximum bus capacitance permitted by I2CTM Specification VDD - 0.7 VDD - 0.7 -- -- V V IOH = -3.0 mA, VDD = 4.5V, -40C to +85C IOH = -1.3 mA, VDD = 4.5V, -40C to +85C -- -- 0.6 0.6 V V IOL = 8.5 mA, VDD = 4.5V, -40C to +85C IOL = 1.6 mA, VDD = 4.5V, -40C to +85C 50 400 A VDD = 5V, VPIN = VSS Min Max Units Conditions
DC CHARACTERISTICS Param Symbol No. IPU D070 D080 D083 IPURB VOL
D101
CIO
All I/O Pins and OSC2 (in RC mode) SCL, SDA
--
50
pF
D102
CB
--
400
pF
Note 1: 2:
3:
In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the PIC(R) device be driven with an external clock while in RC mode. The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified levels represent normal operating conditions. Higher leakage current may be measured at different input voltages. Negative current is defined as current sourced by the pin.
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TABLE 27-1: MEMORY PROGRAMMING REQUIREMENTS
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Characteristic Data EEPROM Memory D120 D121 ED VDRW Byte Endurance VDD for Read/Write 1M VMIN 10M -- -- 5.5 E/W -40C to +85C V Using EECON to read/write, VMIN = Minimum operating voltage Min Typ Max Units Conditions DC CHARACTERISTICS Param No. Sym
D122 D123 D124 D125
TDEW
Erase/Write Cycle Time
-- 40 100K --
4 -- 1M 10
-- -- -- --
ms Year Provided no other specifications are violated E/W -40C to +85C mA
TRETD Characteristic Retention TREF IDDP Number of Total Erase/Write Cycles before Refresh(1) Supply Current during Programming Program Flash Memory Cell Endurance VDD for Read VDD for Block Erase VDD for Self-Timed Write Self-Timed Write Cycle Time
D130 D131 D132
EP VPR VIE
10K VMIN 3.0 VMIN -- 40 --
100K -- -- -- 2 100 10
-- 5.5 5.5 5.5 -- -- --
E/W -40C to +85C V V V ms Year Provided no other specifications are violated mA VMIN = Minimum operating voltage Using ICSPTM port, 25C VMIN = Minimum operating voltage
D132B VPEW D133A TIW D134 D135
TRETD Characteristic Retention IDDP Supply Current during Programming
Data in "Typ" column is at 5.0V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Refer to Section 8.7 "Using the Data EEPROM" for a more detailed discussion on data EEPROM endurance.
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TABLE 27-2: COMPARATOR SPECIFICATIONS
Operating Conditions: 3.0V < VDD < 5.5V, -40C < TA < +85C for industrial (unless otherwise stated) -40C < TA < +125C for extended (unless otherwise stated) Param No. D300 D301 D302 D303 D303A D304 Note 1: TMC2OV Comparator Mode Change to Output Valid Sym VIOFF VICM CMRR TRESP Characteristics Input Offset Voltage Input Common Mode Voltage Common Mode Rejection Ratio Response Time(1) Min -- 0 55 -- -- -- Typ 5.0 -- -- 150 150 -- Max 10 VDD - 1.5 -- 400 600 10 Units mV V dB ns ns s PIC18FXXXX PIC18LFXXXX, VDD = 2.0V Comments
Response time measured with one comparator input at (VDD - 1.5)/2, while the other input transitions from VSS to VDD.
TABLE 27-3:
VOLTAGE REFERENCE SPECIFICATIONS
Operating Conditions: 3.0V < VDD < 5.5V, -40C < TA < +85C for industrial (unless otherwise stated) -40C < TA < +125C for extended (unless otherwise stated) Param No. D310 D311 D312 D310 Note 1: Sym VRES VRAA VRUR TSET Characteristics Resolution Absolute Accuracy Unit Resistor Value (R) Settling Time(1) Min VDD/24 -- -- -- Typ -- -- 2k -- Max VDD/32 1/2 -- 10 Units LSb LSb s Comments
Settling time measured while CVRR = 1 and CVR<3:0> transitions from `0000' to `1111'.
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FIGURE 27-4: HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
VDD (HLVDIF can be cleared in software)
VLVD (HLVDIF set by hardware)
HLVDIF(1) Note 1: VDIRMAG = 0.
TABLE 27-4:
HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param Symbol No. D420 Characteristic HLVD Voltage on VDD LVV = 0000 Transition High-to-Low LVV = 0001 LVV = 0010 LVV = 0011 LVV = 0100 LVV = 0101 LVV = 0110 LVV = 0111 LVV = 1000 LVV = 1001 LVV = 1010 LVV = 1011 LVV = 1100 LVV = 1101 LVV = 1110 LVV = 1111 Min 2.06 2.12 2.24 2.32 2.47 2.65 2.74 2.96 3.22 3.37 3.52 3.70 3.90 4.11 4.36 1.10 Typ 2.17 2.23 2.36 2.44 2.60 2.79 2.89 3.12 3.39 3.55 3.71 3.90 4.11 4.33 4.59 1.20 Max 2.28 2.34 2.48 2.56 2.73 2.93 3.04 3.28 3.56 3.73 3.90 4.10 4.32 4.55 4.82 1.30 Units V V V V V V V V V V V V V V V V HLVDIN Input/Internal Reference Voltage Conditions
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27.4
27.4.1
AC (Timing) Characteristics
TIMING PARAMETER SYMBOLOGY
The timing parameter symbols have been created using one of the following formats: 1. TppS2ppS 2. TppS T F Frequency Lowercase letters (pp) and their meanings: pp cc CCP1 ck CLKO cs CS di SDI do SDO dt Data in io I/O port mc MCLR Uppercase letters and their meanings: S F Fall H High I Invalid (High-impedance) L Low I2C only AA output access BUF Bus free TCC:ST (I2C specifications only) CC HD Hold ST DAT DATA input hold STA Start condition 3. TCC:ST 4. Ts T (I2C specifications only) (I2C specifications only) Time
osc rd rw sc ss t0 t1 wr
OSC1 RD RD or WR SCK SS T0CKI T13CKI WR
P R V Z High Low
Period Rise Valid High-impedance High Low
SU STO
Setup Stop condition
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27.4.2 TIMING CONDITIONS
Note: The temperature and voltages specified in Table 27-5 apply to all timing specifications unless otherwise noted. Figure 27-5 specifies the load conditions for the timing specifications. Because of space limitations, the generic terms "PIC18FXXXX" and "PIC18LFXXXX" are used throughout this section to refer to the PIC18F2221/2321/4221/4321 and PIC18LF2221/2321/4221/4321 families of devices specifically and only those devices.
TABLE 27-5:
TEMPERATURE AND VOLTAGE SPECIFICATIONS - AC
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Operating voltage VDD range as described in DC spec Section 27.1 and Section 27.3. LF parts operate for industrial temperatures only.
AC CHARACTERISTICS
FIGURE 27-5:
LOAD CONDITIONS FOR DEVICE TIMING SPECIFICATIONS
Load Condition 1 VDD/2 RL Pin VSS Pin VSS CL RL = 464 CL = 50 pF for all pins except OSC2/CLKO and including D and E outputs as ports CL Load Condition 2
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27.4.3 TIMING DIAGRAMS AND SPECIFICATIONS EXTERNAL CLOCK TIMING (ALL MODES EXCEPT PLL)
Q4 Q1 Q2 Q3 Q4 Q1
FIGURE 27-6:
OSC1
1 2 3 3 4 4
CLKO
TABLE 27-6:
Param. No. 1A
EXTERNAL CLOCK TIMING REQUIREMENTS
Characteristic External CLKI Frequency(1) Min DC DC DC 4 DC Oscillator Frequency(1) DC 0.1 4 5 Max 1 25 40 10 50 4 4 25 200 -- -- -- 250 -- -- 1 250 209 -- -- -- -- -- 20 50 7.5 Units MHz MHz MHz MHz kHz MHz MHz MHz kHz ns ns ns ns s ns s ns s ns ns ns s ns ns ns ns Conditions XT, RC Oscillator mode HS Oscillator mode EC Oscillator mode HS+PLL Oscillator mode LP Oscillator mode RC Oscillator mode XT Oscillator mode HS Oscillator mode LP Oscillator mode XT, RC Oscillator mode HS Oscillator mode EC Oscillator mode HS+PLL Oscillator mode LP Oscillator mode RC Oscillator mode XT Oscillator mode HS Oscillator mode LP Oscillator mode TCY = 4/FOSC, Industrial TCY = 4/FOSC, Extended XT Oscillator mode LP Oscillator mode HS Oscillator mode XT Oscillator mode LP Oscillator mode HS Oscillator mode
Symbol FOSC
1
TOSC
External CLKI Period(1)
1000 40 25 100 32
Oscillator
Period(1)
250 250 40 5
2 3
TCY TOSL, TOSH TOSR, TOSF
Instruction Cycle Time(1) External Clock in (OSC1) High or Low Time External Clock in (OSC1) Rise or Fall Time
100 160 30 2.5 10 -- -- --
4
Note 1:
Instruction cycle period (TCY) equals four times the input oscillator time base period for all configurations except PLL. All specified values are based on characterization data for that particular oscillator type under standard operating conditions with the device executing code. Exceeding these specified limits may result in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested to operate at "min." values with an external clock applied to the OSC1/CLKI pin. When an external clock input is used, the "max." cycle time limit is "DC" (no clock) for all devices.
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TABLE 27-7:
Param No. F10 F11 F12 F13 Sym
PLL CLOCK TIMING SPECIFICATIONS (VDD = 4.2V TO 5.5V)
Characteristic Min 4 16 -- -2 Typ -- -- -- -- Max 10 40 2 +2 Units Conditions
FOSC Oscillator Frequency Range FSYS On-Chip VCO System Frequency trc CLK PLL Start-up Time (Lock Time) CLKO Stability (Jitter)
MHz HS mode only MHz HS mode only ms %
Data in "Typ" column is at 5V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested.
TABLE 27-8:
AC CHARACTERISTICS: INTERNAL RC ACCURACY
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Min Typ Max Units Conditions
INTOSC Accuracy @ Freq = 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz, 125 kHz, 31 kHz(1) PIC18LF2221/2321/4221/4321 -2 -5 -10 PIC18F2221/2321/4221/4321 -2 -5 -10 INTRC Accuracy @ Freq = 31 kHz PIC18LF2221/2321/4221/4321 26.562 PIC18F2221/2321/4221/4321 26.562 Note 1: -- -- 35.938 35.938 kHz kHz -40C to +85C -40C to +85C VDD = 2.0-5.5V VDD = 4.2-5.5V +/-1 -- +/-1 +/-1 -- +/-1 2 5 10 2 5 10 % % % % % % +25C -10C to +85C -40C to +85C +25C -10C to +85C -40C to +85C VDD = 2.0-5.5V VDD = 2.0-5.5V VDD = 2.0-5.5V VDD = 4.2-5.5V VDD = 4.2-5.5V VDD = 4.2-5.5V
Frequency calibrated at 25C. OSCTUNE register can be used to compensate for temperature drift.
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FIGURE 27-7: CLKO AND I/O TIMING
Q4 OSC1 10 CLKO 13 14 I/O pin (Input) 17 I/O pin (Output) Old Value 20, 21 Refer to Figure 27-5 for load conditions. 15 New Value 19 18 12 16 11 Q1 Q2 Q3
Note:
TABLE 27-9:
Param No. 10 11 12 13 14 15 16 17 18 18A 19 20 20A 21 21A 22 23 TINP TRBP TioF
CLKO AND I/O TIMING REQUIREMENTS
Characteristic Min -- -- -- -- -- 0.25 TCY + 25 0 -- 100 200 0 -- -- -- -- TCY TCY PIC18FXXXX PIC18LFXXXX Typ 75 75 35 35 -- -- -- 50 -- -- -- 10 -- 10 -- -- -- Max 200 200 100 100 0.5 TCY + 20 -- -- 150 -- -- -- 25 60 25 60 -- -- Units Conditions ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns VDD = 2.0V VDD = 2.0V VDD = 2.0V (Note 1) (Note 1) (Note 1) (Note 1) (Note 1) (Note 1) (Note 1)
Symbol
TosH2ckL OSC1 to CLKO TosH2ckH OSC1 to CLKO TckR TckF TckL2ioV TckH2ioI TosH2ioI CLKO Rise Time CLKO Fall Time CLKO to Port Out Valid Port In Hold after CLKO OSC1 (Q2 cycle) to Port Input Invalid (I/O in hold time) Port Output Rise Time Port Output Fall Time
TioV2ckH Port In Valid before CLKO TosH2ioV OSC1 (Q1 cycle) to Port Out Valid
TioV2osH Port Input Valid to OSC1 (I/O in setup time) TioR PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX INTx Pin High or Low Time RB<7:4> Change INTx High or Low Time
These parameters are asynchronous events not related to any internal clock edges. Note 1: Measurements are taken in RC mode, where CLKO output is 4 x TOSC.
DS39689F-page 356
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FIGURE 27-8: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP TIMER TIMING
VDD MCLR Internal POR PWRT Time-out OSC Time-out Internal Reset Watchdog Timer Reset 34 I/O pins 33 32 30
31
34
FIGURE 27-9:
BROWN-OUT RESET TIMING
VDD BVDD 35 VIRVST
Enable Internal Reference Voltage Internal Reference Voltage Stable
36
TABLE 27-10: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER AND BROWN-OUT RESET REQUIREMENTS
Param. Symbol No. 30 31 32 33 34 35 36 37 38 39 TmcL TWDT TOST TPWRT TIOZ TBOR TIRVST TLVD TCSD TIOBST Characteristic MCLR Pulse Width (low) Watchdog Timer Time-out Period (no postscaler) Oscillation Start-up Timer Period Power-up Timer Period I/O High-Impedance from MCLR Low or Watchdog Timer Reset Brown-out Reset Pulse Width Time for Internal Reference Voltage to become Stable High/Low-Voltage Detect Pulse Width CPU Start-up Time Time for INTOSC to Stabilize Min 2 3.56 1024 TOSC 57 -- 200 -- 200 -- -- Typ -- 4.19 -- 67 2 -- 20 -- 10 1 Max -- 4.82 1024 TOSC 77 -- -- 50 -- -- -- Units s ms -- ms s s s s s s VDD VLVD VDD BVDD (see D005) TOSC = OSC1 period Conditions
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FIGURE 27-10: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI
40 42 T1OSO/T13CKI
41
45 47 TMR0 or TMR1
46
48
TABLE 27-11: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param No. 40 41 42 Symbol Tt0H Tt0L Tt0P Characteristic T0CKI High Pulse Width T0CKI Low Pulse Width T0CKI Period No prescaler With prescaler No prescaler With prescaler No prescaler With prescaler Min 0.5 TCY + 20 10 0.5 TCY + 20 10 TCY + 10 Greater of: 20 ns or (TCY + 40)/N 0.5 TCY + 20 10 25 30 50 0.5 TCY + 5 10 25 30 50 Greater of: 20 ns or (TCY + 40)/N 60 DC 2 TOSC Max -- -- -- -- -- -- Units Conditions ns ns ns ns ns ns N = prescale value (1, 2, 4,..., 256)
45
Tt1H
T13CKI Synchronous, no prescaler High Time Synchronous, PIC18FXXXX with prescaler PIC18LFXXXX Asynchronous PIC18FXXXX PIC18LFXXXX
-- -- -- -- -- -- -- -- -- -- --
ns ns ns ns ns ns ns ns ns ns ns VDD = 2.0V N = prescale value (1, 2, 4, 8) VDD = 2.0V VDD = 2.0V VDD = 2.0V
46
Tt1L
T13CKI Low Time
Synchronous, no prescaler Synchronous, with prescaler Asynchronous PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX
47
Tt1P
T13CKI Input Period
Synchronous
Asynchronous Ft1 48 T13CKI Oscillator Input Frequency Range Tcke2tmrI Delay from External T13CKI Clock Edge to Timer Increment
-- 50 7 TOSC
ns kHz --
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FIGURE 27-11: CAPTURE/COMPARE/PWM TIMINGS (ALL CCP MODULES)
CCPx (Capture Mode)
50 52
51
CCPx (Compare or PWM Mode) 53 54
TABLE 27-12: CAPTURE/COMPARE/PWM REQUIREMENTS (ALL CCP MODULES)
Param Symbol No. 50 TccL Characteristic CCPx Input Low No prescaler Time With PIC18FXXXX prescaler PIC18LFXXXX CCPx Input High Time No prescaler With prescaler PIC18FXXXX PIC18LFXXXX Min 0.5 TCY + 20 10 20 0.5 TCY + 20 10 20 3 TCY + 40 N PIC18FXXXX PIC18LFXXXX 54 TccF CCPx Output Fall Time PIC18FXXXX PIC18LFXXXX -- -- -- -- Max -- -- -- -- -- -- -- 25 45 25 45 Units ns ns ns ns ns ns ns ns ns ns ns VDD = 2.0V VDD = 2.0V VDD = 2.0V N = prescale value (1, 4 or 16) VDD = 2.0V Conditions
51
TccH
52 53
TccP TccR
CCPx Input Period CCPx Output Fall Time
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FIGURE 27-12:
RE2/CS
PARALLEL SLAVE PORT TIMING (PIC18F4221/4321)
RE0/RD
RE1/WR
65 RD<7:0> 62 63 Note: Refer to Figure 27-5 for load conditions.
64
TABLE 27-13: PARALLEL SLAVE PORT REQUIREMENTS (PIC18F4221/4321)
Param. No. 62 63 64 65 66 Symbol TdtV2wrH TwrH2dtI TrdL2dtV TrdH2dtI TibfINH Characteristic Data In Valid before WR or CS (setup time) WR or CS to Data-In Invalid (hold time) PIC18FXXXX PIC18LFXXXX Min 20 20 35 -- 10 -- Max -- -- -- 80 30 3 TCY Units ns ns ns ns ns VDD = 2.0V Conditions
RD and CS to Data-Out Valid RD or CS to Data-Out Invalid Inhibit of the IBF Flag bit being Cleared from WR or CS
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FIGURE 27-13:
SS
EXAMPLE SPI MASTER MODE TIMING (CKE = 0)
SCK (CKP = 0) 78 SCK (CKP = 1) 79 MSb 75, 76 SDI MSb In 74 73 bit 6 - - - -1 LSb In bit 6 - - - - - -1 78 LSb 79
80 SDO
TABLE 27-14: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 0)
Param No. 73 73A 74 75 76 78 79 80 Symbol TdiV2scH, TdiV2scL Tb2b TscH2diL, TscL2diL TdoR TdoF TscR TscF TscH2doV, TscL2doV Characteristic Setup Time of SDI Data Input to SCK Edge Last Clock Edge of Byte 1 to the 1st Clock Edge of Byte 2 Hold Time of SDI Data Input to SCK Edge SDO Data Output Rise Time SDO Data Output Fall Time SCK Output Rise Time SCK Output Fall Time SDO Data Output Valid after SCK Edge PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX Min 20 1.5 TCY + 40 40 -- -- -- -- -- -- -- -- Max Units -- -- -- 25 45 25 25 45 25 50 100 ns ns ns ns ns ns ns ns ns ns ns VDD = 2.0V VDD = 2.0V VDD = 2.0V Conditions
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FIGURE 27-14:
SS 81 SCK (CKP = 0) 79
EXAMPLE SPI MASTER MODE TIMING (CKE = 1)
73 SCK (CKP = 1)
80 78 MSb 75, 76 bit 6 - - - - - -1 LSb
SDO
SDI
MSb In 74
bit 6 - - - -1
LSb In
TABLE 27-15: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 1)
Param. No. 73 73A 74 75 76 78 79 80 81 Symbol TdiV2scH, TdiV2scL Tb2b TscH2diL, TscL2diL TdoR TdoF TscR TscF TscH2doV, TscL2doV TdoV2scH, TdoV2scL Characteristic Setup Time of SDI Data Input to SCK Edge Last Clock Edge of Byte 1 to the 1st Clock Edge of Byte 2 Hold Time of SDI Data Input to SCK Edge SDO Data Output Rise Time SDO Data Output Fall Time SCK Output Rise Time SCK Output Fall Time SDO Data Output Valid after SCK Edge PIC18FXXXX PIC18LFXXXX TCY PIC18FXXXX PIC18LFXXXX -- -- PIC18FXXXX PIC18LFXXXX -- -- Min 20 1.5 TCY + 40 40 -- Max Units -- -- -- 25 45 25 25 45 25 50 100 -- ns ns ns ns ns ns ns ns ns ns ns ns VDD = 2.0V VDD = 2.0V VDD = 2.0V Conditions
SDO Data Output Setup to SCK Edge
DS39689F-page 362
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FIGURE 27-15:
SS 70 SCK (CKP = 0) 71 72 83
EXAMPLE SPI SLAVE MODE TIMING (CKE = 0)
SCK (CKP = 1)
80 SDO MSb 75, 76 SDI MSb In 73 74 bit 6 - - - -1 LSb In bit 6 - - - - - -1 LSb 77
TABLE 27-16: EXAMPLE SPI MODE REQUIREMENTS (SLAVE MODE TIMING, CKE = 0)
Param No. 70 71 71A 72 72A 73 73A 74 75 76 77 80 83 Note 1: 2: TscL SCK Input Low Time Symbol Characteristic Min 3 TCY Continuous Single Byte Continuous Single Byte TdiV2scH, Setup Time of SDI Data Input to SCK Edge TdiV2scL Tb2b TscH2diL, Hold Time of SDI Data Input to SCK Edge TscL2diL TdoR TdoF SDO Data Output Rise Time SDO Data Output Fall Time PIC18FXXXX PIC18LFXXXX -- 10 -- 1.5 TCY + 40 TssH2doZ SS to SDO Output High-Impedance TscH2doV, SDO Data Output Valid after SCK Edge PIC18FXXXX TscL2doV PIC18LFXXXX TscH2ssH, SS after SCK edge TscL2ssH Requires the use of Parameter #73A. Only if Parameter #71A and #72A are used. 1.25 TCY + 30 40 1.25 TCY + 30 40 20 Max Units Conditions -- -- -- -- -- -- -- -- 25 45 25 50 50 100 -- ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns VDD = 2.0V VDD = 2.0V (Note 2) (Note 1) (Note 1)
TssL2scH, SS to SCK or SCK Input TssL2scL TscH SCK Input High Time
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40 40 --
(c) 2009 Microchip Technology Inc.
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FIGURE 27-16:
SS
EXAMPLE SPI SLAVE MODE TIMING (CKE = 1)
82
SCK (CKP = 0)
70 83 71 72
SCK (CKP = 1) 80
SDO
MSb 75, 76
bit 6 - - - - - -1
LSb 77
SDI
MSb In 74
bit 6 - - - -1
LSb In
TABLE 27-17: EXAMPLE SPI SLAVE MODE REQUIREMENTS (CKE = 1)
Param No. 70 71 71A 72 72A 73A 74 75 76 77 80 82 83 Tb2b TscL SCK Input Low Time Symbol Characteristic Min 3 TCY Continuous Single Byte Continuous Single Byte TscH2diL, Hold Time of SDI Data Input to SCK Edge TscL2diL TdoR TdoF SDO Data Output Rise Time SDO Data Output Fall Time PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX -- 10 -- -- -- -- 1.5 TCY + 40 TssH2doZ SS to SDO Output High-Impedance TscH2doV, SDO Data Output Valid after SCK TscL2doV Edge TssL2doV SDO Data Output Valid after SS Edge TscH2ssH, SS after SCK Edge TscL2ssH Requires the use of Parameter #73A. Only if Parameter #71A and #72A are used. 1.25 TCY + 30 40 1.25 TCY + 30 40 40 -- Max Units Conditions -- -- -- -- -- -- -- 25 45 25 50 50 100 50 100 -- ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns VDD = 2.0V VDD = 2.0V VDD = 2.0V (Note 1) (Note 2) (Note 1)
TssL2scH, SS to SCK or SCK Input TssL2scL TscH SCK Input High Time
Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40
Note 1: 2:
DS39689F-page 364
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FIGURE 27-17: I2CTM BUS START/STOP BITS TIMING
SCL 91 90 92 93
SDA
Start Condition
Stop Condition
TABLE 27-18: I2CTM BUS START/STOP BITS REQUIREMENTS (SLAVE MODE)
Param. Symbol No. 90 91 92 93 TSU:STA THD:STA TSU:STO Setup Time Start Condition Hold Time Stop Condition Setup Time THD:STO Stop Condition Hold Time Characteristic Start Condition 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode Min 4700 600 4000 600 4700 600 4000 600 Max -- -- -- -- -- -- -- -- ns ns ns Units ns Conditions Only relevant for Repeated Start condition After this period, the first clock pulse is generated
FIGURE 27-18:
I2CTM BUS DATA TIMING
103 100 101 102
SCL
90 91
106
107 92
SDA In
110 109 109
SDA Out
(c) 2009 Microchip Technology Inc.
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TABLE 27-19: I2CTM BUS DATA REQUIREMENTS (SLAVE MODE)
Param. Symbol No. 100 THIGH Characteristic Clock High Time 100 kHz mode 400 kHz mode MSSP Module 101 TLOW Clock Low Time 100 kHz mode 400 kHz mode MSSP Module 102 TR SDA and SCL Rise 100 kHz mode Time 400 kHz mode SDA and SCL Fall Time 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode D102 Note 1: 2: CB Bus Capacitive Loading Min 4.0 0.6 1.5 TCY 4.7 1.3 1.5 TCY -- 20 + 0.1 CB -- 20 + 0.1 CB 4.7 0.6 4.0 0.6 0 0 250 100 4.7 0.6 -- -- 4.7 1.3 -- Max -- -- -- -- -- -- 1000 300 300 300 -- -- -- -- -- 0.9 -- -- -- -- 3500 -- -- -- 400 ns ns ns ns s s s s ns s ns ns s s ns ns s s pF Time the bus must be free before a new transmission can start (Note 1) (Note 2) CB is specified to be from 10 to 400 pF Only relevant for Repeated Start condition After this period, the first clock pulse is generated CB is specified to be from 10 to 400 pF s s Units s s Conditions
103
TF
90 91 106 107 92 109 110
TSU:STA Start Condition Setup Time THD:STA Start Condition Hold Time THD:DAT Data Input Hold Time TSU:DAT Data Input Setup Time TSU:STO Stop Condition Setup Time TAA TBUF Output Valid from Clock Bus Free Time
As a transmitter, the device must provide this internal minimum delay time to bridge the undefined region (min. 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions. A Fast mode I2C bus device can be used in a Standard mode I2C bus system, but the requirement TSU:DAT 250 ns must then be met. This will automatically be the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line, TR max. + TSU:DAT = 1000 + 250 = 1250 ns (according to the Standard mode I2C bus specification), before the SCL line is released.
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FIGURE 27-19: MASTER SSP I2CTM BUS START/STOP BITS TIMING WAVEFORMS
SCL 90 SDA
91 92
93
Start Condition
Stop Condition
TABLE 27-20: MASTER SSP I2CTM BUS START/STOP BITS REQUIREMENTS
Param. Symbol No. 90 TSU:STA Characteristic Start Condition Setup Time 91 THD:STA Start Condition Hold Time 92 TSU:STO Stop Condition Setup Time 93 THD:STO Stop Condition Hold Time 100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 1 MHz mode(1) Note 1: Maximum pin capacitance = 10 pF for all I2C Min 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) pins. Max -- -- -- -- -- -- -- -- -- -- -- -- ns ns ns Units ns Conditions Only relevant for Repeated Start condition After this period, the first clock pulse is generated
FIGURE 27-20:
MASTER SSP I2CTM BUS DATA TIMING
103 100 101 102
SCL SDA In
90
91
106
107
92
109
109
110
SDA Out
(c) 2009 Microchip Technology Inc.
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TABLE 27-21: MASTER SSP I2CTM BUS DATA REQUIREMENTS
Param. Symbol No. 100 THIGH Characteristic Clock High Time 100 kHz mode 400 kHz mode 1 MHz mode(1) 101 TLOW Clock Low Time 100 kHz mode 400 kHz mode 1 MHz mode 102 TR SDA and SCL Rise Time SDA and SCL Fall Time Start Condition Setup Time
(1)
Min 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) -- 20 + 0.1 CB -- -- 20 + 0.1 CB -- 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 0 0 250 100 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) 2(TOSC)(BRG + 1) -- -- -- 4.7 1.3 --
2C
Max -- -- -- -- -- -- 1000 300 300 300 300 100 -- -- -- -- -- -- -- 0.9 -- -- -- -- -- 3500 1000 -- -- -- 400
Units ms ms ms ms ms ms ns ns ns ns ns ns ms ms ms ms ms ms ns ms ns ns ms ms ms ns ns ns ms ms pF
Conditions
100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 100 kHz mode 400 kHz mode 1 MHz mode(1) 100 kHz mode 400 kHz mode 1 MHz mode
(1)
CB is specified to be from 10 to 400 pF CB is specified to be from 10 to 400 pF Only relevant for Repeated Start condition After this period, the first clock pulse is generated
103
TF
90
TSU:STA
91
THD:STA Start Condition Hold Time THD:DAT Data Input Hold Time TSU:DAT Data Input Setup Time
106 107 92
(Note 2)
TSU:STO Stop Condition Setup Time TAA Output Valid from Clock Bus Free Time
109
110
TBUF
100 kHz mode 400 kHz mode
Time the bus must be free before a new transmission can start
D102 Note 1: 2:
CB
Bus Capacitive Loading
Maximum pin capacitance = 10 pF for all I pins. A Fast mode I2C bus device can be used in a Standard mode I2C bus system, but parameter 107 250 ns must then be met. This will automatically be the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line, parameter 102 + parameter 107 = 1000 + 250 = 1250 ns (for 100 kHz mode), before the SCL line is released.
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FIGURE 27-21: EUSART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
RC6/TX/CK pin RC7/RX/DT pin 120
121
121
122
TABLE 27-22: EUSART SYNCHRONOUS TRANSMISSION REQUIREMENTS
Param No. 120 Symbol Characteristic Min Max Units Conditions
TckH2dtV SYNC XMIT (MASTER & SLAVE) Clock High to Data Out Valid Tckrf Tdtrf Clock Out Rise Time and Fall Time (Master mode) Data Out Rise Time and Fall Time
PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX
-- -- -- -- -- --
40 100 20 50 20 50
ns ns ns ns ns ns VDD = 2.0V VDD = 2.0V VDD = 2.0V
121 122
FIGURE 27-22:
RC6/TX/CK pin RC7/RX/DT pin
EUSART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
125
126
TABLE 27-23: EUSART SYNCHRONOUS RECEIVE REQUIREMENTS
Param. No. 125 126 Symbol TdtV2ckl TckL2dtl Characteristic SYNC RCV (MASTER & SLAVE) Data Hold before CK (DT hold time) Data Hold after CK (DT hold time) Min Max Units Conditions
10 15
-- --
ns ns
(c) 2009 Microchip Technology Inc.
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TABLE 27-24: A/D CONVERTER CHARACTERISTICS
Param Symbol No. A01 A03 A04 A06 A07 A10 A20 A21 A22 A25 A30 A50 NR EIL EDL EOFF EGN -- VREF VREFH VREFL VAIN ZAIN IREF Characteristic Resolution Integral Linearity Error Differential Linearity Error Offset Error Gain Error Monotonicity Reference Voltage Range (VREFH - VREFL) Reference Voltage High Reference Voltage Low Analog Input Voltage Recommended Impedance of Analog Voltage Source VREF Input Current(2) 1.8 3 -- VSS - 0.3V VREFL -- -- -- Min -- -- -- -- -- Typ -- -- -- -- -- Guaranteed(1) -- -- -- -- -- -- -- -- -- -- VDD + 3.0V -- VREFH 2.5 5 150 Max 10 <1 <1 <2 <1 Units bit Conditions VREF 3.0V
LSb VREF 3.0V LSb VREF 3.0V LSb VREF 3.0V LSb VREF 3.0V -- V V V V V k A A During VAIN acquisition. During A/D conversion cycle. VSS VAIN VREF VDD < 3.0V VDD 3.0V
Note 1: 2:
The A/D conversion result never decreases with an increase in the input voltage and has no missing codes. VREFH current is from RA3/AN3/VREF+ pin or VDD, whichever is selected as the VREFH source. VREFL current is from RA2/AN2/VREF-/CVREF pin or VSS, whichever is selected as the VREFL source.
DS39689F-page 370
(c) 2009 Microchip Technology Inc.
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FIGURE 27-23: A/D CONVERSION TIMING
BSF ADCON0, GO (Note 2) Q4 A/D CLK
(1)
131 130
132
A/D DATA
9
8
7
...
...
2
1
0
ADRES ADIF GO
OLD_DATA
NEW_DATA TCY DONE
SAMPLE Note 1: 2:
SAMPLING STOPPED
If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock starts. This allows the SLEEP instruction to be executed. This is a minimal RC delay (typically 100 ns), which also disconnects the holding capacitor from the analog input.
TABLE 27-25: A/D CONVERSION REQUIREMENTS
Param Symbol No. 130 TAD Characteristic A/D Clock Period PIC18FXXXX PIC18LFXXXX PIC18FXXXX PIC18LFXXXX 131 132 135 137 Note 1: 2: 3: 4: TCNV TACQ TSWC TDIS Conversion Time (not including acquisition time)(2) Acquisition Time(3) Switching Time from Convert Sample Discharge Time Min 0.7 1.4 -- -- 11 1.4 -- 0.2 Max 25.0(1) 25.0(1) 1 3 12 -- (Note 4) -- s Units s s s s TAD s -40C to +85C Conditions TOSC based, VREF 3.0V VDD = 2.0V; TOSC based, VREF full range A/D RC mode VDD = 2.0V; A/D RC mode
The time of the A/D clock period is dependent on the device frequency and the TAD clock divider. ADRES register may be read on the following TCY cycle. The time for the holding capacitor to acquire the "New" input voltage when the voltage changes full scale after the conversion (VDD to VSS or VSS to VDD). The source impedance (RS) on the input channels is 50. On the following cycle of the device clock.
(c) 2009 Microchip Technology Inc.
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NOTES:
DS39689F-page 372
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28.0
28.1
PACKAGING INFORMATION
Package Marking Information
28-Lead SPDIP
XXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXX YYWWNNN
Example
PIC18F2321-I/SP e3 0910017
28-Lead SOIC
XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXX YYWWNNN
Example
PIC18F2321-E/SO e3 0910017
28-Lead QFN
Example
XXXXXXXX XXXXXXXX YYWWNNN
18F2321 /ML e3 0910017
28-Lead SSOP XXXXXXXXXXXX XXXXXXXXXXXX YYWWNNN
Example PIC18F2321 -I/SS e3 0910017
Legend: XX...X Y YY WW NNN
e3
* Note:
Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week `01') Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package.
In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information.
(c) 2009 Microchip Technology Inc.
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28.1 Package Marking Information (Continued)
40-Lead PDIP
XXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXX YYWWNNN
Example
PIC18F4321-I/P e3 0910017
44-Lead QFN
Example
XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX YYWWNNN
PIC18F4321 -I/ML e3 0910017
44-Lead TQFP
Example
XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX YYWWNNN
PIC18F4321 -I/PT e3 0910017
DS39689F-page 374
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APPENDIX A: REVISION HISTORY
Revision A (July 2005)
Original data sheet for PIC18F2221/2321/4221/4321 devices.
Revision B (August 2006)
Updated Section 26.0 "Electrical Characteristic".
Revision C (October 2006)
This revision includes updates to the packaging diagrams.
Revision D (January 2007)
This revision includes updates to the packaging diagrams.
Revision E (February 2007)
This revision includes updates to the packaging diagrams.
Revision F (September 2009)
This revision includes a new chapter, Section 2.0 "Guidelines for Getting Started with PIC18F Microcontrollers". There are also updates to Section 27.0 "Electrical Characteristics", Section 28.0 "Packaging Information" and minor text edits throughout document.
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APPENDIX B: DEVICE DIFFERENCES
The differences between the devices listed in this data sheet are shown in Table B-1.
TABLE B-1:
DEVICE DIFFERENCES
PIC18F2221 4096 2048 19 Ports A, B, C, (E) 2 0 No 10 input channels 28-pin SPDIP 28-pin SOIC 28-pin SSOP 28-pin QFN PIC18F2321 8192 4096 19 Ports A, B, C, (E) 2 0 No 10 input channels 28-pin SPDIP 28-pin SOIC 28-pin SSOP 28-pin QFN PIC18F4221 4096 2048 20 1 1 Yes 13 input channels 40-pin PDIP 44-pin TQFP 44-pin QFN PIC18F4321 8192 4096 20 1 1 Yes 13 input channels 40-pin PDIP 44-pin TQFP 44-pin QFN
Features Program Memory (Bytes) Program Memory (Instructions) Interrupt Sources I/O Ports Capture/Compare/PWM Modules Enhanced Capture/Compare/ PWM Modules Parallel Communications (PSP) 10-Bit Analog-to-Digital Module Packages
Ports A, B, C, D, E Ports A, B, C, D, E
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APPENDIX C: CONVERSION CONSIDERATIONS APPENDIX D: MIGRATION FROM BASELINE TO ENHANCED DEVICES
This appendix discusses the considerations for converting from previous versions of a device to the ones listed in this data sheet. Typically, these changes are due to the differences in the process technology used. An example of this type of conversion is from a PIC16C74A to a PIC16C74B. The PIC18F2221/2321/4221/4321 family of devices is functionally the same as the PIC18F4320 family. Code written for a PIC18F4320 will generally work on a PIC18F4321 with few or no changes. The following is a list of changes the user should be aware of when migrating an application from the PIC18F4320 to the PIC18F4321. Code written for the PIC18F4321 may not run as expected due to these differences. 1. Entry to power-managed modes has changed. Modifying the SCS1:SCS0 bits (OSCCON<1:0>) immediately changes the current clock source. It is not necessary to execute a SLEEP instruction to change clock sources. Refer to Section 4.1.2 "Entering Power-Managed Modes" for details. Exit from power-managed modes has changed. A WDT wake or interrupt does not cause an automatic return to PRI_RUN mode. The controller will execute code while continuing to use the current clock source. If the controller was operating in RC_IDLE or RC_RUN mode, an interrupt will cause entry to RC_RUN mode until code selects another power-managed mode. Refer to Section 4.4 "Idle Modes" for details. The extended instruction set can be configured as enabled using the XINST bit (CONFIG4L<6>). The access memory map is also modified when the extended instruction set is enabled. Refer to Section 6.5 "Data Memory and the Extended Instruction Set" and Section 24.2 "Extended Instruction Set" for details. There may also be changes to the electrical specifications. Refer to Section 27.0 "Electrical Characteristics" for details.
This section discusses how to migrate from a Baseline device (i.e., PIC16C5X) to an Enhanced MCU device (i.e., PIC18FXXX). The following are the list of modifications over the PIC16C5X microcontroller family: Not Currently Available
2.
3.
4.
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APPENDIX E: MIGRATION FROM MID-RANGE TO ENHANCED DEVICES APPENDIX F: MIGRATION FROM HIGH-END TO ENHANCED DEVICES
A detailed discussion of the differences between the mid-range MCU devices (i.e., PIC16CXXX) and the Enhanced devices (i.e., PIC18FXXX) is provided in AN716, "Migrating Designs from PIC16C74A/74B to PIC18C442". The changes discussed, while device specific, are generally applicable to all mid-range to Enhanced device migrations. This Application Note is available as Literature Number DS00716.
A detailed discussion of the migration pathway and differences between the high-end MCU devices (i.e., PIC17CXXX) and the Enhanced devices (i.e., PIC18FXXX) is provided in AN726, "PIC17CXXX to PIC18CXXX Migration". This Application Note is available as Literature Number DS00726.
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INDEX
A
A/D ................................................................................... 233 Acquisition Requirements ........................................ 238 ADCON0 Register .................................................... 233 ADCON1 Register .................................................... 233 ADCON2 Register .................................................... 233 ADRESH Register ............................................ 233, 236 ADRESL Register .................................................... 233 Analog Port Pins, Configuring .................................. 240 Associated Registers ............................................... 242 Configuring the Module ............................................ 237 Conversion Clock (TAD) ........................................... 239 Conversion Requirements ....................................... 371 Conversion Status (GO/DONE Bit) .......................... 236 Conversions ............................................................. 241 Converter Characteristics ........................................ 370 Converter Interrupt, Configuring .............................. 237 Discharge ................................................................. 241 Operation in Power-Managed Modes ...................... 240 Selecting and Configuring Acquisition Time ............ 239 Special Event Trigger (CCP) .................................... 242 Special Event Trigger (ECCP) ................................. 154 Use of the CCP2 Trigger .......................................... 242 Absolute Maximum Ratings ............................................. 333 AC (Timing) Characteristics ............................................. 352 Load Conditions for Device Timing Specifications ................................................... 353 Parameter Symbology ............................................. 352 Temperature and Voltage Specifications ................. 353 Timing Conditions .................................................... 353 AC Characteristics Internal RC Accuracy ............................................... 355 Access Bank Mapping with Indexed Literal Offset Addressing Mode ............................................... 77 ACKSTAT ........................................................................ 201 ACKSTAT Status Flag ..................................................... 201 ADCON0 Register ............................................................ 233 GO/DONE Bit ........................................................... 236 ADCON1 Register ............................................................ 233 ADCON2 Register ............................................................ 233 ADDFSR .......................................................................... 322 ADDLW ............................................................................ 285 ADDULNK ........................................................................ 322 ADDWF ............................................................................ 285 ADDWFC ......................................................................... 286 ADRESH Register ............................................................ 233 ADRESL Register .................................................... 233, 236 Analog-to-Digital Converter. See A/D. ANDLW ............................................................................ 286 ANDWF ............................................................................ 287 Assembler MPASM Assembler .................................................. 330 Auto-Wake-up on Sync Break Character ......................... 226 Block Diagrams A/D ........................................................................... 236 Analog Input Model .................................................. 237 Baud Rate Generator .............................................. 197 Capture Mode Operation ......................................... 147 Comparator Analog Input Model .............................. 247 Comparator I/O Operating Modes ........................... 244 Comparator Output .................................................. 246 Comparator Voltage Reference ............................... 250 Comparator Voltage Reference Output Buffer Example ................................................ 251 Compare Mode Operation ....................................... 148 Device Clock .............................................................. 35 Enhanced PWM ....................................................... 155 EUSART Receive .................................................... 225 EUSART Transmit ................................................... 222 External Power-on Reset Circuit (Slow VDD Power-up) ........................................ 49 Fail-Safe Clock Monitor ........................................... 272 Generic I/O Port ....................................................... 111 High/Low-Voltage Detect with External Input .......... 254 HSPLL ....................................................................... 31 Interrupt Logic ............................................................ 98 INTOSC and PLL ....................................................... 32 MSSP (I2C Master Mode) ........................................ 195 MSSP (I2C Mode) .................................................... 176 MSSP (SPI Mode) ................................................... 167 On-Chip Reset Circuit ................................................ 47 PIC18F2221/2321 ..................................................... 12 PIC18F4221/4321 ..................................................... 13 PORTD and PORTE (Parallel Slave Port) ............... 126 PWM Operation (Simplified) .................................... 150 Reads from Flash Program Memory ......................... 83 Single Comparator ................................................... 245 Table Read Operation ............................................... 79 Table Write Operation ............................................... 80 Table Writes to Flash Program Memory .................... 85 Timer0 in 16-Bit Mode ............................................. 130 Timer0 in 8-Bit Mode ............................................... 130 Timer1 ..................................................................... 134 Timer1 (16-Bit Read/Write Mode) ............................ 134 Timer2 ..................................................................... 140 Timer3 ..................................................................... 142 Timer3 (16-Bit Read/Write Mode) ............................ 142 Watchdog Timer ...................................................... 269 BN .................................................................................... 288 BNC ................................................................................. 289 BNN ................................................................................. 289 BNOV .............................................................................. 290 BNZ ................................................................................. 290 BOR. See Brown-out Reset. BOV ................................................................................. 293 BRA ................................................................................. 291 Break Character (12-Bit) Transmit and Receive .............. 227 BRG. See Baud Rate Generator. Brown-out Reset (BOR) ..................................................... 50 Detecting ................................................................... 50 Disabling in Sleep Mode ............................................ 50 Software Enabled ...................................................... 50 BSF .................................................................................. 291 BTFSC ............................................................................. 292 BTFSS ............................................................................. 292 BTG ................................................................................. 293 BZ .................................................................................... 294
B
Bank Select Register (BSR) ............................................... 65 Baud Rate Generator ....................................................... 197 BC .................................................................................... 287 BCF .................................................................................. 288 BF .................................................................................... 201 BF Status Flag ................................................................. 201
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C
C Compilers MPLAB C18 ............................................................. 330 MPLAB C30 ............................................................. 330 CALL ................................................................................ 294 CALLW ............................................................................. 323 Capture (CCP Module) ..................................................... 147 Associated Registers ............................................... 149 CCP Pin Configuration ............................................. 147 CCPRxH:CCPRxL Registers ................................... 147 Prescaler .................................................................. 147 Software Interrupt .................................................... 147 Timer1/Timer3 Mode Selection ................................ 147 Capture (ECCP Module) .................................................. 154 Capture/Compare/PWM (CCP) ........................................ 145 Capture Mode. See Capture. CCPRxH Register .................................................... 146 CCPRxL Register ..................................................... 146 Compare Mode. See Compare. Interaction of Two CCP Modules ............................. 146 Module Configuration ............................................... 146 Pin Assignment ........................................................ 146 Timer Resources ...................................................... 146 Clock Sources .................................................................... 35 Selecting the 31 kHz Source ...................................... 36 Selection Using OSCCON Register ........................... 36 CLRF ................................................................................ 295 CLRWDT .......................................................................... 295 Code Examples 16 x 16 Signed Multiply Routine ................................ 96 16 x 16 Unsigned Multiply Routine ............................ 96 8 x 8 Signed Multiply Routine .................................... 95 8 x 8 Unsigned Multiply Routine ................................ 95 Address Masking ..................................................... 182 Changing Between Capture Prescalers ................... 147 Computed GOTO Using an Offset Value ................... 62 Data EEPROM Read ................................................. 91 Data EEPROM Refresh Routine ................................ 92 Data EEPROM Write ................................................. 91 Erasing a Flash Program Memory Row ..................... 84 Fast Register Stack .................................................... 62 How to Clear RAM (Bank 1) Using Indirect Addressing ......................................................... 73 Implementing a Real-Time Clock Using a Timer1 Interrupt Service .................................. 137 Initializing PORTA .................................................... 111 Initializing PORTB .................................................... 114 Initializing PORTC .................................................... 117 Initializing PORTD .................................................... 120 Initializing PORTE .................................................... 123 Loading the SSPBUF (SSPSR) Register ................. 170 Reading a Flash Program Memory Word .................. 83 Saving STATUS, WREG and BSR Registers in RAM ............................................. 109 Writing to Flash Program Memory ....................... 86-87 Code Protection ....................................................... 259, 274 Associated Registers ............................................... 275 Configuration Register Protection ............................ 277 Data EEPROM ......................................................... 277 Program Memory ..................................................... 275 COMF ............................................................................... 296 Comparator ...................................................................... 243 Analog Input Connection Considerations ................. 247 Associated Registers ............................................... 247 Configuration ............................................................ 244 Effects of a Reset .................................................... 246 Interrupts ................................................................. 246 Operation ................................................................. 245 Operation During Sleep ........................................... 246 Outputs .................................................................... 245 Reference ................................................................ 245 External Signal ................................................ 245 Internal Signal .................................................. 245 Response Time ........................................................ 245 Comparator Specifications ............................................... 350 Comparator Voltage Reference ....................................... 249 Accuracy and Error .................................................. 250 Associated Registers ............................................... 251 Configuring .............................................................. 249 Connection Considerations ...................................... 250 Effects of a Reset .................................................... 250 Operation During Sleep ........................................... 250 Compare (CCP Module) .................................................. 148 CCPRx Register ...................................................... 148 Pin Configuration ..................................................... 148 Software Interrupt .................................................... 148 Special Event Trigger .............................. 143, 148, 242 Timer1/Timer3 Mode Selection ................................ 148 Compare (ECCP Module) ................................................ 154 Special Event Trigger .............................................. 154 Computed GOTO ............................................................... 62 Configuration Bits ............................................................ 259 Context Saving During Interrupts ..................................... 109 Conversion Considerations .............................................. 387 CPFSEQ .......................................................................... 296 CPFSGT .......................................................................... 297 CPFSLT ........................................................................... 297 Crystal Oscillator/Ceramic Resonator ................................ 29 Customer Change Notification Service ............................ 399 Customer Notification Service ......................................... 399 Customer Support ............................................................ 399
D
Data Addressing Modes .................................................... 73 Comparing Options with the Extended Instruction Set Enabled ..................................... 76 Direct ......................................................................... 73 Indexed Literal Offset ................................................ 75 Instructions Affected .......................................... 75 Indirect ....................................................................... 73 Inherent and Literal .................................................... 73 Data EEPROM Memory ..................................................... 89 Associated Registers ................................................. 93 EEADR Register ........................................................ 89 EECON1 Register ...................................................... 89 EECON2 Register ...................................................... 89 EEDATA Register ...................................................... 89 Operation During Code-Protect ................................. 92 Protection Against Spurious Write ............................. 92 Reading ..................................................................... 91 Using ......................................................................... 92 Write Verify ................................................................ 91 Writing ....................................................................... 91 Data Memory ..................................................................... 65 Access Bank .............................................................. 67 and the Extended Instruction Set .............................. 75 Bank Select Register (BSR) ...................................... 65 General Purpose Registers ....................................... 67 Map for PIC18F2221/2321/4221/4321 Family ........... 66 Special Function Registers ........................................ 68
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DAW ................................................................................. 298 DC Characteristics ........................................................... 347 Power-Down and Supply Current ............................ 337 Supply Voltage ......................................................... 336 DCFSNZ .......................................................................... 299 DECF ............................................................................... 298 DECFSZ ........................................................................... 299 Development Support ...................................................... 329 Device Differences ........................................................... 386 Device Overview .................................................................. 9 Details on Individual Family Members ....................... 10 Features (table) .......................................................... 11 New Core Features ...................................................... 9 Other Special Features .............................................. 10 Device Reset Timers .......................................................... 51 Oscillator Start-up Timer (OST) ................................. 51 PLL Lock Time-out ..................................................... 51 Power-up Timer (PWRT) ........................................... 51 Time-out Sequence .................................................... 51 Direct Addressing ............................................................... 74 Synchronous Master Mode ...................................... 228 Associated Registers, Receive ........................ 230 Associated Registers, Transmit ....................... 229 Reception ........................................................ 230 Transmission ................................................... 228 Synchronous Slave Mode ........................................ 231 Associated Registers, Receive ........................ 232 Associated Registers, Transmit ....................... 231 Reception ........................................................ 232 Transmission ................................................... 231 Extended Instruction Set ADDFSR .................................................................. 322 ADDULNK ............................................................... 322 and Using MPLAB Tools ......................................... 328 CALLW .................................................................... 323 Considerations for Use ............................................ 326 MOVSF .................................................................... 323 MOVSS .................................................................... 324 PUSHL ..................................................................... 324 SUBFSR .................................................................. 325 SUBULNK ................................................................ 325 Syntax ...................................................................... 321 External Clock Input ........................................................... 30
E
Effect on Standard PIC MCU Instructions ........................ 326 Effects of Power-Managed Modes on Various Clock Sources ............................................................ 38 Electrical Characteristics .................................................. 333 Enhanced Capture/Compare/PWM (ECCP) .................... 153 Associated Registers ............................................... 166 Capture and Compare Modes .................................. 154 Capture Mode. See Capture (ECCP Module). Outputs and Configuration ....................................... 154 Pin Configurations for ECCP1 ................................. 154 PWM Mode. See PWM (ECCP Module). Standard PWM Mode ............................................... 154 Timer Resources ...................................................... 154 Enhanced PWM Mode. See PWM (ECCP Module). ........ 155 Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART). See EUSART. Equations A/D Acquisition Time ................................................ 238 A/D Minimum Charging Time ................................... 238 Calculating the Minimum Required Acquisition Time .............................................. 238 Errata ................................................................................... 8 EUSART Asynchronous Mode ................................................ 221 12-Bit Break Transmit and Receive ................. 227 Associated Registers, Receive ........................ 225 Associated Registers, Transmit ....................... 223 Auto-Wake-up on Sync Break ......................... 226 Receiver ........................................................... 224 Setting up 9-Bit Mode with Address Detect ..... 224 Transmitter ....................................................... 221 Baud Rate Generator Operation in Power-Managed Mode ................ 215 Baud Rate Generator (BRG) .................................... 215 Associated Registers ....................................... 216 Auto-Baud Rate Detect .................................... 219 Baud Rate Error, Calculating ........................... 216 Baud Rates, Asynchronous Modes ................. 217 High Baud Rate Select (BRGH Bit) ................. 215 Sampling .......................................................... 215
F
Fail-Safe Clock Monitor ........................................... 259, 272 Exiting Operation ..................................................... 272 Interrupts in Power-Managed Modes ...................... 273 POR or Wake From Sleep ....................................... 273 WDT During Oscillator Failure ................................. 272 Fast Register Stack ........................................................... 62 Firmware Instructions ...................................................... 279 Flash Program Memory ..................................................... 79 Associated Registers ................................................. 87 Control Registers ....................................................... 80 EECON1 and EECON2 ..................................... 80 TABLAT (Table Latch) Register ........................ 82 TBLPTR (Table Pointer) Register ...................... 82 Erase Sequence ........................................................ 84 Erasing ...................................................................... 84 Operation During Code-Protect ................................. 87 Reading ..................................................................... 83 Table Pointer Boundaries ........................................................ 82 Boundaries Based on Operation ....................... 82 Operations with TBLRD and TBLWT (table) ..... 82 Table Reads and Table Writes .................................. 79 Write Sequence ......................................................... 85 Writing ....................................................................... 85 Protection Against Spurious Writes ................... 87 Unexpected Termination ................................... 87 Write Verify ........................................................ 87 FSCM. See Fail-Safe Clock Monitor.
G
GOTO .............................................................................. 300
H
Hardware Multiplier ............................................................ 95 Introduction ................................................................ 95 Operation ................................................................... 95 Performance Comparison .......................................... 95
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High/Low-Voltage Detect ................................................. 253 Applications .............................................................. 256 Associated Registers ............................................... 257 Characteristics ......................................................... 351 Current Consumption ............................................... 255 Effects of a Reset ..................................................... 257 Operation ................................................................. 254 During Sleep .................................................... 257 Setup ........................................................................ 255 Start-up Time ........................................................... 255 Typical Application ................................................... 256 HLVD. See High/Low-Voltage Detect. ............................. 253 Instruction Cycle ................................................................ 63 Clocking Scheme ....................................................... 63 Instruction Flow/Pipelining ................................................. 63 Instruction Set .................................................................. 279 ADDLW .................................................................... 285 ADDWF .................................................................... 285 ADDWF (Indexed Literal Offset Mode) .................... 327 ADDWFC ................................................................. 286 ANDLW .................................................................... 286 ANDWF .................................................................... 287 BC ............................................................................ 287 BCF ......................................................................... 288 BN ............................................................................ 288 BNC ......................................................................... 289 BNN ......................................................................... 289 BNOV ...................................................................... 290 BNZ ......................................................................... 290 BOV ......................................................................... 293 BRA ......................................................................... 291 BSF .......................................................................... 291 BSF (Indexed Literal Offset Mode) .......................... 327 BTFSC ..................................................................... 292 BTFSS ..................................................................... 292 BTG ......................................................................... 293 BZ ............................................................................ 294 CALL ........................................................................ 294 CLRF ....................................................................... 295 CLRWDT ................................................................. 295 COMF ...................................................................... 296 CPFSEQ .................................................................. 296 CPFSGT .................................................................. 297 CPFSLT ................................................................... 297 DAW ........................................................................ 298 DCFSNZ .................................................................. 299 DECF ....................................................................... 298 DECFSZ .................................................................. 299 Extended Instruction Set ......................................... 321 General Format ........................................................ 281 GOTO ...................................................................... 300 INCF ........................................................................ 300 INCFSZ .................................................................... 301 INFSNZ .................................................................... 301 IORLW ..................................................................... 302 IORWF ..................................................................... 302 LFSR ....................................................................... 303 MOVF ...................................................................... 303 MOVFF .................................................................... 304 MOVLB .................................................................... 304 MOVLW ................................................................... 305 MOVWF ................................................................... 305 MULLW .................................................................... 306 MULWF .................................................................... 306 NEGF ....................................................................... 307 NOP ......................................................................... 307 Opcode Field Descriptions ....................................... 280 POP ......................................................................... 308 PUSH ....................................................................... 308 RCALL ..................................................................... 309 RESET ..................................................................... 309 RETFIE .................................................................... 310 RETLW .................................................................... 310 RETURN .................................................................. 311 RLCF ....................................................................... 311 RLNCF ..................................................................... 312 RRCF ....................................................................... 312
I
I/O Ports ........................................................................... 111 I2C Mode (MSSP) Acknowledge Sequence Timing ............................... 204 Associated Registers ............................................... 210 Baud Rate Generator ............................................... 197 Bus Collision During a Repeated Start Condition .................. 208 During a Start Condition ................................... 206 During a Stop Condition ................................... 209 Clock Arbitration ....................................................... 198 Clock Stretching ....................................................... 190 10-Bit Slave Receive Mode (SEN = 1) ............. 190 10-Bit Slave Transmit Mode ............................. 190 7-Bit Slave Receive Mode (SEN = 1) ............... 190 7-Bit Slave Transmit Mode ............................... 190 Clock Synchronization and the CKP Bit ................... 191 Effects of a Reset ..................................................... 205 General Call Address Support ................................. 194 I2C Clock Rate w/BRG ............................................. 197 Master Mode ............................................................ 195 Operation ......................................................... 196 Reception ......................................................... 201 Repeated Start Condition Timing ..................... 200 Start Condition Timing ..................................... 199 Transmission .................................................... 201 Multi-Master Communication, Bus Collision and Arbitration .................................................. 205 Multi-Master Mode ................................................... 205 Operation ................................................................. 181 Read/Write Bit Information (R/W Bit) ....................... 181 Read/Write Bit Information (R/W Bit) ....................... 183 Registers .................................................................. 176 Serial Clock (RC3/SCK/SCL) ................................... 183 Slave Mode .............................................................. 181 Address Masking ............................................. 182 Addressing ....................................................... 181 Reception ......................................................... 183 Transmission .................................................... 183 Sleep Operation ....................................................... 205 Stop Condition Timing .............................................. 204 ID Locations ............................................................. 259, 277 INCF ................................................................................. 300 INCFSZ ............................................................................ 301 In-Circuit Debugger .......................................................... 277 In-Circuit Serial Programming (ICSP) ...................... 259, 277 Single-Supply ........................................................... 277 Indexed Literal Offset Addressing and Standard PIC18 Instructions ............................. 326 Indexed Literal Offset Mode ............................................. 326 Indirect Addressing ............................................................ 74 INFSNZ ............................................................................ 301 Initialization Conditions for all Registers ...................... 55-58
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RRNCF .................................................................... 313 SETF ........................................................................ 313 SETF (Indexed Literal Offset Mode) ........................ 327 SLEEP ..................................................................... 314 Standard Instructions ............................................... 279 SUBFWB .................................................................. 314 SUBLW .................................................................... 315 SUBWF .................................................................... 315 SUBWFB .................................................................. 316 SWAPF .................................................................... 316 TBLRD ..................................................................... 317 TBLWT ..................................................................... 318 TSTFSZ ................................................................... 319 XORLW .................................................................... 319 XORWF .................................................................... 320 INTCON Registers ..................................................... 99-101 Inter-Integrated Circuit. See I2C. Internal Oscillator Block ..................................................... 32 Adjustment ................................................................. 32 INTIO Modes .............................................................. 32 INTOSC Frequency Drift ............................................ 33 INTOSC Output Frequency ........................................ 32 OSCTUNE Register ................................................... 32 PLL in INTOSC Modes .............................................. 33 Internal RC Oscillator Use with WDT .......................................................... 269 Internet Address ............................................................... 399 Interrupt Sources ............................................................. 259 A/D Conversion Complete ....................................... 237 Capture Complete (CCP) ......................................... 147 Compare Complete (CCP) ....................................... 148 Interrupt-on-Change (RB7:RB4) .............................. 114 INTx Pin ................................................................... 109 PORTB, Interrupt-on-Change .................................. 109 TMR0 ....................................................................... 109 TMR0 Overflow ........................................................ 131 TMR1 Overflow ........................................................ 133 TMR2 to PR2 Match (PWM) ............................ 150, 155 TMR3 Overflow ................................................ 141, 143 Interrupts ............................................................................ 97 INTOSC, INTRC. See Internal Oscillator Block. IORLW ............................................................................. 302 IORWF ............................................................................. 302 IPR Registers ................................................................... 106 MOVSS ............................................................................ 324 MOVWF ........................................................................... 305 MPLAB ASM30 Assembler, Linker, Librarian .................. 330 MPLAB ICD 2 In-Circuit Debugger .................................. 331 MPLAB ICE 2000 High-Performance Universal In-Circuit Emulator ................................................... 331 MPLAB Integrated Development Environment Software .................................................................. 329 MPLAB PM3 Device Programmer ................................... 331 MPLAB REAL ICE In-Circuit Emulator System ............... 331 MPLINK Object Linker/MPLIB Object Librarian ............... 330 MSSP ACK Pulse ....................................................... 181, 183 Control Registers (general) ..................................... 167 I2C Mode. See I2C Mode. Module Overview ..................................................... 167 SPI Master/Slave Connection .................................. 171 SPI Mode. See SPI Mode. SSPBUF Register .................................................... 172 SSPSR Register ...................................................... 172 MULLW ............................................................................ 306 MULWF ............................................................................ 306
N
NEGF ............................................................................... 307 NOP ................................................................................. 307
O
Oscillator Configuration ..................................................... 29 EC .............................................................................. 29 ECIO .......................................................................... 29 HS .............................................................................. 29 HSPLL ....................................................................... 29 Internal Oscillator Block ............................................. 32 INTIO1 ....................................................................... 29 INTIO2 ....................................................................... 29 LP .............................................................................. 29 RC ............................................................................. 29 RCIO .......................................................................... 29 XT .............................................................................. 29 Oscillator Selection .......................................................... 259 Oscillator Start-up Timer (OST) ................................... 38, 51 Oscillator Switching ........................................................... 35 Oscillator Transitions ......................................................... 36 Oscillator, Timer1 ..................................................... 133, 143 Oscillator, Timer3 ............................................................. 141
L
LFSR ................................................................................ 303 Low-Voltage ICSP Programming. See Single-Supply ICSP Programming
P
Packaging Information ..................................................... 373 Marking .................................................................... 373 Parallel Slave Port (PSP) ......................................... 120, 126 Associated Registers ............................................... 127 CS (Chip Select) ...................................................... 126 PORTD .................................................................... 126 RD (Read Input) ...................................................... 126 Select (PSPMODE Bit) .................................... 120, 126 WR (Write Input) ...................................................... 126 PICSTART Plus Development Programmer .................... 332 PIE Registers ................................................................... 104 Pin Functions MCLR/VPP/RE3 ................................................... 14, 18 OSC1/CLKI/RA7 .................................................. 14, 18 OSC2/CLKO/RA6 ................................................ 14, 18 RA0/AN0 .............................................................. 15, 19 RA1/AN1 .............................................................. 15, 19
M
Master Clear (MCLR) ......................................................... 49 Master Synchronous Serial Port (MSSP). See MSSP. Memory Organization ......................................................... 59 Data Memory ............................................................. 65 Program Memory ....................................................... 59 Memory Programming Requirements .............................. 349 Microchip Internet Web Site ............................................. 399 Migration from Baseline to Enhanced Devices ................ 387 Migration from High-End to Enhanced Devices ............... 388 Migration from Mid-Range to Enhanced Devices ............ 388 MOVF ............................................................................... 303 MOVFF ............................................................................ 304 MOVLB ............................................................................ 304 MOVLW ........................................................................... 305 MOVSF ............................................................................ 323
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RA2/AN2/VREF-/CVREF ........................................ 15, 19 RA3/AN3/VREF+ ................................................... 15, 19 RA4/T0CKI/C1OUT .............................................. 15, 19 RA5/AN4/SS/HLVDIN/C2OUT ............................. 15, 19 RB0/INT0/FLT0/AN12 .......................................... 16, 20 RB1/INT1/AN10 ................................................... 16, 20 RB2/INT2/AN8 ..................................................... 16, 20 RB3/AN9/CCP2 ................................................... 16, 20 RB4/KBI0/AN11 ................................................... 16, 20 RB5/KBI1/PGM .................................................... 16, 20 RB6/KBI2/PGC .................................................... 16, 20 RB7/KBI3/PGD .................................................... 16, 20 RC0/T1OSO/T13CKI ........................................... 17, 21 RC1/T1OSI/CCP2 ................................................ 17, 21 RC2/CCP1 ................................................................. 17 RC2/CCP1/P1A ......................................................... 21 RC3/SCK/SCL ..................................................... 17, 21 RC4/SDI/SDA ...................................................... 17, 21 RC5/SDO ............................................................. 17, 21 RC6/TX/CK .......................................................... 17, 21 RC7/RX/DT .......................................................... 17, 21 RD0/PSP0 .................................................................. 22 RD1/PSP1 .................................................................. 22 RD2/PSP2 .................................................................. 22 RD3/PSP3 .................................................................. 22 RD4/PSP4 .................................................................. 22 RD5/PSP5/P1B .......................................................... 22 RD6/PSP6/P1C .......................................................... 22 RD7/PSP7/P1D .......................................................... 22 RE0/RD/AN5 .............................................................. 23 RE1/WR/AN6 ............................................................. 23 RE2/CS/AN7 .............................................................. 23 VDD ....................................................................... 17, 23 VSS ....................................................................... 17, 23 Pinout I/O Descriptions PIC18F2221/2321 ...................................................... 14 PIC18F4221/4321 ...................................................... 18 PIR Registers ................................................................... 102 PLL Frequency Multiplier ................................................... 31 HSPLL Oscillator Mode .............................................. 31 Use with INTOSC ....................................................... 31 POP .................................................................................. 308 POR. See Power-on Reset. PORTA Associated Registers ............................................... 113 LATA Register .......................................................... 111 PORTA Register ...................................................... 111 TRISA Register ........................................................ 111 PORTB Associated Registers ............................................... 116 LATB Register .......................................................... 114 PORTB Register ...................................................... 114 TRISB Register ........................................................ 114 PORTC Associated Registers ............................................... 119 LATC Register ......................................................... 117 PORTC Register ...................................................... 117 RC3/SCK/SCL Pin ................................................... 183 TRISC Register ........................................................ 117 PORTD Associated Registers ............................................... 122 LATD Register ......................................................... 120 Parallel Slave Port (PSP) Function .......................... 120 PORTD Register ...................................................... 120 TRISD Register ........................................................ 120 PORTE Associated Registers ............................................... 125 LATE Register ......................................................... 123 PORTE Register ...................................................... 123 PSP Mode Select (PSPMODE Bit) .......................... 120 TRISE Register ........................................................ 123 Power-Managed Modes ..................................................... 39 and A/D Operation ................................................... 240 and EUSART Operation .......................................... 215 and PWM Operation ................................................ 165 and SPI Operation ................................................... 175 Clock Sources ............................................................ 39 Clock Transitions and Status Indicators .................... 40 Effects on Clock Sources ........................................... 38 Entering ..................................................................... 39 Exiting Idle and Sleep Modes .................................... 45 By Interrupt ........................................................ 45 By Reset ............................................................ 45 By WDT Time-out .............................................. 45 Without an Oscillator Start-up Delay ................. 46 Idle Modes ................................................................. 43 PRI_IDLE ........................................................... 44 RC_IDLE ........................................................... 45 SEC_IDLE ......................................................... 44 Multiple Sleep Commands ......................................... 40 Run Modes ................................................................ 40 PRI_RUN ........................................................... 40 RC_RUN ............................................................ 41 SEC_RUN ......................................................... 40 Sleep Mode ............................................................... 43 Summary (table) ........................................................ 39 Power-on Reset (POR) ...................................................... 49 Power-up Timer (PWRT) ........................................... 51 Time-out Sequence ................................................... 51 Power-up Delays ............................................................... 38 Power-up Timer (PWRT) ................................................... 38 Prescaler Timer2 ..................................................................... 156 Prescaler, Timer0 ............................................................ 131 Prescaler, Timer2 ............................................................ 151 PRI_IDLE Mode ................................................................. 44 PRI_RUN Mode ................................................................. 40 Program Counter ............................................................... 60 PCL, PCH and PCU Registers .................................. 60 PCLATH and PCLATU Registers .............................. 60 Program Memory and Extended Instruction Set .................................... 77 Instructions ................................................................ 64 Two-Word .......................................................... 64 Interrupt Vector .......................................................... 59 Look-up Tables .......................................................... 62 Map and Stack (diagram) .......................................... 59 Reset Vector .............................................................. 59 Program Verification ........................................................ 274 Programming, Device Instructions ................................... 279 PSP. See Parallel Slave Port. Pulse-Width Modulation. See PWM (CCP Module) and PWM (ECCP Module). PUSH ............................................................................... 308 PUSH and POP Instructions .............................................. 61 PUSHL ............................................................................. 324 PWM (CCP Module) Associated Registers ............................................... 152 Auto-Shutdown (CCP1 Only) ................................... 151 Duty Cycle ............................................................... 150
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Example Frequencies/Resolutions .......................... 151 Operation Setup ....................................................... 151 Period ....................................................................... 150 TMR2 to PR2 Match ........................................ 150, 155 PWM (ECCP Module) ...................................................... 155 CCPR1H:CCPR1L Registers ................................... 155 Duty Cycle ................................................................ 156 Effects of a Reset ..................................................... 165 Enhanced PWM Auto-Shutdown ............................. 162 Example Frequencies/Resolutions .......................... 156 Full-Bridge Application Example .............................. 160 Full-Bridge Mode ...................................................... 159 Direction Change ............................................. 160 Half-Bridge Mode ..................................................... 158 Half-Bridge Output Mode Applications Example ........................................................... 158 Operation in Power-Managed Modes ...................... 165 Operation with Fail-Safe Clock Monitor ................... 165 Output Configurations .............................................. 156 Output Relationships (Active-High) .......................... 157 Output Relationships (Active-Low) ........................... 157 Period ....................................................................... 155 Programmable Dead-Band Delay ............................ 162 Setup for PWM Operation ........................................ 165 Start-up Considerations ........................................... 164 ECCP1DEL (PWM Dead-Band Delay) .................... 162 EECON1 (Data EEPROM Control 1) ................... 81, 90 HLVDCON (High/Low-Voltage Detect Control) ....... 253 INTCON (Interrupt Control) ....................................... 99 INTCON2 (Interrupt Control 2) ................................ 100 INTCON3 (Interrupt Control 3) ................................ 101 IPR1 (Peripheral Interrupt Priority 1) ....................... 106 IPR2 (Peripheral Interrupt Priority 2) ....................... 107 OSCCON (Oscillator Control) .................................... 37 OSCTUNE (Oscillator Tuning) ................................... 33 PIE1 (Peripheral Interrupt Enable 1) ....................... 104 PIE2 (Peripheral Interrupt Enable 2) ....................... 105 PIR1 (Peripheral Interrupt Request (Flag) 1) ........... 102 PIR2 (Peripheral Interrupt Request (Flag) 2) ........... 103 RCON (Reset Control) ....................................... 48, 108 RCSTA (Receive Status and Control) ..................... 213 SSPADD(MSSP Address) ....................................... 180 SSPCON1 (MSSP Control 1, I2C Mode) ................. 178 SSPCON1 (MSSP Control 1, SPI Mode) ................ 169 SSPCON2 (MSSP Control 2, I2C Mode) ................. 179 SSPSTAT (MSSP Status, I2C Mode) ...................... 177 SSPSTAT (MSSP Status, SPI Mode) ...................... 168 STATUS .................................................................... 72 STKPTR (Stack Pointer) ............................................ 61 T0CON (Timer0 Control) ......................................... 129 T1CON (Timer1 Control) ......................................... 133 T2CON (Timer2 Control) ......................................... 139 T3CON (Timer3 Control) ......................................... 141 TRISE (PORTE/PSP Control) ................................. 124 TXSTA (Transmit Status and Control) ..................... 212 WDTCON (Watchdog Timer Control) ...................... 270 RESET ............................................................................. 309 Reset State of Registers .................................................... 54 Resets ....................................................................... 47, 259 Brown-out Reset (BOR) ........................................... 259 Oscillator Start-up Timer (OST) ............................... 259 Power-on Reset (POR) ............................................ 259 Power-up Timer (PWRT) ......................................... 259 RETFIE ............................................................................ 310 RETLW ............................................................................ 310 RETURN .......................................................................... 311 Return Address Stack ........................................................ 60 Associated Registers ................................................. 60 Return Stack Pointer (STKPTR) ........................................ 61 Revision History ............................................................... 385 RLCF ............................................................................... 311 RLNCF ............................................................................. 312 RRCF ............................................................................... 312 RRNCF ............................................................................ 313
Q
Q Clock .................................................................... 151, 156
R
RAM. See Data Memory. RC Oscillator RCIO Oscillator Mode ................................................ 31 RC_IDLE Mode .................................................................. 45 RC_RUN Mode .................................................................. 41 RCALL ............................................................................. 309 RCON Register Bit Status During Initialization .................................... 54 Reader Response ............................................................ 400 Register File ....................................................................... 67 Register File Summary ................................................ 69-71 Registers ADCON0 (A/D Control 0) ......................................... 233 ADCON1 (A/D Control 1) ......................................... 234 ADCON2 (A/D Control 2) ......................................... 235 BAUDCON (Baud Rate Control) .............................. 214 CCP1CON (Enhanced Capture/Compare/PWM Control 1) ......................................................... 153 CCPxCON (CCPx Control) ...................................... 145 CMCON (Comparator Control) ................................ 243 CONFIG1H (Configuration 1 High) .......................... 260 CONFIG2H (Configuration 2 High) .......................... 262 CONFIG2L (Configuration 2 Low) ............................ 261 CONFIG3H (Configuration 3 High) .......................... 263 CONFIG4L (Configuration 4 Low) ............................ 264 CONFIG5H (Configuration 5 High) .......................... 265 CONFIG5L (Configuration 5 Low) ............................ 265 CONFIG6H (Configuration 6 High) .......................... 266 CONFIG6L (Configuration 6 Low) ............................ 266 CONFIG7H (Configuration 7 High) .......................... 267 CONFIG7L (Configuration 7 Low) ............................ 267 CVRCON (Comparator Voltage Reference Control) .......................................... 249 DEVID1 (Device ID 1) .............................................. 268 DEVID2 (Device ID 2) .............................................. 268 ECCP1AS (ECCP Auto-Shutdown Control) ............. 163
S
SCK ................................................................................. 167 SDI ................................................................................... 167 SDO ................................................................................. 167 SEC_IDLE Mode ............................................................... 44 SEC_RUN Mode ................................................................ 40 Serial Clock, SCK ............................................................ 167 Serial Data In (SDI) .......................................................... 167 Serial Data Out (SDO) ..................................................... 167 Serial Peripheral Interface. See SPI Mode. SETF ............................................................................... 313 Single-Supply ICSP Programming. Slave Select (SS) ............................................................. 167 SLEEP ............................................................................. 314 Sleep OSC1 and OSC2 Pin States ...................................... 38
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Software Simulator (MPLAB SIM) .................................... 330 Special Event Trigger. See Compare (CCP Mode). Special Event Trigger. See Compare (ECCP Module). Special Features of the CPU ............................................ 259 Special Function Registers ................................................ 68 Map ............................................................................ 68 SPI Mode (MSSP) Associated Registers ............................................... 175 Bus Mode Compatibility ........................................... 175 Effects of a Reset ..................................................... 175 Enabling SPI I/O ...................................................... 171 Master Mode ............................................................ 172 Master/Slave Connection ......................................... 171 Operation ................................................................. 170 Operation in Power-Managed Modes ...................... 175 Serial Clock .............................................................. 167 Serial Data In ........................................................... 167 Serial Data Out ........................................................ 167 Slave Mode .............................................................. 173 Slave Select ............................................................. 167 Slave Select Synchronization .................................. 173 SPI Clock ................................................................. 172 Typical Connection .................................................. 171 SS .................................................................................... 167 SSPOV ............................................................................. 201 SSPOV Status Flag .......................................................... 201 SSPSTAT Register R/W Bit ............................................................. 181, 183 Stack Full/Underflow Resets .............................................. 62 SUBFSR ........................................................................... 325 SUBFWB .......................................................................... 314 SUBLW ............................................................................ 315 SUBULNK ........................................................................ 325 SUBWF ............................................................................ 315 SUBWFB .......................................................................... 316 SWAPF ............................................................................ 316 TMR1L Register ....................................................... 133 Use as a Real-Time Clock ....................................... 136 Timer2 .............................................................................. 139 Associated Registers ............................................... 140 Interrupt ................................................................... 140 Operation ................................................................. 139 Output ...................................................................... 140 PR2 Register ................................................... 150, 155 TMR2 to PR2 Match Interrupt .................................. 155 TMR2-to-PR2 Match Interrupt ................................. 150 Timer3 .............................................................................. 141 16-Bit Read/Write Mode .......................................... 143 Associated Registers ............................................... 143 Operation ................................................................. 142 Oscillator .......................................................... 141, 143 Overflow Interrupt ............................................ 141, 143 Special Event Trigger (CCP) ................................... 143 TMR3H Register ...................................................... 141 TMR3L Register ....................................................... 141 Timing Diagrams A/D Conversion ........................................................ 371 Acknowledge Sequence .......................................... 204 Asynchronous Reception ......................................... 225 Asynchronous Transmission .................................... 222 Asynchronous Transmission (Back to Back) ........... 222 Automatic Baud Rate Calculation ............................ 220 Auto-Wake-up Bit (WUE) During Normal Operation ............................................ 226 Auto-Wake-up Bit (WUE) During Sleep ................... 226 Baud Rate Generator with Clock Arbitration ............ 198 BRG Overflow Sequence ......................................... 220 BRG Reset Due to SDA Arbitration During Start Condition ................................................. 207 Brown-out Reset (BOR) ........................................... 357 Bus Collision During a Repeated Start Condition (Case 1) ........................................... 208 Bus Collision During a Repeated Start Condition (Case 2) ........................................... 208 Bus Collision During a Start Condition (SCL = 0) ......................................................... 207 Bus Collision During a Stop Condition (Case 1) ...... 209 Bus Collision During a Stop Condition (Case 2) ...... 209 Bus Collision During Start Condition (SDA Only) ...................................................... 206 Bus Collision for Transmit and Acknowledge .......... 205 Capture/Compare/PWM (All CCP Modules) ............ 359 CLKO and I/O .......................................................... 356 Clock Synchronization ............................................. 191 Clock/Instruction Cycle .............................................. 63 EUSART Synchronous Receive (Master/Slave) ...... 369 EUSART Synchronous Transmission (Master/Slave) ................................................. 369 Example SPI Master Mode (CKE = 0) ..................... 361 Example SPI Master Mode (CKE = 1) ..................... 362 Example SPI Slave Mode (CKE = 0) ....................... 363 Example SPI Slave Mode (CKE = 1) ....................... 364 External Clock (All Modes Except PLL) ................... 354 Fail-Safe Clock Monitor ........................................... 273 First Start Bit Timing ................................................ 199 Full-Bridge PWM Output .......................................... 159 Half-Bridge PWM Output ......................................... 158 High/Low-Voltage Detect Characteristics ................ 351 High-Voltage Detect Operation (VDIRMAG = 1) ..... 256 I2C Bus Data ............................................................ 365 I2C Bus Start/Stop Bits ............................................ 365
T
Table Reads/Table Writes .................................................. 62 TBLRD ............................................................................. 317 TBLWT ............................................................................. 318 Time-out in Various Situations (table) ................................ 51 Timer0 .............................................................................. 129 Associated Registers ............................................... 131 Operation ................................................................. 130 Overflow Interrupt .................................................... 131 Prescaler .................................................................. 131 Prescaler Assignment (PSA Bit) .............................. 131 Prescaler Select (T0PS2:T0PS0 Bits) ..................... 131 Prescaler. See Prescaler, Timer0. Reads and Writes in 16-Bit Mode ............................ 130 Source Edge Select (T0SE Bit) ................................ 130 Source Select (T0CS Bit) ......................................... 130 Switching Prescaler Assignment .............................. 131 Timer1 .............................................................................. 133 16-Bit Read/Write Mode ........................................... 135 Associated Registers ............................................... 137 Interrupt .................................................................... 136 Operation ................................................................. 134 Oscillator .......................................................... 133, 135 Layout Considerations ..................................... 136 Low-Power Option ........................................... 135 Overflow Interrupt .................................................... 133 Resetting, Using the CCP Special Event Trigger ..... 136 Special Event Trigger (ECCP) ................................. 154 TMR1H Register ...................................................... 133
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I2C Master Mode (7 or 10-Bit Transmission) ........... 202 I2C Master Mode (7-Bit Reception) .......................... 203 I2C Slave Mode (10-Bit Reception, SEN = 0, ADMSK = 01001) ............................................. 187 I2C Slave Mode (10-Bit Reception, SEN = 0) .......... 188 I2C Slave Mode (10-Bit Reception, SEN = 1) .......... 193 I2C Slave Mode (10-Bit Transmission) ..................... 189 I2C Slave Mode (7-Bit Reception, SEN = 0, ADMSK = 01011) ............................................. 185 I2C Slave Mode (7-Bit Reception, SEN = 0) ............ 184 I2C Slave Mode (7-Bit Reception, SEN = 1) ............ 192 I2C Slave Mode (7-Bit Transmission) ....................... 186 I2C Slave Mode General Call Address Sequence (7 or 10-Bit Addressing Mode) ........ 194 I2C Stop Condition Receive or Transmit Mode ........ 204 Low-Voltage Detect Operation (VDIRMAG = 0) ...... 255 Master SSP I2C Bus Data ........................................ 367 Master SSP I2C Bus Start/Stop Bits ........................ 367 Parallel Slave Port (PIC18F4221/4321) ................... 360 Parallel Slave Port (PSP) Read ............................... 127 Parallel Slave Port (PSP) Write ............................... 127 PWM Auto-Shutdown (PRSEN = 0, Auto-Restart Disabled) .................................... 164 PWM Auto-Shutdown (PRSEN = 1, Auto-Restart Enabled) ..................................... 164 PWM Direction Change ........................................... 161 PWM Direction Change at Near 100% Duty Cycle ............................................. 161 PWM Output ............................................................ 150 Repeated Start Condition ......................................... 200 Reset, Watchdog Timer (WDT), Oscillator Start-up Timer (OST), Power-up Timer (PWRT) ........... 357 Send Break Character Sequence ............................ 227 Slave Synchronization ............................................. 173 Slow Rise Time (MCLR Tied to VDD, VDD Rise > TPWRT) ............................................ 53 SPI Mode (Master Mode) ......................................... 172 SPI Mode (Slave Mode, CKE = 0) ........................... 174 SPI Mode (Slave Mode, CKE = 1) ........................... 174 Synchronous Reception (Master Mode, SREN) ...... 230 Synchronous Transmission ...................................... 228 Synchronous Transmission (Through TXEN) .......... 229 Time-out Sequence on POR w/PLL Enabled (MCLR Tied to VDD) ........................................... 53 Time-out Sequence on Power-up (MCLR Not Tied to VDD, Case 1) ....................... 52 Time-out Sequence on Power-up (MCLR Not Tied to VDD, Case 2) ....................... 52 Time-out Sequence on Power-up (MCLR Tied to VDD, VDD Rise < TPWRT) ........... 52 Timer0 and Timer1 External Clock .......................... 358 Transition for Entry to Idle Mode ................................ 44 Transition for Entry to SEC_RUN Mode .................... 41 Transition for Entry to Sleep Mode ............................ 43 Transition for Two-Speed Start-up (INTOSC to HSPLL) ........................................ 271 Transition for Wake from Idle to Run Mode ............... 44 Transition for Wake from Sleep (HSPLL) ................... 43 Transition from RC_RUN Mode to PRI_RUN Mode .. 42 Transition from SEC_RUN Mode to PRI_RUN Mode (HSPLL) .................................. 41 Transition to RC_RUN Mode ..................................... 42 Timing Diagrams and Specifications ............................... 354 Capture/Compare/PWM Requirements (All CCP Modules) ........................................... 359 CLKO and I/O Requirements ................................... 356 EUSART Synchronous Receive Requirements ....... 369 EUSART Synchronous Transmission Requirements .... 369 Example SPI Mode Requirements (Master Mode, CKE = 0) .................................. 361 Example SPI Mode Requirements (Master Mode, CKE = 1) .................................. 362 Example SPI Mode Requirements (Slave Mode, CKE = 0) .................................... 363 Example SPI Mode Requirements (Slave Mode, CKE = 1) .................................... 364 External Clock Requirements .................................. 354 I2C Bus Data Requirements (Slave Mode) .............. 366 I2C Bus Start/Stop Requirements (Slave Mode) ..... 365 Master SSP I2C Bus Data Requirements ................ 368 Master SSP I2C Bus Start/Stop Bits Requirements .................................................. 367 Parallel Slave Port Requirements (PIC18F4221/4321) ......................................... 360 PLL Clock ................................................................ 355 Reset, Watchdog Timer, Oscillator Start-up Timer, Power-up Timer and Brown-out Reset Requirements ...................... 357 Timer0 and Timer1 External Clock Requirements .................................................. 358 Top-of-Stack Access .......................................................... 60 TRISE Register PSPMODE Bit ......................................................... 120 TSTFSZ ........................................................................... 319 Two-Speed Start-up ................................................. 259, 271 Two-Word Instructions Example Cases ......................................................... 64 TXSTA Register BRGH Bit ................................................................. 215
V
Voltage Reference Specifications .................................... 350
W
Watchdog Timer (WDT) ........................................... 259, 269 Associated Registers ............................................... 270 Control Register ....................................................... 269 During Oscillator Failure .......................................... 272 Programming Considerations .................................. 269 WCOL ...................................................... 199, 200, 201, 204 WCOL Status Flag ................................... 199, 200, 201, 204 WWW Address ................................................................ 399 WWW, On-Line Support ...................................................... 8
X
XORLW ........................................................................... 319 XORWF ........................................................................... 320
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NOTES:
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PIC18F2221/2321/4221/4321 FAMILY
READER RESPONSE
It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150. Please list the following information, and use this outline to provide us with your comments about this document. To: RE: Technical Publications Manager Reader Response Total Pages Sent ________
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Device: PIC18F2221/2321/4221/4321 Family Questions: 1. What are the best features of this document?
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DS39689F-page 400
(c) 2009 Microchip Technology Inc.
PIC18F2221/2321/4221/4321 FAMILY
PIC18F2221/2321/4221/4321 PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. Device X Temperature Range /XX Package XXX Pattern Examples:
a) b) Device PIC18F2221/2321(1), PIC18F4221/4321(1), PIC18F2221/2321T(2), PIC18F4221/4321T(2); VDD range 4.2V to 5.5V PIC18LF2221/2321(1), PIC18LF4221/4321(1), PIC18LF2221/2321T(2), PIC18LF4221/4321T(2); VDD range 2.0V to 5.5V I E PT SO SS SP P ML = = = = = = = = -40C to +85C (Industrial) -40C to +125C (Extended) TQFP (Thin Quad Flatpack) SOIC SSOP Skinny Plastic DIP PDIP QFN c) PIC18F4321-I/P 301 = Industrial temp., PDIP package, Extended VDD limits, QTP pattern #301. PIC18LF2321-I/SO = Industrial temp., SOIC package, Extended VDD limits. PIC18LF4321-I/P = Industrial temp., PDIP package, normal VDD limits.
Temperature Range
Package
Note 1: 2:
F = Standard Voltage Range LF = Wide Voltage Range T = in tape and reel
Pattern
QTP, SQTP, Code or Special Requirements (blank otherwise)
(c) 2009 Microchip Technology Inc.
DS39689F-page 401
WORLDWIDE SALES AND SERVICE
AMERICAS
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ASIA/PACIFIC
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ASIA/PACIFIC
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EUROPE
Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 France - Paris Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 Germany - Munich Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 Spain - Madrid Tel: 34-91-708-08-90 Fax: 34-91-708-08-91 UK - Wokingham Tel: 44-118-921-5869 Fax: 44-118-921-5820
03/26/09
DS39689F-page 402
(c) 2009 Microchip Technology Inc.

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