View PIC16FT688-IST_1296145.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

PIC16F688 Data Sheet
14-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology
2004 Microchip Technology Inc.
Preliminary
DS41203B
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."
*
* *
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip's code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip's products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights.
Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, PowerSmart and rfPIC are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. AmpLab, FilterLab, microID, MXDEV, MXLAB, PICMASTER, SEEVAL, SmartShunt and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Application Maestro, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB, Select Mode, SmartSensor, SmartTel and Total Endurance are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. Serialized Quick Turn Programming (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) 2004, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper.
Microchip received ISO/TS-16949:2002 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona and Mountain View, California in October 2003. The Company's quality system processes and procedures are for its PICmicro(R) 8-bit MCUs, 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.
DS41203B-page ii
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology
High-Performance RISC CPU
* Only 35 instructions to learn: - All single-cycle instructions except branches * Operating speed: - DC - 20 MHz oscillator/clock input - DC - 200 ns instruction cycle * Interrupt capability * 8-level deep hardware stack * Direct, Indirect and Relative Addressing modes
Low-Power Features
* Standby Current: - 1 nA @ 2.0V, typical * Operating Current: - 8.5 A @ 32 kHz, 2.0V, typical - 100 A @ 1 MHz, 2.0V, typical * Watchdog Timer Current: - 1 A @ 2.0V, typical
Peripheral Features Special Microcontroller Features
* Precision Internal Oscillator: - Factory calibrated to 1% - Software selectable frequency range of 8 MHz to 31 kHz - Software tunable - Two-Speed Start-up mode - Crystal fail detect for critical applications - Clock mode switching during operation for power savings * Power saving Sleep mode * Wide operating voltage range (2.0V-5.5V) * Industrial and Extended temperature range * Power-on Reset (POR) * Power-up Timer (PWRT) and Oscillator Start-up Timer (OST) * Brown-out Detect (BOD) with software control option * Enhanced Low-Current Watchdog Timer (WDT) with on-chip oscillator (software selectable nominal 268 seconds with full prescaler) with software enable * Multiplexed Master Clear with pull-up/input pin * Programmable code protection * High-Endurance Flash/EEPROM cell: - 100,000 write Flash endurance - 1,000,000 write EEPROM endurance - Flash/Data EEPROM retention: > 40 years Program Memory Device Flash (words) PIC16F688 4096 SRAM (bytes) 256 EEPROM (bytes) 256 12 * 12 I/O pins with individual direction control: - High-current source/sink for direct LED drive - Interrupt-on-pin change - Individually programmable weak pull-ups - Ultra Low-Power Wake-up * Analog comparator module with: - Two analog comparators - Programmable on-chip voltage reference (CVREF) module (% of VDD) - Comparator inputs and outputs externally accessible * A/D Converter: - 10-bit resolution and 8 channels * Timer0: 8-bit timer/counter with 8-bit programmable prescaler * Enhanced Timer1: - 16-bit timer/counter with prescaler - External Gate Input mode - Option to use OSC1 and OSC2 in LP mode as Timer1 oscillator if INTOSC mode selected * Enhanced USART Module: - Supports RS-485, RS-232, and LIN 1.2 - Auto baud detect - Auto-wake-up on Start bit * In-Circuit Serial ProgrammingTM (ICSPTM) via two pins
Data Memory I/O 10-bit A/D (ch) 8 Comparators Timers 8/16-bit 1/1
2
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 1
PIC16F688
Pin Diagram
14-pin PDIP, SOIC, TSSOP
VDD RA5/T1CKI/OSC1/CLKIN RA4/AN3/T1G/OSC2/CLKOUT RA3/MCLR/VPP RC5/RX/DT RC4/C2OUT/TX/CK RC3/AN7
1 2 3 4 5 6 7
14 13 12 11 10 9 8
VSS RA0/AN0/C1IN+/ICSPDAT/ULPWU RA1/AN1/C1IN-/VREF/ICSPCLK RA2/AN2/T0CKI/INT/C1OUT RC0/AN4/C2IN+ RC1/AN5/C2INRC2/AN6
DS41203B-page 2
Preliminary
PIC16F688
2004 Microchip Technology Inc.
PIC16F688
Table of Contents
1.0 Device Overview ......................................................................................................................................................................... 5 2.0 Memory Organization .................................................................................................................................................................. 7 3.0 Clock Sources ........................................................................................................................................................................... 21 4.0 I/O Ports .................................................................................................................................................................................... 31 5.0 Timer0 Module .......................................................................................................................................................................... 45 6.0 Timer1 Module with Gate Control.............................................................................................................................................. 49 7.0 Comparator Module................................................................................................................................................................... 53 8.0 Analog-to-Digital Converter (A/D) Module................................................................................................................................. 63 9.0 Data EEPROM and Flash Program Memory Control ................................................................................................................ 71 10.0 Enhanced Universal Asynchronous Receiver Transmitter (EUSART) ...................................................................................... 77 11.0 Special Features of the CPU..................................................................................................................................................... 99 12.0 Instruction Set Summary ......................................................................................................................................................... 119 13.0 Development Support .............................................................................................................................................................. 129 14.0 Electrical Specifications........................................................................................................................................................... 135 15.0 DC and AC Characteristics Graphs and Tables...................................................................................................................... 157 16.0 Packaging Information............................................................................................................................................................. 159 Appendix A: Data Sheet Revision History......................................................................................................................................... 163 Appendix B: Migrating from other PICmicro(R) Devices ..................................................................................................................... 163 Index ................................................................................................................................................................................................. 165 On-line Support ................................................................................................................................................................................. 169 Systems Information and Upgrade Hot Line ..................................................................................................................................... 169 Reader Response ............................................................................................................................................................................. 170 Product Identification System ........................................................................................................................................................... 171
TO OUR VALUED CUSTOMERS
It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and enhanced as new volumes and updates are introduced. If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via E-mail at docerrors@mail.microchip.com or fax the Reader Response Form in the back of this data sheet to (480) 792-4150. We welcome your feedback.
Most Current Data Sheet
To obtain the most up-to-date version of this data sheet, please register at our Worldwide Web site at: http://www.microchip.com You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page. The last character of the literature number is the version number, (e.g., DS30000A is version A of document DS30000).
Errata
An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the revision of silicon and revision of document to which it applies. To determine if an errata sheet exists for a particular device, please check with one of the following: * Microchip's Worldwide Web site; http://www.microchip.com * Your local Microchip sales office (see last page) * The Microchip Corporate Literature Center; U.S. FAX: (480) 792-7277 When contacting a sales office or the literature center, please specify which device, revision of silicon and data sheet (include literature number) you are using.
Customer Notification System
Register on our web site at www.microchip.com/cn to receive the most current information on all of our products.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 3
PIC16F688
NOTES:
DS41203B-page 4
Preliminary
2004 Microchip Technology Inc.
PIC16F688
1.0 DEVICE OVERVIEW
This document contains device specific information for the PIC16F688. Additional information may be found in the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023), downloaded from the Microchip web site. The Reference Manual should be considered a complementary document to this data sheet and is highly recommended reading for a better understanding of the device architecture and operation of the peripheral modules. The PIC16F688 is covered by this data sheet. It is available in 14-pin PDIP, SOIC and TSSOP packages. Figure 1-1 shows a block diagram of the PIC16F688 device. Table 1-1 shows the pinout description.
FIGURE 1-1:
PIC16F688 BLOCK DIAGRAM
INT Configuration 13 Program Counter Flash 4k x 14 Program Memory Data Bus 8 PORTA RA0 RA1 8-Level Stack (13 bit) RAM 256 bytes File Registers RAM Addr 9 Addr MUX Direct Addr 7 Indirect Addr PORTC RC0 RC1 RC2 RC3 RC4 RC5 3 Power-up Timer Instruction Decode & Control Oscillator Start-up Timer Power-on Reset Watchdog Timer Brown-out Detect Internal Oscillator Block 8 W Reg MUX RA2 RA3 RA4 RA5
Program Bus
14
Instruction reg
8
FSR Reg Status Reg 8
ALU
OSC1/CLKIN OSC2/CLKOUT
Timing Generation
RX/DT MCLR VDD VSS
TX/CK
T1G T1CKI Timer0 T0CKI
Timer1
EUSART
Analog-to-Digital Converter
2 Analog Comparators and Reference
EEDAT 256 bytes 8 DATA EEPROM EEADDR
VREF
AN0 AN1 AN2 AN3 AN4 AN5 AN6 AN7 C1IN- C1IN+ C1OUT C2IN- C2IN+ C2OUT
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 5
PIC16F688
TABLE 1-1: PIC16F688 PINOUT DESCRIPTION
Name RA0/AN0/C1IN+/ICSPDAT/ULPWU Function RA0 AN0 C1IN+ ICSPDAT ULPWU RA1/AN1/C1IN-/VREF/ICSPCLK RA1 AN1 C1INVREF ICSPCLK RA2/AN2/T0CKI/INT/C1OUT RA2 AN2 T0CKI INT C1OUT RA3/MCLR/VPP RA3 MCLR VPP RA4/AN3/T1G/OSC2/CLKOUT RA4 AN3 T1G OSC2 CLKOUT RA5/T1CKI/OSC1/CLKIN RA5 T1CKI OSC1 CLKIN RC0/AN4/C2IN+ RC0 AN4 C2IN+ RC1/AN5/C2INRC1 AN5 C2INRC2/AN6 RC3/AN7 RC4/C2OUT/TX/CK RC2 AN6 RC3 AN7 RC4 C2OUT TX CK RC5/RX/DT RC5 RX DT VSS VDD Legend: AN TTL HV VSS VDD = Analog input or output = TTL compatible input = High Voltage Input Type TTL AN AN TTL AN TTL AN AN AN ST ST AN ST ST -- TTL ST HV TTL AN ST -- -- TTL ST XTAL ST TTL AN AN TTL AN AN TTL AN TTL AN ST -- -- ST ST ST ST Power Power CMOS -- CMOS -- CMOS CMOS CMOS CMOS CMOS CMOS CMOS -- -- CMOS -- Output Type CMOS -- -- CMOS -- CMOS -- -- -- -- CMOS -- -- -- CMOS -- -- -- CMOS -- -- XTAL CMOS CMOS -- -- -- CMOS -- A/D Channel 0 input Comparator 1 input Serial Programming Data I/O Ultra Low-Power Wake-up input PORTA I/O w/prog pull-up and interrupt-on-change A/D Channel 1 input Comparator 1 input External Voltage Reference for A/D Serial Programming Clock PORTA I/O w/prog pull-up and interrupt-on-change A/D Channel 2 input Timer0 clock input External Interrupt Comparator 1 output PORTA input with interrupt-on-change Master Clear w/internal pull-up Programming voltage PORTA I/O w/prog pull-up and interrupt-on-change A/D Channel 3 input Timer1 gate Crystal/Resonator FOSC/4 output PORTA I/O w/prog pull-up and interrupt-on-change Timer1 clock Crystal/Resonator External clock input/RC oscillator connection PORTC I/O A/D Channel 4 input Comparator 2 input PORTC I/O A/D Channel 5 input Comparator 2 input PORTC I/O A/D Channel 6 input PORTC I/O A/D Channel 7 input PORTC I/O Comparator 2 output USART asynchronous output USART asynchronous clock Port C I/O USART asynchronous input USART asynchronous data Ground reference Positive supply OC = Open collector output Description PORTA I/O w/prog pull-up and interrupt-on-change
CMOS = CMOS compatible input or output ST = Schmitt Trigger input with CMOS levels XTAL = Crystal
DS41203B-page 6
Preliminary
2004 Microchip Technology Inc.
PIC16F688
2.0
2.1
MEMORY ORGANIZATION
Program Memory Organization
2.2
Data Memory Organization
The PIC16F688 has a 13-bit program counter capable of addressing a 4k x 14 program memory space. Only the first 4k x 14 (0000h-01FFF) for the PIC16F688 is physically implemented. Accessing a location above these boundaries will cause a wrap around within the first 4k x 14 space. The Reset vector is at 0000h and the interrupt vector is at 0004h (see Figure 2-1).
The data memory is partitioned into multiple banks, which contain the General Purpose Registers (GPR) and the Special Function Registers (SFR). Bits RP0 and RP1 are bank select bits. RP0 RP1 (Status<6:5>) = 00 : Bank 0 = 01: Bank 1 = 10: Bank 2 = 11: Bank 3 Each bank extends up to 7Fh (128 bytes). The lower locations of each bank are reserved for the Special Function Registers. Above the Special Function Registers are the General Purpose Registers, implemented as static RAM. All implemented banks contain Special Function Registers. Some frequently used Special Function Registers from one bank are mirrored in another bank for code reduction and quicker access.
FIGURE 2-1:
PROGRAM MEMORY MAP AND STACK FOR THE PIC16F688
PC<12:0>
CALL, RETURN RETFIE, RETLW
13
Stack Level 1 Stack Level 2
2.2.1
Stack Level 8 Reset Vector
GENERAL PURPOSE REGISTER FILE
000h
The register file is organized as 256 x 8 in the PIC16F688. Each register is accessed, either directly or indirectly, through the File Select Register (FSR) (see Section 2.4 "Indirect Addressing, INDF and FSR Registers").
Interrupt Vector
0004 0005
2.2.2
SPECIAL FUNCTION REGISTERS
On-chip Program Memory 0FFFh 0800h
The Special Function Registers are registers used by the CPU and peripheral functions for controlling the desired operation of the device (see Tables 2-1, 2-2, 2-3 and 2-4). These registers are static RAM. The special registers can be classified into two sets: core and peripheral. The Special Function Registers associated with the "core" are described in this section. Those related to the operation of the peripheral features are described in the section of that peripheral feature.
1FFFh
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 7
PIC16F688
FIGURE 2-2: PIC16F688 SPECIAL FUNCTION REGISTERS
File Address Indirect addr. (1) 80h OPTION_REG 81h PCL 82h STATUS 83h FSR 84h TRISA 85h 86h TRISC 87h 88h 89h PCLATH 8Ah INTCON 8Bh PIE1 8Ch 8Dh PCON 8Eh OSCCON 8Fh OSCTUNE 90h ANSEL 91h 92h 93h 94h WPUA 95h IOCA 96h EEDATH 97h EEADRH 98h VRCON 99h EEDAT 9Ah EEADR 9Bh EECON1 9Ch EECON2(1) 9Dh ADRESL 9Eh ADCON1 9Fh A0h General Purpose Register 80 Bytes 96 Bytes 7Fh Bank 0 accesses Bank 0 Bank1 EFh F0h FFh File Address Indirect addr. (1) 100h TMR0 101h PCL 102h STATUS 103h FSR 104h PORTA 105h 106h PORTC 107h 108h 109h PCLATH 10Ah INTCON 10Bh 10Ch 10Dh 10Eh 10Fh 110h 111h 112h 113h 114h 115h 116h 117h 118h 119h 11Ah 11Bh 11Ch 11Dh 11Eh 11Fh 120h General Purpose Register 80 Bytes accesses Bank 0 Bank2 accesses Bank 0 Bank3 File Address Indirect addr. (1) 180h OPTION_REG 181h PCL 182h STATUS 183h FSR 184h TRISA 185h 186h TRISC 187h 188h 189h PCLATH 18Ah INTCON 18Bh 18Ch 18Dh 18Eh 18Fh 190h 191h 192h 193h 194h 195h 196h 197h 198h 199h 19Ah 19Bh 19Ch 19Dh 19Eh 19Fh 1A0h File Address Indirect addr. (1) 00h TMR0 01h PCL 02h STATUS 03h FSR 04h PORTA 05h 06h PORTC 07h 08h 09h PCLATH 0Ah INTCON 0Bh PIR1 0Ch 0Dh TMR1L 0Eh TMR1H 0Fh T1CON 10h BAUDCTL 11h SPBRGH 12h SPBRG 13h RCREG 14h TXREG 15h TXSTA 16h RCSTA 17h WDTCON 18h CMCON0 19h CMCON1 1Ah 1Bh 1Ch 1Dh ADRESH 1Eh ADCON0 1Fh 20h
General Purpose Register
17Fh
1FFh
Unimplemented data memory locations, read as `0'. Note 1: Not a physical register.
DS41203B-page 8
Preliminary
2004 Microchip Technology Inc.
PIC16F688
TABLE 2-1:
Addr Bank 0 00h 01h 02h 03h 04h 05h 06h 07h 08h 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 11h 12h 13h 14h 15h 16h 17h 18h 19h 1Ah 1Bh 1Ch 1Dh 1Eh 1Fh INDF TMR0 PCL STATUS FSR PORTA -- PORTC -- -- PCLATH INTCON PIR1 -- TMR1L TMR1H T1CON BAUDCTL SPBRGH SPBRG RCREG TXREG TXSTA RCSTA WDTCON CMCON0 CMCON1 -- -- -- ADRESH ADCON0 Addressing this location uses contents of FSR to address data memory (not a physical register) Timer0 Module's register Program Counter's (PC) Least Significant Byte IRP RP1 RP0 TO PD Z DC C xxxx xxxx xxxx xxxx 0000 0000 0001 1xxx xxxx xxxx RA4 RA3 RA2 RA1 RA0 --xx xx00 -- RC5 RC4 RC3 RC2 RC1 RC0 --xx xx00 -- -- -- T0IE RCIF Write Buffer for upper 5 bits of Program Counter INTE C2IF RAIE C1IF T0IF OSFIF INTF TXIF RAIF(2) TMR1IF ---0 0000 0000 0000 0000 0000 -- xxxx xxxx xxxx xxxx TMR1CS WUE TMR1ON ABDEN 0000 0000 01-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 SYNC CREN WDTPS3 C1INV -- SENDB ADDEN WDTPS2 CIS -- BRGH FERR WDTPS1 CM2 -- TRMT OERR WDTPS0 CM1 T1GSS TX9D RX9D SWDTEN CM0 C2SYNC 0000 0010 0000 000x ---0 1000 0000 0000 ---- --10 -- -- -- xxxx xxxx ADON 00-0 0000 xxxx xxxx uuuu uuuu 0000 0000 000q quuu uuuu uuuu --uu uuuu -- --uu uuuu -- -- ---0 0000 0000 0000 0000 0000 -- uuuu uuuu uuuu uuuu uuuu uuuu 01-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 000x ---0 1000 0000 0000 ---- --10 -- -- -- uuuu uuuu 00-0 0000 Name
PIC16F688 SPECIAL REGISTERS SUMMARY BANK 0
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR/BOD Reset Value on all other Resets(1)
Indirect Data Memory Address Pointer -- -- RA5
Unimplemented -- --
Unimplemented Unimplemented -- GIE EEIF -- PEIE ADIF
Unimplemented Holding Register for the Least Significant Byte of the 16-bit TMR1 Holding Register for the Most Significant Byte of the 16-bit TMR1 T1GINV ABDOVF TMR1GE RCIDL T1CKPS1 -- T1CKPS0 SCKP T1OSCEN BRG16 T1SYNC --
USART Baud Rate High Generator USART Baud Rate Generator USART Receive Register USART Transmit Register CSRC SPEN -- C2OUT -- TX9 RX9 -- C1OUT -- TXEN SREN -- C2INV --
Unimplemented Unimplemented Unimplemented Most Significant 8 bits of the left shifted A/D result or 2 bits of right shifted result ADFM VCFG -- CHS2 CHS1 CHS0 GO/DONE
Legend: Note 1: 2:
- = Unimplemented locations read as `0', u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation. MCLR and WDT Reset does not affect the previous value data latch. The RAIF bit will be cleared upon reset but will set again if the mismatched exists.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 9
PIC16F688
TABLE 2-2:
Addr Bank 1 80h 81h 82h 83h 84h 85h 86h 87h 88h 89h 8Ah 8Bh 8Ch 8Dh 8Eh 8Fh 90h 91h 92h 93h 94h 95h 96h 97h 98h 99h 9Ah 9Bh 9Ch 9Dh 9Eh 9Fh Legend: Note 1: 2: 3: IOCA EEDATH EEADRH VRCON EEDAT EEADR EECON1 EECON2 ADRESL ADCON1 PCON OSCCON OSCTUNE ANSEL -- -- -- WPUA(2) TRISC -- -- PCLATH INTCON PIE1 -- INDF OPTION_REG PCL STATUS FSR TRISA -- Addressing this location uses contents of FSR to address data memory (not a physical register) RAPU IRP -- -- INTEDG RP1 -- -- T0CS RP0 TRISA5 TRISC5 T0SE TO TRISA4 TRISC4 PSA PD TRISA3 TRISC3 PS2 Z TRISA2 TRISC2 PS1 DC TRISA1 TRISC1 PS0 C TRISA0 TRISC0 Program Counter's (PC) Least Significant Byte Indirect Data Memory Address Pointer Unimplemented Unimplemented Unimplemented -- GIE EEIE -- -- -- ANS7 -- PEIE ADIE -- IRCF2 -- ANS6 -- T0IE RCIE ULPWUE IRCF1 -- ANS5 Write Buffer for upper 5 bits of Program Counter INTE C2IE SBODEN IRCF0 TUN4 ANS4 RAIE C1IE -- OSTS TUN3 ANS3 T0IF OSFIE -- HTS TUN2 ANS2 INTF TXIE POR LTS TUN1 ANS1 RAIF(3) TMR1IE BOD SCS TUN0 ANS0 xxxx xxxx 1111 1111 0000 0000 0001 1xxx xxxx xxxx --11 1111 -- --11 1111 -- -- ---0 0000 0000 0000 0000 0000 -- --01 --qq -110 x000 ---0 0000 1111 1111 -- -- -- WPUA5 IOCA5 -- VRR EEDAT5 EEADR5 -- WPUA4 IOCA4 -- -- EEDAT4 EEADR4 -- -- IOCA3 WPUA2 IOCA2 WPUA1 IOCA1 WPUA0 IOCA0 --11 -111 --00 0000 --00 0000 EEPROM Address Register VR3 EEDAT3 WRERR VR2 EEDAT2 WREN VR1 EEDAT1 WR VR0 EEDAT0 RD ---- 0000 0-0- 0000 0000 0000 0000 0000 x--- x000 ---- ---xxxx xxxx -- -000 ----- -- xxxx xxxx 1111 1111 0000 0000 000q quuu uuuu uuuu --11 1111 -- --11 1111 -- -- ---0 0000 0000 0000 0000 0000 -- --0u --uu -110 x000 ---u uuuu 1111 1111 -- -- -- --11 -111 --00 0000 0000 0000 0000 0000 0-0- 0000 0000 0000 0000 0000 u--- q000 ---- ---uuuu uuuu -000 ---Name
PIC16F688 SPECIAL FUNCTION REGISTERS SUMMARY BANK 1
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR/BOD Reset Value on all other Resets(1)
Unimplemented
Unimplemented Unimplemented Unimplemented -- -- -- -- VREN EEDAT7 EEADR7 EEPGD -- -- -- -- -- EEDAT6 EEADR6 --
EEPROM Data Register
EEADR3 EEADR2 EEADR1 EEADR0
EEPROM Control 2 Register (not a physical register) Least Significant 2 bits of the left shifted result or 8 bits of the right shifted result -- ADCS2 ADCS1 ADCS0 --
- = Unimplemented locations read as `0', u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation. RA3 pull-up is enabled when pin is configured as MCLR in the Configuration Word register. MCLR and WDT Reset does not affect the previous value data latch. The RAIF bit will be cleared upon reset but will set again if the mismatched exists.
DS41203B-page 10
Preliminary
2004 Microchip Technology Inc.
PIC16F688
TABLE 2-3:
Addr Bank 2 100h 101h 102h 103h 104h 105h 106h 107h 108h 109h 10Ah 10Bh 10Ch 10Dh 10Eh 10Fh 110h 111h 112h 113h 114h 115h 116h 117h 118h 119h 11Ah 11Bh 11Ch 11Dh 11Eh 11Fh Legend: Note 1: 2: INDF TMR0 PCL STATUS FSR PORTA -- PORTC -- -- PCLATH INTCON -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Addressing this location uses contents of FSR to address data memory (not a physical register) Timer0 Module's register Program Counter's (PC) Least Significant Byte IRP RP1 RP0 TO PD Z DC C xxxx xxxx xxxx xxxx 0000 0000 0001 1xxx xxxx xxxx RA3 RA2 RA1 RA0 --xx xx00 -- RC5 RC4 RC3 RC2 RC1 RC0 --xx xx00 -- -- -- T0IE Write Buffer for upper 5 bits of Program Counter INTE RAIE T0IF INTF RAIF(2) ---0 0000 0000 0000 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- xxxx xxxx uuuu uuuu 0000 0000 000q quuu uuuu uuuu --uu uuuu -- --uu uuuu -- -- ---0 0000 0000 0000 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Name
PIC16F688 SPECIAL REGISTERS SUMMARY BANK 2
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR/BOD Reset Value on all other Resets(1)
Indirect Data Memory Address Pointer -- -- RA5 RA4
Unimplemented -- --
Unimplemented Unimplemented -- GIE -- PEIE
Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented
- = Unimplemented locations read as `0', u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation. MCLR and WDT Reset does not affect the previous value data latch. The RAIF bit will be cleared upon reset but will set again if the mismatched exists.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 11
PIC16F688
TABLE 2-4:
Addr Bank 3 180h 181h 182h 183h 184h 185h 186h 187h 188h 189h 18Ah 18Bh 18Ch 18Dh 190h 191h 192h 193h 194h 195h 196h 19Ah 19Bh 199h 19Ah 19Bh 19Ch 19Dh 19Eh 19Fh Legend: Note 1: 2: INDF OPTION_REG PCL STATUS FSR TRISA -- TRISC -- -- PCLATH INTCON -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Addressing this location uses contents of FSR to address data memory (not a physical register) RAPU IRP -- -- INTEDG RP1 -- -- T0CS RP0 TRISA5 TRISC5 T0SE TO TRISA4 TRISC4 PSA PD TRISA3 TRISC3 PS2 Z TRISA2 TRISC2 PS1 DC TRISA1 TRISC1 PS0 C TRISA0 TRISC0 Program Counter's (PC) Least Significant Byte Indirect Data Memory Address Pointer Unimplemented Unimplemented Unimplemented -- GIE -- PEIE -- T0IE Write Buffer for upper 5 bits of Program Counter INTE RAIE T0IF INTF RAIF(2) xxxx xxxx 1111 1111 0000 0000 0001 1xxx xxxx xxxx --11 1111 -- --11 1111 -- -- ---0 0000 0000 0000 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- xxxx xxxx 1111 1111 0000 0000 000q quuu uuuu uuuu --11 1111 -- --11 1111 -- -- ---0 0000 0000 0000 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Name
PIC16F688 SPECIAL FUNCTION REGISTERS SUMMARY BANK 3
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR/BOD Reset Value on all other Resets(1)
Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented Unimplemented
-- Unimplemented -- -- - = Unimplemented locations read as `0', u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation. MCLR and WDT Reset does not affect the previous value data latch. The RAIF bit will be cleared upon reset but will set again if the mismatched exists.
DS41203B-page 12
Preliminary
2004 Microchip Technology Inc.
PIC16F688
2.2.2.1 Status Register
The Status register, shown in Register 2-1, contains: * the arithmetic status of the ALU * the Reset status * the bank select bits for data memory (SRAM) The Status register can be the destination for any instruction, like any other register. If the Status register is the destination for an instruction that affects the Z, DC or C bits, then the write to these three bits is disabled. These bits are set or cleared according to the device logic. Furthermore, the TO and PD bits are not writable. Therefore, the result of an instruction with the Status register as destination may be different than intended. For example, CLRF STATUS will clear the upper three bits and set the Z bit. This leaves the Status register as `000u u1uu' (where u = unchanged). It is recommended, therefore, that only BCF, BSF, SWAPF and MOVWF instructions are used to alter the Status register, because these instructions do not affect any Status bits. For other instructions not affecting any Status bits (see Section 12.0 "Instruction Set Summary"). Note 1: Bits IRP and RP1 (Status<7:6>) are not used by the PIC16F688 and should be maintained as clear. Use of these bits is not recommended, since this may affect upward compatibility with future products. 2: The C and DC bits operate as a Borrow and Digit Borrow out bit, respectively, in subtraction. See the SUBLW and SUBWF instructions for examples.
REGISTER 2-1:
STATUS - STATUS REGISTER (ADDRESS: 03h, 83h, 103h, OR 183h)
R/W-0 IRP bit 7 R/W-0 RP1 R/W-0 RP0 R-1 TO R-1 PD R/W-x Z R/W-x DC R/W-x C bit 0
bit 7
IRP: Register Bank Select bit (used for indirect addressing) 1 = Bank 2, 3 (100h-1FFh) 0 = Bank 0, 1 (00h-FFh) RP<1:0>: Register Bank Select bits (used for direct addressing) 00 = Bank 0 (00h-7Fh) 01 = Bank 1 (80h-FFh) 10 = Bank 2 (100h-17Fh) 11 = Bank 3 (180h-1FFh) TO: Time-out bit 1 = After power-up, CLRWDT instruction or SLEEP instruction 0 = A WDT time-out occurred PD: Power-down bit 1 = After power-up or by the CLRWDT instruction 0 = By execution of the SLEEP instruction 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 (ADDWF, ADDLW,SUBLW,SUBWF instructions) For borrow, the polarity is reversed. 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 C: Carry/borrow bit (ADDWF, ADDLW, SUBLW, 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 1: For borrow, the polarity is reversed. A subtraction is executed by adding the two'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.
bit 6-5
bit 4
bit 3
bit 2
bit 1
bit 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 13
PIC16F688
2.2.2.2 Option Register
Note: To achieve a 1:1 prescaler assignment for TMR0, assign the prescaler to the WDT by setting PSA bit to `1' (Option<3>). See Section 5.4 "Prescaler". The Option register is a readable and writable register, which contains various control bits to configure: * * * * TMR0/WDT prescaler External RA2/INT interrupt TMR0 Weak pull-ups on PORTA
REGISTER 2-2:
OPTION_REG - OPTION REGISTER (ADDRESS: 81h OR 181h)
R/W-1 RAPU bit 7 R/W-1 INTEDG R/W-1 T0CS R/W-1 T0SE R/W-1 PSA R/W-1 PS2 R/W-1 PS1 R/W-1 PS0 bit 0
bit 7
RAPU: PORTA Pull-up Enable bit 1 = PORTA pull-ups are disabled 0 = PORTA pull-ups are enabled by individual port latch values INTEDG: Interrupt Edge Select bit 1 = Interrupt on rising edge of RA2/INT pin 0 = Interrupt on falling edge of RA2/INT pin T0CS: TMR0 Clock Source Select bit 1 = Transition on RA2/T0CKI pin 0 = Internal instruction cycle clock (CLKOUT) T0SE: TMR0 Source Edge Select bit 1 = Increment on high-to-low transition on RA2/T0CKI pin 0 = Increment on low-to-high transition on RA2/T0CKI pin PSA: Prescaler Assignment bit 1 = Prescaler is assigned to the WDT 0 = Prescaler is assigned to the Timer0 module PS<2:0>: Prescaler Rate Select bits BIT VALUE TMR0 RATE WDT RATE 000 001 010 011 100 101 110 111 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 1 : 256 1:1 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128
bit 6
bit 5
bit 4
bit 3
bit 2-0
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
DS41203B-page 14
Preliminary
2004 Microchip Technology Inc.
PIC16F688
2.2.2.3 INTCON Register
Note: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit, GIE (INTCON<7>). User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. The INTCON register is a readable and writable register, which contains the various enable and flag bits for TMR0 register overflow, PORTA change and external RA2/INT pin interrupts.
REGISTER 2-3:
INTCON - INTERRUPT CONTROL REGISTER (ADDRESS: 0Bh OR 8Bh)
R/W-0 GIE bit 7 R/W-0 PEIE R/W-0 T0IE R/W-0 INTE R/W-0 RAIE R/W-0 T0IF R/W-0 INTF R/W-0 RAIF bit 0
bit 7
GIE: Global Interrupt Enable bit 1 = Enables all unmasked interrupts 0 = Disables all interrupts PEIE: Peripheral Interrupt Enable bit 1 = Enables all unmasked peripheral interrupts 0 = Disables all peripheral interrupts T0IE: TMR0 Overflow Interrupt Enable bit 1 = Enables the TMR0 interrupt 0 = Disables the TMR0 interrupt INTE: RA2/INT External Interrupt Enable bit 1 = Enables the RA2/INT external interrupt 0 = Disables the RA2/INT external interrupt RAIE: PORTA Change Interrupt Enable bit(1) 1 = Enables the PORTA change interrupt 0 = Disables the PORTA change interrupt T0IF: TMR0 Overflow Interrupt Flag bit(2) 1 = TMR0 register has overflowed (must be cleared in software) 0 = TMR0 register did not overflow INTF: RA2/INT External Interrupt Flag bit 1 = The RA2/INT external interrupt occurred (must be cleared in software) 0 = The RA2/INT external interrupt did not occur RAIF: PORTA Change Interrupt Flag bit 1 = When at least one of the PORTA <5:0> pins changed state (must be cleared in software) 0 = None of the PORTA <5:0> pins have changed state Note 1: IOCA register must also be enabled. 2: T0IF bit is set when Timer0 rolls over. Timer0 is unchanged on Reset and should be initialized before clearing T0IF 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
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 15
PIC16F688
2.2.2.4 PIE1 Register
Note: Bit PEIE (INTCON<6>) must be set to enable any peripheral interrupt. The PIE1 register contains the interrupt enable bits, as shown in Register 2-4.
REGISTER 2-4:
PIE1 - PERIPHERAL INTERRUPT ENABLE REGISTER 1 (ADDRESS: 8Ch)
R/W-0 EEIE bit 7 R/W-0 ADIE R/W-0 RCIE R/W-0 C2IE R/W-0 C1IE R/W-0 OSFIE R/W-0 TXIE R/W-0 TMR1IE bit 0
bit 7
EEIE: EE Write Complete Interrupt Enable bit 1 = Enables the EE write complete interrupt 0 = Disables the EE write complete interrupt ADIE: A/D Converter Interrupt Enable bit 1 = Enables the A/D converter interrupt 0 = Disables the A/D converter interrupt RCIE: USART Receive Interrupt Enable bit 1 = Enables the USART receive interrupt 0 = Disables the USART receive interrupt C2IE: Comparator 2 Interrupt Enable bit 1 = Enables the Comparator 2 interrupt 0 = Disables the Comparator 2 interrupt C1IE: Comparator 1 Interrupt Enable bit 1 = Enables the Comparator 1 interrupt 0 = Disables the Comparator 1 interrupt OSFIE: Oscillator Fail Interrupt Enable bit 1 = Enables the oscillator fail interrupt 0 = Disables the oscillator fail interrupt TXIE: USART Transmit Interrupt Enable bit 1 = Enables the USART transmit interrupt 0 = Disables the USART transmit interrupt TMR1IE: Timer1 Overflow Interrupt Enable bit 1 = Enables the Timer1 overflow interrupt 0 = Disables the Timer1 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
DS41203B-page 16
Preliminary
2004 Microchip Technology Inc.
PIC16F688
2.2.2.5 PIR1 Register
Note: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit, GIE (INTCON<7>). User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. The PIR1 register contains the interrupt flag bits, as shown in Register 2-5.
REGISTER 2-5:
PIR1 - PERIPHERAL INTERRUPT REQUEST REGISTER 1 (ADDRESS: 0Ch)
R/W-0 EEIF bit 7 R/W-0 ADIF R-0 RCIF R/W-0 C2IF R/W-0 C1IF R/W-0 OSFIF R-0 TXIF R/W-0 TMR1IF bit 0
bit 7
EEIF: EEPROM Write Operation Interrupt Flag bit 1 = The write operation completed (must be cleared in software) 0 = The write operation has not completed or has not been started ADIF: A/D Interrupt Flag bit 1 = A/D conversion complete 0 = A/D conversion has not completed or has not been started RCIF: USART Receive Interrupt Flag bit 1 = The USART receive buffer is full 0 = The USART receive buffer is empty C2IF: Comparator 2 Interrupt Flag bit 1 = Comparator 2 output has changed (must be cleared in software) 0 = Comparator 2 output has not changed C1IF: Comparator 1 Interrupt Flag bit 1 = Comparator 1 output has changed (must be cleared in software) 0 = Comparator 1 output has not changed OSFIF: Oscillator Fail Interrupt Flag bit 1 = System oscillator failed, clock input has changed to INTOSC (must be cleared in software) 0 = System clock operating TXIF: USART Transmit Interrupt Flag bit 1 = The USART transmit buffer is empty 0 = The USART transmit buffer is full TMR1IF: Timer1 Overflow Interrupt Flag bit 1 = Timer1 register overflowed (must be cleared in software) 0 = Timer1 has not overflowed 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 17
PIC16F688
2.2.2.6 PCON Register
The Power Control (PCON) register (See Table 12-2) contains flag bits to differentiate between a: * * * * Power-on Reset (POR) Brown-out Detect (BOD) Watchdog Timer Reset (WDT) External MCLR Reset
The PCON register also controls the Ultra Low-Power Wake-up and software enable of the BOD. The PCON register bits are shown in Register 2-6.
REGISTER 2-6:
PCON - POWER CONTROL REGISTER (ADDRESS: 8Eh)
U-0 -- bit 7 U-0 -- R/W-0 R/W-1 U-0 -- U-0 -- R/W-0 POR R/W-x BOD bit 0 ULPWUE SBODEN
bit 7-6 bit 5
Unimplemented: Read as `0' ULPWUE: Ultra Low-Power Wake-up Enable bit 1 = Ultra low-power wake-up enabled 0 = Ultra low-power wake-up disabled SBODEN: Software BOD Enable bit(1) 1 = BOD enabled 0 = BOD disabled Unimplemented: Read as `0' POR: Power-on Reset Status bit 1 = No Power-on Reset occurred 0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs) BOD: Brown-out Detect Status bit 1 = No Brown-out Detect occurred 0 = A Brown-out Detect occurred (must be set in software after a Brown-out Detect occurs) Note 1: BODEN<1:0> = 01 in the Configuration Word register for this bit to control the BOD. 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 4
bit 3-2 bit 1
bit 0
DS41203B-page 18
Preliminary
2004 Microchip Technology Inc.
PIC16F688
2.3 PCL and PCLATH
2.3.2 STACK
The program counter (PC) is 13 bits wide. The low byte comes from the PCL register, which is a readable and writable register. The high byte (PC<12:8>) is not directly readable or writable and comes from PCLATH. On any Reset, the PC is cleared. Figure 2-3 shows the two situations for the loading of the PC. The upper example in Figure 2-3 shows how the PC is loaded on a write to PCL (PCLATH<4:0> PCH). The lower example in Figure 2-3 shows how the PC is loaded during a CALL or GOTO instruction (PCLATH<4:3> PCH). The PIC16F688 family has an 8-level x 13-bit wide hardware stack (see Figure 2-1). The stack space is not part of either program or data space and the stack pointer is not readable or writable. The PC is PUSHed onto the stack when a CALL instruction is executed or an interrupt causes a branch. The stack is POPed in the event of a RETURN, RETLW or a RETFIE instruction execution. PCLATH is not affected by a PUSH or POP operation. The stack operates as a circular buffer. This means that after the stack has been PUSHed eight times, the ninth push overwrites the value that was stored from the first push. The tenth push overwrites the second push (and so on). Note 1: There are no Status bits to indicate stack overflow or stack underflow conditions. 2: There are no instructions/mnemonics called PUSH or POP. These are actions that occur from the execution of the CALL, RETURN, RETLW and RETFIE instructions or the vectoring to an interrupt address.
FIGURE 2-3:
PCH 12 PC 5 8 7
LOADING OF PC IN DIFFERENT SITUATIONS
PCL 0 Instruction with PCL as Destination ALU Result
PCLATH<4:0>
8
PCLATH PCH 12 PC 2 PCLATH<4:3> 11 OPCODE<10:0> PCLATH 11 10 8 7 PCL 0 GOTO, CALL
2.3.1
COMPUTED GOTO
A computed GOTO is accomplished by adding an offset to the program counter (ADDWF PCL). When performing a table read using a computed GOTO method, care should be exercised if the table location crosses a PCL memory boundary (each 256-byte block). Refer to the Application Note AN556, "Implementing a Table Read" (DS00556).
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 19
PIC16F688
2.4 Indirect Addressing, INDF and FSR Registers
A simple program to clear RAM location 20h-2Fh using indirect addressing is shown in Example 2-1.
The INDF register is not a physical register. Addressing the INDF register will cause indirect addressing. Indirect addressing is possible by using the INDF register. Any instruction using the INDF register actually accesses data pointed to by the File Select Register (FSR). Reading INDF itself indirectly will produce 00h. Writing to the INDF register indirectly results in a no operation (although Status bits may be affected). An effective 9-bit address is obtained by concatenating the 8-bit FSR register and the IRP bit (Status<7>), as shown in Figure 2-4.
EXAMPLE 2-1:
MOVLW MOVWF NEXT CLRF INCF BTFSS GOTO CONTINUE 0x20 FSR INDF FSR FSR,4 NEXT
INDIRECT ADDRESSING
;initialize pointer ;to RAM ;clear INDF register ;inc pointer ;all done? ;no clear next ;yes continue
FIGURE 2-4:
DIRECT/INDIRECT ADDRESSING PIC16F688
Indirect Addressing 0 IRP 7 File Select Register 0
Direct Addressing RP1 RP0 6 From Opcode
Bank Select
Location Select 00 00h 01 10 11
Bank Select 180h
Location Select
Data Memory
7Fh Bank 0 Note: Bank 1 Bank 2 Bank 3
1FFh
For memory map detail, see Figure 2-2.
DS41203B-page 20
Preliminary
2004 Microchip Technology Inc.
PIC16F688
3.0
3.1
CLOCK SOURCES
Overview
The PIC16F688 can be configured in one of eight clock modes. 1. 2. 3. 4. 5. 6. 7. 8. EC - External clock with I/O on RA4. LP - Low gain Crystal or Ceramic Resonator Oscillator mode. XT - Medium gain Crystal or Ceramic Resonator Oscillator mode. HS - High gain Crystal or Ceramic Resonator mode. RC - External Resistor-Capacitor (RC) with FOSC/4 output on RA4. RCIO - External Resistor-Capacitor with I/O on RA4. INTRC - Internal oscillator with FOSC/4 output on RA4 and I/O on RA5. INTRCIO - Internal oscillator with I/O on RA4 and RA5.
The PIC16F688 has a wide variety of clock sources and selection features to allow it to be used in a wide range of applications while maximizing performance and minimizing power consumption. Figure 3-1 illustrates a block diagram of the PIC16F688 clock sources. Clock sources can be configured from external oscillators, quartz crystal resonators, ceramic resonators, and Resistor-Capacitor (RC) circuits. In addition, the system clock source can be configured from one of two internal oscillators, with a choice of speeds selectable via software. Additional clock features include: * Selectable system clock source between external or internal via software. * Two-Speed Clock Start-up mode, which minimizes latency between external oscillator start-up and code execution. * Fail-Safe Clock Monitor (FSCM) designed to detect a failure of the external clock source (LP, XT, HS, EC or RC modes) and switch to the Internal Oscillator.
Clock source modes are configured by the FOSC<2:0> bits in the Configuration Word register (see Section 11.0 "Special Features Of The CPU"). The internal clock can be generated by two oscillators. The HFINTOSC is a high-frequency calibrated oscillator. The LFINTOSC is a low-frequency uncalibrated oscillator.
FIGURE 3-1:
PIC16F688 CLOCK SOURCE BLOCK DIAGRAM
FOSC<2:0> (Configuration Word) SCS (OSCCON<0>)
External Oscillator OSC2 Sleep OSC1 IRCF<2:0> (OSCCON<6:4>) 8 MHz Internal Oscillator 4 MHz 2 MHz Postscaler 101 100 500 kHz 250 kHz 125 kHz LFINTOSC 31 kHz 31 kHz 011 010 001 000 MUX 1 MHz HFINTOSC 8 MHz 111 110
LP, XT, HS, RC, RCIO, EC MUX
System Clock (CPU and Peripherals)
Power-up Timer (PWRT) Watchdog Timer (WDT) Fail-Safe Clock Monitor (FSCM)
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 21
PIC16F688
3.2 Clock Source Modes 3.3
3.3.1
External Clock Modes
OSCILLATOR START-UP TIMER (OST)
Clock source modes can be classified as external or internal. * External clock modes rely on external circuitry for the clock source. Examples are oscillator modules (EC mode), quartz crystal resonators or ceramic resonators (LP, XT and HS modes), and Resistor-Capacitor (RC mode) circuits. * Internal clock sources are contained internally within the PIC16F688. The PIC16F688 has two internal oscillators: the 8 MHz High-Frequency Internal Oscillator (HFINTOSC) and 31 kHz Low-Frequency Internal Oscillator (LFINTOSC). The system clock can be selected between external or internal clock sources via the System Clock Selection (SCS) bit (see Section 3.5 "Clock Switching").
If the PIC16F688 is configured for LP, XT or HS modes, the Oscillator Start-up Timer (OST) counts 1024 oscillations from the OSC1 pin, following a Power-on Reset (POR) and the Power-up Timer (PWRT) has expired (if configured), or a wake-up from Sleep. During this time, the program counter does not increment and program execution is suspended. The OST ensures that the oscillator circuit, using a quartz crystal resonator or ceramic resonator, has started and is providing a stable system clock to the PIC16F688. When switching between clock sources a delay is required to allow the new clock to stabilize. These oscillator delays are shown in Table 3-1. In order to minimize latency between external oscillator start-up and code execution, the Two-Speed Clock Start-up mode can be selected (see Section 3.6 "Two-Speed Clock Start-up Mode").
TABLE 3-1:
OSCILLATOR DELAY EXAMPLES
Switch To LFINTOSC HFINTOSC EC, RC EC, RC LP, XT, HS HFINTOSC Frequency 31 kHz 125 kHz-8 MHz DC - 20 MHz DC - 20 MHz 31 kHz-20 MHz 125 kHz-8 MHz 1024 Clock Cycles (OST) 1 s (approx.) Oscillator Delay
Switch From Sleep/POR Sleep/POR LFINTOSC (31 kHz) Sleep/POR LFINTOSC (31 kHz) Note 1:
5 s-10 s (approx.) CPU Start-up(1)
The 5 s to 10 s start-up delay is based on a 1 MHz system clock.
3.3.2
EC MODE
FIGURE 3-2:
The External Clock (EC) mode allows an externally generated logic level as the system clock source. When operating in this mode, an external clock source is connected to the OSC1 pin and the RA5 pin is available for general purpose I/O. Figure 3-2 shows the pin connections for EC mode. The Oscillator Start-up Timer (OST) is disabled when EC mode is selected. Therefore, there is no delay in operation after a Power-on Reset (POR) or wake-up from Sleep. Because the PIC16F688 design is fully static, stopping the external clock input will have the effect of halting the device while leaving all data intact. Upon restarting the external clock, the device will resume operation as if no time had elapsed.
EXTERNAL CLOCK (EC) MODE OPERATION
OSC1/CLKIN PIC16F688 RA4 I/O (OSC2)
Clock from Ext. System
DS41203B-page 22
Preliminary
2004 Microchip Technology Inc.
PIC16F688
3.3.3 LP, XT, HS MODES FIGURE 3-4:
The LP, XT and HS modes support the use of quartz crystal resonators or ceramic resonators connected to the OSC1 and OSC2 pins (Figure 3-1). The mode selects a low, medium or high gain setting of the internal inverter-amplifier to support various resonator types and speed. LP Oscillator mode selects the lowest gain setting of the internal inverter-amplifier. LP mode current consumption is the least of the three modes. This mode is best suited to drive resonators with a low drive level specification, for example, tuning fork type crystals. XT Oscillator mode selects the intermediate gain setting of the internal inverter-amplifier. XT mode current consumption is the medium of the three modes. This mode is best suited to drive resonators with a medium drive level specification, for example, low-frequency/AT-cut quartz crystal resonators. HS Oscillator mode selects the highest gain setting of the internal inverter-amplifier. HS mode current consumption is the highest of the three modes. This mode is best suited for resonators that require a high drive setting, for example, high-frequency/AT-cut quartz crystal resonators or ceramic resonators. Figure 3-3 and Figure 3-4 show typical circuits for quartz crystal and ceramic resonators, respectively.
CERAMIC RESONATOR OPERATION (XT OR HS MODE)
PIC16F688
OSC1
C1
To Internal Logic RP(3) OSC2 RS(1) RF(2) Sleep
C2 Ceramic Resonator
Note 1: A series resistor (RS) may be required for ceramic resonators with low drive level. 2: The value of RF varies with the oscillator mode selected (typically between 2 M to 10 M). 3: An additional parallel feedback resistor (RP) may be required for proper ceramic resonator operation (typical value 1 M).
FIGURE 3-3:
QUARTZ CRYSTAL OPERATION (LP, XT OR HS MODE)
PIC16F688
OSC1
C1 Quartz Crystal OSC2 RS(1) C2
To Internal Logic RF(2) Sleep
Note 1: 2:
A series resistor (RS) may be required for quartz crystals with low drive level. The value of RF varies with the oscillator mode selected (typically between 2 M to 10 M).
Note 1: Quartz crystal characteristics vary according to type, package and manufacturer. The user should consult the manufacturer data sheets for specifications and recommended application. 2: Always verify oscillator performance over the VDD and temperature range that is expected for the application.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 23
PIC16F688
3.3.4 EXTERNAL RC MODES
3.4
Internal Clock Modes
The External Resistor-Capacitor (RC) modes support the use of an external RC circuit. This allows the designer maximum flexibility in frequency choice while keeping costs to a minimum when clock accuracy is not required. There are two modes, RC and RCIO. In RC mode, the RC circuit connects to the OSC1 pin. The OSC2/CLKOUT pin outputs the RC oscillator frequency divided by 4. This signal may be used to provide a clock for external circuitry, synchronization, calibration, test or other application requirements. Figure 3-5 shows the RC mode connections.
The PIC16F688 has two independent, internal oscillators that can be configured or selected as the system clock source. 1. The HFINTOSC (High-Frequency Internal Oscillator) is factory calibrated and operates at 8 MHz. The frequency of the HFINTOSC can be user adjusted 12% via software using the OSCTUNE register (Register 3-1). The LFINTOSC (Low-Frequency Internal Oscillator) is uncalibrated and operates at approximately 31 kHz.
2.
FIGURE 3-5:
VDD REXT
RC MODE
The system clock speed can be selected via software using the Internal Oscillator Frequency Select (IRCF) bits.
Internal Clock
OSC1 CEXT VSS
The system clock can be selected between external or internal clock sources via the System Clock Selection (SCS) bit (see Section 3.5 "Clock Switching").
PIC16F688
3.4.1
INTRC AND INTRCIO MODES
OSC2/CLKOUT FOSC/4 Recommended values: 3 k REXT 100 k CEXT > 20 pF
The INTRC and INTRCIO modes configure the internal oscillators as the system clock source when the device is programmed using the Oscillator Selection (FOSC) bits in the Configuration Word register (Register 11-1). In INTRC mode, the OSC1 pin is available for general purpose I/O. The OSC2/CLKOUT pin outputs the selected internal oscillator frequency divided by 4. The CLKOUT signal may be used to provide a clock for external circuitry, synchronization, calibration, test or other application requirements. In INTRCIO mode, the OSC1 and OSC2 pins are available for general purpose I/O.
In RCIO mode, the RC circuit is connected to the OSC1 pin. The OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 4 of PORTA (RA4). Figure 3-6 shows the RCIO mode connections.
FIGURE 3-6:
VDD REXT
RCIO MODE
OSC1 CEXT VSS RA4 I/O (OSC2)
Internal Clock
3.4.2
HFINTOSC
PIC16F688
The High-Frequency Internal Oscillator (HFINTOSC) is a factory calibrated 8 MHz internal clock source. The frequency of the HFINTOSC can be altered approximately 12% via software using the OSCTUNE register (Register 3-1). The output of the HFINTOSC connects to a postscaler and multiplexer (see Figure 3-1). One of seven frequencies can be selected via software using the IRCF bits (see Section 3.4.4 "Frequency Select Bits (IRCF)"). The HFINTOSC is enabled by selecting any frequency between 8 MHz and 125 kHz (IRCF 000) as the system clock source (SCS = 1), or when Two-Speed Start-up is enabled (IESO = 1 and IRCF 000). The HF Internal Oscillator (HTS) bit (OSCCON<2>) indicates whether the HFINTOSC is stable or not.
Recommended values: 3 k REXT 100 k CEXT > 20 pF
The RC oscillator frequency is a function of the supply voltage, the resistor (REXT) and capacitor (CEXT) values and the operating temperature. Other factors affecting the oscillator frequency are: * threshold voltage variation * component tolerances * packaging variations in capacitance The user also needs to take into account variation due to tolerance of external RC components used.
DS41203B-page 24
Preliminary
2004 Microchip Technology Inc.
PIC16F688
3.4.2.1 OSCTUNE Register
The HFINTOSC is factory calibrated but can be adjusted in software by writing to the OSCTUNE register (Register 3-1). The OSCTUNE register has a tuning range of 12%. The default value of the OSCTUNE register is `0'. The value is a 5-bit two's complement number. Due to process variation, the monotonicity and frequency step cannot be specified. When the OSCTUNE register is modified, the HFINTOSC frequency will begin shifting to the new frequency. The HFINTOSC clock will stabilize within 1 ms. Code execution continues during this shift. There is no indication that the shift has occurred. OSCTUNE does not affect the LFINTOSC frequency. Operation of features that depend on the LFINTOSC clock source frequency, such as the Power-up Timer (PWRT), Watchdog Timer (WDT), Fail-Safe Clock Monitor (FSCM), and peripherals, are not affected by the change in frequency.
REGISTER 3-1:
OSCTUNE - OSCILLATOR TUNING RESISTOR (ADDRESS: 90h)
U-0 -- bit 7 U-0 -- 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 7-5 bit 4-0
Unimplemented: Read as `0' TUN<4:0>: Frequency Tuning bits 01111 = Maximum frequency 01110 = * * * 00001 = 00000 = 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 25
PIC16F688
3.4.3 LFINTOSC 3.4.5
The Low-Frequency Internal Oscillator (LFINTOSC) is an uncalibrated (approximate) 31 kHz internal clock source. The output of the LFINTOSC connects to a postscaler and multiplexer (see Figure 3-1). 31 kHz can be selected via software using the IRCF bits (see Section 3.4.4 "Frequency Select Bits (IRCF)"). The LFINTOSC is also the frequency for the Power-up Timer (PWRT), Watchdog Timer (WDT) and Fail-Safe Clock Monitor (FSCM). The LFINTOSC is enabled by selecting 31 kHz (IRCF = 000) as the system clock source (SCS = 1), or when any of the following are enabled: * * * * Two-Speed Start-up (IESO = 1 and IRCF = 000) Power-up Timer (PWRT) Watchdog Timer (WDT) Fail-Safe Clock Monitor (FSCM)
HF AND LF INTOSC CLOCK SWITCH TIMING
When switching between the LFINTOSC and the HFINTOSC, the new oscillator may already be shut down to save power. If this is the case, there is a 10 s delay after the IRCF bits are modified before the frequency selection takes place. The LTS/HTS bits will reflect the current active status of the LFINTOSC and the HFINTOSC oscillators. The timing of a frequency selection is as follows: 1. 2. 3. 4. 5. 6. IRCF bits are modified. If the new clock is shut down, a 10 s clock start-up delay is started. Clock switch circuitry waits for a falling edge of the current clock. CLKOUT is held low and the clock switch circuitry waits for a rising edge in the new clock. CLKOUT is now connected with the new clock. HTS/LTS bits are updated as required. Clock switch is complete.
The LF Internal Oscillator (LTS) bit (OSCCON<1>) indicates whether the LFINTOSC is stable or not.
3.4.4
FREQUENCY SELECT BITS (IRCF)
The output of the 8 MHz HFINTOSC and 31 kHz LFINTOSC connect to a postscaler and multiplexer (see Figure 3-1). The Internal Oscillator Frequency select bits, IRCF<2:0> (OSCCON<6:4>), select the frequency output of the internal oscillators. One of eight frequencies can be selected via software: * * * * * * * * 8 MHz 4 MHz (Default after Reset) 2 MHz 1 MHz 500 kHz 250 kHz 125 kHz 31 kHz Note: Following any Reset, the IRCF bits are set to `110' and the frequency selection is set to 4 MHz. The user can modify the IRCF bits to select a different frequency.
If the internal oscillator speed selected is between 8 MHz and 125 kHz, there is no start-up delay before the new frequency is selected. This is because the old and the new frequencies are derived from the HFINTOSC via the postscaler and multiplexer.
DS41203B-page 26
Preliminary
2004 Microchip Technology Inc.
PIC16F688
3.5 Clock Switching
The system clock source can be switched between external and internal clock sources via software using the System Clock Select (SCS) bit. When the PIC16F688 is configured for LP, XT or HS modes, the Oscillator Start-up Timer (OST) is enabled (see Section 3.3.1 "Oscillator Start-up Timer (OST)"). The OST timer will suspend program execution until 1024 oscillations are counted. Two-Speed Start-up mode minimizes the delay in code execution by operating from the internal oscillator as the OST is counting. When the OST count reaches 1024 and the OSTS bit (OSCCON<3>) is set, program execution switches to the external oscillator.
3.5.1
SYSTEM CLOCK SELECT (SCS) BIT
The System Clock Select (SCS) bit (OSCCON<0>) selects the system clock source that is used for the CPU and peripherals. * When SCS = 0, the system clock source is determined by configuration of the FOSC<2:0> bits in the Configuration Word register (CONFIG). * When SCS = 1, the system clock source is chosen by the internal oscillator frequency selected by the IRCF bits. After a Reset, SCS is always cleared. Note: Any automatic clock switch, which may occur from Two-Speed Start-up or Fail-Safe Clock Monitor, does not update the SCS bit. The user can monitor the OSTS (OSCCON<3>) to determine the current system clock source.
3.6.1
TWO-SPEED START-UP MODE CONFIGURATION
Two-Speed Start-up mode is configured by the following settings: * IESO = 1 (CONFIG<10>) Internal/External Switch Over bit. * SCS = 0. * FOSC configured for LP, XT or HS mode. Two-Speed Start-up mode is entered after: * Power-on Reset (POR) and, if enabled, after PWRT has expired, or * Wake-up from Sleep. If the external clock oscillator is configured to be anything other than LP, XT or HS mode, then Two-Speed Start-up is disabled. This is because the external clock oscillator does not require any stabilization time after POR or an exit from Sleep.
3.5.2
OSCILLATOR START-UP TIME-OUT STATUS BIT
The Oscillator Start-up Time-out Status (OSTS) bit (OSCCON<3>) indicates whether the system clock is running from the external clock source, as defined by the FOSC bits, or from internal clock source. In particular, OSTS indicates that the Oscillator Start-up Timer (OST) has timed out for LP, XT or HS modes.
3.6.2
1. 2.
TWO-SPEED START-UP SEQUENCE
3.6
Two-Speed Clock Start-up Mode
Two-Speed Start-up mode provides additional power savings by minimizing the latency between external oscillator start-up and code execution. In applications that make heavy use of the Sleep mode, Two-Speed Start-up will remove the external oscillator start-up time from the time spent awake and can reduce the overall power consumption of the device. This mode allows the application to wake-up from Sleep, perform a few instructions using the INTOSC as the clock source and go back to Sleep without waiting for the primary oscillator to become stable. Note: Executing a SLEEP instruction will abort the oscillator start-up time and will cause the OSTS bit (OSCCON<3>) to remain clear.
3. 4. 5. 6. 7.
Wake-up from Power-on Reset or Sleep. Instructions begin execution by the internal oscillator at the frequency set in the IRCF bits (OSCCON<6:4>). OST enabled to count 1024 clock cycles. OST timed out, wait for falling edge of the internal oscillator. OSTS is set. System clock held low until the next falling edge of new clock (LP, XT or HS mode). System clock is switched to external clock source.
3.6.3
CHECKING EXTERNAL/INTERNAL CLOCK STATUS
Checking the state of the OSTS bit (OSCCON<3>) will confirm if the PIC16F688 is running from the external clock source as defined by the FOSC bits in the Configuration Word (CONFIG) or the internal oscillator.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 27
PIC16F688
FIGURE 3-7: TWO-SPEED START-UP
Q1 INTOSC T TOST OSC1 0 1 1022 1023 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1
OSC2 Program Counter PC PC + 1 PC + 2
System Clock
3.7
Fail-Safe Clock Monitor
The Fail-Safe Clock Monitor (FSCM) is designed to allow the device to continue to operate in the event of an oscillator failure. The FSCM can detect oscillator failure at any point after the device has exited a Reset or Sleep condition and the Oscillator Start-up Timer (OST) has expired.
The frequency of the internal oscillator will depend upon the value contained in the IRCF bits (OSCCON<6:4>). Upon entering the Fail-Safe condition, the OSTS bit (OSCCON<3>) is automatically cleared to reflect that the internal oscillator is active and the WDT is cleared. The SCS bit (OSCCON<0>) is not updated. Enabling FSCM does not affect the LTS bit. The FSCM sample clock is generated by dividing the INTRC clock by 64. This will allow enough time between FSCM sample clocks for a system clock edge to occur. Figure 3-8 shows the FSCM block diagram. On the rising edge of the sample clock, the monitoring latch (CM = 0) will be cleared. On a falling edge of the primary system clock, the monitoring latch will be set (CM = 1). In the event that a falling edge of the sample clock occurs, and the monitoring latch is not set, a clock failure has been detected. The assigned internal oscillator is enabled when FSCM is enabled as reflected by the IRCF. Note: Two-Speed Start-up is automatically enabled when the Fail-Safe Clock Monitor mode is enabled. Primary clocks with a frequency ~488 Hz will be considered failed by the FSCM. A slow starting oscillator can cause an FSCM interrupt.
FIGURE 3-8:
FSCM BLOCK DIAGRAM
Primary Clock
Clock Fail Detector / 64
LFINTOSC Oscillator
Clock Failure Detected
The FSCM function is enabled by setting the FCMEN bit in the Configuration Word (CONFIG). It is applicable to all external clock options (LP, XT, HS, EC, RC or IO modes). In the event of an external clock failure, the FSCM will set the OSFIF bit (PIR1<2>) and generate an oscillator fail interrupt if the OSFIE bit (PIE1<2>) is set. The device will then switch the system clock to the internal oscillator. The system clock will continue to come from the internal oscillator unless the external clock recovers and the Fail-Safe condition is exited.
Note:
DS41203B-page 28
Preliminary
2004 Microchip Technology Inc.
PIC16F688
3.7.1 FAIL-SAFE CONDITION CLEARING
The Fail-Safe condition is cleared after a Reset, the execution of a SLEEP instruction, or a modification of the SCS bit. While in Fail-Safe condition, the PIC16F688 uses the internal oscillator as the system clock source. The IRCF bits (OSCCON<6:4>) can be modified to adjust the internal oscillator frequency without exiting the Fail-Safe condition. The Fail-Safe condition must be cleared before the OSFIF flag can be cleared.
FIGURE 3-9:
Sample Clock System Clock Output CM Output (Q)
FSCM TIMING DIAGRAM
Oscillator Failure
Failure Detected OSCFIF
CM Test Note:
CM Test
CM Test
The system clock is normally at a much higher frequency than the sample clock. The relative frequencies in this example have been chosen for clarity.
3.7.2
RESET OR WAKE-UP FROM SLEEP
The FSCM is designed to detect oscillator failure at any point after the device has exited a Reset or Sleep condition and the Oscillator Start-up Timer (OST) has expired. If the external clock is EC or RC mode, monitoring will begin immediately following these events. For LP, XT or HS mode the external oscillator may require a start-up time considerably longer than the FSCM sample clock time, a false clock failure may be detected (see Figure 3-9). To prevent this, the internal oscillator is automatically configured as the system clock and functions until the external clock is stable (the OST has timed out). This is identical to Two-Speed Start-up mode. Once the external oscillator is stable, the LFINTOSC returns to its role as the FSCM source.
Note:
Due to the wide range of oscillator start-up times, the Fail-Safe circuit is not active during oscillator start-up (i.e., after exiting Reset or Sleep). After an appropriate amount of time, the user should check the OSTS bit (OSCCON<3>) to verify the oscillator start-up and system clock switchover has successfully completed.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 29
PIC16F688
REGISTER 3-2: OSCCON - OSCILLATOR CONTROL REGISTER (ADDRESS: 8Fh)
U-0 -- bit 7 bit 7 bit 6-4 R/W-1 IRCF2 R/W-1 IRCF1 R/W-0 IRCF0 R-1 OSTS(1) R-0 HTS R-0 LTS R/W-0 SCS bit 0
bit 3
bit 2
bit 1
bit 0
Unimplemented: Read as `0' IRCF<2:0>: Internal Oscillator Frequency Select bits 000 = 31 kHz 001 = 125 kHz 010 = 250 kHz 011 = 500 kHz 100 = 1 MHz 101 = 2 MHz 110 = 4 MHz 111 = 8 MHz OSTS: Oscillator Start-up Time-out Status bit 1 = Device is running from the external system clock defined by FOSC<2:0> 0 = Device is running from the internal system clock (HFINTOSC or LFINTOSC) HTS: HFINTOSC (High Frequency - 8 MHz to 125 kHz) Status bit 1 = HFINTOSC is stable 0 = HFINTOSC is not stable LTS: LFINTOSC (Low Frequency - 31 kHz) Stable bit 1 = LFINTOSC is stable 0 = LFINTOSC is not stable SCS: System Clock Select bit 1 = Internal oscillator is used for system clock 0 = Clock source defined by FOSC<2:0> Note 1: Bit resets to `0' with Two-Speed Start-up and LP, XT or HS selected as the Oscillator mode or Fail-Safe mode is enabled. 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
TABLE 3-2:
Address 0Ch 8Ch 8Fh 90h 2007h
(1)
SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES
Bit 7 EEIF EEIE -- -- CPD Bit 6 ADIF ADIE IRCF2 -- CP Bit 5 RCIF RCIE IRCF1 -- Bit 4 C2IF C2IE IRCF0 TUN4 Bit 3 C1IF C1IE OSTS(2) TUN3 WDTE Bit 2 OSFIF OSFIE HTS TUN2 FOSC2 Bit 1 TXIF TXIE LTS TUN1 FOSC1 Bit 0 Value on: POR, BOD Value on all other Resets
Name PIR1 PIE1 OSCCON OSCTUNE CONFIG
TMR1IF 0000 0000 0000 0000 TMR1IE 0000 0000 0000 0000 SCS TUN0 FOSC0 -110 x000 -110 x000 ---0 0000 ---u uuuu -- --
MCLRE PWRTE
Legend: Note 1: 2:
x = unknown, u = unchanged, -- = unimplemented locations read as `0'. Shaded cells are not used by oscillators. See Register 11-1 for operation of all Configuration Word bits. See Register 3-2 for details.
DS41203B-page 30
Preliminary
2004 Microchip Technology Inc.
PIC16F688
4.0 I/O PORTS
EXAMPLE 4-1:
BCF CLRF MOVLW MOVWF BSF CLRF MOVLW MOVWF BCF STATUS,RP0 PORTA 07h CMCON0 STATUS,RP0 ANSEL 0Ch TRISA STATUS,RP0
INITIALIZING PORTA
;Bank 0 ;Init PORTA ;Set RA<2:0> to ;digital I/O ;Bank 1 ;digital I/O ;Set RA<3:2> as inputs ;and set RA<5:4,1:0> ;as outputs ;Bank 0
There are as many as twelve general purpose I/O pins available. Depending on which peripherals are enabled, some or all of the pins may not be available as general purpose I/O. In general, when a peripheral is enabled, the associated pin may not be used as a general purpose I/O pin. Note: Additional information on I/O ports may be found in the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023).
4.1
PORTA and the TRISA Registers
4.2
Additional Pin Functions
PORTA is a 6-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 Hi-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). The exception is RA3, which is input only and its TRISA bit will always read as `1'. Example 4-1 shows how to initialize PORTA. Reading the PORTA register reads the status of the pins, whereas writing to it will write to the port latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, this value is modified and then written to the port data latch. RA3 reads `0' when MCLRE = 1. 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. I/O pins configured as analog input always read `0'. Note: The ANSEL (91h) and CMCON0 (19h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read `0'.
Every PORTA pin on the PIC16F688 has an interrupton-change option and a weak pull-up option. PORTA also provides an Ultra Low-Power Wake-up option. The next three sections describe these functions.
4.2.1
WEAK PULL-UPS
Each of the PORTA pins, except RA3, has an individually configurable internal weak pull-up. Control bits WPUAx enable or disable each pull-up. Refer to Register 4-3. Each 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 by the RAPU bit (Option<7>). A weak pull-up is automatically enabled for RA3 when configured as MCLR and _disabled when RA3 is an I/O. There is no software control of the MCLR pull-up.
REGISTER 4-1:
PORTA - PORTA REGISTER (ADDRESS: 05h OR 105h)
U-0 -- bit 7 U-0 -- R/W-x RA5 R/W-x RA4 R/W-x RA3 R/W-x RA2 R/W-0 RA1 R/W-0 RA0 bit 0
bit 7-6: bit 5-0:
Unimplemented: Read as `0' PORTA<5:0>: PORTA I/O pins 1 = Port pin is > VIH 0 = Port pin is < VIL 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 31
PIC16F688
REGISTER 4-2: TRISA - PORTA TRI-STATE REGISTER (ADDRESS: 85h OR 185h)
U-0 -- bit 7 bit 7-6: bit 5-0: Unimplemented: Read as `0' TRISA<5:0>: PORTA Tri-State Control bits 1 = PORTA pin configured as an input (tri-stated) 0 = PORTA pin configured as an output Note 1: TRISA<3> always reads `1'. 2: TRISA<5:4> always reads `1' in XT, HS and LP OSC modes. 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-1 TRISA5 R/W-1 TRISA4 R-1 TRISA3 R/W-1 TRISA2 R/W-1 TRISA1 R/W-1 TRISA0 bit 0
REGISTER 4-3:
WPUA - WEAK PULL-UP REGISTER (ADDRESS: 95h)
U-0 -- bit 7 U-0 -- R/W-1 WPUA5 R/W-1 WPUA4 U-0 -- R/W-1 WPUA2 R/W-1 WPUA1 R/W-1 WPUA0 bit 0
bit 7-6 bit 5-4
Unimplemented: Read as `0' WPUA<5:4>: Weak Pull-up Register bits 1 = Pull-up enabled 0 = Pull-up disabled Unimplemented: Read as `0' WPUA<2:0>: Weak Pull-up Register bits 1 = Pull-up enabled 0 = Pull-up disabled Note 1: Global RAPU must be enabled for individual pull-ups to be enabled. 2: The weak pull-up device is automatically disabled if the pin is in output mode (TRISA = 0). 3: The RA3 pull-up is enabled when configured as MCLR and disabled as an I/O in the Configuration Word. 4: WPUA<5:4> always reads `1' in XT, HS and LP OSC modes. 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 bit 2-0
DS41203B-page 32
Preliminary
2004 Microchip Technology Inc.
PIC16F688
4.2.2 INTERRUPT-ON-CHANGE
Each of the PORTA pins is individually configurable as an interrupt-on-change pin. Control bits IOCAx enable or disable the interrupt function for each pin. Refer to Register 4-4. The interrupt-on-change is disabled on a Power-on Reset. For enabled interrupt-on-change pins, the values are compared with the old value latched on the last read of PORTA. The `mismatch' outputs of the last read are OR'd together to set the PORTA Change Interrupt Flag bit (RAIF) in the INTCON register. This interrupt can wake the device from Sleep. The user, in the Interrupt Service Routine, clears the interrupt by: a) b) Any read or write of PORTA. This will end the mismatch condition, then Clear the flag bit RAIF.
A mismatch condition will continue to set flag bit RAIF. Reading PORTA will end the mismatch condition and allow flag bit RAIF to be cleared. The latch holding the last read value is not affected by a MCLR nor BOD Reset. After these Resets, the RAIF flag will continue to be set if a mismatch is present. Note: If a change on the I/O pin should occur when the read operation is being executed (start of the Q2 cycle), then the RAIF interrupt flag may not get set.
REGISTER 4-4:
IOCA - INTERRUPT-ON-CHANGE PORTA REGISTER (ADDRESS: 96h)
U-0 -- bit 7 U-0 -- R/W-0 IOCA5 R/W-0 IOCA4 R/W-0 IOCA3 R/W-0 IOCA2 R/W-0 IOCA1 R/W-0 IOCA0 bit 0
bit 7-6 bit 5-0
Unimplemented: Read as `0' IOCA<5:0>: Interrupt-on-change PORTA Control bits 1 = Interrupt-on-change enabled 0 = Interrupt-on-change disabled Note 1: Global Interrupt Enable (GIE) must be enabled for individual interrupts to be recognized. 2: IOCA<5:4> always reads `1' in XT, HS and LP OSC modes. 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 33
PIC16F688
4.2.3 ULTRA LOW-POWER WAKE-UP EXAMPLE 4-2:
BCF BSF MOVLW MOVWF BSF BCF BCF CALL BSF BSF BSF MOVLW MOVWF SLEEP
The Ultra Low-Power Wake-up (ULPWU) on RA0 allows a slow falling voltage to generate an interrupton-change on RA0 without excess current consumption. The mode is selected by setting the ULPWUE bit (PCON<5>). This enables a small current sink which can be used to discharge a capacitor on RA0. To use this feature, the RA0 pin is configured to output `1' to charge the capacitor, interrupt-on-change for RA0 is enabled, and RA0 is configured as an input. The ULPWUE bit is set to begin the discharge and a SLEEP instruction is performed. When the voltage on RA0 drops below VIL, an interrupt will be generated which will cause the device to wake-up. Depending on the state of the GIE bit (INTCON<7>), the device will either jump to the interrupt vector (0004h) or execute the next instruction when the interrupt event occurs. See Section 4.2.2 "INTERRUPT-ON-CHANGE" and Section 11.5.3 "PORTA Interrupt" for more information. This feature provides a low-power technique for periodically waking up the device from Sleep. The time-out is dependent on the discharge time of the RC circuit on RA0. See Example 4-2 for initializing the Ultra Low-Power Wake-up module. The series resistor provides overcurrent protection for the RA0 pin and can allow for software calibration of the time-out. (see Figure 4-1). A timer can be used to measure the charge time and discharge time of the capacitor. The charge time can then be adjusted to provide the desired interrupt delay. This technique will compensate for the affects of temperature, voltage and component accuracy. The Ultra Low-Power Wake-up peripheral can also be configured as a simple programmable low voltage detect or temperature sensor. Note: For more information, refer to Application Note AN879, "Using the Microchip Ultra Low-Power Wake-up Module" (DS00879).
ULTRA LOW-POWER WAKE-UP INITIALIZATION
;Bank 0 ;Set RA0 data latch ;Turn off ; comparators ;Bank 1 ;RA0 to digital I/O ;Output high to ; charge capacitor ;Enable ULP Wake-up ;Select RA0 IOC ;RA0 to input ;Enable interrupt ; and clear flag ;Wait for IOC
STATUS,RP0 PORTA,0 H'7' CMCON0 STATUS,RP0 ANSEL,0 TRISA,0 CapDelay PCON,ULPWUE IOCA,0 TRISA,0 B'10001000' INTCON
DS41203B-page 34
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 4-1: BLOCK DIAGRAM OF RA0
Analog(1) Input Mode VDD Data Bus D WR WPUDA RD WPUDA Q Weak RAPU CK Q
VDD
D WR PORTA
Q I/O PIN
CK Q
VSS
+ D WR TRISA RD TRISA RD PORTA D WR IOCA RD IOCA Q Q D EN Q D EN Interrupt-onChange RD PORTA To Comparator To A/D Converter Q3 Q IULP 0 Analog(1) Input Mode 1 Vss ULPWUE
VT
CK Q
CK Q
Note
1:
Comparator mode and ANSEL determines analog input mode.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 35
PIC16F688
4.2.4 PIN DESCRIPTIONS AND DIAGRAMS FIGURE 4-2:
Data Bus WR WPUA RD WPUA
BLOCK DIAGRAM OF RA1
Analog(1) Input Mode VDD Weak RAPU
Each PORTA pin is multiplexed with other functions. The pins and their combined functions are briefly described here. For specific information about individual functions such as the comparator or the A/D, refer to the appropriate section in this data sheet.
D
Q
CK Q
4.2.4.1
RA0/AN0/C1IN+/ICSPDAT/ULPWU
Figure * shows the diagram for this pin. The RA0 pin is configurable to function as one of the following: * * * * * a general purpose I/O an analog input for the A/D an analog input to the comparator an analog input to the Ultra Low-Power Wake-up In-Circuit Serial ProgrammingTM data
WR PORTA
D
Q
VDD
CK Q I/O pin D Q VSS Analog(1) Input Mode
WR TRISA RD TRISA RD PORTA
CK Q
4.2.4.2
RA1/AN1/C1IN-/VREF/ICSPCLK
Figure * shows the diagram for this pin. The RA1 pin is configurable to function as one of the following: * * * * * a general purpose I/O an analog input for the A/D an analog input to the comparator a voltage reference input for the A/D In-Circuit Serial Programming clock
D WR IOCA RD IOCA
Q Q D EN Q D EN Q3
CK Q
Interrupt-onchange RD PORTA To Comparator To A/D Converter
Note
1:
Comparator mode and ANSEL determines analog input mode.
DS41203B-page 36
Preliminary
2004 Microchip Technology Inc.
PIC16F688
4.2.4.3 RA2/AN2/T0CKI/INT/C1OUT 4.2.4.4 RA3/MCLR/VPP
Figure 4-3 shows the diagram for this pin. The RA2 pin is configurable to function as one of the following: * * * * * a general purpose I/O an analog input for the A/D the clock input for TMR0 an external edge triggered interrupt a digital output from the comparator Figure 4-4 shows the diagram for this pin. The RA3 pin is configurable to function as one of the following: * a general purpose input * as Master Clear Reset with weak pull-up
FIGURE 4-4:
BLOCK DIAGRAM OF RA3
VDD MCLRE Weak
FIGURE 4-3:
Data Bus WR WPUA RD WPUA
BLOCK DIAGRAM OF RA2
Analog(1) Input Mode VDD Weak RAPU C1OUT Enable RD TRISA RD PORTA D WR IOCA RD IOCA I/O pin Interrupt-onchange VSS Analog(1) Input Mode CK Q Data Bus
D CK
Q Q
Reset VSS
MCLRE
Input pin
MCLRE
VSS
Q Q
D EN Q3
D WR PORTA CK
Q Q C1OUT 1 0
VDD
Q
D EN
D WR TRISA RD TRISA RD PORTA D WR IOCA RD IOCA CK CK
Q Q
RD PORTA
Q Q Q EN Q D EN Q3 D
Interrupt-onchange
RD PORTA
To TMR0 To INT To A/D Converter Note 1: Analog Input mode is based upon ANSEL.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 37
PIC16F688
4.2.4.5 RA4/AN3/T1G/OSC2/CLKOUT 4.2.4.6 RA5/T1CKI/OSC1/CLKIN
Figure 4-5 shows the diagram for this pin. The RA4 pin is configurable to function as one of the following: * * * * * a general purpose I/O an analog input for the A/D a TMR1 gate input a crystal/resonator connection a clock output Figure 4-6 shows the diagram for this pin. The RA5 pin is configurable to function as one of the following: * * * * a general purpose I/O a TMR1 clock input a crystal/resonator connection a clock input
FIGURE 4-6: FIGURE 4-5: BLOCK DIAGRAM OF RA4
Analog(3) Input Mode Data Bus WR WPUA RD WPUA OSC1 CLKOUT Enable D WR PORTA CK Q Q CLKOUT Enable VSS D WR TRISA RD TRISA RD PORTA D WR IOCA RD IOCA CK Q Q Q EN Q D EN Q3 D CK Q Q INTOSC/ RC/EC(2) CLKOUT Enable Analog(3) Input Mode Fosc/4 1 0 I/O pin WR TRISA RD TRISA RD PORTA D WR IOCA RD IOCA CK Q VDD WR PORTA D CK Q Q D CK Q Q RAPU Oscillator Circuit
BLOCK DIAGRAM OF RA5
INTOSC Mode
CLK(1) Modes VDD Weak
TMR1LPEN(1) VDD Weak
Data Bus WR WPUA RD WPUA
D CK
Q Q RAPU Oscillator Circuit OSC2
VDD
I/O pin D CK Q Q INTOSC Mode (2) VSS
Q Q
D EN Q3
Q
D EN
Interrupt-onchange RD PORTA
Interrupt-onchange
RD PORTA To T1G To A/D Converter Note Note 1: CLK modes are XT, HS, LP, LPTMR1 and CLKOUT Enable. 2: With CLKOUT option. 3: Analog Input mode is ANSEL.
To TMR1 or CLKGEN
1: Timer1 LP oscillator enabled. 2: When using Timer1 with LP oscillator, the Schmitt Trigger is bypassed.
DS41203B-page 38
Preliminary
2004 Microchip Technology Inc.
PIC16F688
TABLE 4-1:
Addr 05h/105h 0Bh/8Bh 19h 81h 85h/185h 91h 95h 96h Legend:
SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Name Bit 7 -- GIE C2OUT RAPU -- ANS7 -- -- Bit 6 -- PEIE C1OUT INTEDG -- ANS6 -- -- Bit 5 RA5 T0IE C2INV T0CS TRISA5 ANS5 WPUA5 IOCA5 Bit 4 RA4 INTE C1INV T0SE TRISA4 ANS4 WPUA4 IOCA4 Bit 3 RA3 RAIE CIS PSA TRISA3 ANS3 -- IOCA3 Bit 2 RA2 T0IF CM2 PS2 TRISA2 ANS2 WPUA2 IOCA2 Bit 1 RA1 INTF CM1 PS1 TRISA1 ANS1 WPUA1 IOCA1 Bit 0 RA0 RAIF CM0 PS0 TRISA0 ANS0 WPUA0 IOCA0 Value on: POR, BOD --xx xx00 0000 0000 0000 0000 1111 1111 --11 1111 1111 1111 --11 -111 --00 0000 Value on all other Resets --uu uu00 0000 0000 0000 0000 1111 1111 --11 1111 1111 1111 --11 -111 --00 0000
PORTA INTCON CMCON0 OPTION_REG TRISA ANSEL WPUA IOCA
x = unknown, u = unchanged, - = unimplemented locations read as `0'. Shaded cells are not used by PORTA.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 39
PIC16F688
4.3 PORTC
4.3.1 RC0/AN4/C2IN+
PORTC is a general purpose I/O port consisting of 6 bidirectional pins. The pins can be configured for either digital I/O or analog input to A/D converter or comparator. For specific information about individual functions such as the EUSART or the A/D, refer to the appropriate section in this data sheet. Note: The ANSEL (91h) and CMCON0 (19h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read `0'. The RC0 is configurable to function as one of the following: * a general purpose I/O * an analog input for the A/D Converter * an analog input to the comparator
4.3.2
RC1/AN5/C2IN-
The RC1 is configurable to function as one of the following: * a general purpose I/O * an analog input for the A/D Converter * an analog input to the comparator
EXAMPLE 4-3:
BCF CLRF MOVLW MOVWF BSF CLRF MOVLW MOVWF BCF STATUS,RP0 PORTC 07h CMCON0 STATUS,RP0 ANSEL 0Ch TRISC STATUS,RP0
INITIALIZING PORTC
;Bank 0 ;Init PORTC ;Set RC<4,1:0> to ;digital I/O ;Bank 1 ;digital I/O ;Set RC<3:2> as inputs ;and set RC<5:4,1:0> ;as outputs ;Bank 0
FIGURE 4-7:
Data Bus
BLOCK DIAGRAM OF RC0 AND RC1
D WR PORTC CK
Q Q
VDD
I/O Pin D WR TRISC RD TRISC RD PORTC To Comparators To A/D Converter Note 1: Analog Input mode is based upon Comparator mode and ANSEL. CK Q Q Analog Input Mode(1) VSS
DS41203B-page 40
Preliminary
2004 Microchip Technology Inc.
PIC16F688
4.3.3 RC2/AN6 4.3.5 RC4/C2OUT/TX/CK
The RC2 is configurable to function as one of the following: * a general purpose I/O * an analog input for the A/D Converter The RC4 is configurable to function as one of the following: * a general purpose I/O * a digital output from the comparator * a digital I/O for the EUSART
4.3.4
RC3/AN7
The RC3 is configurable to function as one of the following: * a general purpose I/O * an analog input for the A/D Converter
FIGURE 4-9:
USART Select(1) C2OUT EN
BLOCK DIAGRAM OF RC4
FIGURE 4-8:
Data Bus
BLOCK DIAGRAM OF RC2 AND RC3
EUSART TX/CLKOUT Data Bus C2OUT
VDD 0 0 1 1 I/O Pin
D WR PORTC CK
Q Q
VDD WR PORTC I/O Pin
D
Q
CK Q VSS
D WR TRISC RD TRISC RD PORTC CK
Q Q Analog Input Mode(1) VSS WR TRISC RD TRISC RD PORTC
D
Q
CK Q
To A/D Converter Note
To EUSART CLK Input
Note
1:
Analog Input mode comes from ANSEL.
1: USART Select signals selects between port data and peripheral output.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 41
PIC16F688
4.3.6 RC5/RX/DT
The RC5 is configurable to function as one of the following: * a general purpose I/O * a digital I/O for the EUSART
FIGURE 4-10:
Data Bus
BLOCK DIAGRAM OF RC5 PIN
EUSART Out Enable
D WR PORTC CK
Q Q EUSART DT Out 1 0
VDD
I/O Pin
D WR TRISC RD TRISC RD PORTC CK
Q Q VSS
To EUSART RX/DT In
DS41203B-page 42
Preliminary
2004 Microchip Technology Inc.
PIC16F688
REGISTER 4-5: PORTC - PORTC REGISTER (ADDRESS: 07h OR 107h)
U-0 -- bit 7 bit 7-6: bit 5-0: Unimplemented: Read as `0' PORTC<5:0>: General Purpose I/O Pin bits 1 = Port pin is >VIH 0 = Port pin is REGISTER 4-6:
TRISC - PORTC TRI-STATE REGISTER (ADDRESS: 87h OR 187h)
U-0 -- bit 7 U-0 -- R/W-1 TRISC5 R/W-1 TRISC4 R/W-1 TRISC3 R/W-1 TRISC2 R/W-1 TRISC1 R/W-1 TRISC0 bit 0
bit 7-6: bit 5-0:
Unimplemented: Read as `0' TRISC<5:0>: PORTC Tri-State Control bits 1 = PORTC pin configured as an input (tri-stated) 0 = PORTC pin configured as an 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
TABLE 4-2:
Address 07h 19h 87h 91h
SUMMARY OF REGISTERS ASSOCIATED WITH PORTC
Name Bit 7 -- -- ANS7 Bit 6 -- -- ANS6 Bit 5 RC5 C2INV ANS5 Bit 4 RC4 C1INV ANS4 Bit 3 RC3 CIS ANS3 Bit 2 RC2 CM2 ANS2 Bit 1 RC1 CM1 ANS1 Bit 0 RC0 CM0 ANS0 Value on: POR, BOD Value on all other Resets
PORTC CMCON0 TRISC ANSEL
--xx xx00 --uu uu00 0000 0000 0000 0000
C2OUT C1OUT
TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 --11 1111 1111 1111 1111 1111
Legend: x = unknown, u = unchanged, - = unimplemented locations read as `0'. Shaded cells are not used by PORTC.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 43
PIC16F688
NOTES:
DS41203B-page 44
Preliminary
2004 Microchip Technology Inc.
PIC16F688
5.0 TIMER0 MODULE
The Timer0 module timer/counter has the following features: * * * * * * 8-bit timer/counter Readable and writable 8-bit software programmable prescaler Internal or external clock select Interrupt on overflow from FFh to 00h Edge select for external clock Counter mode is selected by setting the T0CS bit (OPTION_REG<5>). In this mode, the Timer0 module will increment either on every rising or falling edge of pin RA2/T0CKI. The incrementing edge is determined by the source edge (T0SE) control bit (OPTION_REG<4>). Clearing the T0SE bit selects the rising edge. Note: Counter mode has specific external clock requirements. Additional information on these requirements is available in the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023).
Figure 5-1 is a block diagram of the Timer0 module and the prescaler shared with the WDT. Note: Additional information on the Timer0 module is available in the "PICmicro(R) MidRange MCU Family Reference Manual" (DS33023).
5.2
Timer0 Interrupt
5.1
Timer0 Operation
Timer mode is selected by clearing the T0CS bit (OPTION_REG<5>). In Timer mode, the Timer0 module will increment every instruction cycle (without prescaler). If TMR0 is written, 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.
A Timer0 interrupt is generated when the TMR0 register timer/counter overflows from FFh to 00h. This overflow sets the T0IF bit (INTCON<2>). The interrupt can be masked by clearing the T0IE bit (INTCON<5>). The T0IF bit must be cleared in software by the Timer0 module Interrupt Service Routine before re-enabling this interrupt. The Timer0 interrupt cannot wake the processor from Sleep, since the timer is shut off during Sleep.
FIGURE 5-1:
CLKOUT (= FOSC/4)
BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
Data Bus 0 1 1 SYNC 2 Cycles 0 0 8-bit Prescaler 1 8 Set Flag bit T0IF on Overflow PSA TMR0 8
T0CKI pin T0SE T0CS
WDTE SWDTEN
PSA
PS<2:0> 16-bit Prescaler 31 kHz INTRC Watchdog Timer WDTPS<3:0>
1 WDT Time-out
16
0
PSA
Note 1: T0SE, T0CS, PSA, PS<2:0> are bits in the Option register, WDTPS<3:0> are bits in the WDTCON register.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 45
PIC16F688
5.3 Using Timer0 with an External Clock
When no prescaler is used, the external clock input is the same as the prescaler output. The synchronization of T0CKI, with the internal phase clocks, is accomplished by sampling the prescaler output on the Q2 and Q4 cycles of the internal phase clocks. Therefore, it is necessary for T0CKI to be high for at least 2 TOSC (and a small RC delay of 20 ns) and low for at least 2 TOSC (and a small RC delay of 20 ns). Refer to the electrical specification of the desired device. Note: The ANSEL (91h) and CMCON0 (19h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read `0'.
REGISTER 5-1:
OPTION_REG - OPTION REGISTER (ADDRESS: 81h OR 181h)
R/W-1 RAPU bit 7 R/W-1 INTEDG R/W-1 T0CS R/W-1 T0SE R/W-1 PSA R/W-1 PS2 R/W-1 PS1 R/W-1 PS0 bit 0
bit 7
RAPU: PORTA Pull-up Enable bit 1 = PORTA pull-ups are disabled 0 = PORTA pull-ups are enabled by individual port latch values in WPUA register INTEDG: Interrupt Edge Select bit 1 = Interrupt on rising edge of RA2/INT pin 0 = Interrupt on falling edge of RA2/INT pin T0CS: TMR0 Clock Source Select bit 1 = Transition on RA2/T0CKI pin 0 = Internal instruction cycle clock (CLKOUT) T0SE: TMR0 Source Edge Select bit 1 = Increment on high-to-low transition on RA2/T0CKI pin 0 = Increment on low-to-high transition on RA2/T0CKI pin PSA: Prescaler Assignment bit 1 = Prescaler is assigned to the WDT 0 = Prescaler is assigned to the Timer0 module PS<2:0>: Prescaler Rate Select bits Bit Value 000 001 010 011 100 101 110 111 TMR0 Rate WDT Rate(1) 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 1 : 256 1:1 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128
bit 6
bit 5
bit 4
bit 3
bit 2-0
Note 1: A dedicated 16-bit WDT postscaler is available for the PIC16F688. See Section 11.7 "Watchdog Timer (WDT)" for more 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
DS41203B-page 46
Preliminary
2004 Microchip Technology Inc.
PIC16F688
5.4 Prescaler
EXAMPLE 5-1:
BCF STATUS,RP0 CLRWDT CLRF TMR0 BSF STATUS,RP0
An 8-bit counter is available as a prescaler for the Timer0 module, or as a postscaler for the Watchdog Timer. For simplicity, this counter will be referred to as "prescaler" throughout this data sheet. The prescaler assignment is controlled in software by the control bit PSA (OPTION_REG<3>). Clearing the PSA bit will assign the prescaler to Timer0. Prescale values are selectable via the PS<2:0> bits (OPTION_REG<2:0>). The prescaler is not readable or writable. When assigned to the Timer0 module, all instructions writing to the TMR0 register (e.g., CLRF 1, MOVWF 1, BSF 1, x....etc.) will clear the prescaler. When assigned to WDT, a CLRWDT instruction will clear the prescaler along with the Watchdog Timer.
CHANGING PRESCALER (TIMER0WDT)
;Bank 0 ;Clear WDT ;Clear TMR0 and ; prescaler ;Bank 1 ;Required if desired ; PS2:PS0 is ; 000 or 001 ; ;Set postscaler to ; desired WDT rate ;Bank 0
MOVLW b'00101111' MOVWF OPTION_REG CLRWDT MOVLW MOVWF BCF b'00101xxx' OPTION_REG STATUS,RP0
5.4.1
SWITCHING PRESCALER ASSIGNMENT
To change prescaler from the WDT to the TMR0 module, use the sequence shown in Example 5-2. This precaution must be taken even if the WDT is disabled.
The prescaler assignment is fully under software control (i.e., it can be changed "on-the-fly" during program execution). To avoid an unintended device Reset, the following instruction sequence (Example 5-1 and Example 5-2) must be executed when changing the prescaler assignment from Timer0 to WDT.
EXAMPLE 5-2:
CLRWDT BSF MOVLW STATUS,RP0
CHANGING PRESCALER (WDTTIMER0)
;Clear WDT and ; prescaler ;Bank 1 ;Select TMR0, ; prescale, and ; clock source ; ;Bank 0
b'xxxx0xxx'
MOVWF BCF
OPTION_REG STATUS,RP0
TABLE 5-1:
Address 01h 0Bh/8Bh 81h
REGISTERS ASSOCIATED WITH TIMER0
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOD Value on all other Resets
TMR0 INTCON OPTION_REG
Timer0 Module register GIE RAPU -- PEIE INTEDG -- T0IE T0CS INTE T0SE RAIE PSA T0IF PS2 INTF PS1 RAIF PS0
xxxx xxxx uuuu uuuu 0000 0000 0000 0000 1111 1111 1111 1111
85h/185h TRISA
TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111
Legend: - = Unimplemented locations, read as `0', u = unchanged, x = unknown. Shaded cells are not used by the Timer0 module.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 47
PIC16F688
NOTES:
DS41203B-page 48
Preliminary
2004 Microchip Technology Inc.
PIC16F688
6.0 TIMER1 MODULE WITH GATE CONTROL
The Timer1 Control register (T1CON), shown in Register 6-1, is used to enable/disable Timer1 and select the various features of the Timer1 module. Note: Additional information on timer modules is available in the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023).
The PIC16F688 has a 16-bit timer. Figure 5-1 shows the basic block diagram of the Timer1 module. Timer1 has the following features: 16-bit timer/counter (TMR1H:TMR1L) Readable and writable Internal or external clock selection Synchronous or asynchronous operation Interrupt-on-overflow from FFFFh to 0000h Wake-up upon overflow (Asynchronous mode) Optional external enable input - Selectable gate source: T1G or C2 output (T1GSS) - Selectable gate polarity (T1GINV) * Optional LP oscillator * * * * * * *
FIGURE 6-1:
TIMER1 ON THE PIC16F688 BLOCK DIAGRAM
TMR1ON TMR1GE TMR1ON TMR1GE TMR1(1) TMR1H Oscillator (2) TMR1L To C2 Comparator Module TMR1 Clock 0 1 T1SYNC 1 FOSC/4 Internal Clock Prescaler 1, 2, 4, 8 0 2 T1CKPS<1:0> TMR1CS 1 Sleep Input Synchronize det Synchronized Clock Input T1GINV
Set Flag bit TMR1IF on Overflow
OSC1/T1CKI
OSC2/T1G INTOSC without CLKOUT T1OSCEN
C2OUT
0 T1GSS
Note 1: 2:
Timer1 increments on the rising edge. ST Buffer is low power type when using LP oscillator or high-speed type when using T1CKI.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 49
PIC16F688
6.1 Timer1 Modes of Operation 6.3 Timer1 Prescaler
Timer1 can operate in one of three modes: * 16-bit timer with prescaler * 16-bit synchronous counter * 16-bit asynchronous counter In Timer mode, Timer1 is incremented on every instruction cycle. In Counter mode, Timer1 is incremented on the rising edge of the external clock input T1CKI. In addition, the Counter mode clock can be synchronized to the microcontroller system clock or run asynchronously. In Counter and Timer modules, the counter/timer clock can be gated by the Timer1 gate, which can be selected as either the T1G pin or Comparator 2 output. If an external clock oscillator is needed (and the microcontroller is using the INTOSC without CLKOUT), Timer1 can use the LP oscillator as a clock source. Note: In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge. Timer1 has four prescaler options allowing 1, 2, 4 or 8 divisions of the clock input. The T1CKPS bits (T1CON<5:4>) control the prescale counter. The prescale counter is not directly readable or writable; however, the prescaler counter is cleared upon a write to TMR1H or TMR1L.
6.4
Timer1 Gate
Timer1 gate source is software configurable to be the T1G pin or the output of Comparator 2. This allows the device to directly time external events using T1G or analog events using Comparator 2. See CMCON1 (Register 7-2) for selecting the Timer1 gate source. This feature can simplify the software for a Delta-Sigma A/D converter and many other applications. For more information on Delta-Sigma A/D converters, see the Microchip web site (www.microchip.com). Note: TMR1GE bit (T1CON<6>) must be set to use either T1G or C2OUT as the Timer1 gate source. See Register 7-2 for more information on selecting the Timer1 gate source.
6.2
Timer1 Interrupt
The Timer1 register pair (TMR1H:TMR1L) increments to FFFFh and rolls over to 0000h. When Timer1 rolls over, the Timer1 interrupt flag bit (PIR1<0>) is set. To enable the interrupt on rollover, you must set these bits: * Timer1 Interrupt Enable bit (PIE1<0>) * PEIE bit (INTCON<6>) * GIE bit (INTCON<7>) The interrupt is cleared by clearing the TMR1IF bit in the Interrupt Service Routine. Note: The TMR1H:TTMR1L register pair and the TMR1IF bit should be cleared before enabling interrupts.
Timer1 gate can be inverted using the T1GINV bit (T1CON<7>), whether it originates from the T1G pin or Comparator 2 output. This configures Timer1 to measure either the active-high or active-low time between events.
FIGURE 6-2:
T1CKI = 1 when TMR1 Enabled
TIMER1 INCREMENTING EDGE
T1CKI = 0 when TMR1 Enabled Note 1: 2: Arrows indicate counter increments. In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge of the clock.
DS41203B-page 50
Preliminary
2004 Microchip Technology Inc.
PIC16F688
REGISTER 6-1: T1CON - TIMER1 CONTROL REGISTER (ADDRESS: 10h)
R/W-0 T1GINV bit 7 bit 7 T1GINV: Timer1 Gate Invert bit(1) 1 = Timer1 gate is inverted 0 = Timer1 gate is not inverted TMR1GE: Timer1 Gate Enable bit(2) If TMR1ON = 0: This bit is ignored. If TMR1ON = 1: 1 = Timer1 is on if Timer1 gate is not active 0 = Timer1 is on 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: LP Oscillator Enable Control bit If INTOSC without CLKOUT oscillator is active: 1 = LP oscillator is enabled for Timer1 clock 0 = LP oscillator is off Else: This bit is ignored. T1SYNC: Timer1 External Clock Input Synchronization Control bit TMR1CS = 1: 1 = Do not synchronize external clock input 0 = Synchronize external clock input TMR1CS = 0: This bit is ignored. Timer1 uses the internal clock. TMR1CS: Timer1 Clock Source Select bit 1 = External clock from T1CKI pin (on the rising edge) 0 = Internal clock (FOSC/4) TMR1ON: Timer1 On bit 1 = Enables Timer1 0 = Stops Timer1 Note 1: T1GINV bit inverts the Timer1 gate logic, regardless of source. 2: TMR1GE bit must be set to use either T1G pin or C2OUT, as selected by the T1GSS bit (CMCON1<1>), as a Timer1 gate source. 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 T1SYNC R/W-0 TMR1CS R/W-0 TMR1ON bit 0 TMR1GE T1CKPS1 T1CKPS0 T1OSCEN
bit 6
bit 5-4
bit 3
bit 2
bit 1
bit 0
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 51
PIC16F688
6.5 Timer1 Operation in Asynchronous Counter Mode 6.6 Timer1 Oscillator
A crystal oscillator circuit is built-in between pins OSC1 (input) and OSC2 (amplifier output). It is enabled by setting control bit, T1OSCEN (T1CON<3>). The oscillator is a low power oscillator rated up to 32 kHz. It will continue to run during Sleep. It is primarily intended for a 32 kHz crystal. Table 3-1 shows the capacitor selection for the Timer1 oscillator. The Timer1 oscillator is shared with the system LP oscillator. Thus, Timer1 can use this mode only when the primary system clock is derived from the internal oscillator. As with the system LP oscillator, the user must provide a software time delay to ensure proper oscillator start-up. TRISA5 and TRISA4 bits are set when the Timer1 oscillator is enabled. RA5 and RA4 read as `0' and TRISA5 and TRISA4 bits read as `1'. Note: The oscillator requires a start-up and stabilization time before use. Thus, T1OSCEN should be set and a suitable delay observed prior to enabling Timer1.
If control bit T1SYNC (T1CON<2>) is set, the external clock input is not synchronized. The timer continues to increment asynchronous to the internal phase clocks. The timer will continue to run during Sleep and can generate an interrupt-on-overflow, which will wake-up the processor. However, special precautions in software are needed to read/write the timer (see Section 6.5.1 "Reading and Writing Timer1 in Asynchronous Counter Mode"). Note: The ANSEL (91h) and CMCON0 (19h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read `0'.
6.5.1
READING AND WRITING TIMER1 IN ASYNCHRONOUS COUNTER MODE
Reading TMR1H or TMR1L, while the timer is running from an external asynchronous clock, will ensure a valid read (taken care of in hardware). However, the user should keep in mind that reading the 16-bit timer in two 8-bit values itself, poses certain problems, since the timer may overflow between the reads. For writes, it is recommended that the user simply stop the timer and write the desired values. A write contention may occur by writing to the timer registers, while the register is incrementing. This may produce an unpredictable value in the timer register. Reading the 16-bit value requires some care. Examples in the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023) show how to read and write Timer1 when it is running in Asynchronous mode.
6.7
Timer1 Operation During Sleep
Timer1 can only operate during Sleep when setup in Asynchronous Counter mode. In this mode, an external crystal or clock source can be used to increment the counter. To set up the timer to wake the device: * Timer1 must be on (T1CON<0>) * TMR1IE bit (PIE1<0>) must be set * PEIE bit (INTCON<6>) must be set The device will wake-up on an overflow. If the GIE bit (INTCON<7>) is set, the device will wake-up and jump to the Interrupt Service Routine (0004h) on an overflow. If the GIE bit is clear, execution will continue with the next instruction.
TABLE 6-1:
Addr 0Bh/ 8Bh 0Ch 0Eh 0Fh 10h 1Ah 8Ch Name INTCON PIR1 TMR1L TMR1H T1CON CMCON1 PIE1
REGISTERS ASSOCIATED WITH TIMER1
Bit 7 GIE EEIF Bit 6 PEIE ADIF Bit 5 T0IE RCIF Bit 4 INTE C2IF Bit 3 RAIE C1IF Bit 2 T0IF OSFIF Bit 1 INTF TXIF Bit 0 RAIF Value on POR, BOD Value on all other Resets
0000 0000 0000 0000
TMR1IF 0000 0000 0000 0000 xxxx xxxx uuuu uuuu xxxx xxxx uuuu uuuu C2SYNC ---- --10 ---- --10 TMR1IE 0000 0000 0000 0000
Holding register for the Least Significant Byte of the 16-bit TMR1 register Holding register for the Most Significant Byte of the 16-bit TMR1 register -- EEIE -- ADIE -- RCIE -- C2IE -- C1IE -- OSFIE T1GSS TXIE
T1GINV TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu
Legend: x = unknown, u = unchanged, - = unimplemented, read as `0'. Shaded cells are not used by the Timer1 module.
DS41203B-page 52
Preliminary
2004 Microchip Technology Inc.
PIC16F688
7.0 COMPARATOR MODULE
The comparator module contains two analog comparators. The inputs to the comparators are multiplexed with I/O port pins RA0, RA1, RC0 and RC1, while the outputs are multiplexed to pins RA2 and RC4. An on-chip Comparator Voltage Reference (CVREF) can also be applied to the inputs of the comparators. The CMCON0 register (Register 7-1) controls the comparator input and output multiplexers. A block diagram of the various comparator configurations is shown in Figure 7-3.
REGISTER 7-1:
CMCON0 - COMPARATOR CONFIGURATION REGISTER (ADDRESS: 19h)
R-0 C2OUT bit 7 R-0 C1OUT R/W-0 C2INV R/W-0 C1INV R/W-0 CIS R/W-0 CM2 R/W-0 CM1 R/W-0 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> = 010: 1 = C1 VIN- connects to RA0/AN0 C2 VIN- connects to RC0/AN4 0 = C1 VIN- connects to RA1/AN1 C2 VIN- connects to RC1/AN5 When CM<2:0> = 001: 1 = C1 VIN- connects to RA0/AN0 0 = C1 VIN- connects to RA1/AN1 CM<2:0>: Comparator Mode bits Figure 7-3 shows the Comparator modes and 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 53
PIC16F688
7.1 Comparator Operation 7.2
A single comparator is shown in Figure 7-1 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 7-1 represent the uncertainty due to input offsets and response time. Note: To use CIN+ and CIN- pins as analog inputs, the appropriate bits must be programmed in the CMCON0 (19h) register.
Analog Input Connection Considerations
A simplified circuit for an analog input is shown in Figure 7-2. 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 range by more than 0.6V in either direction, one of the diodes is forward biased and a latch-up 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. 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 as analog inputs according to the 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.
The polarity of the comparator output can be inverted by setting the CxINV bits (CMCON0<5:4>). Clearing CxINV results in a non-inverted output. A complete table showing the output state versus input conditions and the polarity bit is shown in Table 7-1.
TABLE 7-1:
OUTPUT STATE VS. INPUT CONDITIONS
CINV 0 0 1 1 CxOUT 0 1 1 0
Input Conditions VIN- > VIN+ VIN- < VIN+ VIN- > VIN+ VIN- < VIN+
FIGURE 7-1:
VIN+ VIN-
SINGLE COMPARATOR
+ -
Output
VINVIN- VIN+ VIN+
Output Output
DS41203B-page 54
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 7-2: ANALOG INPUT MODEL
VDD Rs < 10K AIN VA CPIN 5 pF VT = 0.6V Leakage 500 nA VT = 0.6V RIC
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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 55
PIC16F688
7.3 Comparator Configuration
There are eight modes of operation for the comparators. The CMCON0 register is used to select these modes. Figure 7-3 shows the eight possible modes. If the Comparator mode is changed, the comparator output level may not be valid for the specified mode change delay shown in Section 14.0 "Electrical Specifications". Note: Comparator interrupts should be disabled during a Comparator mode change. Otherwise, a false interrupt may occur.
FIGURE 7-3:
COMPARATOR I/O OPERATING MODES
Comparators Off CM<2:0> = 111
RA1/AN1 RA0/AN0
D D
Comparators Reset (POR Default Value) CM<2:0> = 000 A VINRA1/AN1
RA0/AN0
A
VINVIN+
C1 Off (Read as `0')
VIN+
C1
Off (Read as `0')
RC1/AN5 RC0/AN4
A A
VINVIN+
C2 Off (Read as `0')
RC1/AN5 RC0/AN4
D D
VINVIN+
C2 Off (Read as `0')
Two Independent Comparators CM<2:0> = 100 A VINRA1/AN1
RA0/AN0
A
Four Inputs Multiplexed to Two Comparators CM<2:0> = 010
RA1/AN1 C1OUT RA0/AN0 RC1/AN5
A A
VIN+
C1
CIS = 0 CIS = 1
VINVIN+ VINVIN+
C2 C2OUT C1 C1OUT
A A
RC1/AN5 RC0/AN4
A A
VINVIN+
C2 C2OUT
RC0/AN4
CIS = 0 CIS = 1
From CVREF Module
Two Common Reference Comparators CM<2:0> = 011 A VINRA1/AN1
RA0/AN0
D
Two Common Reference Comparators with Outputs CM<2:0> = 110 A VINRA1/AN1 VIN+
C1 C1OUT RA2
VIN+
C1
C1OUT
RC1/AN5 RC0/AN4
A A
VINVIN+
C2 C2OUT
RC1/AN5 RC0/AN4
A A
VINVIN+
C2 C2OUT RC4
One Independent Comparator CM<2:0> = 101 D VINRA1/AN1
RA0/AN0
D
Three Inputs Multiplexed to Two Comparators CM<2:0> = 001
Off (Read as `0') RA1/AN1 RA0/AN0
A A
VIN+
C1
CIS = 0 CIS = 1
VINVIN+ VINVIN+
C2 C2OUT C1 C1OUT
RC1/AN5 RC0/AN4
A A
VINVIN+
C2 C2OUT
RC1/AN5 RC0/AN4
A A
Legend: A = Analog Input, ports always read `0' D = Digital Input
CIS (CMCON0<3>) is the Comparator Input Switch
DS41203B-page 56
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 7-4: MODIFIED COMPARATOR C1 OUTPUT BLOCK DIAGRAM
MULTIPLEX Port Pins
C1INV
To C1OUT pin To Data Bus Q EN RD CMCON D Q3
Set C1IF bit
Q
D EN RD CMCON
CL
NReset
FIGURE 7-5:
COMPARATOR C2 OUTPUT BLOCK DIAGRAM
MULTIPLEX Port Pins C2SYNC To TMR1 0
C2INV
To C2OUT pin 1 Q EN D TMR1 clock source(1)
To Data Bus
Q EN RD CMCON
D
Q3
Set C2IF bit
Q
D EN
CL
RD CMCON
Reset Note 1: Comparator 2 output is latched on falling edge of T1 clock source.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 57
PIC16F688
REGISTER 7-2: CMCON1 - COMPARATOR CONFIGURATION REGISTER (ADDRESS: 1Ah)
U-0 -- bit 7 bit 7-2: bit 1 Unimplemented: Read as `0' T1GSS: Timer1 Gate Source Select bit 1 = Timer1 gate source is T1G pin (RA4 must be configured as digital input) 0 = Timer1 gate source is Comparator 2 Output C2SYNC: Comparator 2 Synchronize bit 1 = C2 output synchronized with falling edge of Timer1 clock 0 = C2 output not synchronized with Timer1 clock 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 -- U-0 -- U-0 -- U-0 -- U-0 -- R/W-1 T1GSS R/W-0 C2SYNC bit 0
bit 0
7.4
Comparator Outputs
7.5
Comparator Interrupts
The comparator outputs are read through the CMCON0 register. These bits are read-only. The comparator outputs may also be directly output to the RA2 and RC4 I/O pins. When enabled, multiplexors in the output path of the RA2 and RC4 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 7-4 and Figure 7-5 show the output block diagram for Comparator 1 and 2. The TRIS bits will still function as an output enable/ disable for the RA2 and RC4 pins while in this mode. The polarity of the comparator outputs can be changed using the C1INV and C2INV bits (CMCON0<5:4>). Timer1 gate source can be configured to use the T1G pin or Comparator 2 output as selected by the T1GSS bit (CMCON1<1>). This feature can be used to time the duration or interval of analog events. The output of Comparator 2 can also be synchronized with Timer1 by setting the C2SYNC bit (CMCON1<0>). When enabled, the output of Comparator 2 is latched on the falling edge of Timer1 clock source. If a prescaler is used with Timer1, Comparator 2 is latched after the prescaler. To prevent a race condition, the Comparator 2 output is latched on the falling edge of the Timer1 clock source and Timer1 increments on the rising edge of its clock source. See (Figure 7-5), Comparator 2 Block Diagram and (Figure 6-1), Timer1 Block Diagram for more information. It is recommended to synchronize Comparator 2 with Timer1 by setting the C2SYNC bit when Comparator 2 is used as the Timer1 gate source. This ensures Timer1 does not miss an increment if Comparator 2 changes during an increment.
The comparator interrupt flags are set whenever there is a change in the output value of its respective comparator. Software will need to maintain information about the status of the output bits, as read from CMCON0<7:6>, to determine the actual change that has occurred. The CxIF bits, PIR1<4:3>, are the Comparator Interrupt flags. This bit must be reset in software by clearing it to `0'. Since it is also possible to write a `1' to this register, a simulated interrupt may be initiated. The CxIE bits (PIE1<4:3>) and the PEIE bit (INTCON<6>) must be set to enable the interrupts. In addition, the GIE bit must also be set. If any of these bits are cleared, the interrupt is not enabled, though the CxIF bits will still be set if an interrupt condition occurs. The user, in the Interrupt Service Routine, can clear the interrupt in the following manner: a) b) Any read or write of CMCON0. This will end the mismatch condition. Clear flag bit CxIF
A mismatch condition will continue to set flag bit CxIF. Reading CMCON0 will end the mismatch condition and allow flag bits CxIF to be cleared. Note: If a change in the CMCON0 register (CxOUT) should occur when a read operation is being executed (start of the Q2 cycle), then the CxIF (PIR1<3>) interrupt flag may not get set.
DS41203B-page 58
Preliminary
2004 Microchip Technology Inc.
PIC16F688
7.6 Comparator Reference
7.6.2
The comparator module also allows the selection of an internally generated voltage reference for one of the comparator inputs. The VRCON register, Register 7-3, controls the voltage reference module shown in Figure 7-6.
VOLTAGE REFERENCE ACCURACY/ERROR
7.6.1
CONFIGURING THE VOLTAGE REFERENCE
The voltage reference can output 32 distinct voltage levels, 16 in a high range and 16 in a low range. The following equation determines the output voltages:
The full range of VSS to VDD cannot be realized due to the construction of the module. The transistors on the top and bottom of the resistor ladder network (Figure 7-6) keep CVREF from approaching VSS or VDD. The exception is when the module is disabled by clearing the VREN bit (VRCON<7>). When disabled, the reference voltage is VSS when VR<3:0> = 0000. This allows the comparators to detect a zero-crossing and not consume CVREF module current. The voltage reference is VDD derived and therefore, the CVREF output changes with fluctuations in VDD. The tested absolute accuracy of the comparator voltage reference can be found in Section 14.0 "Electrical Specifications".
EQUATION 7-1:
VRR = 1 (low range): CVREF = (VR3:VR0/24) x VDD VRR = 0 (high range): CVREF = (VDD/4) + (VR3:VR0 x VDD/32)
FIGURE 7-6:
COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM
16 Stages 8R R R R R
VDD 8R 16-1 Analog MUX VREN CVREF to Comparator Input VRR
VR<3:0>
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 59
PIC16F688
7.7 Comparator Response Time 7.9 Effects of a Reset
Response time is the minimum time, after selecting a new reference voltage or input source, before the comparator output is ensured to have 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 (Table 14-9). A device Reset forces the CMCON0, CMCON1 and VRCON registers to their Reset states. This forces the comparator module to be in the Comparator Reset mode, CM<2:0> = 000 and the voltage reference to its off state. Thus, all potential inputs are analog inputs with the comparator and voltage reference disabled to consume the smallest current possible.
7.8
Operation During Sleep
The comparators and voltage reference, if enabled before entering Sleep mode, remain active during Sleep. This results in higher Sleep currents than shown in the power-down specifications. The additional current consumed by the comparator and the voltage reference is shown separately in the specifications. To minimize power consumption while in Sleep mode, turn off the comparator, CM<2:0> = 111, and voltage reference, VRCON<7> = 0. While the comparator is enabled during Sleep, an interrupt will wake-up the device. If the GIE bit (INTCON<7>) is set, the device will jump to the interrupt vector (0004h), and if clear, continues execution with the next instruction. If the device wakes up from Sleep, the contents of the CMCON0, CMCON1 and VRCON registers are not affected.
DS41203B-page 60
Preliminary
2004 Microchip Technology Inc.
PIC16F688
REGISTER 7-3: VRCON - VOLTAGE REFERENCE CONTROL REGISTER (ADDRESS: 99h)
R/W-0 VREN bit 7 bit 7 VREN: CVREF Enable bit 1 = CVREF circuit powered on 0 = CVREF circuit powered down, no IDD drain and CVREF = VSS. Unimplemented: Read as `0' VRR: CVREF Range Selection bit 1 = Low range 0 = High range Unimplemented: Read as `0' VR<3:0>: CVREF value selection 0 VR<3:0> 15 When VRR = 1: CVREF = (VR<3:0>/24) * VDD When VRR = 0: CVREF = VDD/4 + (VR<3:0>/32) * VDD 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 VRR R/W-0 -- R/W-0 VR3 R/W-0 VR2 R/W-0 VR1 R/W-0 VR0 bit 0
bit 6 bit 5
bit 4 bit 3-0
TABLE 7-2:
Address 0Bh/8Bh 0Ch 19h 1Ah 85h/185h 87h/187h 8Ch 99h Legend: Name INTCON PIR1
REGISTERS ASSOCIATED WITH COMPARATOR MODULE
Bit 7 GIE EEIF C2OUT -- -- -- EEIE VREN Bit 6 PEIE ADIF C1OUT -- -- -- ADIE -- Bit 5 T0IE RCIF C2INV -- TRISA5 TRISC5 RCIE VRR Bit 4 INTE C2IF C1INV -- TRISA4 TRISC4 C2IE -- Bit 3 RAIE C1IF CIS -- TRISA3 TRISC3 C1IE VR3 Bit 2 T0IF OSFIF CM2 -- TRISA2 TRISC2 OSFIE VR2 Bit 1 INTF TXIF CM1 T1GSS TRISA1 TRISC1 TXIE VR1 Bit 0 RAIF TMR1IF CM0 C2SYNC TRISA0 TRISC0 TMR1IE VR0 Value on POR, BOD 0000 0000 0000 0000 0000 0000 ---- --10 --11 1111 --11 1111 0000 0000 0-0- 0000 Value on all other Resets 0000 0000 0000 0000 0000 0000 ---- --10 --11 1111 --11 1111 0000 0000 0-0- 0000
CMCON0 CMCON1 TRISA TRISC PIE1 VRCON
x = unknown, u = unchanged, - = unimplemented, read as `0'. Shaded cells are not used by the comparator or Comparator Voltage Reference module.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 61
PIC16F688
NOTES:
DS41203B-page 62
Preliminary
2004 Microchip Technology Inc.
PIC16F688
8.0 ANALOG-TO-DIGITAL CONVERTER (A/D) MODULE
The output of the sample and hold is connected to the input of the converter. The converter generates a binary result via successive approximation and stores the result in a 10-bit register. The voltage reference used in the conversion is software selectable to either VDD or a voltage applied by the VREF pin. Figure 8-1 shows the block diagram of the A/D on the PIC16F688.
The analog-to-digital converter (A/D) allows conversion of an analog input signal to a 10-bit binary representation of that signal. The PIC16F688 has eight analog inputs, multiplexed into one sample and hold circuit.
FIGURE 8-1:
A/D BLOCK DIAGRAM
VDD
VCFG = 0
VREF
VCFG = 1
RA0/AN0 RA1/AN1/VREF RA2/AN2 RA4/AN3 RC0/AN4 RC1/AN5 RC2/AN6 RC3/AN7 ADON ADRESH VSS CHS<2:0> GO/DONE ADFM 10 ADRESL A/D 10
8.1
A/D Configuration and Operation
8.1.3
VOLTAGE REFERENCE
There are three registers available to control the functionality of the A/D module: 1. 2. 3. ANSEL (Register 8-1) ADCON0 (Register 8-2) ADCON1 (Register 8-3)
There are two options for the voltage reference to the A/D converter: either VDD is used, or an analog voltage applied to VREF is used. The VCFG bit (ADCON0<6>) controls the voltage reference selection. If VCFG is set, then the voltage on the VREF pin is the reference; otherwise, VDD is the reference.
8.1.1
ANALOG PORT PINS
The ANS<7:0> bits (ANSEL<7:0>) and the TRIS bits control the operation of the A/D port pins. Set the corresponding TRIS bits to set the pin output driver to its high-impedance state. Likewise, set the corresponding ANSEL bit to disable the digital input buffer. Note: Analog voltages on any pin that is defined as a digital input may cause the input buffer to conduct excess current.
8.1.2
CHANNEL SELECTION
There are eight analog channels on the PIC16F688, AN0 through AN7. The CHS<2:0> bits (ADCON0<4:2>) control which channel is connected to the sample and hold circuit.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 63
PIC16F688
8.1.4 CONVERSION CLOCK
The A/D conversion cycle requires 11 TAD. The source of the conversion clock is software selectable via the ADCS bits (ADCON1<6:4>). There are seven possible clock options: * * * * * * * FOSC/2 FOSC/4 FOSC/8 FOSC/16 FOSC/32 FOSC/64 FRC (dedicated internal oscillator) For correct conversion, the A/D conversion clock (1/TAD) must be selected to ensure a minimum TAD of 1.6 s. Table 8-1 shows a few TAD calculations for selected frequencies.
TABLE 8-1:
TAD vs. DEVICE OPERATING FREQUENCIES
Device Frequency
A/D Clock Source (TAD)
Operation ADCS<2:0> 20 MHz 5 MHz 4 MHz 1.25 MHz 000 100 ns(2) 400 ns(2) 500 ns(2) 1.6 s 2 TOSC 4 TOSC 100 200 ns(2) 800 ns(2) 1.0 s(2) 3.2 s (2) 8 TOSC 001 400 ns 1.6 s 2.0 s 6.4 s 16 TOSC 101 800 ns(2) 3.2 s 4.0 s 12.8 s(3) 32 TOSC 010 1.6 s 6.4 s 8.0 s(3) 25.6 s(3) 64 TOSC 110 3.2 s 12.8 s(3) 16.0 s(3) 51.2 s(3) (1,4) (1,4) (1,4) A/D RC x11 2-6 s 2-6 s 2-6 s 2-6 s(1,4) Legend: Shaded cells are outside of recommended range. Note 1: The A/D RC source has a typical TAD time of 4 s for VDD > 3.0V. 2: These values violate the minimum required TAD time. 3: For faster conversion times, the selection of another clock source is recommended. 4: When the device frequency is greater than 1 MHz, the A/D RC clock source is only recommended if the conversion will be performed during Sleep.
8.1.5
STARTING A CONVERSION
The A/D conversion is initiated by setting the GO/DONE bit (ADCON0<1>). When the conversion is complete, the A/D module: * Clears the GO/DONE bit * Sets the ADIF flag (PIR1<6>) * Generates an interrupt (if enabled) If the conversion must be aborted, the GO/DONE bit can be cleared in software. The ADRESH:ADRESL registers will not be updated with the partially complete A/D conversion sample. Instead, the ADRESH:ADRESL registers will retain the value of the previous conversion. After an aborted conversion, a 2 TAD delay is required before another acquisition can be initiated. Following the delay, an input acquisition is automatically started on the selected channel. Note: The GO/DONE bit should not be set in the same instruction that turns on the A/D.
DS41203B-page 64
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 8-2: A/D CONVERSION TAD CYCLES
TAD2 b9 Conversion Starts Holding Capacitor is Disconnected from Analog Input (typically 100 ns) Set GO bit TAD3 b8 TAD4 b7 TAD5 b6 TAD6 b5 TAD7 b4 TAD8 b3 TAD9 TAD10 TAD11 b2 b1 b0 TCY to TAD TAD1
ADRESH and ADRESL registers are Loaded, GO bit is Cleared, ADIF bit is Set, Holding Capacitor is Connected to Analog Input
8.1.6
CONVERSION OUTPUT
The A/D conversion can be supplied in two formats: left or right shifted. The ADFM bit (ADCON0<7>) controls the output format. Figure 8-3 shows the output formats.
FIGURE 8-3:
10-BIT A/D RESULT FORMAT
ADRESH ADRESL LSB bit 0 bit 7 bit 0
(ADFM = 0)
MSB bit 7
10-bit A/D Result (ADFM = 1) bit 7 MSB bit 0 bit 7
Unimplemented: Read as `0' LSB bit 0
Unimplemented: Read as `0'
10-bit A/D Result
REGISTER 8-1:
ANSEL - ANALOG SELECT REGISTER (ADDRESS: 91h)
R/W-1 ANS7 bit 7 R/W-1 ANS6 R/W-1 ANS5 R/W-1 ANS4 R/W-1 ANS3 R/W-1 ANS2 R/W-1 ANS1 R/W-1 ANS0 bit 0
bit 7-0:
ANS<7:0>: Analog Select bits Analog select between analog or digital function on pins AN<7:0>, respectively. 1 = Analog input. Pin is assigned as analog input.(1) 0 = Digital I/O. Pin is assigned to port or special function. Note 1: Setting a pin to an analog input automatically disables the digital input circuitry, weak pull-ups, and interrupt-on-change if available. The corresponding TRIS bit must be set to Input mode in order to allow external control of the voltage on the pin. 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 65
PIC16F688
REGISTER 8-2: ADCON0 - A/D CONTROL REGISTER (ADDRESS: 1Fh)
R/W-0 ADFM bit 7 bit 7 ADFM: A/D Result Formed Select bit 1 = Right justified 0 = Left justified VCFG: Voltage Reference bit 1 = VREF pin 0 = VDD Unimplemented: Read as `0' CHS<2:0>: Analog Channel Select bits 000 = Channel 00 (AN0) 001 = Channel 01 (AN1) 010 = Channel 02 (AN2) 011 = Channel 03 (AN3) 100 = Channel 04 (AN4) 101 = Channel 05 (AN5) 110 = Channel 06 (AN6) 111 = Channel 07 (AN7) GO/DONE: A/D Conversion Status bit 1 = A/D conversion cycle in progress. Setting this bit starts an A/D conversion cycle. This bit is automatically cleared by hardware when the A/D conversion has completed. 0 = A/D conversion completed/not in progress ADON: A/D Conversion Status bit 1 = A/D converter module is operating 0 = A/D converter is shut off and consumes no operating current 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 VCFG U-0 -- R/W-0 CHS2 R/W-0 CHS1 R/W-0 CHS0 R/W-0 GO/DONE R/W-0 ADON bit 0
bit 6
bit 5 bit 4-2
bit 1
bit 0
REGISTER 8-3:
ADCON1 - A/D CONTROL REGISTER 1 (ADDRESS: 9Fh)
U-0 -- bit 7 R/W-0 ADCS2 R/W-0 ADCS1 R/W-0 ADCS0 U-0 -- U-0 -- U-0 -- U-0 -- bit 0
bit 7 bit 6-4
Unimplemented: Read as `0' ADCS<2:0>: A/D Conversion Clock Select bits 000 = FOSC/2 001 = FOSC/8 010 = FOSC/32 x11 = FRC (clock derived from a dedicated internal oscillator = 500 kHz max) 100 = FOSC/4 101 = FOSC/16 110 = FOSC/64 Unimplemented: 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
bit 3-0
DS41203B-page 66
Preliminary
2004 Microchip Technology Inc.
PIC16F688
8.1.7 CONFIGURING THE A/D EXAMPLE 8-1: A/D CONVERSION
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 inputs. To determine sample time, see Section 14.0 "Electrical Specifications". After this sample time has elapsed, the A/D conversion can be started. These steps should be followed for an A/D conversion: 1. Configure the A/D module: * Configure analog/digital I/O (ANSEL) * Configure voltage reference (ADCON0) * Select A/D input channel (ADCON0) * Select A/D conversion clock (ADCON1) * Turn on A/D module (ADCON0) Configure A/D interrupt (if desired): * Clear ADIF bit (PIR1<6>) * Set ADIE bit (PIE1<6>) * Set PEIE and GIE bits (INTCON<7:6>) Wait the required acquisition time. Start conversion: * Set GO/DONE bit (ADCON0<0>) Wait for A/D conversion to complete, by either: * Polling for the GO/DONE bit to be cleared (with interrupts disabled); OR * Waiting for the A/D interrupt Read A/D Result register pair (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.
;This code block configures the A/D ;for polling, Vdd reference, R/C clock ;and RA0 input. ; ;Conversion start & wait for complete ;polling code included. ; BSF STATUS,RP0 ;Bank 1 MOVLW B'01110000' ;A/D RC clock MOVWF ADCON1 BSF TRISA,0 ;Set RA0 to input BSF ANSEL,0 ;Set RA0 to analog BCF STATUS,RP0 ;Bank 0 MOVLW B'10000001' ;Right, Vdd Vref, AN0 MOVWF ADCON0 CALL SampleTime ;Wait min sample time BSF ADCON0,GO ;Start conversion BTFSC ADCON0,GO ;Is conversion done? GOTO $-1 ;No, test again MOVF ADRESH,W ;Read upper 2 bits MOVWF RESULTHI BSF STATUS,RP0 ;Bank 1 MOVF ADRESL,W ;Read lower 8 bits MOVWF RESULTLO
2.
3. 4. 5.
6. 7.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 67
PIC16F688
8.2 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 8-4. 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), see Figure 8-4. The maximum recommended impedance for analog sources is 10 k. As the impedance is decreased, the acquisition time may be decreased. After the analog input channel is selected (changed), this acquisition must be done before the conversion can be started. To calculate the minimum acquisition time, Equation 8-1 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. To calculate the minimum acquisition time, TACQ, see the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023).
EQUATION 8-1:
ACQUISITION TIME
TACQ = Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient = TAMP + TC + TCOFF = 2 s + TC + [(Temperature -25C)(0.05 s/C)] TC = CHOLD (RIC + RSS + RS) In(1/2047) = -120 pF(1 k + 7 k + 10 k) In(0.0004885) = 16.47 s TACQ = 2 s + 16.47 s + [(50C -25C)(0.05 s/C)] = 19.72 s
Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out. 2: The charge holding capacitor (CHOLD) is not discharged after each conversion. 3: The maximum recommended impedance for analog sources is 10 k. This is required to meet the pin leakage specification.
FIGURE 8-4:
ANALOG INPUT MODEL
VDD RS VA ANx CPIN 5 pF VT = 0.6V RIC 1k ILEAKAGE 500 nA Sampling Switch SS RSS CHOLD = DAC capacitance = 120 pF VSS
VT = 0.6V
Legend: CPIN = Input Capacitance = Threshold Voltage VT ILEAKAGE = Leakage Current at the pin due to various junctions RIC = Interconnect Resistance SS = Sampling Switch CHOLD = Sample/Hold Capacitance (from DAC)
6V 5V VDD 4V 3V 2V 5 6 7 8 9 10 11 Sampling Switch (k)
DS41203B-page 68
Preliminary
2004 Microchip Technology Inc.
PIC16F688
8.3 A/D Operation During Sleep
The A/D converter module can operate during Sleep. This requires the A/D clock source to be set to the internal oscillator. When the RC clock source is selected, the A/D waits one instruction before starting the conversion. This allows the SLEEP instruction to be executed, thus eliminating much of the switching noise from the conversion. When the conversion is complete, the GO/DONE bit is cleared and the result is loaded into the ADRESH:ADRESL registers. If the A/D interrupt is enabled, the device awakens from Sleep. If the GIE bit (INTCON<7>) is set, the program counter is set to the interrupt vector (0004h), if GIE is clear, the next instruction is executed. If the A/D interrupt is not enabled, the A/D module is turned off, although the ADON bit remains set. When the A/D clock source is something other than RC, a SLEEP instruction causes the present conversion to be aborted, and the A/D module is turned off. The ADON bit remains set.
FIGURE 8-5:
A/D TRANSFER FUNCTION
Full-Scale Range 1 LSB Ideal 3FFh 3FEh 3FDh 3FCh A/D Output 3FBh 1/2 LSB Ideal
004h 003h 002h 001h 000h
Full-Scale Transition
Center of Full-Scale Code
Analog Input VREF 1/2 LSB Ideal
Zero-Scale
Zero-Scale Transition
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 69
PIC16F688
8.4 Effects of Reset
A device Reset forces all registers to their Reset state. Thus, the A/D module is turned off and any pending conversion is aborted. The ADRESH:ADRESL registers are unchanged.
TABLE 8-2:
Addr 05h/ 105h 07h/ 107h 0Bh/ 8Bh 0Ch 1Eh 1Fh 85h/ 185h 87h/ 187h 8Ch 91h 9Eh 9Fh Name PORTA PORTC INTCON PIR1 ADRESH ADCON0 TRISA TRISC PIE1 ANSEL ADRESL ADCON1
SUMMARY OF A/D REGISTERS
Bit 7 -- -- GIE EEIF Bit 6 -- -- PEIE ADIF Bit 5 RA5 RC5 T0IE RCIF Bit 4 RA4 RC4 INTE C2IF Bit 3 RA3 RC3 RAIE C1IF Bit 2 RA2 RC2 T0IF OSFIF Bit 1 RA1 RC1 INTF TXIF Bit 0 RA0 RC0 RAIF TMR1IF Value on: POR, BOD --xx xxxx --xx xxxx 0000 0000 0000 0000 xxxx xxxx ADON TRISA0 TRISC0 TMR1IE ANS0 00-0 0000 --11 1111 --11 1111 0000 0000 1111 1111 xxxx xxxx -- -000 ---Value on all other Resets --uu uuuu --uu uuuu 0000 0000 0000 0000 uuuu uuuu 00-0 0000 --11 1111 --11 1111 0000 0000 1111 1111 uuuu uuuu -000 ----
Most Significant 8 bits of the left shifted A/D result or 2 bits of the right shifted result ADFM -- -- EEIE ANS7 VCFG -- -- ADIE ANS6 -- TRISA5 TRISC5 RCIE ANS5 CHS2 TRISA4 TRISC4 C2IE ANS4 CHS1 TRISA3 TRISC3 C1IE ANS3 CHS0 TRISA2 TRISC2 OSFIE ANS2 GO/DONE TRISA1 TRISC1 TXIE ANS1
Least Significant 2 bits of the left shifted A/D result or 8 bits of the right shifted result -- ADCS2 ADCS1 ADCS0 -- -- --
Legend:
x = unknown, u = unchanged, - = unimplemented read as `0'. Shaded cells are not used for A/D module.
DS41203B-page 70
Preliminary
2004 Microchip Technology Inc.
PIC16F688
9.0 DATA EEPROM AND FLASH PROGRAM MEMORY CONTROL
9.1 EEADR and EEADRH Registers
The EEADR and EEADRH registers can address up to a maximum of 256 bytes of data EEPROM or up to a maximum of 4K words of program EEPROM. When selecting a program address value, the MSB of the address is written to the EEADRH register and the LSB is written to the EEADR register. When selecting a data address value, only the LSB of the address is written to the EEADR register.
Data EEPROM memory is readable and writable and the Flash program memory is readable during normal operation (full VDD range). These memories are not directly mapped in the register file space. Instead, they are indirectly addressed through the Special Function Registers. There are six SFRs used to access these memories: * * * * * * EECON1 EECON2 EEDAT EEDATH EEADR EEADRH
9.1.1
EECON1 AND EECON2 REGISTERS
EECON1 is the control register for EE memory accesses. Control bit EEPGD determines if the access will be a program or data memory access. When clear, as it is when reset, any subsequent operations will operate on the data memory. When set, any subsequent operations will operate on the program memory. Program memory can only be read. Control bits RD and WR initiate read and write, respectively. These bits cannot be cleared, only set, in software. They are cleared in hardware at completion of the read or write operation. The inability to clear the WR bit in software prevents the accidental, premature termination of a write operation. The WREN bit, when set, will allow a write operation to data EEPROM. On power-up, the WREN bit is clear. The WRERR bit is set when a write operation is interrupted by a MCLR or a WDT Time-out Reset during normal operation. In these situations, following Reset, the user can check the WRERR bit and rewrite the location. The data and address will be unchanged in the EEDAT and EEADR registers. Interrupt flag bit EEIF (PIR1<7>), is set when write is complete. It must be cleared in the software. EECON2 is not a physical register. Reading EECON2 will read all `0's. The EECON2 register is used exclusively in the data EEPROM write sequence.
When interfacing the data memory block, EEDAT holds the 8-bit data for read/write, and EEADR holds the address of the EE data location being accessed. This device has 256 bytes of data EEPROM with an address range from 0h to 0FFh. When interfacing the program memory block, the EEDAT and EEDATH registers form a 2-byte word that holds the 14-bit data for read/write, and the EEADR and EEADRH registers form a 2-byte word that holds the 12-bit address of the EEPROM location being accessed. This device has 4K words of program EEPROM with an address range from 0h to 0FFFh. The program memory allows one word reads. The EEPROM data memory allows byte read and write. 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. The write/erase voltages are generated by an on-chip charge pump rated to operate over the voltage range of the device for byte or word operations. When the device is code-protected, the CPU may continue to read and write the data EEPROM memory and read the program memory. When code-protected, the device programmer can no longer access data or program memory. Additional information on the data EEPROM is available in the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023).
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 71
PIC16F688
REGISTER 9-1: EEDAT - EEPROM DATA REGISTER (ADDRESS: 9Ah)
R/W-0 EEDAT7 bit 7 bit 7-0 EEDATn: Byte Value to Write to or Read From Data EEPROM 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 R/W-0 EEDAT6 R/W-0 EEDAT5 R/W-0 EEDAT4 R/W-0 EEDAT3 R/W-0 EEDAT2 R/W-0 EEDAT1 R/W-0 EEDAT0 bit 0
REGISTER 9-2:
EEADR - EEPROM ADDRESS REGISTER (ADDRESS: 9Bh)
R/W-0 EEADR7 bit 7 R/W-0 EEADR6 R/W-0 EEADR5 R/W-0 EEADR4 R/W-0 EEADR3 R/W-0 EEADR2 R/W-0 EEADR1 R/W-0 EEADR0 bit 0
bit 7-0
EEADR: Specifies One of 256 Locations for EEPROM Read/Write Operation 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
REGISTER 9-3:
EECON1 - EEPROM CONTROL REGISTER 1 (ADDRESS: 9Ch)
R/W-0 EEPGD bit 7 U-0 -- U-0 -- U-0 -- R/W-x WRERR R/W-0 WREN R/S-0 WR R/S-0 RD bit 0
bit 7
EEPGD: Program/Data EEPROM Select bit 1 = Accesses program memory 0 = Accesses data memory Unimplemented: Read as `0' WRERR: EEPROM Error Flag bit 1 = A write operation is prematurely terminated (any MCLR Reset, any WDT Reset during normal operation or BOD detect) 0 = The write operation completed WREN: EEPROM Write Enable bit 1 = Allows write cycles 0 = Inhibits write to the data EEPROM WR: Write Control bit EEPGD = 1: This bit is ignored EEPGD = 0: 1 = Initiates a write cycle (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 data EEPROM is complete RD: Read Control bit 1 = Initiates an memory read (Read takes one cycle. RD is cleared in hardware. The RD bit can only be set, not cleared, in software.) 0 = Does not initiate an memory read Legend: S = Bit can only be set 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 6-4 bit 3
bit 2
bit 1
bit 0
DS41203B-page 72
Preliminary
2004 Microchip Technology Inc.
PIC16F688
9.1.2 READING THE DATA EEPROM MEMORY 9.1.3 WRITING TO THE DATA EEPROM MEMORY
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 in the very next cycle, in the EEDAT register; therefore, it can be read in the next instruction. EEDAT will hold this value until another read or until it is written to by the user (during a write operation). To write an EEPROM data location, the user must first write the address to the EEADR register and the data to the EEDAT register. Then the user must follow a specific sequence to initiate the write for each byte. The write will not initiate if the above sequence is not followed exactly (write 55h to EECON2, write AAh to EECON2, then set WR bit) for each byte. Interrupts should be disabled during this code segment. Additionally, the WREN bit in EECON1 must be set to enable write. This mechanism prevents accidental writes to data EEPROM due to errant (unexpected) code execution (i.e., lost programs). The user should keep the WREN bit clear at all times, except when updating EEPROM. The WREN bit is not cleared by hardware. After a write sequence has been initiated, clearing the WREN bit will not affect this write cycle. The WR bit will be inhibited from being set unless the WREN bit is set. At the completion of the write cycle, the WR bit is cleared in hardware and the EE Write Complete Interrupt Flag bit (EEIF) is set. The user can either enable this interrupt or poll this bit. EEIF must be cleared by software.
EXAMPLE 9-1:
BSF BCF MOVLW MOVWF BCF BSF MOVF
DATA EEPROM READ
; ; Bank 1 ; ; Data Memory ; Address to read EECON1, EEPGD ; Point to DATA ; memory EECON1, RD ; EE Read EEDAT, W ; W = EEDAT
STATUS, RP0 STATUS, RP1 DATA_EE_ADDR EEADR
EXAMPLE 9-2:
BSF BCF MOVLW MOVWF MOVLW MOVWF BCF BSF BCF MOVLW MOVWF MOVLW MOVWF BSF BSF SLEEP BCF
DATA EEPROM WRITE
STATUS, RP0 ; STATUS, RP1 ; Bank 1 DATA_EE_ADDR ; EEADR ; Data Memory Address to write DATA_EE_DATA ; EEDAT ; Data Memory Value to write EECON1, EEPGD ; Point to DATA memory EECON1, WREN ; Enable writes INTCON, GIE 55h EECON2 AAh EECON2 EECON1, WR INTCON, GIE ; ; ; ; ; ; ; Disable INTs. Write 55h Write AAh Set WR bit to begin write Enable INTs.
Required Sequence
EECON1, WREN
; Wait for interrupt to signal write complete ; Disable writes
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 73
PIC16F688
9.1.4 READING THE FLASH PROGRAM MEMORY
To read a program memory location, the user must write two bytes of the address to the EEADR and EEADRH registers, set the EEPGD control bit (EECON1<7>), and then set control bit RD (EECON1<0>). Once the read control bit is set, the program memory Flash controller will use the second instruction cycle to read the data. This causes the second instruction immediately following the "BSF EECON1,RD" instruction to be ignored. The data is available in the very next cycle, in the EEDAT and EEDATH registers; therefore, it can be read as two bytes in the following instructions. EEDAT and EEDATH registers will hold this value until another read or until it is written to by the user (during a write operation). Note 1: The two instructions following a program memory read are required to be NOP's. This prevents the user from executing a two-cycle instruction on the next instruction after the RD bit is set. 2: If the WR bit is set when EEPGD = 1, it will be immediately reset to `0' and no operation will take place.
EXAMPLE 9-3:
BSF BCF MOVLW MOVWF MOVLW MOVWF BSF BSF ;
FLASH PROGRAM READ
; ; ; ; ; ; ; ; Bank 1 MS Byte of Program Address to read LS Byte of Program Address to read Point to PROGRAM memory EE Read
STATUS, RP0 STATUS, RP1 MS_PROG_EE_ADDR EEADRH LS_PROG_EE_ADDR EEADR EECON1, EEPGD EECON1, RD
; First instruction after BSF EECON1,RD executes normally NOP NOP ; MOVF MOVF EEDAT, W EEDATH, W ; W = LS Byte of Program EEDAT ; W = MS Byte of Program EEDAT ; Any instructions here are ignored as program ; memory is read in second cycle after BSF EECON1,RD
DS41203B-page 74
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 9-1: FLASH PROGRAM MEMORY READ CYCLE EXECUTION
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Flash ADDR
PC
PC+1
EEADRH,EEADR
PC+3 PC+3
PC+4
PC+5
Flash Data
INSTR (PC)
INSTR (PC+1)
EEDATH,EEDAT
INSTR (PC+3)
INSTR (PC+4)
INSTR(PC-1) executed here
BSF EECON1,RD executed here
INSTR(PC+1) executed here
Forced NOP executed here
INSTR(PC+3) executed here
INSTR(PC+4) executed here
RD bit
EEDATH EEDAT Register
EERHLT
TABLE 9-1:
Addr 0Bh/8Bh 0Ch 8Ch 97h 98h 9Ah 9Bh 9Ch 9Dh Legend: Note 1:
REGISTERS/BITS ASSOCIATED WITH DATA EEPROM
Bit 7 GIE EEIF EEIE Bit 6 PEIE ADIF ADIE Bit 5 T0IE RCIF RCIE Bit 4 INTE C2IF C2IE Bit 3 RAIE C1IF C1IE Bit 2 T0IF OSFIF OSFIE Bit 1 INTF TXIF TXIE Bit 0 RAIF Value on POR, BOD Value on all other Resets
Name INTCON PIR1 PIE1 EEDATH EEADRH EEDAT EEADR EECON1 EECON2(1)
0000 0000 0000 0000
TMR1IF 0000 0000 0000 0000 TMR1IE 0000 0000 0000 0000 --00 0000 0000 0000 ---- 0000 0000 0000
EEPROM Data register, high byte EEPROM Address register, high byte
EEDAT7 EEDAT6 EEDAT5 EEDAT4 EEDAT3 EEDAT2 EEDAT1 EEDAT0 0000 0000 0000 0000 EEADR7 EEADR6 EEADR5 EEADR4 EEADR3 EEADR2 EEADR1 EEADR0 0000 0000 0000 0000 EEPGD -- -- -- -- -- -- -- WRERR -- WREN -- WR -- RD -- ---- x000 ---- q000 -- --
x = unknown, u = unchanged, - = unimplemented read as `0', q = value depends upon condition. Shaded cells are not used by data EEPROM module. EECON2 is not a physical register.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 75
PIC16F688
NOTES:
DS41203B-page 76
Preliminary
2004 Microchip Technology Inc.
PIC16F688
10.0 ENHANCED UNIVERSAL ASYNCHRONOUS RECEIVER TRANSMITTER (EUSART)
10.1 Clock Accuracy With Asynchronous Operation
The Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) module is the serial I/O module available for PIC16F688 . (EUSART 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 half-duplex synchronous system that can communicate with peripheral devices, such as A/D or D/A integrated circuits, serial EEPROMs, etc. The EUSART module implements additional features, including automatic baud rate detection and calibration, automatic wake-up on Break reception and 13-bit Break character transmit. These make it ideally suited for use in Local Interconnect Network (LIN) bus systems. The USART can be configured in the following modes: * Asynchronous (full-duplex) with: - Auto-wake-up on Break - Auto baud calibration - 13-bit Break character transmission * Synchronous - Master (half-duplex) with selectable clock polarity * Synchronous - Slave (half-duplex) with selectable clock polarity In order to configure pins RC4/C2OUT/TX/CK and RC5/RX/DT as the Universal Synchronous Asynchronous Receiver Transmitter: * SPEN (RCSTA<7>) bit must be set (= 1), * TRISC<5> bit must be set (= 1), and * TRISC<4> bit must be set (= 1). Note: The USART control will automatically reconfigure the pin from input to output as needed.
The factory calibrates the internal oscillator block output (INTOSC) for 8 MHz. However, this frequency may drift as VDD or temperature changes, and this directly affects the asynchronous baud rate. Two methods may be used to adjust the baud rate clock, but both require a reference clock source of some kind. The first (preferred) method uses the OSCTUNE register to adjust the INTOSC output back to 8 MHz. Adjusting the value in the OSCTUNE register allows for fine resolution changes to the system clock source (see Section 3.4 "Internal Clock Modes" for more information). The other method adjusts the value in the baud rate generator. There may not be fine enough resolution when adjusting the Baud Rate Generator to compensate for a gradual change in the peripheral clock frequency.
The operation of the EUSART module is controlled through three registers: * Transmit Status and Control (TXSTA) * Receive Status and Control (RCSTA) * Baud Rate Control (BAUDCTL) These are detailed in on the following pages in Register 10-1, Register 10-2 and Register 10-3, respectively.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 77
PIC16F688
REGISTER 10-1: TXSTA - TRANSMIT STATUS AND CONTROL REGISTER (ADDRESS: 16h)
R/W-0 CSRC bit 7 bit 7 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
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: SREN/CREN overrides TXEN in Sync mode. SYNC: USART 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
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
DS41203B-page 78
Preliminary
2004 Microchip Technology Inc.
PIC16F688
REGISTER 10-2: RCSTA - RECEIVE STATUS AND CONTROL REGISTER (ADDRESS: 17h)
R/W-0 SPEN bit 7 bit 7 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
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, enable interrupt and load 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 8-bit (RX9 = 0): Don't care FERR: Framing Error bit 1 = Framing error (can be updated by reading RCREG register and receive 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
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 79
PIC16F688
REGISTER 10-3: BAUDCTL - BAUD RATE CONTROL REGISTER (ADDRESS: 11h)
R-0 ABDOVF bit 7 bit 7 ABDOVF: Auto Baud Detect Overflow bit Asynchronous mode: 1 = Auto baud timer overflowed 0 = Auto baud timer did not overflow Synchronous mode: Don't care RCIDL: Receive IDLE Flag bit Asynchronous mode: 1 = Receiver is IDLE 0 = Start bit has been received and the receiver is receiving Synchronous mode: Don't care Unimplemented: Read as `0' SCKP: Synchronous Clock Polarity Select bit Asynchronous mode: 1 = Transmit pin TX 0 = Transmit pin TX Synchronous mode: 1 = Data is clocked on rising edge of the clock 0 = Data is clocked on falling edge of the clock BRG16: 16-bit Baud Rate Generator bit 1 = 16-bit baud rate generator is used 0 = 8-bit baud rate generator is used Unimplemented: Read as `0' WUE: Wake-up Enable bit 1 = Next falling RX/DT edge will generate interrupt (automatically cleared on next rising edge after falling edge) 0 = RX/DT edges do not generate interrupts ABDEN: Auto Baud Detect Enable bit Asynchronous mode: 1 = Auto Baud mode is enabled (clears when auto baud is complete) 0 = Auto Baud mode is disabled Synchronous mode: Don't care 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 U-0 -- R/W-0 SCKP 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
DS41203B-page 80
Preliminary
2004 Microchip Technology Inc.
PIC16F688
10.2 USART Baud Rate Generator (BRG)
10.2.1 SAMPLING
The data on the RC5/RX/DT 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.
The BRG is a dedicated 8-bit or 16-bit generator, that supports both the Asynchronous and Synchronous modes of the USART. By default, the BRG operates in 8-bit mode; setting the BRG16 bit (BAUDCTL<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 also control the baud rate. In Synchronous mode, bit BRGH is ignored. Table 10-1 shows the formula for computation of the baud rate for different USART 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 10-1. From this, the error in baud rate can be determined. An example calculation is shown in Example 10-1. Typical baud rates and error values for the various asynchronous modes are shown in Table 10-2. 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. If the system clock is changed during an active receive operation, a receive error or data loss may result. To avoid this problem, check the status of the RCIDL bit and make sure that the receive operation is IDLE before changing the system clock.
EXAMPLE 10-1:
CALCULATING BAUD RATE ERROR
For a device with FOSC of 16 MHz, desired baud rate of 9600, Asynchronous mode, 8-bit BRG:
FOSC Desired Baud Rate = -------------------------------------------------------------------64 ( [SPBRGH:SPBRG] + 1 )
Solving for SPBRGH:SPBRG:
FOSC -------------------------------------------Desired Baud Rate X = --------------------------------------------- - 1 64 16000000 ----------------------9600 = ----------------------- - 1 64 = [ 25.042 ] = 25 16000000Calculated Baud Rate = -------------------------64 ( 25 + 1 ) = 9615 Calc. Baud Rate - Desired Baud RateError = ------------------------------------------------------------------------------------------Desired Baud Rate ( 9615 - 9600 ) = ---------------------------------- = 0.16% 9600
Note:
When BRGH = 1 and BRG16 = 1 then SPBRGH:SPBRG values 4 are invalid.
TABLE 10-1:
SYNC 0 0 0 0 1 1 Legend:
BAUD RATE FORMULAS
BRG/USART Mode BRG16 0 0 1 1 0 1 BRGH 0 1 0 1 x x 8-bit/Asynchronous 8-bit/Asynchronous FOSC/[16 (n+1)] 16-bit/Asynchronous 16-bit/Asynchronous 8-bit/Synchronous 16-bit/Synchronous FOSC/[4 (n+1)] FOSC/[64 (n+1)] Baud Rate Formula
Configuration Bits
x = Don't care, n = value of SPBRGH:SPBRG register pair
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 81
PIC16F688
TABLE 10-2:
Addr 11h 12h 13h 16h 17h Legend: Name BAUDCTL SPBRGH SPBRG TXSTA RCSTA CSRC SPEN TX9 RX9
REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Bit 7 ABDOVF Bit 6 RCIDL Bit 5 -- Bit 4 SCKP Bit 3 BRG16 Bit 2 -- Bit 1 WUE Bit 0 Value on: POR, BOD Value on all other Resets
ABDEN -1-1 0-00 -1-1 0-00 0000 0000 0000 0000 0000 0000 0000 0000
Baud Rate Generator register, high byte Baud Rate Generator register, low byte TXEN SREN SYNC CREN SENDB ADDEN BRGH FERR TRMT OERR TX9D RX9D
0000 -010 0000 -010 0000 000x 0000 000x
x = unknown, u = unchanged, -- = unimplemented locations read as `0'. Shaded cells are not used by oscillators.
TABLE 10-3:
BAUD RATE (K)
BAUD RATES FOR ASYNCHRONOUS MODES
SYNC = 0, BRGH = 0, BRG16 = 0 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 = 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 = 8.000 MHz Actual Rate (K) -- 1201 2403 9615 -- -- -- % Error -- -0.16 -0.16 -0.16 -- -- -- SPBRG value
(decimal)
0.3 1.2 2.4 9.6 19.2 57.6 115.2
-- 255 129 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) 300 1201 2403 -- -- -- -- % Error -0.16 -0.16 -0.16 -- -- -- -- SPBRG value
(decimal)
FOSC = 1.000 MHz Actual Rate (K) 300 1201 -- -- -- -- -- % 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 = 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) 2403 9615 19230 55555 -- % Error -0.16 -0.16 -0.16 3.55 -- SPBRG value
(decimal)
2.4 9.6 19.2 57.6 115.2
-- 129 64 21 10
255 64 31 10 4
207 51 25 8 --
DS41203B-page 82
Preliminary
2004 Microchip Technology Inc.
PIC16F688
TABLE 10-3:
BAUD RATE (K)
BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
SYNC = 0, BRGH = 1, BRG16 = 0 FOSC = 2.000 MHz Actual Rate (K) -- 1201 2403 9615 -- -- -- % Error -- -0.16 -0.16 -0.16 -- -- -- SPBRG value
(decimal)
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 = 1.000 MHz Actual Rate (K) 300 1201 2403 -- -- -- -- % 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 -- -- -- --
SYNC = 0, BRGH = 0, BRG16 = 1 BAUD RATE (K) 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 = 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) 300 1201 2403 9615 19230 55555 -- % 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
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) 300 1201 2403 9615 -- -- -- % Error -0.16 -0.16 -0.16 -0.16 -- -- -- SPBRG value
(decimal)
FOSC = 1.000 MHz Actual Rate (K) 300 1201 2403 -- -- -- -- % 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 = 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) 300 1200 2400 9615 19230 57142 117647 % 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
16665 4165 2082 520 259 86 42
8332 2082 1040 259 129 42 21
6665 1665 832 207 103 34 16
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 83
PIC16F688
TABLE 10-3: BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)
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) 300 1201 2403 9615 19230 55555 -- % Error -0.04 -0.16 -0.16 -0.16 -0.16 3.55 -- SPBRG value
(decimal)
FOSC = 1.000 MHz Actual Rate (K) 300 1201 2403 9615 19230 -- -- % 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 -- --
10.2.2
AUTO BAUD RATE DETECT
The EUSART 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 10-1) begins whenever a Start bit is received and the ABDEN bit is set. The calculation is selfaveraging. 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 Detect must receive a byte with the value 55h (ASCII "U", which is also the LIN bus sync character), in order to calculate the proper bit rate. The measurement takes 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 registers. Once the 5th edge is seen (should correspond to the Stop bit), the ABDEN bit is automatically cleared. While calibrating the baud rate period, the BRG registers are clocked at 1/8th the pre-configured clock rate. Note that the BRG clock will be configured by the BRG16 and BRGH bits. Independent of the BRG16 bit setting, both the SPBRG and SPBRGH will be used 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 10-4 for counter clock rates to the BRG.
While the ABD sequence takes place, the USART 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. RCREG content 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 (see Section 10.3.4 "Auto-Wake-up on SYNC 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 USART 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.
TABLE 10-4:
BRG16 0 0 1 1 Note: BRGH 0 1 0 1
BRG COUNTER CLOCK RATES
BRG Counter Clock FOSC/512 FOSC/128 FOSC/128 FOSC/32
During the ABD sequence, SPBRG and SPBRGH are both used as a 16-bit counter, independent of BRG16 setting.
DS41203B-page 84
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 10-1:
BRG Value RX pin
AUTOMATIC BAUD RATE CALCULATION
XXXXh 0000h Edge #1 Bit 1 Edge #2 Bit 3 Edge #3 Bit 5 Edge #4 Bit 7 001Ch Edge #5 Stop Bit
Start
Bit 0
Bit 2
Bit 4
Bit 6
BRG Clock Set by User ABDEN bit RCIDL RCIF bit (Interrupt) Read RCREG SPBRG SPBRGH Note 1: XXXXh XXXXh The ABD sequence requires the USART module to be configured in Asynchronous mode and WUE = 0. 1Ch 00h Auto Cleared
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 85
PIC16F688
10.3 USART Asynchronous Mode
10.3.1
The Asynchronous mode of operation is selected by clearing the SYNC bit (TXSTA<4>). In this mode, the USART 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 USART transmits and receives the LSb first. The USART'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 BAUDCTL<3>). Parity is not supported by the hardware, but can be implemented in software and stored as the 9th data bit. Asynchronous mode is available in all times. It is available in Sleep mode only when auto-wake-up on Sync Break is enabled. The baud rate generator values may need to be adjusted if the clocks are changed. When operating in Asynchronous mode, the USART module consists of the following important elements: * * * * * * * Baud Rate Generator Sampling Circuit Asynchronous Transmitter Asynchronous Receiver Auto-wake-up on Sync Break Character 13-bit Break Character Transmit Auto Baud Rate Detection
USART ASYNCHRONOUS TRANSMITTER
The USART transmitter block diagram is shown in Figure 10-2. The heart of the transmitter is the Transmit (serial) Shift Register (TSR). The shift register obtains its data from the read/write transmit buffer, 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). Once the TXREG register transfers the data to the TSR register (occurs in one TCY), the TXREG register is empty and flag bit TXIF (PIR1<4>) is set. This interrupt can be enabled/disabled by setting/clearing enable bit TXIE (PIE1<4>). Flag bit TXIF will be set, regardless of the state of enable bit TXIE and cannot be cleared in software. Flag bit TXIF is not cleared immediately upon loading the transmit buffer register TXREG. TXIF becomes valid in the second instruction cycle following the load instruction. Polling TXIF immediately following a load of TXREG will return invalid results. While flag bit TXIF indicates the status of the TXREG register, another bit, TRMT (TXSTA<1>), shows the status of the TSR register. Status bit 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. 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 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).
2. 3. 4. 5. 6. 7.
If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set.
DS41203B-page 86
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 10-2: USART 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 RC4/C2OUT/TX/CK pin
Baud Rate Generator
FIGURE 10-3:
Write to TXREG BRG Output (Shift Clock) RC4/C2OUT/TX/CK pin TXIF bit (Transmit Buffer Reg. Empty Flag)
ASYNCHRONOUS TRANSMISSION
Word 1
Start bit
bit 0
bit 1 Word 1
bit 7/8
Stop bit
1 TCY
TRMT bit (Transmit Shift Reg. Empty Flag)
Word 1 Transmit Shift Reg
FIGURE 10-4:
Write to TXREG BRG Output (Shift Clock) RC4/C2OUT/TX/CK pin TXIF bit (Interrupt Reg. Flag) TRMT bit (Transmit Shift Reg. Empty Flag)
ASYNCHRONOUS TRANSMISSION (BACK TO BACK)
Word 1 Word 2
Start bit 1 TCY
bit 0
bit 1 Word 1
bit 7/8
Stop bit
Start bit Word 2
bit 0
1 TCY Word 1 Transmit Shift Reg. Word 2 Transmit Shift Reg.
Note:
This timing diagram shows two consecutive transmissions.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 87
PIC16F688
TABLE 10-5:
Addr 0Ch 11h 12h 13h 14h 15h 16h 17h 8Ch Name PIR1 SPBRGH SPBRG RCREG TXREG TXSTA RCSTA PIE1
REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION
Bit 7 EEIF Bit 6 ADIF RCIDL Bit 5 RCIF -- Bit 4 C2IF SCKP Bit 3 C1IF BRG16 Bit 2 OSFIF -- Bit 1 TXIF WUE Bit 0 TMR1IF ABDEN Value on POR, BOD Value on all other Resets
BAUDCTL ABDOVF
USART Baud Rate High Generator USART Baud Rate Generator USART Receive Register USART Transmit Register CSRC SPEN EEIE TX9 RX9 ADIE TXEN SREN RCIE SYNC CREN C2IE SENDB ADDEN C1IE BRGH FERR OSFIE TRMT OERR TXIE
0000 00-0 0000 0000 0000 0000 TX9D 0000 RX9D 0000 TMR1IE 0000
0000 0-00 0000 0000 0000 0000 0010 000X 0000
0000 00-0 0000 0000 0000 0000 0000 0000 0000
0000 0-00 0000 0000 0000 0000 0010 000X 0000
Legend:
x = unknown, - = unimplemented locations read as `0'. Shaded cells are not used for Asynchronous Transmission.
DS41203B-page 88
Preliminary
2004 Microchip Technology Inc.
PIC16F688
10.3.2 USART ASYNCHRONOUS RECEIVER 10.3.3 SETTING UP 9-BIT MODE WITH ADDRESS DETECT
The receiver block diagram is shown in Figure 10-5. The data is received on the RC5/RX/DT pin and drives the data recovery block. The data recovery block is actually a high-speed shifter operating at 16 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. 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 interrupts are desired, set enable bit RCIE. 4. If 9-bit reception is desired, set bit RX9. 5. Enable the reception by setting bit CREN. 6. Flag bit RCIF will be set when reception is complete and 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 enable bit CREN. 10. 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: 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 interrupts are required, set the RCEN bit and select the desired priority level with the RCIP bit. 4. Set the RX9 bit to enable 9-bit reception. 5. Set the ADDEN bit to enable address detect. 6. Enable reception by setting the CREN bit. 7. The RCIF bit will be set when reception is complete. The interrupt will be acknowledged if the RCIE and GIE bits are set. 8. Read the RCSTA register to determine if any error occurred during reception, as well as read bit 9 of data (if applicable). 9. Read RCREG to determine if the device is being addressed. 10. If any error occurred, clear the CREN bit. 11. If the device has been addressed, clear the ADDEN bit to allow all received data into the receive buffer and interrupt the CPU. 1.
FIGURE 10-5:
USART RECEIVE BLOCK DIAGRAM
CREN x64 Baud Rate CLK OERR FERR RCIDL
BRG16
SPBRGH
SPBRG
Baud Rate Generator
/ 64 or / 16 or /4
MSb Stop (8) 7
RSR Register *** 1
LSb 0 START
RX9 RC5/RX/DT pin Pin Buffer and Control Data Recovery RX9D RCREG Register FIFO SPEN 8 Interrupt RCIF RCIE Data Bus
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 89
PIC16F688
FIGURE 10-6:
RX (pin) Rcv Shift Reg Rcv Buffer Reg RCIDL Read Rcv Buffer Reg RCREG RCIF (Interrupt Flag) OERR bit CREN
ASYNCHRONOUS RECEPTION
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
Note:
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 10-6:
Addr 0Ch 11h 12h 13h 14h 15h 16h 17h 8Ch Name PIR1
REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Bit 7 EEIF Bit 6 ADIF RCIDL Bit 5 RCIF -- Bit 4 C2IF SCKP Bit 3 C1IF BRG16 Bit 2 OSFIF -- Bit 1 TXIF WUE Bit 0 TMR1IF ABDEN Value on POR, BOD 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 SYNC CREN C2IE SENDB ADDEN C1IE BRGH FERR OSFIE TRMT OERR TXIE TX9D RX9D TMR1IE 0000 0010 0000 000X 0000 0000 Value on all other Resets 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 000X 0000 0000
BAUDCTL ABDOVF SPBRG RCREG TXREG TXSTA RCSTA PIE1
SPBRGH USART Baud Rate High Generator USART Baud Rate Generator USART Receive Register USART Transmit Register CSRC SPEN EEIE TX9 RX9 ADIE TXEN SREN RCIE
Legend:
x = unknown, - = unimplemented locations read as `0'. Shaded cells are not used for Asynchronous Reception.
DS41203B-page 90
Preliminary
2004 Microchip Technology Inc.
PIC16F688
10.3.4 AUTO-WAKE-UP ON SYNC BREAK CHARACTER
The auto-wake-up feature allows the controller to wake-up due to activity on the RX/DT line, despite the baud clock being turned off. This allows communications systems to save power by only responding to direct requests. Setting the WUE bit (BAUDCTL<1>) enables the auto-wake-up feature. When the auto-wake-up feature is enabled, the next falling edge on the RX/DT line will trigger an RCIF interrupt. The WUE bit will automatically clear after the rising RX/DT edge after triggering a falling edge. Receiving a RCIF interrupt after setting the WUE bit signals to the user that the wake-up event has occurred. See Figure 10-7 and Figure 10-8 for timing details of the auto-wake-up process. application must wait before receiving valid data. Special care should be taken when using the two-speed start-up or the fail-safe clock monitor because the application will start running from the internal oscillator before the primary oscillator is ready. Because the auto-wake-up feature uses the RCIF flag to signify the wake-up event, the application should discard the data read from RCREG when servicing the RCIF flag after setting the WUE bit. When entering Sleep with auto-wake-up enabled, the following procedure should be used. 1. 2. 3. 4. Clear all interrupt flags including RCIF. Check RCIDL to ensure no receive is currently in progress. No characters are being received so the WUE bit can be set. Sleep.
10.3.4.1
Special Considerations Using Auto- Wake-up
The auto-wake-up function is edge sensitive. To prevent data errors or framing errors, the data following the Break should be all `0's until the baud clock is stable. If the LP, XT or HS oscillators are used, the oscillator start-up time will affect the amount of time the
FIGURE 10-7:
OSC1
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 Q1Q2 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 WUE bit RX/DT Line RCIF Auto Cleared
Cleared due to User Read of RCREG
Note: The USART remains in IDLE while the WUE bit is set.
FIGURE 10-8:
AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Auto Cleared
Q1Q2Q3 Q4 Q1Q2 Q3 Q4 Q1Q2 Q3 Q4 OSC1 Bit Set by User WUE bit RX/DT Line RCIF Sleep Command Executed
Cleared due to User Read of RCREG Sleep Ends
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 91
PIC16F688
10.3.5 BREAK CHARACTER SEQUENCE 10.3.5.1 Break and Sync Transmit Sequence
The EUSART module has the capability of sending the special Break character sequences that are required by the LIN bus standard. The Break character transmit consists of a Start bit, followed by 12 `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 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 10-9 for the timing of the Break character 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 bus master. 1. 2. 3. 4. 5. Configure the USART for the desired mode. Set the TXEN and SENDB bits to setup 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 Pre-Configured mode.
When the TXREG becomes empty, as indicated by the TXIF, the next data byte can be written to TXREG.
10.3.6
RECEIVING A BREAK CHARACTER
The Enhanced USART module can receive a Break character in two ways. The first method forces to configure 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 10.3.4 "Auto-Wake-up on SYNC Break Character". By enabling this feature, the USART 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 before placing the USART in its Sleep mode.
FIGURE 10-9:
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
DS41203B-page 92
Preliminary
2004 Microchip Technology Inc.
PIC16F688
10.4 USART Synchronous Master Mode
Once the TXREG register transfers the data to the TSR register (occurs in one TCYCLE), the TXREG is empty and interrupt bit TXIF (PIR1<4>) is set. The interrupt can be enabled/disabled by setting/clearing enable bit TXIE (PIE1<4>). Flag bit TXIF will be set, regardless of the state of enable bit TXIE, and 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 BRGH and BRG16 bits, as required, to achieve the desired baud rate. Enable the synchronous master serial port by setting bits SYNC, SPEN and CSRC. 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 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 RC4/C2OUT/TX/CK and RC5/RX/DT I/O 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 is selected with the SCKP bit (BAUDCTL<5>); setting SCKP sets the IDLE state on CK as high, while clearing the bit, sets the IDLE state low. This option is provided to support Microwire(R) devices with this module.
10.4.1
USART SYNCHRONOUS MASTER TRANSMISSION
2. 3. 4. 5. 6. 7. 8.
The USART transmitter block diagram is shown in Figure 10-2. 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 10-10:
SYNCHRONOUS TRANSMISSION
Q3Q4 Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4 bit 7 bit 0 bit 1 Word 2 bit 7
Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4 RC5/RX/ DT pin RC4/C2OUT/ TX/CK pin (SCKP = 0) RC4/C2OUT/ TX/CK pin (SCKP = 1) Write to TXREG Reg TXIF bit (Interrupt Flag) TRMT bit Write Word 1 bit 0 bit 1 Word 1 bit 2
Write Word 2
TXEN bit
`1'
`1'
Note: Sync Master mode, SPBRG = 0, continuous transmission of two 8-bit words.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 93
PIC16F688
FIGURE 10-11: SYNCHRONOUS TRANSMISSION (THROUGH TXEN)
bit 0 bit 1 bit 2 bit 6 bit 7 RC5/RX/DT pin
RC4/C2OUT/TX/CK pin Write to TXREG Reg
TXIF bit
TRMT bit
TXEN bit
TABLE 10-7:
Addr 0Ch 11h 12h 13h 14h 15h 16h 17h 8Ch Name PIR1
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION
Bit 7 EEIF Bit 6 ADIF RCIDL Bit 5 RCIF -- Bit 4 C2IF SCKP Bit 3 C1IF BRG16 Bit 2 OSFIF -- Bit 1 TXIF WUE Bit 0 TMR1IF ABDEN Value on POR, BOD 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 SYNC CREN C2IE SENDB ADDEN C1IE BRGH FERR OSFIE TRMT OERR TXIE TX9D RX9D TMR1IE 0000 0010 0000 000X 0000 0000 Value on all other Resets 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 000X 0000 0000
BAUDCTL ABDOVF SPBRG RCREG TXREG TXSTA RCSTA PIE1
SPBRGH USART Baud Rate High Generator USART Baud Rate Generator USART Receive Register USART Transmit Register CSRC SPEN EEIE TX9 RX9 ADIE TXEN SREN RCIE
Legend:
x = unknown, - = unimplemented locations read as `0'. Shaded cells are not used for Asynchronous Reception.
DS41203B-page 94
Preliminary
2004 Microchip Technology Inc.
PIC16F688
10.4.2 USART SYNCHRONOUS MASTER RECEPTION
To set up a Synchronous Master 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 synchronous master serial port by setting bits SYNC, SPEN and CSRC. 3. Ensure bits CREN and SREN are clear. 4. If interrupts are desired, set enable bit RCIE. 5. If 9-bit reception is desired, set bit RX9. 6. If a single reception is required, set bit SREN. For continuous reception, set bit CREN. 7. Interrupt flag bit RCIF will be set when reception is complete and an interrupt will be generated if the 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 bit CREN. 11. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. 1. 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 RC5/RX/DT 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.
FIGURE 10-12:
RC5/RX/ DT pin RC4/C2OUT/ TX/CK pin (SCKP = 0) RC4/C2OUT/ TX/CK pin (SCKP = 1) Write to bit SREN SREN bit CREN bit `0' RCIF bit (Interrupt) Read RXREG Note:
SYNCHRONOUS RECEPTION (MASTER MODE, SREN)
Q2 Q3Q4Q1Q2Q3Q4Q1Q2 Q3Q4 Q1Q2Q3Q4Q1Q2 Q3Q4 Q1Q2Q3Q4Q1Q2Q3 Q4 Q1Q2 Q3Q4 Q1Q2Q3 Q4 Q1Q2 Q3Q4 Q1Q2Q3Q4 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.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 95
PIC16F688
TABLE 10-8:
Addr 0Ch 11h 12h 13h 14h 15h 16h 17h 8Ch Name PIR1
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
Bit 7 EEIF Bit 6 ADIF RCIDL Bit 5 RCIF -- Bit 4 C2IF SCKP Bit 3 C1IF BRG16 Bit 2 OSFIF -- Bit 1 TXIF WUE Bit 0 Value on POR, BOD Value on all other Resets
TMR1IF 0000 0000 0000 0000 ABDEN
BAUDCTL ABDOVF
00-0 0-00 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
SPBRGH USART Baud Rate High Generator SPBRG RCREG TXREG TXSTA RCSTA PIE1 USART Baud Rate Generator USART Receive Register USART Transmit Register CSRC SPEN EEIE TX9 RX9 ADIE TXEN SREN RCIE SYNC CREN C2IE SENDB ADDEN C1IE BRGH FERR OSFIE TRMT OERR TXIE TX9D RX9D
0000 0010 0000 0010 0000 000X 0000 000X
TMR1IE 0000 0000 0000 0000
Legend: x = unknown, - = unimplemented locations read as `0'. Shaded cells are not used for Asynchronous Reception.
DS41203B-page 96
Preliminary
2004 Microchip Technology Inc.
PIC16F688
10.5 USART 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 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 TXREG 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 RC4/C2OUT/TX/CK pin (instead of being supplied internally in Master mode). This allows the device to transfer or receive data while in any Low-power mode.
2. 3. 4. 5. 6. 7. 8.
10.5.1
USART SYNCHRONOUS SLAVE TRANSMIT
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 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 10-9:
Addr 0Ch 11h 12h 13h 14h 15h 16h 17h 8Ch Name PIR1
REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION
Bit 7 EEIF Bit 6 ADIF RCIDL Bit 5 RCIF -- Bit 4 C2IF SCKP Bit 3 C1IF BRG16 Bit 2 OSFIF -- Bit 1 TXIF WUE Bit 0 TMR1IF ABDEN Value on POR, BOD 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 SYNC CREN C2IE SENDB ADDEN C1IE BRGH FERR OSFIE TRMT OERR TXIE TX9D RX9D TMR1IE 0000 0010 0000 000X 0000 0000 Value on all other Resets 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 000X 0000 0000
BAUDCTL ABDOVF SPBRG RCREG TXREG TXSTA RCSTA PIE1
SPBRGH USART Baud Rate High Generator USART Baud Rate Generator USART Receive Register USART Transmit Register CSRC SPEN EEIE TX9 RX9 ADIE TXEN SREN RCIE
Legend:
x = unknown, - = unimplemented locations read as `0'. Shaded cells are not used for Asynchronous Reception.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 97
PIC16F688
10.5.2 USART 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. If interrupts are desired, set enable bit RCIE. If 9-bit reception is desired, set bit RX9. To enable reception, set enable bit CREN. Flag bit RCIF will be set when reception is complete. An interrupt will be generated if enable bit RCIE was set. Read the RCSTA register to get the 9th bit (if enabled) and determine if any error occurred during reception. Read the 8-bit received data by reading the RCREG register. If any error occurred, clear the error by clearing bit CREN. 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, then a word may be received. 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 Sleep. If the global interrupt is enabled, the program will branch to the interrupt vector.
2. 3. 4. 5.
6.
7. 8. 9.
TABLE 10-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION
Addr 0Ch 11h 12h 13h 14h 15h 16h 17h 8Ch Name PIR1 Bit 7 EEIF Bit 6 ADIF RCIDL Bit 5 RCIF -- Bit 4 C2IF SCKP Bit 3 C1IF BRG16 Bit 2 OSFIF -- Bit 1 TXIF WUE Bit 0 TMR1IF ABDEN Value on POR, BOD 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 SYNC CREN C2IE SENDB ADDEN C1IE BRGH FERR OSFIE TRMT OERR TXIE TX9D RX9D TMR1IE 0000 0010 0000 000X 0000 0000 Value on all other Resets 0000 0000 00-0 0-00 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0000 000X 0000 0000
BAUDCTL ABDOVF SPBRG RCREG TXREG TXSTA RCSTA PIE1
SPBRGH USART Baud Rate High Generator USART Baud Rate Generator USART Receive Register USART Transmit Register CSRC SPEN EEIE TX9 RX9 ADIE TXEN SREN RCIE
Legend:
x = unknown, - = unimplemented locations read as `0'. Shaded cells are not used for Asynchronous Reception.
DS41203B-page 98
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.0 SPECIAL FEATURES OF THE CPU
The PIC16F688 has two timers that offer necessary delays on power-up. One is the Oscillator Start-up Timer (OST), intended to keep the chip in Reset until the crystal oscillator is stable. The other is the Powerup Timer (PWRT), which provides a fixed delay of 64 ms (nominal) on power-up only, designed to keep the part in Reset while the power supply stabilizes. There is also circuitry to reset the device if a brownout occurs, which can use the Power-up Timer to provide at least a 64 ms Reset. With these three functions-on-chip, most applications need no external Reset circuitry. The Sleep mode is designed to offer a very low -current Power-down mode. The user can wake-up from Sleep through: * External Reset * Watchdog Timer Wake-up * An interrupt Several oscillator options are also made available to allow the part to fit the application. The INTOSC option saves system cost while the LP crystal option saves power. A set of configuration bits are used to select various options (see Register 11-1).
The PIC16F688 has a host of features intended to maximize system reliability, minimize cost through elimination of external components, provide power saving features and offer code protection. These features are: * Reset - Power-on Reset (POR) - Power-up Timer (PWRT) - Oscillator Start-up Timer (OST) - Brown-out Detect (BOD) * Interrupts * Watchdog Timer (WDT) * Oscillator Selection * Sleep * Code Protection * ID Locations * In-Circuit Serial Programming
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 99
PIC16F688
11.1 Configuration Bits
Note: Address 2007h is beyond the user program memory space. It belongs to the special configuration memory space (2000h3FFFh), which can be accessed only during programming. See "PIC12F6XX/16F6XX Memory Programming Specification" (DS41204) for more information. The configuration bits can be programmed (read as `0'), or left unprogrammed (read as `1') to select various device configurations as shown in Register 11-1. These bits are mapped in program memory location 2007h.
REGISTER 11-1:
-- bit 13 bit 13-12 bit 11 --
CONFIG - CONFIGURATION WORD (ADDRESS: 2007h)
IESO BODEN1 BODEN0 CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0 bit 0
FCMEN
Unimplemented: Read as `1' FCMEN: Fail-Safe Clock Monitor Enabled bit 1 = Fail-Safe Clock Monitor is enabled 0 = Fail-Safe Clock Monitor is disabled IESO: Internal External Switchover bit 1 = Internal External Switchover mode is enabled 0 = Internal External Switchover mode is disabled BODEN<1:0>: Brown-out Detect Selection bits(1) 11 = BOD enabled 10 = BOD enabled during operation and disabled in Sleep 01 = BOD controlled by SBODEN bit (PCON<4>) 00 = BOD disabled CPD: Data Code Protection bit(2) 1 = Data memory code protection is disabled 0 = Data memory code protection is enabled CP: Code Protection bit(3) 1 = Program memory code protection is disabled 0 = Program memory code protection is enabled MCLRE: RA3/MCLR pin function select bit(4) 1 = RA3/MCLR pin function is MCLR 0 = RA3/MCLR pin function is digital input, MCLR internally tied to VDD PWRTE: Power-up Timer Enable bit 1 = PWRT disabled 0 = PWRT enabled WDTE: Watchdog Timer Enable bit 1 = WDT enabled 0 = WDT disabled and can be enabled by SWDTEN bit (WDTCON<0>) FOSC<2:0>: Oscillator Selection bits 111 = RC oscillator: CLKOUT function on RA4/OSC2/CLKOUT pin, RC on RA5/OSC1/CLKIN 110 = RCIO oscillator: I/O function on RA4/OSC2/CLKOUT pin, RC on RA5/OSC1/CLKIN 101 = INTOSC oscillator: CLKOUT function on RA4/OSC2/CLKOUT pin, I/O function on RA5/OSC1/CLKIN 100 = INTOSCIO oscillator: I/O function on RA4/OSC2/CLKOUT pin, I/O function on RA5/OSC1/CLKIN 011 = EC: I/O function on RA4/OSC2/CLKOUT pin, CLKIN on RA5/OSC1/CLKIN 010 = HS oscillator: High-speed crystal/resonator on RA4/OSC2/CLKOUT and RA5/OSC1/CLKIN 001 = XT oscillator: Crystal/resonator on RA4/OSC2/CLKOUT and RA5/OSC1/CLKIN 000 = LP oscillator: Low-power crystal on RA4/OSC2/CLKOUT and RA5/OSC1/CLKIN Note 1: 2: 3: 4: 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 Enabling Brown-out Detect does not automatically enable Power-up Timer. The entire data EEPROM will be erased when the code protection is turned off. The entire program memory will be erased when the code protection is turned off. When MCLR is asserted in INTOSC or RC mode, the internal clock oscillator is disabled.
bit 10
bit 9-8
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
DS41203B-page 100
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.2 Calibration Bits
Note: Address 2008h is beyond the user program memory space. It belongs to the special configuration memory space (2000h3FFFh), which can be accessed only during programming. See "PIC12F6XX/16F6XX Memory Programming Specification" (DS41204) for more information. The Brown-out Detect (BOD), Power-on Reset (POR) and 8 MHz internal oscillator (HFINTOSC) are factory calibrated. These calibration values are stored in the Calibration Word, as shown in Register 11-2 and are mapped in program memory location 2008h. The Calibration Word is not erased when the device is erased when using the procedure described in the "PIC12F6XX/16F6XX Memory Programming Specification" (DS41204). Therefore, it is not necessary to store and reprogram these values when the device is erased.
REGISTER 11-2:
-- FCAL6 FCAL5
CALIB - CALIBRATION WORD (ADDRESS: 2008h)
FCAL4 FCAL3 FCAL2 FCAL1 FCAL0 -- POR1 POR0 BOD2 BOD1 BOD0
bit 13
bit 13 bit 12-6 Unimplemented: Read as `0' FCAL<6:0>: Internal Oscillator Calibration bits 0111111 = Maximum frequency . . 0000001 0000000 = Center frequency 1111111 . . 1000000 = Minimum frequency Unimplemented: Read as `0' POR<1:0>: POR Calibration bits 00 = Lowest POR voltage 11 = Highest POR voltage BOD<2:0>: BOD Calibration bits 000 = Reserved 001 = Lowest BOD voltage 111 = Highest BOD voltage Note 1: 2:
bit 0
bit 5 bit 4-3
bit 2-0
This location does not participate in bulk erase operations if the "PIC12F6XX/16F6XX Memory Programming Specification" (DS41204) procedure is used. Calibration bits are reserved for factory calibration. These values can and will change across the entire range; therefore, specific values and available adjustment range can not be specified.
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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 101
PIC16F688
11.3 Reset
The PIC16F688 differentiates between various kinds of Reset: a) b) c) d) e) f) Power-on Reset (POR) WDT Reset during normal operation WDT Reset during Sleep MCLR Reset during normal operation MCLR Reset during Sleep Brown-out Detect (BOD) They are not affected by a WDT wake-up since this is viewed as the resumption of normal operation. TO and PD bits are set or cleared differently in different Reset situations, as indicated in Table 11-2. These bits are used in software to determine the nature of the Reset. See Table 11-4 for a full description of Reset states of all registers. A simplified block diagram of the On-Chip Reset Circuit is shown in Figure 11-1. The MCLR Reset path has a noise filter to detect and ignore small pulses. See Section 14.0 "Electrical Specifications" for pulse width specifications.
Some registers are not affected in any Reset condition; their status is unknown on POR and unchanged in any other Reset. Most other registers are reset to a "Reset state" on: * * * * * Power-on Reset MCLR Reset MCLR Reset during Sleep WDT Reset Brown-out Detect (BOD)
FIGURE 11-1:
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
External Reset
MCLR/VPP pin SLEEP WDT Module VDD Rise Detect VDD Brown-out(1) Detect Power-on Reset BODEN SBODEN WDT Time-out Reset
S
OST/PWRT OST 10-bit Ripple Counter OSC1/ CLKI pin PWRT LFINTOSC 11-bit Ripple Counter R Q Chip_Reset
Enable PWRT Enable OST
Note
1:
Refer to the Configuration Word register (Register 11-1).
DS41203B-page 102
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.4 Power-On Reset
FIGURE 11-2:
VDD PIC16F688 R1 1 k (or greater) MCLR C1 0.1 F (optional, not critical)
The on-chip POR circuit holds the chip in Reset until VDD has reached a high enough level for proper operation. To take advantage of the POR, simply connect the MCLR pin through a resistor to VDD. This will eliminate external RC components usually needed to create Power-on Reset. A maximum rise time for VDD is required. See Section 14.0 "Electrical Specifications" for details. If the BOD is enabled, the maximum rise time specification does not apply. The BOD circuitry will keep the device in Reset until VDD reaches VBOD (see Section 11.4.4 "Brown-Out Detect (BOD)"). Note: The POR circuit does not produce an internal Reset when VDD declines. To re-enable the POR, VDD must reach Vss for a minimum of 100 s.
RECOMMENDED MCLR CIRCUIT
11.4.2
POWER-ON RESET (POR)
When the device starts normal operation (exits the Reset condition), device operating parameters (i.e., 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. For additional information, refer to Application Note AN607, "Power-up Trouble Shooting" (DS00607).
11.4.1
MCLR
The on-chip POR circuit holds the chip in Reset until VDD has reached a high enough level for proper operation. To take advantage of the POR, simply connect the MCLR pin through a resistor to VDD. This will eliminate external RC components usually needed to create Power-on Reset. A maximum rise time for VDD is required. See Section 14.0 "Electrical Specifications" for details. If the BOD is enabled, the maximum rise time specification does not apply. The BOD circuitry will keep the device in Reset until VDD reaches VBOD (see Section 11.4.4 "Brown-Out Detect (BOD)"). Note: The POR circuit does not produce an internal Reset when VDD declines. To re-enable the POR, VDD must reach Vss for a minimum of 100 s.
PIC16F688 has a noise filter in the MCLR Reset path. The filter will detect and ignore small pulses. It should be noted that a WDT Reset does not drive MCLR pin low. The behavior of the ESD protection on the MCLR pin has been altered from early devices of this family. Voltages applied to the pin that exceed its specification can result in both MCLR Resets and excessive current beyond the device specification during the ESD event. For this reason, Microchip recommends that the MCLR pin no longer be tied directly to VDD. The use of an RC network, as shown in Figure 11-2, is suggested. An internal MCLR option is enabled by clearing the MCLRE bit in the Configuration Word register. When cleared, MCLR is internally tied to VDD and an internal weak pull-up is enabled for the MCLR pin. In-Circuit Serial Programming is not affected by selecting the internal MCLR option.
When the device starts normal operation (exits the Reset condition), device operating parameters (i.e., 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. For additional information, refer to Application Note AN607, "Power-up Trouble Shooting" (DS00607).
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 103
PIC16F688
11.4.3 POWER-UP TIMER (PWRT)
The Power-up Timer provides a fixed 64 ms (nominal) time-out on power-up only, from POR or Brown-out Detect. The Power-up Timer operates from the 31 kHz LFINTOSC oscillator. For more information, see Section 3.4 "Internal Clock Modes". The chip is kept in Reset as long as PWRT is active. The PWRT delay allows the VDD to rise to an acceptable level. A configuration bit, PWRTE, can disable (if set) or enable (if cleared or programmed) the Power-up Timer. The Power-up Timer should be enabled when Brown-out Detect is enabled, although it is not required. The Power-up Timer delay will vary from chip-to-chip and vary due to: * VDD variation * Temperature variation * Process variation See DC parameters for details "Electrical Specifications"). (Section 14.0 If VDD falls below VBOD for greater than parameter (TBOD) (see Section 14.0 "Electrical Specifications"), the Brown-out situation will reset the device. This will occur regardless of VDD slew rate. A Reset is not insured to occur if VDD falls below VBOD for less than parameter (TBOD). On any Reset (Power-on, Brown-out Detect, Watchdog Timer, etc.), the chip will remain in Reset until VDD rises above VBOD (see Figure 11-3). The Power-up Timer will now be invoked, if enabled and will keep the chip in Reset an additional 64 ms. Note: The Power-up Timer is enabled by the PWRTE bit in the Configuration Word.
If VDD drops below VBOD while the Power-up Timer is running, the chip will go back into a Brown-out Detect and the Power-up Timer will be re-initialized. Once VDD rises above VBOD, the Power-up Timer will execute a 64 ms Reset.
11.4.5
BOD CALIBRATION
11.4.4
BROWN-OUT DETECT (BOD)
The BODEN0 and BODEN1 bits in the Configuration Word register selects one of four BOD modes. Two modes have been added to allow software or hardware control of the BOD enable. When BODEN<1:0> = 01, the SBODEN bit (PCON<4>) enables/disables the BOD allowing it to be controlled in software. By selecting BODEN<1:0>, the BOD is automatically disabled in Sleep to conserve power and enabled on wake-up. In this mode, the SBODEN bit is disabled. See Register 11-1 for the configuration word definition.
The PIC16F688 stores the BOD calibration values in fuses located in the Calibration Word (2008h). The Calibration Word is not erased when using the specified bulk erase sequence in the PIC12F6XX/16F6XX Memory Programming Specification (DS41204) and thus, does not require reprogramming. Note: Address 2008h is beyond the user program memory space. It belongs to the special configuration memory space (2000h3FFFh), which can be accessed only during programming. See PIC12F6XX/16F6XX Memory Programming Specification (DS41204) for more information.
FIGURE 11-3:
VDD
BROWN-OUT SITUATIONS
VBOD
Internal Reset VDD
64 ms(1)
VBOD < 64 ms
Internal Reset
64 ms(1)
VDD
VBOD
Internal Reset Note 1: 64 ms delay only if PWRTE bit is programmed to `0'.
64 ms(1)
DS41203B-page 104
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.4.6 TIME-OUT SEQUENCE 11.4.7
On power-up, the time-out sequence is as follows: first, PWRT time-out is invoked after POR has expired, then OST is activated after the PWRT time-out has expired. The total time-out will vary based on oscillator configuration and PWRTE bit status. For example, in EC mode with PWRTE bit erased (PWRT disabled), there will be no time-out at all. Figure 11.4, Figure 11-5 and Figure 11-6 depict time-out sequences. The device can execute code from the INTOSC while OST is active by enabling Two-Speed Start-up or Fail-Safe Monitor (see Section 3.6.2 "Two-Speed Start-up Sequence" and Section 3.7 "Fail-Safe Clock Monitor"). Since the time-outs occur from the POR pulse, if MCLR is kept low long enough, the time-outs will expire. Then, bringing MCLR high will begin execution immediately (see Figure 11-5). This is useful for testing purposes or to synchronize more than one PIC16F688 device operating in parallel. Table 11-5 shows the Reset conditions for some special registers, while Table 11-4 shows the Reset conditions for all the registers.
POWER CONTROL (PCON) REGISTER
The Power Control (PCON) register (address 8Eh) has two status bits to indicate what type of Reset that last occurred. Bit 0 is BOD (Brown-out). BOD is unknown on Poweron Reset. It must then be set by the user and checked on subsequent Resets to see if BOD = 0, indicating that a Brown-out has occurred. The BOD status bit is a "don't care" and is not necessarily predictable if the brown-out circuit is disabled (BODEN<1:0> = 00 in the Configuration Word register). Bit 1 is POR (Power-on Reset). It is a `0' on Power-on Reset and unaffected otherwise. The user must write a `1' to this bit following a Power-on Reset. On a subsequent Reset, if POR is `0', it will indicate that a Power-on Reset has occurred (i.e., VDD may have gone too low). For more information, see Section 4.2.3 "Ultra LowPower Wake-up" and Section 11.4.4 "Brown-Out Detect (BOD)".
TABLE 11-1:
TIME-OUT IN VARIOUS SITUATIONS
Power-up Brown-out Detect PWRTE = 0 TPWRT + 1024 * TOSC TPWRT PWRTE = 1 1024 * TOSC -- Wake-up from Sleep 1024 * TOSC --
Oscillator Configuration PWRTE = 0 XT, HS, LP RC, EC, INTOSC TPWRT + 1024 * TOSC TPWRT PWRTE = 1 1024 * TOSC --
TABLE 11-2:
POR 0 1 u u u u
PCON BITS AND THEIR SIGNIFICANCE
TO 1 1 0 0 u 1 PD 1 1 u 0 u 0 Power-on Reset Brown-out Detect WDT Reset WDT Wake-up MCLR Reset during normal operation MCLR Reset during Sleep Condition
BOD u 0 u u u u
Legend: u = unchanged, x = unknown
TABLE 11-3:
Address 03h 8Eh Legend: Note 1: Name
SUMMARY OF REGISTERS ASSOCIATED WITH BROWN-OUT
Bit 7 IRP -- Bit 6 RP1 -- Bit 5 RPO Bit 4 TO Bit 3 PD -- Bit 2 Z -- Bit 1 DC POR Bit 0 C BOD Value on POR, BOD 0001 1xxx --01 --qq Value on all other Resets(1) 000q quuu --0u --uu
STATUS PCON
ULPWUE SBODEN
u = unchanged, x = unknown, -- = unimplemented bit, reads as `0', q = value depends on condition. Shaded cells are not used by BOD. Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 105
PIC16F688
FIGURE 11-4: TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR)
VDD MCLR Internal POR TPWRT PWRT Time-out
TOST
OST Time-out
Internal Reset
FIGURE 11-5:
TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR)
VDD MCLR Internal POR TPWRT PWRT Time-out
TOST
OST Time-out
Internal Reset
FIGURE 11-6:
VDD MCLR Internal POR
TIME-OUT SEQUENCE ON POWER-UP (MCLR WITH VDD)
TPWRT PWRT Time-out
TOST
OST Time-out
Internal Reset
DS41203B-page 106
Preliminary
2004 Microchip Technology Inc.
PIC16F688
TABLE 11-4:
Register
INITIALIZATION CONDITION FOR REGISTERS
Address Power-on Reset xxxx xxxx xxxx xxxx xxxx xxxx 0000 0000 0001 1xxx xxxx xxxx --xx xx00 --xx xx00 ---0 0000 0000 0000 0000 0000 xxxx xxxx xxxx xxxx 0000 0000 01-0 0-00 -000 0000 0000 0000 0000 0000 0000 0000 0000 0010 000x 000x ---0 1000 0000 0000 ---- --10 xxxx xxxx 00-0 0000 1111 1111 --11 1111 --11 1111 0000 0000 --01 --0x MCLR Reset WDT Reset Brown-out Detect(1) uuuu uuuu xxxx xxxx uuuu uuuu 0000 0000 000q quuu(4) uuuu uuuu --00 0000 --00 0000 ---0 0000 0000 0000 0000 0000 uuuu uuuu uuuu uuuu uuuu uuuu 01-0 0-00 -000 0000 0000 0000 0000 0000 0000 0000 0000 0010 000x 000x ---0 1000 0000 0000 ---- --10 uuuu uuuu 00-0 0000 1111 1111 --11 1111 --11 1111 0000 0000 --0u --uu(1,5) Wake-up from Sleep through Interrupt Wake-up from Sleep through WDT Time-out uuuu uuuu uuuu uuuu uuuu uuuu PC + 1(3) uuuq quuu(4) uuuu uuuu --uu uuuu --uu uuuu ---u uuuu uuuu uuuu(2) uuuu uuuu(2) uuuu uuuu uuuu uuuu -uuu uuuu uu-u u-uu -uuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu uuuu ---u uuuu uuuu uuuu ---- --uu uuuu uuuu uu-u uuuu uuuu uuuu --uu uuuu --uu uuuu uuuu uuuu --uu --uu
W INDF TMR0 PCL STATUS FSR PORTA PORTC PCLATH INTCON PIR1 TMR1L TMR1H T1CON BAUDCTL SPBRGH SPBRG RCREG TXREG TXSTA RCSTA WDTCON CMCON0 CMCON1 ADRESH ADCON0 OPTION_REG TRISA TRISC PIE1 PCON Legend: Note 1: 2: 3: 4: 5:
-- 00h/80h/100h/180h 01h/101h 02h/82h/102h/182h 03h/83h/103h/183h 04h/84h/104h/184h 05h/105h 07h/107h 0Ah/8Ah/10Ah/18Ah 0Bh/8Bh/10Bh/18Bh 0Ch 0Eh 0Fh 10h 11h 12h 13h 14h 15h 16h 17h 18h 19h 1Ah 1Eh 1Fh 81h/181h 85h/185h 87h/187h 8Ch 8Eh
u = unchanged, x = unknown, -- = unimplemented bit, reads as `0', q = value depends on condition. If VDD goes too low, Power-on Reset will be activated and registers will be affected differently. One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector (0004h). See Table 11-5 for Reset value for specific condition. If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 107
PIC16F688
TABLE 11-4:
Register
INITIALIZATION CONDITION FOR REGISTERS (CONTINUED)
Address Power-on Reset -110 x000 ---0 0000 1111 1111 --11 -111 --00 0000 --00 0000 ---- 0000 0-0- 0000 0000 0000 0000 0000 x--- x000 ---- ---xxxx xxxx -000 ---* MCLR Reset * WDT Reset * Brown-out Detect(1) -110 x000 ---u uuuu 1111 1111 --11 -111 --00 0000 0000 0000 0000 0000 0-0- 0000 0000 0000 0000 0000 u--- q000 ---- ---uuuu uuuu -000 ---* Wake-up from Sleep through interrupt * Wake-up from Sleep through WDT time-out -uuu uuuu ---u uuuu uuuu uuuu uuuu uuuu --uu uuuu uuuu uuuu uuuu uuuu u-u- uuuu uuuu uuuu uuuu uuuu u--- uuuu ---- ---uuuu uuuu -uuu ----
OSCCON OSCTUNE ANSEL WPUA IOCA EEDATH EEADRH VRCON EEDAT EEADR EECON1 EECON2 ADRESL ADCON1 Legend: Note 1: 2: 3: 4: 5:
8Fh 90h 91h 95h 96h 97h 98h 99h 9Ah 9Bh 9Ch 9Dh 9Eh 9Fh
u = unchanged, x = unknown, -- = unimplemented bit, reads as `0', q = value depends on condition. If VDD goes too low, Power-on Reset will be activated and registers will be affected differently. One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector (0004h). See Table 11-5 for Reset value for specific condition. If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u.
TABLE 11-5:
INITIALIZATION CONDITION FOR SPECIAL REGISTERS
Condition Program Counter 000h 000h 000h 000h PC + 1 000h PC + 1
(1)
Status Register 0001 1xxx 000u uuuu 0001 0uuu 0000 uuuu uuu0 0uuu 0001 1uuu uuu1 0uuu
PCON Register --01 --0x --0u --uu --0u --uu --0u --uu --uu --uu --01 --10 --uu --uu
Power-on Reset MCLR Reset during normal operation MCLR Reset during Sleep WDT Reset WDT Wake-up Brown-out Detect Interrupt Wake-up from Sleep
Legend: u = unchanged, x = unknown, -- = unimplemented bit, reads as `0'. Note 1: When the wake-up is due to an interrupt and Global Interrupt Enable bit, GIE, is set, the PC is loaded with the interrupt vector (0004h) after execution of PC + 1.
DS41203B-page 108
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.5
* * * * * * * *
Interrupts
The PIC16F688 has 11 sources of interrupt: External Interrupt RA2/INT TMR0 Overflow Interrupt PORTA Change Interrupts 2 Comparator Interrupts A/D Interrupt Timer1 Overflow Interrupt EEPROM Data Write Interrupt Fail-Safe Clock Monitor Interrupt
For external interrupt events, such as the INT pin or PORTA change interrupt, the interrupt latency will be three or four instruction cycles. The exact latency depends upon when the interrupt event occurs (see Figure 11-8). The latency is the same for one or twocycle instructions. Once in the Interrupt Service Routine, the source(s) of the interrupt can be determined by polling the interrupt flag bits. The interrupt flag bit(s) must be cleared in software before re-enabling interrupts to avoid multiple interrupt requests. Note 1: Individual interrupt flag bits are set, regardless of the status of their corresponding mask bit or the GIE bit. 2: When an instruction that clears the GIE bit is executed, any interrupts that were pending for execution in the next cycle are ignored. The interrupts, which were ignored, are still pending to be serviced when the GIE bit is set again. For additional information on Timer1, A/D or data EEPROM modules, refer to the respective peripheral section.
The Interrupt Control (INTCON) register and Peripheral Interrupt Request 1 (PIR1) register record individual interrupt requests in flag bits. The INTCON register also has individual and global interrupt enable bits. A Global Interrupt Enable bit, GIE (INTCON<7>), enables (if set) all unmasked interrupts, or disables (if cleared) all interrupts. Individual interrupts can be disabled through their corresponding enable bits in the INTCON register and PIE1 register. GIE is cleared on Reset. The Return from Interrupt instruction, RETFIE, exits the interrupt routine, as well as sets the GIE bit, which re-enables unmasked interrupts. The following interrupt flags are contained in the INTCON register: * INT Pin Interrupt * PORTA Change Interrupt * TMR0 Overflow Interrupt The peripheral interrupt flags are contained in the special register, PIR1. The corresponding interrupt enable bit is contained in special register, PIE1. The following interrupt flags are contained in the PIR1 register: * * * * * EEPROM Data Write Interrupt A/D Interrupt 2 Comparator Interrupts Timer1 Overflow Interrupt Fail-Safe Clock Monitor Interrupt
When an interrupt is serviced: * The GIE is cleared to disable any further interrupt. * The return address is pushed onto the stack. * The PC is loaded with 0004h.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 109
PIC16F688
11.5.1 RA2/INT INTERRUPT 11.5.2 TMR0 INTERRUPT
External interrupt on RA2/INT pin is edge-triggered; either rising if the INTEDG bit (OPTION<6>) is set, or falling, if the INTEDG bit is clear. When a valid edge appears on the RA2/INT pin, the INTF bit (INTCON<1>) is set. This interrupt can be disabled by clearing the INTE control bit (INTCON<4>). The INTF bit must be cleared in software in the Interrupt Service Routine before re-enabling this interrupt. The RA2/INT interrupt can wake-up the processor from Sleep if the INTE bit was set prior to going into Sleep. The status of the GIE bit decides whether or not the processor branches to the interrupt vector following wake-up (0004h). See Section 11.8 "Power-Down Mode (Sleep)" for details on Sleep and Figure 11-10 for timing of wake-up from Sleep through RA2/INT interrupt. Note: The ANSEL (91h) and CMCON0 (19h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read `0'. An overflow (FFh 00h) in the TMR0 register will set the T0IF (INTCON<2>) bit. The interrupt can be enabled/disabled by setting/clearing T0IE (INTCON<5>) bit. See Section 5.0 "Timer0 Module" for operation of the Timer0 module.
11.5.3
PORTA INTERRUPT
An input change on PORTA change sets the RAIF (INTCON<0>) bit. The interrupt can be enabled/ disabled by setting/clearing the RAIE (INTCON<3>) bit. Plus, individual pins can be configured through the IOCA register. Note: If a change on the I/O pin should occur when the read operation is being executed (start of the Q2 cycle), then the RAIF interrupt flag may not get set.
FIGURE 11-7:
INTERRUPT LOGIC
IOC-RA0 IOCA0 IOC-RA1 IOCA1 IOC-RA2 IOCA2 IOC-RA3 IOCA3 IOC-RA4 IOCA4 IOC-RA5 IOCA5 TXIF TXIE TMR1IF TMR1IE C1IF C1IE C2IF C2IE ADIF ADIE EEIF EEIE OSFIF OSFIE RCIF RCIE T0IF T0IE INTF INTE RAIF RAIE PEIE GIE Wake-up (If in Sleep mode)
Interrupt to CPU
DS41203B-page 110
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 11-8:
Q1 OSC1 CLKOUT (3)
(4)
INT PIN INTERRUPT TIMING
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
INT pin INTF Flag (INTCON<1>) GIE bit (INTCON<7>) Instruction Flow PC Instruction Fetched Instruction Executed Note 1: 2: 3: 4: 5:
(1) (5)
(1)
Interrupt Latency (2)
PC Inst (PC) Inst (PC - 1)
PC + 1 Inst (PC + 1) Inst (PC)
PC + 1 -- Dummy Cycle
0004h Inst (0004h) Dummy Cycle
0005h Inst (0005h) Inst (0004h)
INTF flag is sampled here (every Q1). Asynchronous interrupt latency = 3-4 TCY. Synchronous latency = 3 TCY, where TCY = instruction cycle time. Latency is the same whether Inst (PC) is a single cycle or a 2-cycle instruction. CLKOUT is available only in INTOSC and RC Oscillator modes. For minimum width of INT pulse, refer to AC specifications in Section 14.0 "Electrical Specifications". INTF is enabled to be set any time during the Q4-Q1 cycles.
TABLE 11-6:
Address Name
SUMMARY OF INTERRUPT REGISTERS
Bit 7 GIE EEIF EEIE Bit 6 PEIE ADIF ADIE Bit 5 T0IE RCIF RCIE Bit 4 INTE C2IF C2IE Bit 3 RAIE C1IF C1IE Bit 2 T0IF OSFIF OSFIE Bit 1 INTF TXIF TXIE Bit 0 RAIF Value on POR, BOD Value on all other Resets
0Bh, 8Bh INTCON 0Ch 8Ch Legend: PIR1 PIE1
0000 0000 0000 0000
TMR1IF 0000 0000 0000 0000 TMR1IE 0000 0000 0000 0000
x = unknown, u = unchanged, -- = unimplemented read as `0', q = value depends upon condition. Shaded cells are not used by the interrupt module.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 111
PIC16F688
11.6 Context Saving During Interrupts
During an interrupt, only the return PC value is saved on the stack. Typically, users may wish to save key registers during an interrupt (e.g., W and Status registers). This must be implemented in software. Since the lower 16 bytes of all banks are common in the PIC16F688 (see Figure 2-2), temporary holding registers, W_TEMP and STATUS_TEMP, should be placed in here. These 16 locations do not require banking and therefore, make it easier to context save and restore. The same code shown in Example 11-1 can be used to: * * * * * Store the W register Store the Status register Execute the ISR code Restore the Status (and Bank Select Bit register) Restore the W register
Note:
The PIC16F688 normally does not require saving the PCLATH. However, if computed GOTO's are used in the ISR and the main code, the PCLATH must be saved and restored in the ISR.
EXAMPLE 11-1:
MOVWF SWAPF CLRF MOVWF : :(ISR) : SWAPF MOVWF SWAPF SWAPF
SAVING STATUS AND W REGISTERS IN RAM
;Copy ;Swap ;bank ;Save W to TEMP register status to be saved into W 0, regardless of current bank, Clears IRP,RP1,RP0 status to bank zero STATUS_TEMP register
W_TEMP STATUS,W STATUS STATUS_TEMP
;Insert user code here STATUS_TEMP,W STATUS W_TEMP,F W_TEMP,W ;Swap STATUS_TEMP register into W ;(sets bank to original state) ;Move W into Status register ;Swap W_TEMP ;Swap W_TEMP into W
DS41203B-page 112
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.7 Watchdog Timer (WDT)
For PIC16F688, the WDT has been modified from previous 16F devices. The new WDT is code and functionally compatible with previous 16F WDT modules and adds a 16-bit prescaler to the WDT. This allows the user to have a scaler value for the WDT and TMR0 at the same time. In addition, the WDT time-out value can be extended to 268 seconds. WDT is cleared under certain conditions described in Table 11-7. A new prescaler has been added to the path between the INTRC and the multiplexers used to select the path for the WDT. This prescaler is 16 bits and can be programmed to divide the INTRC by 32 to 65536, giving the WDT a nominal range of 1 ms to 268s.
11.7.2
WDT CONTROL
The WDTE bit is located in the Configuration Word register. When set, the WDT runs continuously. When the WDTE bit in the Configuration Word register is set, the SWDTEN bit (WDTCON<0>) has no effect. If WDTE is clear, then the SWDTEN bit can be used to enable and disable the WDT. Setting the bit will enable it and clearing the bit will disable it. The PSA and PS<2:0> bits (OPTION_REG) have the same function as in previous versions of the 16F family of microcontrollers. See Section 5.0 "Timer0 Module" for more information.
11.7.1
WDT OSCILLATOR
The WDT derives its time base from the 31 kHz LFINTOSC. The LTS bit does not reflect that the LFINTOSC is enabled. The value of WDTCON is `---0 1000' on all Resets. This gives a nominal time base of 16 ms, which is compatible with the time base generated with previous 16F microcontroller versions. Note: When the Oscillator Start-up Timer (OST) is invoked, the WDT is held in Reset, because the WDT Ripple Counter is used by the OST to perform the oscillator delay count. When the OST count has expired, the WDT will begin counting (if enabled).
FIGURE 11-9:
WATCHDOG TIMER BLOCK DIAGRAM
From TMR0 Clock Source 0 Prescaler(1) 16-bit WDT Prescaler 1 8 PSA
PS<2:0> To TMR0 0 1 PSA
31 kHz LFINTOSC Clock
WDTPS<3:0>
WDTE from Configuration Word Register SWDTEN from WDTCON WDT Time-out
Note 1: This is the shared Timer0/WDT prescaler. See Section 5.4 "Prescaler" for more information.
TABLE 11-7:
WDT STATUS
Conditions WDT
WDTE = 0 CLRWDT Command Oscillator Fail Detected Exit Sleep + System Clock = T1OSC, EXTRC, INTRC, EXTCLK Exit Sleep + System Clock = XT, HS, LP
Cleared
Cleared until the end of OST
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 113
PIC16F688
REGISTER 11-3: WDTCON - WATCHDOG TIMER CONTROL REGISTER (ADDRESS: 18h)
U-0 -- bit 7 bit 7-5 bit 4-1 Unimplemented: Read as `0' WDTPS<3:0>: Watchdog Timer Period Select bits Bit Value = Prescale Rate 0000 = 1:32 0001 = 1:64 0010 = 1:128 0011 = 1:256 0100 = 1:512 (Reset value) 0101 = 1:1024 0110 = 1:2048 0111 = 1:4096 1000 = 1:8192 1001 = 1:16384 1010 = 1:32768 1011 = 1:65536 1100 = reserved 1101 = reserved 1110 = reserved 1111 = reserved SWDTEN: Software Enable or Disable the Watchdog Timer(1) 1 = WDT is turned on 0 = WDT is turned off (Reset value) Note 1: If WDTE configuration bit = 1, then WDT is always enabled, irrespective of this control bit. If WDTE configuration bit = 0, then it is possible to turn WDT on/off with this control 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 U-0 -- U-0 -- R/W-0 WDTPS3 R/W-1 WDTPS2 R/W-0 WDTPS1 R/W-0 WDTPS0 R/W-0 SWDTEN bit 0
bit 0
TABLE 11-8:
Address 18h 81h 2007h(1)
SUMMARY OF WATCHDOG TIMER REGISTERS
Name Bit 7 -- RAPU CPD Bit 6 -- INTEDG CP Bit 5 -- T0CS MCLRE Bit 4 T0SE PWRTE Bit 3 PSA WDTE Bit 2 PS2 FOSC2 Bit 1 PS1 FOSC1 Bit 0 PS0 FOSC0 WDTPS3 WDTPS2 WSTPS1 WDTPS0 SWDTEN
WDTCON OPTION_REG CONFIG
Legend: Shaded cells are not used by the Watchdog Timer. Note 1: See Register 11-1 for operation of all Configuration Word register bits.
DS41203B-page 114
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.8 Power-Down Mode (Sleep)
The Power-down mode is entered by executing a SLEEP instruction. If the Watchdog Timer is enabled: * * * * * WDT will be cleared but keeps running. PD bit in the Status register is cleared. TO bit is set. Oscillator driver is turned off. I/O ports maintain the status they had before SLEEP was executed (driving high, low or highimpedance). Other peripherals cannot generate interrupts since during Sleep, no on-chip clocks are present. When the SLEEP instruction is being executed, the next instruction (PC + 1) is prefetched. For the device to wake-up through an interrupt event, the corresponding interrupt enable bit must be set (enabled). Wake-up is regardless of the state of the GIE bit. If the GIE bit is clear (disabled), the device continues execution at the instruction after the SLEEP instruction. If the GIE bit is set (enabled), the device executes the instruction after the SLEEP instruction, then branches to the interrupt address (0004h). In cases where the execution of the instruction following SLEEP is not desirable, the user should have a NOP after the SLEEP instruction. Note: If the global interrupts are disabled (GIE is cleared), but any interrupt source has both its interrupt enable bit and the corresponding interrupt flag bits set, the device will immediately wake-up from Sleep. The SLEEP instruction is completely executed.
For lowest current consumption in this mode, all I/O pins should be either at VDD or VSS, with no external circuitry drawing current from the I/O pin, and the comparators and CVREF should be disabled. I/O pins that are high-impedance inputs should be pulled high or low externally to avoid switching currents caused by floating inputs. The T0CKI input should also be at VDD or VSS for lowest current consumption. The contribution from on-chip pull-ups on PORTA should be considered. The MCLR pin must be at a logic high level. Note: It should be noted that a Reset generated by a WDT time-out does not drive MCLR pin low.
The WDT is cleared when the device wakes up from Sleep, regardless of the source of wake-up.
11.8.2
WAKE-UP USING INTERRUPTS
When global interrupts are disabled (GIE cleared) and any interrupt source has both its interrupt enable bit and interrupt flag bit set, one of the following will occur: * If the interrupt occurs before the execution of a SLEEP instruction, the SLEEP instruction will complete as a NOP. Therefore, the WDT and WDT prescaler and postscaler (if enabled) will not be cleared, the TO bit will not be set and the PD bit will not be cleared. * If the interrupt occurs during or after the execution of a SLEEP instruction, the device will immediately wake-up from Sleep. The SLEEP instruction will be completely executed before the wake-up. Therefore, the WDT and WDT prescaler and postscaler (if enabled) will be cleared, the TO bit will be set and the PD bit will be cleared. Even if the flag bits were checked before executing a SLEEP instruction, it may be possible for flag bits to become set before the SLEEP instruction completes. To determine whether a SLEEP instruction executed, test the PD bit. If the PD bit is set, the SLEEP instruction was executed as a NOP. To ensure that the WDT is cleared, a CLRWDT instruction should be executed before a SLEEP instruction.
11.8.1
WAKE-UP FROM SLEEP
The device can wake-up from Sleep through one of the following events: 1. 2. 3. External Reset input on MCLR pin. Watchdog Timer wake-up (if WDT was enabled). Interrupt from RA2/INT pin, PORTA change or a peripheral interrupt.
The first event will cause a device Reset. The two latter events are considered a continuation of program execution. The TO and PD bits in the Status register can be used to determine the cause of device Reset. The PD bit, which is set on power-up, is cleared when Sleep is invoked. TO bit is cleared if WDT wake-up occurred. The following peripheral interrupts can wake the device from Sleep: 1. 2. 3. 4. 5. 6. 7. 8. TMR1 Interrupt. Timer1 must be operating as an asynchronous counter. EUSART Receive Interrupt. ULPWU Interrupt. A/D conversion (when A/D clock source is RC). EEPROM write operation completion. Comparator output changes state. Interrupt-on-change. External Interrupt from INT pin.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 115
PIC16F688
FIGURE 11-10: WAKE-UP FROM SLEEP THROUGH INTERRUPT
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 TOST(2) Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 OSC1 CLKOUT(4) INT pin INTF flag (INTCON<1>) GIE bit (INTCON<7>) Instruction Flow PC Instruction Fetched Instruction Executed Note 1: 2: 3: 4: Processor in Sleep Interrupt Latency (3)
PC Inst(PC) = Sleep Inst(PC - 1)
PC+1 Inst(PC + 1) Sleep
PC+2
PC+2 Inst(PC + 2) Inst(PC + 1)
PC + 2
0004h Inst(0004h)
0005h Inst(0005h) Inst(0004h)
Dummy Cycle
Dummy Cycle
XT, HS or LP Oscillator mode assumed. TOST = 1024 TOSC (drawing not to scale). This delay does not apply to EC and RC Oscillator modes. GIE = 1 assumed. In this case after wake-up, the processor jumps to 0004h. If GIE = 0, execution will continue in-line. CLKOUT is not available in XT, HS, LP or EC Oscillator modes, but shown here for timing reference.
DS41203B-page 116
Preliminary
2004 Microchip Technology Inc.
PIC16F688
11.9 Code Protection
FIGURE 11-11:
If the code protection bit(s) have not been programmed, the on-chip program memory can be read out using ICSP for verification purposes. Note: The entire data EEPROM and Flash program memory will be erased when the code protection is turned off. See the "PIC12F6XX/16F6XX Memory Programming Specification" (DS41204) for more information.
External Connector Signals +5V 0V VPP
TYPICAL IN-CIRCUIT SERIAL PROGRAMMING CONNECTION
To Normal Connections
*
PIC16F688 VDD VSS MCLR/VPP/RA3 RA1 RA0
11.10 ID Locations
Four memory locations (2000h-2003h) are designated as ID locations where the user can store checksum or other code identification numbers. These locations are not accessible during normal execution but are readable and writable during Program/Verify mode. Only the Least Significant 7 bits of the ID locations are used.
CLK Data I/O
*
*
*
11.11 In-Circuit Serial Programming
The PIC16F688 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 * 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. The device is placed into a Program/Verify mode by holding the RA0 and RA1 pins low, while raising the MCLR (VPP) pin from VIL to VIHH. See the "PIC12F6XX/ 16F6XX Memory Programming Specification" (DS41204) for more information. RA0 becomes the programming data and RA1 becomes the programming clock. Both RA0 and RA1 are Schmitt Trigger inputs in this mode. After Reset, to place the device into Program/Verify mode, the Program Counter (PC) is at location 00h. A 6-bit command is then supplied to the device. Depending on the command, 14 bits of program data are then supplied to or from the device, depending on whether the command was a load or a read. For complete details of serial programming, please refer to the "PIC12F6XX/16F6XX Memory Programming Specification" (DS41204). A typical In-Circuit Serial Programming connection is shown in Figure 11-11.
To Normal Connections * Isolation devices (as required)
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 117
PIC16F688
11.12 In-Circuit Debugger
Since in-circuit debugging requires access to the data and MCLR pins, MPLAB(R) ICD 2 development with an 14-pin device is not practical. A special 20-pin PIC16F688 ICD device is used with MPLAB ICD 2 to provide separate clock, data and MCLR pins and frees all normally available pins to the user. A special debugging adapter allows the ICD device to be used in place of a PIC16F688 device. The debugging adapter is the only source of the ICD device. When the ICD pin on the PIC16F688 ICD device is held low, the In-Circuit Debugger functionality is enabled. This function allows simple debugging functions when used with MPLAB ICD 2. When the microcontroller has this feature enabled, some of the resources are not available for general use. Table 11-9 shows which features are consumed by the background debugger: For more information, see "MPLAB ICD 2 In-Circuit Debugger User's Guide" (DS51292), available on Microchip's web site (www.microchip.com).
FIGURE 11-12:
20-Pin PDIP
20-PIN ICD PINOUT
In-Circuit Debug Device
NC ICDMCLR/VPP VDD RA5 RA4 RA3 RC5 RC4 RC3 ICD
1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11
ICDCLK ICDDATA Vss RA0 RA1 RA2 RC0 RC1 RC2 NC
PIC16F688 -ICD
TABLE 11-9:
Resource I/O pins Stack
DEBUGGER RESOURCES
Description ICDCLK, ICDDATA 1 level Address 0h must be NOP 700h-7FFh
Program Memory
DS41203B-page 118
Preliminary
2004 Microchip Technology Inc.
PIC16F688
12.0 INSTRUCTION SET SUMMARY
The PIC16F688 instruction set is highly orthogonal and is comprised of three basic categories: * Byte-oriented operations * Bit-oriented operations * Literal and control operations Each PIC16 instruction is a 14-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 formats for each of the categories is presented in Figure 12-1, while the various opcode fields are summarized in Table 12-1. Table 12-2 lists the instructions recognized by the MPASMTM assembler. A complete description of each instruction is also available in the "PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023). For byte-oriented instructions, `f' represents a file register designator and `d' represents a destination designator. The file register designator specifies which file register is to be used by the instruction. The destination designator specifies where the result of the operation is to be placed. If `d' is zero, the result is placed in the W register. If `d' is one, the result is placed in the file register specified in the instruction. For bit-oriented instructions, `b' represents a bit field designator, which selects the bit affected by the operation, while `f' represents the address of the file in which the bit is located. For literal and control operations, `k' represents an 8-bit or 11-bit constant, or literal value. One instruction cycle consists of four oscillator periods; for an oscillator frequency of 4 MHz, this gives a normal instruction execution time of 1 s. All instructions are executed within a single instruction cycle, unless a conditional test is true, or the program counter is changed as a result of an instruction. When this occurs, the execution takes two instruction cycles, with the second cycle executed as a NOP. Note: To maintain upward compatibility with future products, do not use the OPTION and TRIS instructions. tion, or the destination designator `d'. A read operation is performed on a register even if the instruction writes to that register. For example, a CLRF GPIO instruction will read GPIO, clear all the data bits, then write the result back to GPIO. This example would have the unintended result of clearing the condition that set the GPIF flag.
TABLE 12-1:
Field
f W b k x
OPCODE FIELD DESCRIPTIONS
Description
Register file address (0x00 to 0x7F) Working register (accumulator) Bit address within an 8-bit file register Literal field, constant data or label Don't care location (= 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. Destination select; d = 0: store result in W, d = 1: store result in file register f. Default is d = 1. Program Counter Time-out bit Power-down bit
d
PC TO PD
FIGURE 12-1:
GENERAL FORMAT FOR INSTRUCTIONS
0
Byte-oriented file register operations 13 876 OPCODE d f (FILE #) d = 0 for destination W d = 1 for destination f f = 7-bit file register address Bit-oriented file register operations 13 10 9 76 OPCODE b (BIT #) f (FILE #) b = 3-bit bit address f = 7-bit file register address Literal and control operations General 13 OPCODE k = 8-bit immediate value CALL and GOTO instructions only 13 11 OPCODE 10 k (literal) 8 7 k (literal)
0
All instruction examples use the format `0xhh' to represent a hexadecimal number, where `h' signifies a hexadecimal digit.
0
12.1
READ-MODIFY-WRITE OPERATIONS
Any instruction that specifies a file register as part of the instruction performs a Read-Modify-Write (R-M-W) operation. The register is read, the data is modified, and the result is stored according to either the instruc-
0
k = 11-bit immediate value
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 119
PIC16F688
TABLE 12-2:
Mnemonic, Operands
PIC16F688 INSTRUCTION SET
14-Bit Opcode Description Cycles MSb BYTE-ORIENTED FILE REGISTER OPERATIONS LSb Status Affected Notes
ADDWF ANDWF CLRF CLRW COMF DECF DECFSZ INCF INCFSZ IORWF MOVF MOVWF NOP RLF RRF SUBWF SWAPF XORWF
f, d f, d f f, d f, d f, d f, d f, d f, d f, d f f, d f, d f, d f, d f, d
Add W and f AND W with f Clear f Clear W Complement f Decrement f Decrement f, Skip if 0 Increment f Increment f, Skip if 0 Inclusive OR W with f Move f Move W to f No Operation Rotate Left f through Carry Rotate Right f through Carry Subtract W from f Swap nibbles in f Exclusive OR W with f
1 1 1 1 1 1 1(2) 1 1(2) 1 1 1 1 1 1 1 1 1
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0111 0101 0001 0001 1001 0011 1011 1010 1111 0100 1000 0000 0000 1101 1100 0010 1110 0110
dfff dfff lfff 0xxx dfff dfff dfff dfff dfff dfff dfff lfff 0xx0 dfff dfff dfff dfff dfff
ffff ffff ffff xxxx ffff ffff ffff ffff ffff ffff ffff ffff 0000 ffff ffff ffff ffff ffff
C,DC,Z Z Z Z Z Z Z Z Z
1,2 1,2 2 1,2 1,2 1,2,3 1,2 1,2,3 1,2 1,2
C C C,DC,Z Z
1,2 1,2 1,2 1,2 1,2
BIT-ORIENTED FILE REGISTER OPERATIONS BCF BSF BTFSC BTFSS f, b f, b f, b f, b k k k k k k k k k Bit Clear f Bit Set f Bit Test f, Skip if Clear Bit Test f, Skip if Set Add literal and W AND literal with W Call subroutine Clear Watchdog Timer Go to address Inclusive OR literal with W Move literal to W Return from interrupt Return with literal in W Return from Subroutine Go into Standby mode Subtract W from literal Exclusive OR literal with W 1 1 1 (2) 1 (2) 1 1 2 1 2 1 1 2 2 2 1 1 1 01 01 01 01 00bb 01bb 10bb 11bb bfff bfff bfff bfff ffff ffff ffff ffff C,DC,Z Z TO,PD Z 1,2 1,2 3 3
LITERAL AND CONTROL OPERATIONS ADDLW ANDLW CALL CLRWDT GOTO IORLW MOVLW RETFIE RETLW RETURN SLEEP SUBLW XORLW Note 1: 11 11 10 00 10 11 11 00 11 00 00 11 11 111x 1001 0kkk 0000 1kkk 1000 00xx 0000 01xx 0000 0000 110x 1010 kkkk kkkk kkkk 0110 kkkk kkkk kkkk 0000 kkkk 0000 0110 kkkk kkkk kkkk kkkk kkkk 0100 kkkk kkkk kkkk 1001 kkkk 1000 0011 kkkk kkkk
TO,PD C,DC,Z Z
2: 3:
When an I/O register is modified as a function of itself (e.g., MOVF GPIO, 1), 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 to the Timer0 module. If Program Counter (PC) is modified, or a conditional test is true, the instruction requires two cycles. The second cycle is executed as a NOP.
Note:
Additional information on the mid-range instruction set is available in the PICmicro(R) Mid-Range MCU Family Reference Manual" (DS33023).
DS41203B-page 120
Preliminary
2004 Microchip Technology Inc.
PIC16F688
12.2
ADDLW Syntax: Operands: Operation: Status Affected: Description:
Instruction Descriptions
Add Literal and W [ label ] ADDLW 0 k 255 (W) + k (W) C, DC, Z The contents of the W register are added to the eight-bit literal `k' and the result is placed in the W register. Operation: Status Affected: Description: k BCF Syntax: Operands: Bit Clear f [ label ] BCF 0 f 127 0b7 0 (f) None Bit `b' in register `f' is cleared. f,b
ADDWF Syntax: Operands: Operation: Status Affected: Description:
Add W and f [ label ] ADDWF 0 f 127 d [0,1] (W) + (f) (destination) C, DC, Z Add the contents of the W register with register `f'. If `d' is `0', the result is stored in the W register. If `d' is `1', the result is stored back in register `f'. f,d
BSF Syntax: Operands: Operation: Status Affected: Description:
Bit Set f [ label ] BSF 0 f 127 0b7 1 (f) None Bit `b' in register `f' is set. f,b
ANDLW Syntax: Operands: Operation: Status Affected: Description:
AND Literal with W [ label ] ANDLW 0 k 255 (W) .AND. (k) (W) Z The contents of W register are AND'ed with the eight-bit literal `k'. The result is placed in the W register. k
BTFSS Syntax: Operands: Operation: Status Affected: Description:
Bit Test f, Skip if Set [ label ] BTFSS f,b 0 f 127 0b<7 skip if (f) = 1 None If bit `b' in register `f' is `0', the next instruction is executed. If bit `b' is `1', then the next instruction is discarded and a NOP is executed instead, making this a 2-cycle instruction.
ANDWF Syntax: Operands: Operation: Status Affected: Description:
AND W with f [ label ] ANDWF 0 f 127 d [0,1] (W) .AND. (f) (destination) Z AND the W register with register `f'. If `d' is `0', the result is stored in the W register. If `d' is `1', the result is stored back in register `f'. f,d
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 121
PIC16F688
BTFSC Syntax: Operands: Operation: Status Affected: Description: Bit Test, Skip if Clear [ label ] BTFSC f,b 0 f 127 0b7 skip if (f) = 0 None If bit `b' in register `f' is `1', the next instruction is executed. If bit `b', in register `f', is `0', the next instruction is discarded, and a NOP is executed instead, making this a 2-cycle instruction. Status Affected: Description: CLRWDT Syntax: Operands: Operation: Clear Watchdog Timer [ label ] CLRWDT None 00h WDT 0 WDT prescaler, 1 TO 1 PD TO, PD CLRWDT instruction resets the Watchdog Timer. It also resets the prescaler of the WDT. Status bits TO and PD are set.
CALL Syntax: Operands: Operation:
Call Subroutine [ label ] CALL k 0 k 2047 (PC)+ 1 TOS, k PC<10:0>, (PCLATH<4:3>) PC<12:11> None Call Subroutine. First, return address (PC + 1) is pushed onto the stack. The eleven-bit immediate address is loaded into PC bits <10:0>. The upper bits of the PC are loaded from PCLATH. CALL is a two-cycle instruction.
COMF Syntax: Operands: Operation: Status Affected: Description:
Complement f [ label ] COMF 0 f 127 d [0,1] (f) (destination) Z 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'. f,d
Status Affected: Description:
CLRF Syntax: Operands: Operation: Status Affected: Description:
Clear f [ label ] CLRF 0 f 127 00h (f) 1Z Z The contents of register `f' are cleared and the Z bit is set. f
DECF Syntax: Operands: Operation: Status Affected: Description:
Decrement f [ label ] DECF f,d 0 f 127 d [0,1] (f) - 1 (destination) Z Decrement register `f'. If `d' is `0', the result is stored in the W register. If `d' is `1', the result is stored back in register `f'.
CLRW Syntax: Operands: Operation: Status Affected: Description:
Clear W [ label ] CLRW None 00h (W) 1Z Z W register is cleared. Zero bit (Z) is set.
DS41203B-page 122
Preliminary
2004 Microchip Technology Inc.
PIC16F688
DECFSZ Syntax: Operands: Operation: Status Affected: Description: Decrement f, Skip if 0 [ label ] DECFSZ f,d 0 f 127 d [0,1] (f) - 1 (destination); skip if result = 0 None The contents of register `f' are decremented. If `d' is `0', the result is placed in the W register. If `d' is `1', the result is placed back in register `f'. If the result is `1', the next instruction is executed. If the result is `0', then a NOP is executed instead, making it a 2-cycle instruction. INCFSZ Syntax: Operands: Operation: Status Affected: Description: Increment f, Skip if 0 [ label ] INCFSZ f,d 0 f 127 d [0,1] (f) + 1 (destination), skip if result = 0 None The contents of register `f' are incremented. If `d' is `0', the result is placed in the W register. If `d' is `1', the result is placed back in register `f'. If the result is `1', the next instruction is executed. If the result is `0', a NOP is executed instead, making it a 2-cycle instruction.
GOTO Syntax: Operands: Operation: Status Affected: Description:
Unconditional Branch [ label ] GOTO k 0 k 2047 k PC<10:0> PCLATH<4:3> PC<12:11> None GOTO is an unconditional branch. The eleven-bit immediate value is loaded into PC bits <10:0>. The upper bits of PC are loaded from PCLATH<4:3>. GOTO is a two-cycle instruction.
MOVF Syntax: Operands: Operation: Status Affected: Encoding: Description:
Move f [ label ] MOVF f,d 0 f 127 d [0,1] (f) (dest) Z
00 1000 dfff ffff
INCF Syntax: Operands: Operation: Status Affected: Description:
Increment f [ label ] INCF f,d Words: Cycles: Example 0 f 127 d [0,1] (f) + 1 (destination) Z The contents of register `f' are incremented. If `d' is `0', the result is placed in the W register. If `d' is `1', the result is placed back in register `f'.
The contents of register f is moved to a destination dependent upon the status of d. If d = 0, destination is W register. If d = 1, the destination is file register f itself. d = 1 is useful to test a file register since status flag Z is affected. 1 1
MOVF FSR, 0
After Instruction W= value in FSR register Z=1
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 123
PIC16F688
MOVWF Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Example Move W to f [ label ] (W) (f) None
00 0000 1fff ffff
MOVLW f Syntax: Operands: Operation: Status Affected: Encoding: Description:
Move Literal to W [ label ] k (W) None
11 00xx kkkk kkkk
MOVWF
MOVLW k
0 f 127
0 k 255
Move data from W register to register `f'. 1 1
MOVWF OPTION
The eight bit literal `k' is loaded into W register. The don't cares will assemble as 0's. 1 1
MOVLW 0x5A
Words: Cycles: Example 0xFF 0x4F 0x4F 0x4F NOP Syntax: Operands: Operation: Status Affected: Encoding: Description: Words: Cycles: Example
Before Instruction OPTION = W = After Instruction OPTION = W = IORLW Syntax: Operands: Operation: Status Affected: Description:
After Instruction W=
0x5A
Inclusive OR Literal with W [ label ] IORLW k 0 k 255 (W) .OR. k (W) Z The contents of the W register are OR'ed with the eight-bit literal `k'. The result is placed in the W register.
No Operation [ label ] None No operation None
00 0000 0xx0 0000
NOP
No operation. 1 1
NOP
IORWF Syntax: Operands: Operation: Status Affected: Description:
Inclusive OR W with f [ label ] IORWF f,d 0 f 127 d [0,1] (W) .OR. (f) (destination) Z Inclusive OR the W register with register `f'. If `d' is `0', the result is placed in the W register. If `d' is `1', the result is placed back in register `f'.
DS41203B-page 124
Preliminary
2004 Microchip Technology Inc.
PIC16F688
RETFIE Syntax: Operands: Operation: Status Affected: Encoding: Description: Return from Interrupt [ label ] None TOS PC, 1 GIE None
00 0000 0000 1001
RETLW Syntax: Operands: Operation: Status Affected: Encoding: Description:
Return with Literal in W [ label ] RETLW k 0 k 255 k (W); TOS PC None
11 01xx kkkk kkkk
RETFIE
Return from Interrupt. Stack is POPed and Top-of-Stack (TOS) is loaded in the PC. Interrupts are enabled by setting Global Interrupt Enable bit, GIE (INTCON<7>). This is a two-cycle instruction. 1 2
RETFIE
The W register is loaded with the eight bit literal `k'. The program counter is loaded from the top of the stack (the return address). This is a two-cycle instruction. 1 2 CALL TABLE;W contains table ;offset value * ;W now has table value * * ADDWF PC ;W = offset RETLW k1 ;Begin table RETLW k2 ; * * * RETLW kn ; End of table Before Instruction W = 0x07 After Instruction W = value of k8
Words: Cycles: Example
Words: Cycles: Example
After Interrupt PC = GIE =
TABLE TOS 1
RETURN Syntax: Operands: Operation: Status Affected: Description:
Return from Subroutine [ label ] None TOS PC None Return from subroutine. The stack is POPed and the top of the stack (TOS) is loaded into the program counter. This is a two-cycle instruction. RETURN
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 125
PIC16F688
RLF Syntax: Operands: Operation: Status Affected: Encoding: Description: Rotate Left f through Carry [ label ] 0 f 127 d [0,1] See description below C
00 1101 dfff ffff
SLEEP Syntax: Operands: Operation: [ label ] SLEEP None 00h WDT, 0 WDT prescaler, 1 TO, 0 PD TO, PD The power-down Status bit, PD is cleared. Time-out Status bit, TO is set. Watchdog Timer and its prescaler are cleared. The processor is put into Sleep mode with the oscillator stopped.
RLF
f,d
Status Affected: Description:
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 the W register. If `d' is `1', the result is stored back in register `f'.
C Register f
Words: Cycles: Example
1 1
RLF REG1,0
SUBLW Syntax: Operands:
= = = = = 1110 0110 0 1110 0110 1100 1100 1
Subtract W from Literal [ label ] SUBLW k 0 k 255 k - (W) (W) The W register is subtracted (2's complement method) from the eight-bit literal `k'. The result is placed in the W register.
Before Instruction
REG1 C
Operation: Description:
After Instruction
REG1 W C
Status Affected: C, DC, Z
RRF Syntax: Operands: Operation: Status Affected: Description:
Rotate Right f through Carry [ label ] RRF f,d 0 f 127 d [0,1] See description below C 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 the W register. If `d' is `1', the result is placed back in register `f'.
C Register f
SUBWF Syntax: Operands: Operation: Description:
Subtract W from f [ label ] SUBWF f,d 0 f 127 d [0,1] (f) - (W) (destination) Subtract (2's complement method) W register from register `f'. If `d' is `0', the result is stored in the W register. If `d' is `1', the result is stored back in register `f'.
Status Affected: C, DC, Z
DS41203B-page 126
Preliminary
2004 Microchip Technology Inc.
PIC16F688
SWAPF Syntax: Operands: Operation: Status Affected: Description: Swap Nibbles in f [ label ] SWAPF f,d 0 f 127 d [0,1] (f<3:0>) (destination<7:4>), (f<7:4>) (destination<3:0>) None The upper and lower nibbles of register `f' are exchanged. If `d' is `0', the result is placed in the W register. If `d' is `1', the result is placed in register `f'.
XORLW Syntax: Operands: Operation: Status Affected: Description:
Exclusive OR Literal with W [ label ] XORLW k 0 k 255 (W) .XOR. k (W) Z The contents of the W register are XOR'ed with the eight-bit literal `k'. The result is placed in the W register.
XORWF Syntax: Operands: Operation: Status Affected: Description:
Exclusive OR W with f [ label ] XORWF 0 f 127 d [0,1] (W) .XOR. (f) (destination) Z Exclusive OR the contents of the W register with register `f'. If `d' is `0', the result is stored in the W register. If `d' is `1', the result is stored back in register `f'. f,d
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 127
PIC16F688
NOTES:
DS41203B-page 128
Preliminary
2004 Microchip Technology Inc.
PIC16F688
13.0 DEVELOPMENT SUPPORT
13.1
The PICmicro(R) microcontrollers are supported with a full range of hardware and software development tools: * Integrated Development Environment - MPLAB(R) IDE Software * Assemblers/Compilers/Linkers - MPASMTM Assembler - MPLAB C17 and MPLAB C18 C Compilers - MPLINKTM Object Linker/ MPLIBTM Object Librarian - MPLAB C30 C Compiler - MPLAB ASM30 Assembler/Linker/Library * Simulators - MPLAB SIM Software Simulator - MPLAB dsPIC30 Software Simulator * Emulators - MPLAB ICE 2000 In-Circuit Emulator - MPLAB ICE 4000 In-Circuit Emulator * In-Circuit Debugger - MPLAB ICD 2 * Device Programmers - PRO MATE(R) II Universal Device Programmer - PICSTART(R) Plus Development Programmer - MPLAB PM3 Device Programmer * Low-Cost Demonstration Boards - PICDEMTM 1 Demonstration Board - PICDEM.netTM Demonstration Board - PICDEM 2 Plus Demonstration Board - PICDEM 3 Demonstration Board - PICDEM 4 Demonstration Board - PICDEM 17 Demonstration Board - PICDEM 18R Demonstration Board - PICDEM LIN Demonstration Board - PICDEM USB Demonstration Board * Evaluation Kits - KEELOQ(R) - PICDEM MSC - microID(R) - CAN - PowerSmart(R) - Analog
MPLAB Integrated Development Environment Software
The MPLAB IDE software brings an ease of software development previously unseen in the 8/16-bit microcontroller market. The MPLAB IDE is a Windows(R) based application that contains: * An interface to debugging tools - simulator - programmer (sold separately) - 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 * Extensive on-line help The MPLAB IDE allows you to: * Edit your source files (either assembly or C) * One touch assemble (or compile) and download to PICmicro emulator and simulator tools (automatically updates all project information) * Debug using: - source files (assembly or C) - mixed assembly and C - 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 increasing flexibility and power.
13.2
MPASM Assembler
The MPASM assembler is a full-featured, universal macro assembler for all PICmicro 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 129
PIC16F688
13.3 MPLAB C17 and MPLAB C18 C Compilers 13.6 MPLAB ASM30 Assembler, Linker and Librarian
The MPLAB C17 and MPLAB C18 Code Development Systems are complete ANSI C compilers for Microchip's PIC17CXXX and PIC18CXXX family of microcontrollers. These compilers provide powerful integration capabilities, superior code optimization and ease of use not found with other compilers. For easy source level debugging, the compilers provide symbol information that is optimized to the MPLAB IDE debugger.
MPLAB ASM30 assembler produces relocatable machine code from symbolic assembly language for dsPIC30F devices. MPLAB C30 compiler uses the assembler to produce it's 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 dsPIC30F instruction set Support for fixed-point and floating-point data Command line interface Rich directive set Flexible macro language MPLAB IDE compatibility
13.4
MPLINK Object Linker/ MPLIB Object Librarian
The MPLINK object linker combines relocatable objects created by the MPASM assembler and the MPLAB C17 and MPLAB C18 C compilers. 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
13.7
MPLAB SIM Software Simulator
The MPLAB SIM software simulator allows code development in a PC hosted environment by simulating the PICmicro series microcontrollers on an instruction level. On any given instruction, the data areas can be examined or modified and stimuli can be applied from a file, or user defined key press, to any pin. The execution can be performed in Single-Step, Execute Until Break or Trace mode. The MPLAB SIM simulator fully supports symbolic debugging using the MPLAB C17 and MPLAB C18 C Compilers, as well as the MPASM assembler. The software simulator offers the flexibility to develop and debug code outside of the laboratory environment, making it an excellent, economical software development tool.
13.5
MPLAB C30 C Compiler
13.8
MPLAB SIM30 Software Simulator
The MPLAB C30 C compiler is a full-featured, ANSI compliant, optimizing compiler that translates standard ANSI C programs into dsPIC30F assembly language source. The compiler also supports many command line options and language extensions to take full advantage of the dsPIC30F device hardware capabilities and afford fine control of the compiler code generator. MPLAB C30 is distributed with a complete ANSI C standard library. All library functions have been validated and conform to the ANSI C library standard. The library includes functions for string manipulation, dynamic memory allocation, data conversion, timekeeping and math functions (trigonometric, exponential and hyperbolic). The compiler provides symbolic information for high-level source debugging with the MPLAB IDE.
The MPLAB SIM30 software simulator allows code development in a PC hosted environment by simulating the dsPIC30F series microcontrollers on an instruction level. On any given instruction, the data areas can be examined or modified and stimuli can be applied from a file, or user defined key press, to any of the pins. The MPLAB SIM30 simulator fully supports symbolic debugging using the MPLAB C30 C Compiler and MPLAB ASM30 assembler. The simulator runs in either a Command Line mode for automated tasks, or from MPLAB IDE. This high-speed simulator is designed to debug, analyze and optimize time intensive DSP routines.
DS41203B-page 130
Preliminary
2004 Microchip Technology Inc.
PIC16F688
13.9 MPLAB ICE 2000 High-Performance Universal In-Circuit Emulator 13.11 MPLAB ICD 2 In-Circuit Debugger
Microchip's In-Circuit Debugger, MPLAB ICD 2, is a powerful, low-cost, run-time development tool, connecting to the host PC via an RS-232 or high-speed USB interface. This tool is based on the Flash PICmicro MCUs and can be used to develop for these and other PICmicro microcontrollers. The MPLAB ICD 2 utilizes the in-circuit debugging capability built into the Flash devices. This feature, along with Microchip's In-Circuit Serial ProgrammingTM (ICSPTM) protocol, offers cost effective in-circuit Flash debugging from the graphical user interface of the MPLAB Integrated Development Environment. This enables a designer to develop and debug source code by setting breakpoints, single-stepping and watching variables, CPU status and peripheral registers. Running at full speed enables testing hardware and applications in real-time. MPLAB ICD 2 also serves as a development programmer for selected PICmicro devices.
The MPLAB ICE 2000 universal in-circuit emulator is intended to provide the product development engineer with a complete microcontroller design tool set for PICmicro microcontrollers. Software control of the MPLAB ICE 2000 in-circuit emulator is advanced by the MPLAB Integrated Development Environment, which allows editing, building, downloading and source debugging from a single environment. The MPLAB ICE 2000 is a full-featured emulator system with enhanced trace, trigger and data monitoring features. Interchangeable processor modules allow the system to be easily reconfigured for emulation of different processors. The universal architecture of the MPLAB ICE in-circuit emulator allows expansion to support new PICmicro microcontrollers. The MPLAB ICE 2000 in-circuit emulator system has been designed as a real-time emulation system with advanced features that are typically found on more expensive development tools. The PC platform and Microsoft(R) Windows 32-bit operating system were chosen to best make these features available in a simple, unified application.
13.12 PRO MATE II Universal Device Programmer
The PRO MATE II is a universal, CE compliant device programmer with programmable voltage verification at VDDMIN and VDDMAX for maximum reliability. It features an LCD display for instructions and error messages and a modular detachable socket assembly to support various package types. In Stand-Alone mode, the PRO MATE II device programmer can read, verify and program PICmicro devices without a PC connection. It can also set code protection in this mode.
13.10 MPLAB ICE 4000 High-Performance Universal In-Circuit Emulator
The MPLAB ICE 4000 universal in-circuit emulator is intended to provide the product development engineer with a complete microcontroller design tool set for highend PICmicro microcontrollers. Software control of the MPLAB ICE in-circuit emulator is provided by the MPLAB Integrated Development Environment, which allows editing, building, downloading and source debugging from a single environment. The MPLAB ICD 4000 is a premium emulator system, providing the features of MPLAB ICE 2000, but with increased emulation memory and high-speed performance for dsPIC30F and PIC18XXXX devices. Its advanced emulator features include complex triggering and timing, up to 2 Mb of emulation memory and the ability to view variables in real-time. The MPLAB ICE 4000 in-circuit emulator system has been designed as a real-time emulation system with advanced features that are typically found on more expensive development tools. The PC platform and Microsoft Windows 32-bit operating system were chosen to best make these features available in a simple, unified application.
13.13 MPLAB PM3 Device Programmer
The MPLAB PM3 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 StandAlone mode, the MPLAB PM3 device programmer can read, verify and program PICmicro devices without a PC connection. It can also set code protection in this mode. MPLAB PM3 connects to the host PC via an RS232 or USB cable. MPLAB PM3 has high-speed communications and optimized algorithms for quick programming of large memory devices and incorporates an SD/MMC card for file storage and secure data applications.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 131
PIC16F688
13.14 PICSTART Plus Development Programmer
The PICSTART Plus development programmer is an easy-to-use, low-cost, prototype programmer. It connects to the PC via a COM (RS-232) port. MPLAB Integrated Development Environment software makes using the programmer simple and efficient. The PICSTART Plus development programmer supports most PICmicro devices up to 40 pins. Larger pin count devices, such as the PIC16C92X and PIC17C76X, may be supported with an adapter socket. The PICSTART Plus development programmer is CE compliant.
13.17 PICDEM 2 Plus Demonstration Board
The PICDEM 2 Plus demonstration board supports many 18, 28 and 40-pin microcontrollers, including PIC16F87X and PIC18FXX2 devices. All the necessary hardware and software is included to run the demonstration programs. The sample microcontrollers provided with the PICDEM 2 demonstration board can be programmed with a PRO MATE II device programmer, PICSTART Plus development programmer, or MPLAB ICD 2 with a Universal Programmer Adapter. The MPLAB ICD 2 and MPLAB ICE in-circuit emulators may also be used with the PICDEM 2 demonstration board to test firmware. A prototype area extends the circuitry for additional application components. Some of the features include an RS-232 interface, a 2 x 16 LCD display, a piezo speaker, an on-board temperature sensor, four LEDs and sample PIC18F452 and PIC16F877 Flash microcontrollers.
13.15 PICDEM 1 PICmicro Demonstration Board
The PICDEM 1 demonstration board demonstrates the capabilities of the PIC16C5X (PIC16C54 to PIC16C58A), PIC16C61, PIC16C62X, PIC16C71, PIC16C8X, PIC17C42, PIC17C43 and PIC17C44. All necessary hardware and software is included to run basic demo programs. The sample microcontrollers provided with the PICDEM 1 demonstration board can be programmed with a PRO MATE II device programmer or a PICSTART Plus development programmer. The PICDEM 1 demonstration board can be connected to the MPLAB ICE in-circuit emulator for testing. A prototype area extends the circuitry for additional application components. Features include an RS-232 interface, a potentiometer for simulated analog input, push button switches and eight LEDs.
13.18 PICDEM 3 PIC16C92X Demonstration Board
The PICDEM 3 demonstration board supports the PIC16C923 and PIC16C924 in the PLCC package. All the necessary hardware and software is included to run the demonstration programs.
13.19 PICDEM 4 8/14/18-Pin Demonstration Board
The PICDEM 4 can be used to demonstrate the capabilities of the 8, 14 and 18-pin PIC16XXXX and PIC18XXXX MCUs, including the PIC16F818/819, PIC16F87/88, PIC16F62XA and the PIC18F1320 family of microcontrollers. PICDEM 4 is intended to showcase the many features of these low pin count parts, including LIN and Motor Control using ECCP. Special provisions are made for low-power operation with the supercapacitor circuit and jumpers allow onboard hardware to be disabled to eliminate current draw in this mode. Included on the demo board are provisions for Crystal, RC or Canned Oscillator modes, a five volt regulator for use with a nine volt wall adapter or battery, DB-9 RS-232 interface, ICD connector for programming via ICSP and development with MPLAB ICD 2, 2 x 16 liquid crystal display, PCB footprints for HBridge motor driver, LIN transceiver and EEPROM. Also included are: header for expansion, eight LEDs, four potentiometers, three push buttons and a prototyping area. Included with the kit is a PIC16F627A and a PIC18F1320. Tutorial firmware is included along with the User's Guide.
13.16 PICDEM.net Internet/Ethernet Demonstration Board
The PICDEM.net demonstration board is an Internet/ Ethernet demonstration board using the PIC18F452 microcontroller and TCP/IP firmware. The board supports any 40-pin DIP device that conforms to the standard pinout used by the PIC16F877 or PIC18C452. This kit features a user friendly TCP/IP stack, web server with HTML, a 24L256 Serial EEPROM for Xmodem download to web pages into Serial EEPROM, ICSP/MPLAB ICD 2 interface connector, an Ethernet interface, RS-232 interface and a 16 x 2 LCD display. Also included is the book and CD-ROM "TCP/IP Lean, Web Servers for Embedded Systems," by Jeremy Bentham
DS41203B-page 132
Preliminary
2004 Microchip Technology Inc.
PIC16F688
13.20 PICDEM 17 Demonstration Board
The PICDEM 17 demonstration board is an evaluation board that demonstrates the capabilities of several Microchip microcontrollers, including PIC17C752, PIC17C756A, PIC17C762 and PIC17C766. A programmed sample is included. The PRO MATE II device programmer, or the PICSTART Plus development programmer, can be used to reprogram the device for user tailored application development. The PICDEM 17 demonstration board supports program download and execution from external on-board Flash memory. A generous prototype area is available for user hardware expansion.
13.24 PICDEM USB PIC16C7X5 Demonstration Board
The PICDEM USB Demonstration Board shows off the capabilities of the PIC16C745 and PIC16C765 USB microcontrollers. This board provides the basis for future USB products.
13.25 Evaluation and Programming Tools
In addition to the PICDEM series of circuits, Microchip has a line of evaluation kits and demonstration software for these products. * KEELOQ evaluation and programming tools for Microchip's HCS Secure Data Products * CAN developers kit for automotive network applications * Analog design boards and filter design software * PowerSmart battery charging evaluation/ calibration kits * IrDA(R) development kit * microID development and rfLabTM development software * SEEVAL(R) designer kit for memory evaluation and endurance calculations * PICDEM MSC demo boards for Switching mode power supply, high-power IR driver, delta sigma ADC and flow rate sensor Check the Microchip web page and the latest Product Selector Guide for the complete list of demonstration and evaluation kits.
13.21 PICDEM 18R PIC18C601/801 Demonstration Board
The PICDEM 18R demonstration board serves to assist development of the PIC18C601/801 family of Microchip microcontrollers. It provides hardware implementation of both 8-bit Multiplexed/Demultiplexed and 16-bit Memory modes. The board includes 2 Mb external Flash memory and 128 Kb SRAM memory, as well as serial EEPROM, allowing access to the wide range of memory types supported by the PIC18C601/801.
13.22 PICDEM LIN PIC16C43X Demonstration Board
The powerful LIN hardware and software kit includes a series of boards and three PICmicro microcontrollers. The small footprint PIC16C432 and PIC16C433 are used as slaves in the LIN communication and feature on-board LIN transceivers. A PIC16F874 Flash microcontroller serves as the master. All three microcontrollers are programmed with firmware to provide LIN bus communication.
13.23 PICkitTM 1 Flash Starter Kit
A complete "development system in a box", the PICkit Flash Starter Kit includes a convenient multi-section board for programming, evaluation and development of 8/14-pin Flash PIC(R) microcontrollers. Powered via USB, the board operates under a simple Windows GUI. The PICkit 1 Starter Kit includes the User's Guide (on CD ROM), PICkit 1 tutorial software and code for various applications. Also included are MPLAB(R) IDE (Integrated Development Environment) software, software and hardware "Tips 'n Tricks for 8-pin Flash PIC(R) Microcontrollers" Handbook and a USB interface cable. Supports all current 8/14-pin Flash PIC microcontrollers, as well as many future planned devices.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 133
PIC16F688
NOTES:
DS41203B-page 134
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14.0 ELECTRICAL SPECIFICATIONS
Absolute Maximum Ratings()
Ambient temperature under bias..........................................................................................................-40 to +125C Storage temperature ........................................................................................................................ -65C to +150C Voltage on VDD with respect to VSS ................................................................................................... -0.3V to +6.5V Voltage on MCLR with respect to Vss ............................................................................................... -0.3V to +13.5V Voltage on all other pins with respect to VSS ........................................................................... -0.3V to (VDD + 0.3V) Total power dissipation(1) ............................................................................................................................... 800 mW 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 PORTA and PORTC (combined) .......................................................................... 200 mA Maximum current sourced PORTA and PORTC (combined) .......................................................................... 200 mA Note 1: Power dissipation is calculated as follows: PDIS = VDD x {IDD - IOH} + {(VDD - VOH) x IOH} + (VOL x IOL).
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.
Note:
Voltage spikes below VSS at the MCLR 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 pin, rather than pulling this pin directly to VSS.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 135
PIC16F688
FIGURE 14-1: PIC16F688 VOLTAGE-FREQUENCY GRAPH, -40C TA +125C
5.5 5.0 4.5 VDD (Volts) 4.0 3.5 3.0 2.5 2.0 0 4 8 10 12 16 20
Frequency (MHz) Note 1: The shaded region indicates the permissible combinations of voltage and frequency.
DS41203B-page 136
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14.1 DC Characteristics: PIC16F688 -I (Industrial) PIC16F688 -E (Extended)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Min Typ Max Units Conditions
DC CHARACTERISTICS Param No. D001 D001C D001D D002 D003 VDR VPOR RAM Data Retention Voltage(1) VDD Start Voltage to ensure internal Power-on Reset signal VDD Rise Rate to ensure internal Power-on Reset signal Brown-out Detect
Sym VDD
Characteristic Supply Voltage
2.0 3.0 4.5 1.5* --
-- -- -- -- VSS
5.5 5.5 5.5 -- --
V V V V V
FOSC < = 4 MHz: FOSC < = 10 MHz FOSC < = 20 MHz Device in Sleep mode See Section 11.4.2 "Power-On Reset (POR)" for details.
D004
SVDD
0.05*
--
--
V/ms See Section 11.4.2 "Power-On Reset (POR)" for details. V
D005
VBOD
--
2.1
--
* These parameters are characterized but not tested. 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: This is the limit to which VDD can be lowered in Sleep mode without losing RAM data.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 137
PIC16F688
14.2 DC Characteristics: PIC16F688-I (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Conditions Device Characteristics Supply Current (IDD)
(1, 2)
DC Characteristics Param No. D010
Min -- -- --
Typ 9 18 35 110 190 330 220 370 0.6 70 140 260 180 320 580 TBD TBD TBD 340 500 0.8 180 320 580 2.1 2.4
Max TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD
Units VDD A A A A A A A A mA A A A A A A A A mA A A mA A A A mA mA 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 4.5 5.0 FOSC = 20 MHz HS Oscillator mode FOSC = 4 MHz EXTRC mode FOSC = 4 MHz INTOSC mode FOSC = 31 kHz INTRC mode FOSC = 4 MHz EC Oscillator mode FOSC = 1 MHz EC Oscillator mode FOSC = 4 MHz XT Oscillator mode FOSC = 1 MHz XT Oscillator mode Note FOSC = 32 kHz LP Oscillator mode
D011
-- -- --
D012
-- -- --
D013
-- -- --
D014
-- -- --
D015
-- -- --
D016
-- -- --
D017
-- -- --
D018
-- --
Legend: TBD = To Be Determined 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: 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; MCLR = VDD; WDT disabled. 2: The supply current is mainly a function of the operating voltage and frequency. Other factors, such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature, also have an impact on the current consumption.
DS41203B-page 138
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14.3 DC Characteristics: PIC16F688-I (Industrial)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Conditions Device Characteristics Power-down Base Current (IPD)(4) Min -- -- -- D021 -- -- -- D022 D023 -- -- -- -- -- D024 -- -- -- D025 -- -- -- D026 -- -- Typ 0.99 1.2 2.9 0.3 1.8 8.4 58 109 3.3 6.1 11.5 58 85 138 4.0 4.6 6.0 1.2 0.0022 Max TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD Units VDD nA nA nA A A A A A A A A A A A A A A nA A 2.0 3.0 5.0 2.0 3.0 5.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 3.0 5.0 A/D Current T1OSC Current CVREF Current Comparator Current(3) BOD Current WDT Current Note WDT, BOD, Comparators, VREF and T1OSC disabled DC Characteristics Param No. D020
Legend: TBD = To Be Determined Data in `Typ' column is at 5.0V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 3: The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is enabled. The peripheral current can be determined by subtracting the base IDD or IPD current from this limit. Max values should be used when calculating total current consumption. 4: 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 hi-impedance state and tied to VDD.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 139
PIC16F688
14.4
DC Characteristics: PIC16F688-E (Extended)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +125C for extended Conditions Device Characteristics Min -- -- -- D011E -- -- -- D012E -- -- -- D013E -- -- -- D014E -- -- -- D015E -- -- -- D016E -- -- -- D017E -- -- -- D018E -- -- Typ 9 18 35 110 190 330 220 370 0.6 70 140 260 180 320 580 TBD TBD TBD 340 500 0.8 180 320 580 2.1 2.4 Max TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD Units VDD A A A A A A A A mA A A A A A A A A mA A A mA A A A mA mA 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 4.5 5.0 FOSC = 20 MHz HS Oscillator mode FOSC = 4 MHz EXTRC mode FOSC = 4 MHz INTOSC mode FOSC = 31 kHz INTRC mode FOSC = 4 MHz EC Oscillator mode FOSC = 1 MHz EC Oscillator mode FOSC = 4 MHz XT Oscillator mode FOSC = 1 MHz XT Oscillator mode Note FOSC = 32 kHz LP Oscillator mode DC Characteristics Param No.
D010E Supply Current (IDD)
Legend: TBD = To Be Determined 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: 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; MCLR = VDD; WDT disabled. 2: The supply current is mainly a function of the operating voltage and frequency. Other factors, such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature, also have an impact on the current consumption.
DS41203B-page 140
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14.5
DC Characteristics: PIC16F688-E (Extended)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +125C for extended Conditions Device Characteristics Min -- -- -- D021E -- -- -- D022E D023E -- -- -- -- -- D024E -- -- -- D025E -- -- -- D026E -- -- Typ 0.00099 0.0012 0.0029 0.3 1.8 8.4 58 109 3.3 6.1 11.5 58 85 138 4.0 4.6 6.0 0.0012 0.0022 Max TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD Units VDD A A A A A A A A A A A A A A A A A A A 2.0 3.0 5.0 2.0 3.0 5.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 2.0 3.0 5.0 3.0 5.0 A/D Current(3) T1OSC Current CVREF Current Comparator Current(3) BOD Current WDT Current Note WDT, BOD, Comparators, VREF and T1OSC disabled DC Characteristics Param No.
D020E Power-down Base Current (IPD)(4)
Legend: TBD = To Be Determined Data in `Typ' column is at 5.0V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 3: The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is enabled. The peripheral current can be determined by subtracting the base IDD or IPD current from this limit. Max values should be used when calculating total current consumption. 4: 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.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 141
PIC16F688
14.6 DC Characteristics: PIC16F688 -I (Industrial) PIC16F688 -E (Extended)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Min Typ Max Units Conditions
DC CHARACTERISTICS Param Sym No.
VIL D030 D030A D031 D032 D033 D033A VIH D040 D040A D041 D042 D043 D043A D043B D070 IPUR IIL D060 D061 D063 VOL D080 D083 VOH D090 D092
Characteristic
Input Low Voltage I/O port: with TTL buffer with Schmitt Trigger buffer MCLR, OSC1 (RC mode) OSC1 (XT and LP modes)(1) OSC1 (HS mode)(1) Input High Voltage I/O port: with TTL buffer with Schmitt Trigger buffer MCLR OSC1 (XT and LP modes) OSC1 (HS mode) OSC1 (RC mode) PORTA Weak Pull-up Current Input Leakage Current(2) I/O port MCLR(3) OSC1 Output Low Voltage I/O port OSC2/CLKOUT (RC mode) Output High Voltage I/O port OSC2/CLKOUT (RC mode)
Vss Vss Vss VSS VSS VSS
-- -- -- -- -- -- -- -- -- -- -- -- -- -- 250
0.8 0.15 VDD 0.2 VDD 0.2 VDD 0.3 0.3 VDD
V V V V V V
4.5V VDD 5.5V Otherwise Entire range
2.0 (0.25 VDD + 0.8) 0.8 VDD 0.8 VDD 1.6 0.7 VDD 0.9 VDD 50*
VDD VDD VDD VDD VDD VDD VDD 400*
V V V V V V V
4.5V VDD 5.5V Otherwise Entire range (Note 1) (Note 1) VDD = 5.0V, VPIN = VSS
A
-- -- --
0.1 0.1 0.1
1 5 5
A A A
VSS VPIN VDD, Pin at high-impedance VSS VPIN VDD VSS VPIN VDD, XT, HS and LP osc configuration IOL = 8.5 mA, VDD = 4.5V (Ind.) IOL = 1.6 mA, VDD = 4.5V (Ind.) IOL = 1.2 mA, VDD = 4.5V (Ext.) IOH = -3.0 mA, VDD = 4.5V (Ind.) IOH = -1.3 mA, VDD = 4.5V (Ind.) IOH = -1.0 mA, VDD = 4.5V (Ext.)
-- --
-- --
0.6 0.6
V V
VDD - 0.7 VDD - 0.7
-- --
-- --
V V
* These parameters are characterized but not tested. 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: In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended to use an external clock in RC mode. 2: Negative current is defined as current sourced by the pin. 3: 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.
DS41203B-page 142
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14.7 DC Characteristics: PIC16F688 -I (Industrial), PIC16F688 -E (Extended)
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Characteristic Min -- Typ 200 Max -- Units nA Conditions
DC CHARACTERISTICS Param No. D100
Sym IULP
D100
Ultra Low-Power Wake-up Current Capacitive Loading Specs on Output Pins COSC2 OSC2 pin
--
--
15*
pF
In XT, HS and LP modes when external clock is used to drive OSC1
D101 D120 D120A D121
CIO ED ED VDRW
All I/O pins Data EEPROM Memory Byte Endurance Byte Endurance VDD for Read/Write
-- 100K 10K VMIN
-- 1M 100K --
50* -- -- 5.5
pF E/W -40C TA +85C E/W +85C TA +125C V Using EECON1 to read/write VMIN = Minimum operating voltage ms Year Provided no other specifications are violated E/W -40C TA +85C
D122 D123 D124
TDEW TRETD TREF
Erase/Write Cycle Time Characteristic Retention Number of Total Erase/Write Cycles before Refresh(4) Program Flash Memory Cell Endurance Cell Endurance VDD for Read VDD for Erase/Write Erase/Write cycle time Characteristic Retention
-- 40 1M
5 -- 10M
6 -- --
D130 D130A D131 D132 D133 D134
EP ED VPR VPEW TPEW TRETD
10K 1K VMIN 4.5 -- 40
100K 10K -- -- 2 --
-- -- 5.5 5.5 2.5 --
E/W -40C TA +85C E/W +85C TA +125C V VMIN = Minimum operating voltage V ms Year Provided no other specifications are violated
* These parameters are characterized but not tested. Data in `Typ' column is at 5.0V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 4: See Section 9.0 "Data EEPROM And Flash Program Memory Control" for additional information.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 143
PIC16F688
14.8 Timing Parameter Symbology
The timing parameter symbols have been created with one of the following formats: 1. TppS2ppS 2. TppS T F Frequency Lowercase letters (pp) and their meanings: pp cc RC ck CLKOUT 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
T
Time
osc rd rw sc ss t0 t1 wr
OSC1 RD RD or WR SCK SS T0CKI T1CKI WR
P R V Z
Period Rise Valid High-impedance
FIGURE 14-2:
LOAD CONDITIONS
Load Condition 1 VDD/2 Load Condition 2
RL
Pin VSS
RL = 464 CL = 50 pF 15 pF
CL
Pin VSS
CL
for all pins for OSC2 output
DS41203B-page 144
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14.9 AC Characteristics: PIC16F688 (Industrial, Extended)
EXTERNAL CLOCK TIMING
Q4 Q1 Q2 Q3 Q4 Q1
FIGURE 14-3:
OSC1 1 2 CLKOUT 3 3 4 4
TABLE 14-1:
EXTERNAL CLOCK TIMING REQUIREMENTS
Standard Operating Conditions (unless otherwise stated) Operating Temperature -40C TA +125C Param No. Sym FOSC Characteristic External CLKIN Frequency(1) Min Typ Max Units Conditions
DC -- 37 kHz LP Oscillator mode DC -- 4 MHz XT Oscillator mode DC -- 20 MHz HS Oscillator mode DC -- 20 MHz EC Oscillator mode Oscillator Frequency(1) 5 -- 37 kHz LP Oscillator mode -- 4 -- MHz INTOSC mode DC -- 4 MHz RC Oscillator mode 0.1 -- 4 MHz XT Oscillator mode 1 -- 20 MHz HS Oscillator mode 1 TOSC External CLKIN Period(1) 27 -- s LP Oscillator mode 50 -- ns HS Oscillator mode 50 -- ns EC Oscillator mode 250 -- ns XT Oscillator mode (1) Oscillator Period 27 200 s LP Oscillator mode -- 250 -- ns INTOSC mode 250 -- -- ns RC Oscillator mode 250 -- 10,000 ns XT Oscillator mode 50 -- 1,000 ns HS Oscillator mode 2 TCY Instruction Cycle Time(1) 200 TCY DC ns TCY = 4/FOSC 3 TosL, External CLKIN (OSC1) High 2* -- -- s LP oscillator, TOSC L/H duty cycle TosH External CLKIN Low 20* -- -- ns HS oscillator, TOSC L/H duty cycle 100 * -- -- ns XT oscillator, TOSC L/H duty cycle 4 TosR, External CLKIN Rise -- -- 50* ns LP oscillator TosF External CLKIN Fall -- -- 25* ns XT oscillator -- -- 15* ns HS oscillator * These parameters are characterized but not tested. Data in `Typ' column is at 5V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. 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 OSC1 pin. When an external clock input is used, the `max' cycle time limit is `DC' (no clock) for all devices.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 145
PIC16F688
TABLE 14-2: PRECISION INTERNAL OSCILLATOR PARAMETERS
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C Param No. F10 Sym Characteristic Freq Min Tolerance 1% 2% 5% -- -- -- Typ 8.00 8.00 8.00 Max TBD TBD TBD Units Conditions
FOSC Internal Calibrated INTOSC Frequency(1)
F14
ST
TIOSC Oscillator Wake-up from Sleep Start-up Time*
-- -- --
-- -- --
TBD TBD TBD
TBD TBD TBD
MHz VDD and Temperature TBD MHz 2.5V VDD 5.5V 0C TA +85C MHz 2.0V VDD 5.5V -40C TA +85C (Ind.) -40C TA +125C (Ext.) s VDD = 2.0V, -40C to +85C s VDD = 3.0V, -40C to +85C s VDD = 5.0V, -40C to +85C
Legend: TBD = To Be Determined * These parameters are characterized but not tested. 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: To ensure these oscillator frequency tolerances, VDD and VSS must be capacitively decoupled as close to the device as possible. 0.1 uF and 0.01 uF values in parallel are recommended.
DS41203B-page 146
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 14-4: CLKOUT AND I/O TIMING
Q4 OSC1 10 CLKOUT 13 14 I/O pin (Input) 17 I/O pin (Output) Old Value 20, 21 15 New Value 19 18 22 23 12 16 Q1 Q2 11 Q3
TABLE 14-3:
CLKOUT AND I/O TIMING REQUIREMENTS
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C Param No. 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Sym Characteristic Min -- -- -- -- -- TOSC + 200 ns 0 -- -- TosH2ioI OSC1 (Q2 cycle) to Port Input Invalid (I/O in hold time) 100 0 -- -- 25 TCY Typ 75 75 35 35 -- -- -- 50 -- -- -- 10 10 -- -- Max 200 200 100 100 20 -- -- 150* 300 -- -- 40 40 -- -- Units ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns Conditions (Note 1) (Note 1) (Note 1) (Note 1) (Note 1) (Note 1) (Note 1)
TosH2ckL OSC1 to CLOUT TosH2ckH OSC1 to CLOUT TckR TckF TckL2ioV TioV2ckH TckH2ioI TosH2ioV CLKOUT Rise Time CLKOUT Fall Time CLKOUT to Port Out Valid Port In Valid before CLKOUT Port In Hold after CLKOUT OSC1 (Q1 cycle) to Port Out Valid
TioV2osH Port Input Valid to OSC1 (I/O in setup time) TioR TioF Tinp Trbp Port Output Rise Time Port Output Fall Time INT Pin High or Low Time PORTA change INT high or low time
* These parameters are characterized but not tested. Data in `Typ' column is at 5.0V, 25C unless otherwise stated. Note 1: Measurements are taken in RC mode where CLKOUT output is 4 x TOSC.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 147
PIC16F688
FIGURE 14-5: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP TIMER TIMING
VDD MCLR Internal POR 33 PWRT Time-out OSC Time-out Internal Reset Watchdog Timer Reset 34 I/O pins 32 30
31 34
FIGURE 14-6:
BROWN-OUT DETECT TIMING AND CHARACTERISTICS
VDD BVDD (Device in Brown-out Detect) (Device not in Brown-out Detect)
35
Reset (due to BOD)
64 ms Time-out(1)
Note 1:
64 ms delay only if PWRTE bit in the Configuration Word is programmed to `0'.
DS41203B-page 148
Preliminary
2004 Microchip Technology Inc.
PIC16F688
TABLE 14-4: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER AND BROWN-OUT DETECT REQUIREMENTS
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C Param No. 30 31 32 33* 34 Sym TMCL TWDT TOST TPWRT TIOZ Characteristic MCLR Pulse Width (low) Watchdog Timer Time-out Period (No Prescaler) Oscillation Start-up Timer Period Power-up Timer Period I/O High-impedance from MCLR Low or Watchdog Timer Reset Brown-out Detect Voltage Brown-out Detect Pulse Width Min 2 11 10 10 -- 28* TBD -- Typ -- 18 17 17 1024TOSC 64 TBD -- Max -- 24 25 30 -- 132* TBD 2.0 Units s ms ms ms -- ms ms s Conditions VDD = 5V, -40C to +85C Extended temperature VDD = 5V, -40C to +85C Extended temperature TOSC = OSC1 period VDD = 5V, -40C to +85C Extended Temperature
BVDD 35 TBOD
2.025 100*
-- --
2.175 --
V s VDD BVDD (D005)
Legend: TBD = To Be Determined * These parameters are characterized but not tested. Data in `Typ' column is at 5V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 149
PIC16F688
FIGURE 14-7: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI 40 41
42
T1CKI 45 47 46 48
TMR0 or TMR1
TABLE 14-5:
Param No. 40* 41* 42* Sym Tt0H Tt0L Tt0P
TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Characteristic T0CKI High Pulse Width T0CKI Low Pulse Width T0CKI Period No Prescaler With Prescaler No Prescaler With Prescaler Min 0.5 TCY + 20 10 0.5 TCY + 20 10 Greater of: 20 or TCY + 40 N 0.5 TCY + 20 15 30 0.5 TCY + 20 15 30 Greater of: 30 or TCY + 40 N 60 DC Typ -- -- -- -- -- Max -- -- -- -- -- Units Conditions ns ns ns ns ns
N = prescale value (2, 4, ..., 256)
45*
Tt1H
T1CKI High Time
46*
Tt1L
T1CKI Low Time
47*
Tt1P
T1CKI Input Period
Synchronous, No Prescaler Synchronous, with Prescaler Asynchronous Synchronous, No Prescaler Synchronous, with Prescaler Asynchronous Synchronous
-- -- -- -- -- -- --
-- -- -- -- -- -- --
ns ns ns ns ns ns ns
N = prescale value (1, 2, 4, 8)
48
Asynchronous -- -- ns Timer1 oscillator input frequency range -- 200* kHz (oscillator enabled by setting bit T1OSCEN) TCKEZtmr1 Delay from external clock edge to timer 2 TOSC* -- 7 TOSC* -- increment * These parameters are characterized but not tested. Data in `Typ' column is at 5V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. Ft1
DS41203B-page 150
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 14-8: USART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING
RC4/C2OUT/TX/CK pin RC5/RX/DT pin 120 Note:
121
121
122
Refer to Figure 14-2 for load conditions.
TABLE 14-6:
USART SYNCHRONOUS TRANSMISSION REQUIREMENTS
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C 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
121 122
PIC16F688 PIC16LF688 PIC16F688 PIC16LF688 PIC16F688 PIC16LF688
-- -- -- -- -- --
40 100 20 50 20 50
ns ns ns ns ns ns
FIGURE 14-9:
USART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING
RC4/C2OUT/TX/CK pin RC5/RX/DT pin
125
126 Note: Refer to Figure 14-2 for load conditions.
TABLE 14-7:
USART SYNCHRONOUS RECEIVE REQUIREMENTS
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C 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
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 151
PIC16F688
TABLE 14-8: COMPARATOR SPECIFICATIONS
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +125C Min -- 0 +55* -- -- Typ 5.0 -- -- 150 -- Max 10 VDD - 1.5 -- 400* 10* Units mV V db ns s Comments Comparator Specifications Sym VOS VCM CMRR TRT Characteristics Input Offset Voltage Input Common Mode Voltage Common Mode Rejection Ratio Response Time
(1)
TMC2COV Comparator Mode Change to Output Valid * Note 1:
These parameters are characterized but not tested. Response time measured with one comparator input at (VDD - 1.5)/2 while the other input transitions from VSS to VDD - 1.5V.
TABLE 14-9:
COMPARATOR VOLTAGE REFERENCE SPECIFICATIONS
Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +125C Min -- -- -- -- -- -- Typ VDD/24* VDD/32 -- -- 2K* -- Max -- -- 1/4* 1/2* -- 10* Units LSb LSb LSb LSb s Comments Low Range (VRR = 1) High Range (VRR = 0) Low Range (VRR = 1) High Range (VRR = 0)
Voltage Reference Specifications Sym. Characteristics Resolution Absolute Accuracy Unit Resistor Value (R) Settling Time(1) * Note 1:
These parameters are characterized but not tested. Settling time measured while VRR = 1 and VR<3:0> transitions from `0000' to `1111'.
DS41203B-page 152
Preliminary
2004 Microchip Technology Inc.
PIC16F688
TABLE 14-10: PIC16F688 A/D CONVERTER CHARACTERISTICS:
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C Param No. A01 A02 A03 A04 A05 A06 A07 A10 A20 A20A A25 A30 Sym NR EABS EIL EDL EFS EOFF EGN -- VREF Characteristic Resolution Total Absolute Error*(1) Integral Error Differential Error Full-scale Range Offset Error Gain Error Monotonicity Reference Voltage Min -- -- -- -- 2.2* -- -- -- 2.2 2.5 VSS -- Typ -- -- -- -- -- -- -- guaranteed --
(2)
Max 10 bits 1 1 1 5.5* 1 1 -- -- VDD + 0.3 VREF 10
Units bit LSb VREF = 5.0V LSb VREF = 5.0V
Conditions
LSb No missing codes to 10 bits VREF = 5.0V V LSb VREF = 5.0V LSb VREF = 5.0V -- V Absolute minimum to ensure 10-bit accuracy V k VSS VAIN VREF+
VAIN ZAIN
Analog Input Voltage Recommended Impedance of Analog Voltage Source VREF Input Current*(3)
-- --
A50
IREF
10 --
-- --
1000 10
A A
During VAIN acquisition. Based on differential of VHOLD to VAIN. During A/D conversion cycle.
* These parameters are characterized but not tested. 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: Total Absolute Error includes integral, differential, offset and gain errors. 2: The A/D conversion result never decreases with an increase in the input voltage and has no missing codes. 3: VREF current is from external VREF or VDD pin, whichever is selected as reference input. 4: When A/D is off, it will not consume any current other than leakage current. The power-down current _specification includes any such leakage from the A/D module.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 153
PIC16F688
FIGURE 14-10: PIC16F688 A/D CONVERSION TIMING (NORMAL MODE)
1 TCY 131 130 A/D CLK A/D Data ADRES ADIF GO Sample Note 1: 132 Sampling Stopped 9 8 OLD_DATA 7 6 3 2 1 0 NEW_DATA 1 TCY DONE BSF ADCON0, GO 134 Q4
(TOSC/2)(1)
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.
TABLE 14-11: PIC16F688 A/D CONVERSION REQUIREMENTS
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C Param No. 130 130 Sym TAD TAD Characteristic A/D Clock Period A/D Internal RC Oscillator Period Conversion Time (not including Acquisition Time)(1) Acquisition Time 5* Min 1.6 3.0* 3.0* 2.0* 131 TCNV -- Typ -- -- 6.0 4.0 11 Max -- -- 9.0* 6.0* -- Units s s s s TAD Conditions TOSC-based, VREF 3.0V TOSC-based, VREF full range ADCS<1:0> = 11 (RC mode) At VDD = 2.5V At VDD = 5.0V Set GO bit to new data in A/D Result register
132
TACQ
11.5 --
-- --
s s The minimum time is the amplifier settling time. This may be used if the "new" input voltage has not changed by more than 1 LSb (i.e., 4.1 mV @ 4.096V) from the last sampled voltage (as stored on CHOLD). 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.
134
TGO
Q4 to A/D Clock Start
--
TOSC/2
--
--
* These parameters are characterized but not tested. 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: ADRESH and ADRESL registers may be read on the following TCY cycle. 2: See Table 8-1 for minimum conditions.
DS41203B-page 154
Preliminary
2004 Microchip Technology Inc.
PIC16F688
FIGURE 14-11: PIC16F688 A/D CONVERSION TIMING (SLEEP MODE)
BSF ADCON0, GO 134 Q4 130 A/D CLK A/D Data ADRES ADIF GO Sample 132 Sampling Stopped 9 8 7 6 3 2 1 0 NEW_DATA 1 TCY DONE
(TOSC/2 + TCY)(1)
131
1 TCY
OLD_DATA
Note 1:
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.
TABLE 14-12: PIC16F688 A/D CONVERSION REQUIREMENTS (SLEEP MODE)
Standard Operating Conditions (unless otherwise stated) Operating Temperature-40C TA +125C Param No. 130 Sym TAD Characteristic A/D Internal RC Oscillator Period Conversion Time (not including Acquisition Time)(1) Acquisition Time Min Typ Max Units s s TAD Conditions ADCS<1:0> = 11 (RC mode) At VDD = 2.5V At VDD = 5.0V
3.0* 2.0* --
6.0 4.0 11
9.0* 6.0* --
131
Tcnv
132
TACQ
(2) 5*
11.5 --
-- --
s s The minimum time is the amplifier settling time. This may be used if the "new" input voltage has not changed by more than 1 LSb (i.e., 4.1 mV @ 4.096V) from the last sampled voltage (as stored on CHOLD). 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.
134
TGO
Q4 to A/D Clock Start
--
TOSC/2 + TCY
--
--
* These parameters are characterized but not tested. 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: ADRES register may be read on the following TCY cycle. 2: See Table 8-1 for minimum conditions.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 155
PIC16F688
NOTES:
DS41203B-page 156
Preliminary
2004 Microchip Technology Inc.
PIC16F688
15.0 DC AND AC CHARACTERISTICS GRAPHS AND TABLES
Graphs are not available at this time.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 157
PIC16F688
NOTES:
DS41203B-page 158
Preliminary
2004 Microchip Technology Inc.
PIC16F688
16.0
16.1
PACKAGING INFORMATION
Package Marking Information
14-Lead PDIP (Skinny DIP) XXXXXXXXXXXXXX XXXXXXXXXXXXXX YYWWNNN Example 16F688-I 0215017
14-Lead SOIC XXXXXXXXXXX XXXXXXXXXXX YYWWNNN
Example 16F688-E 0215017
14-Lead TSSOP XXXXXXXX YYWW NNN
Example 16F688 0215 017
Legend: XX...X Y YY WW NNN
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
Note:
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.
*
Standard PICmicro device marking consists of Microchip part number, year code, week code, and traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP price.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 159
PIC16F688
16.2 Package Details
The following sections give the technical details of the packages.
14-Lead Plastic Dual In-line (P) - 300 mil (PDIP)
E1
D
2 n 1
E A A2
c eB A1 B1 B p
L
Number of Pins Pitch Top to Seating Plane A .140 .170 Molded Package Thickness A2 .115 .145 Base to Seating Plane A1 .015 Shoulder to Shoulder Width E .300 .313 .325 Molded Package Width E1 .240 .250 .260 Overall Length D .740 .750 .760 Tip to Seating Plane L .125 .130 .135 c Lead Thickness .008 .012 .015 Upper Lead Width B1 .045 .058 .070 Lower Lead Width B .014 .018 .022 eB Overall Row Spacing .310 .370 .430 Mold Draft Angle Top 5 10 15 Mold Draft Angle Bottom 5 10 15 * Controlling Parameter Significant Characteristic Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010" (0.254mm) per side. JEDEC Equivalent: MS-001 Drawing No. C04-005
Units Dimension Limits n p
MIN
INCHES* NOM 14 .100 .155 .130
MAX
MIN
MILLIMETERS NOM 14 2.54 3.56 3.94 2.92 3.30 0.38 7.62 7.94 6.10 6.35 18.80 19.05 3.18 3.30 0.20 0.29 1.14 1.46 0.36 0.46 7.87 9.40 5 10 5 10
MAX
4.32 3.68 8.26 6.60 19.30 3.43 0.38 1.78 0.56 10.92 15 15
DS41203B-page 160
Preliminary
2004 Microchip Technology Inc.
PIC16F688
14-Lead Plastic Small Outline (SL) - Narrow, 150 mil (SOIC)
E E1
p
D
2 B n 1 h 45 c A A2
L A1
Number of Pins Pitch Overall Height Molded Package Thickness Standoff Overall Width Molded Package Width Overall Length Chamfer Distance Foot Length Foot Angle Lead Thickness Lead Width Mold Draft Angle Top Mold Draft Angle Bottom * Controlling Parameter Significant Characteristic
Units Dimension Limits n p A A2 A1 E E1 D h L c B
MIN
.053 .052 .004 .228 .150 .337 .010 .016 0 .008 .014 0 0
INCHES* NOM 14 .050 .061 .056 .007 .236 .154 .342 .015 .033 4 .009 .017 12 12
MAX
MIN
.069 .061 .010 .244 .157 .347 .020 .050 8 .010 .020 15 15
MILLIMETERS NOM 14 1.27 1.35 1.55 1.32 1.42 0.10 0.18 5.79 5.99 3.81 3.90 8.56 8.69 0.25 0.38 0.41 0.84 0 4 0.20 0.23 0.36 0.42 0 12 0 12
MAX
1.75 1.55 0.25 6.20 3.99 8.81 0.51 1.27 8 0.25 0.51 15 15
Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010" (0.254mm) per side. JEDEC Equivalent: MS-012 Drawing No. C04-065
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 161
PIC16F688
14-Lead Plastic Thin Shrink Small Outline (ST) - 4.4 mm (TSSOP)
E E1 p
D
2 n B 1
A c
L A1 A2
Number of Pins Pitch Overall Height Molded Package Thickness Standoff Overall Width Molded Package Width Molded Package Length Foot Length Foot Angle Lead Thickness Lead Width Mold Draft Angle Top Mold Draft Angle Bottom * Controlling Parameter Significant Characteristic
Units Dimension Limits n p A A2 A1 E E1 D L c B
MIN
INCHES NOM 14 .026 .035 .004 .251 .173 .197 .024 4 .006 .010 5 5
MAX
MIN
.033 .002 .246 .169 .193 .020 0 .004 .007 0 0
.043 .037 .006 .256 .177 .201 .028 8 .008 .012 10 10
MILLIMETERS* NOM MAX 14 0.65 1.10 0.85 0.90 0.95 0.05 0.10 0.15 6.25 6.38 6.50 4.30 4.40 4.50 4.90 5.00 5.10 0.50 0.60 0.70 0 4 8 0.09 0.15 0.20 0.19 0.25 0.30 0 5 10 0 5 10
Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .005" (0.127mm) per side. JEDEC Equivalent: MO-153 Drawing No. C04-087
DS41203B-page 162
Preliminary
2004 Microchip Technology Inc.
PIC16F688
APPENDIX A:
Revision A
This is a new data sheet.
DATA SHEET REVISION HISTORY
APPENDIX B:
MIGRATING FROM OTHER PICmicro(R) DEVICES
This discusses some of the issues in migrating from other PICmicro devices to the PIC16F6XX family of devices.
Revision B
Rewrites of the Oscillator and Special Features of the CPU Sections. General corrections to Figures and formatting.
B.1
PIC16F676 to PIC16F688
FEATURE COMPARISON
PIC16F676 20 MHz 1024 64 10-bit 128 1/1 8 Y RA0/1/2/4/5 RA0/1/2/3 /4/5 1 N N N N 4 MHz N PIC16F688 20 MHz 4K 256 10-bit 256 1/1 8 Y RA0/1/2/4/5, MCLR RA0/1/2/3/4/5 2 Y Y Y Y 32 kHz 8 MHz Y Feature
TABLE B-1:
Max Operating Speed Max Program Memory (Words) SRAM (Bytes) A/D Resolution Data EEPROM (bytes) Timers (8/16-bit) Oscillator Modes Brown-out Detect Internal Pull-ups Interrupt-on-change Comparator EUSART Ultra Low-Power Wake-up Extended WDT Software Control Option of WDT/BOD INTOSC Frequencies Clock Switching Note:
This device has been designed to perform to the parameters of its data sheet. It has been tested to an electrical specification designed to determine its conformance with these parameters. Due to process differences in the manufacture of this device, this device may have different performance characteristics than its earlier version. These differences may cause this device to perform differently in your application than the earlier version of this device.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 163
PIC16F688
NOTES:
DS41203B-page 164
Preliminary
2004 Microchip Technology Inc.
PIC16F688
INDEX
A
A/D Acquisition Requirements ........................................... 68 Analog Port Pins ......................................................... 63 Associated Registers .................................................. 70 Block Diagram............................................................. 63 Calculating Acquisition Time....................................... 68 Channel Selection....................................................... 63 Configuration and Operation....................................... 63 Configuring.................................................................. 67 Configuring Interrupt ................................................... 67 Conversion (TAD) Cycles ............................................ 65 Conversion Clock........................................................ 64 Effects of Reset........................................................... 70 Internal Sampling Switch (RSS) Impedance................ 68 Operation During Sleep .............................................. 69 Output Format............................................................. 65 Reference Voltage (VREF)........................................... 63 Source Impedance...................................................... 68 Specifications............................................ 153, 154, 155 Starting a Conversion ................................................. 64 TAD vs. Operating Frequencies................................... 64 Absolute Maximum Ratings .............................................. 135 AC Characteristics Industrial and Extended ............................................ 145 Load Conditions ........................................................ 144 ADCON0 Register............................................................... 66 ADCON1 Register............................................................... 66 Analog Front-end (AFE) Power-On Reset ....................................................... 103 Analog Input Connections ................................................... 54 Analog-to-Digital Converter Module. See A/D ANSEL Register .................................................................. 65 Assembler MPASM Assembler................................................... 129 Auto Wake-up on SYNC Break Character .......................... 91 TMR0/WDT Prescaler ................................................ 45 USART Receive ......................................................... 89 USART Transmit ........................................................ 87 Watchdog Timer (WDT)............................................ 113 Break Character (12-bit) Transmit and Receive ................. 92 Brown-out Detect (BOD)................................................... 104 Associated Registers................................................ 105 Calibration ................................................................ 104 Specifications ........................................................... 149 Timing and Characteristics ....................................... 148
C
C Compilers MPLAB C17.............................................................. 130 MPLAB C18.............................................................. 130 MPLAB C30.............................................................. 130 CALIB Register ................................................................. 101 Clock Accuracy with Asynchronous Operation ................... 77 CMCON0 Register.............................................................. 53 CMCON1 Register.............................................................. 58 Code Examples A/D Conversion .......................................................... 67 Assigning Prescaler to Timer0.................................... 47 Assigning Prescaler to WDT....................................... 47 Indirect Addressing..................................................... 20 Initializing PORTA ...................................................... 31 Initializing PORTC ...................................................... 40 Saving Status and W Registers in RAM ................... 112 Ultra Low-Power Wake-up Initialization...................... 34 Code Protection ................................................................ 117 Comparator Module ............................................................ 53 Comparator Voltage Reference (CVREF) Associated Registers.................................................. 61 Effects of a Reset ....................................................... 60 Response Time .......................................................... 60 Comparator Voltage Reference (CVREF)............................ 59 Accuracy/Error............................................................ 59 Configuring ................................................................. 59 Specifications ........................................................... 152 Comparators Associated Registers.................................................. 61 C2OUT as T1 Gate............................................... 50, 58 Configurations ............................................................ 56 Effects of a Reset ....................................................... 60 Interrupts .................................................................... 58 Operation.................................................................... 54 Operation During Sleep .............................................. 60 Outputs ....................................................................... 58 Response Time .......................................................... 60 Specifications ........................................................... 152 Synchronizing C2OUT w/ Timer1 ............................... 58 CONFIG Register ............................................................. 100 Configuration Bits ..................................................... 100, 101 CPU Features ..................................................................... 99
B
BAUDCTL Register ............................................................. 80 Block Diagrams A/D .............................................................................. 63 Analog Input Model ............................................... 55, 68 Comparator 1 .............................................................. 57 Comparator 2 .............................................................. 57 Comparator Modes ..................................................... 56 Comparator Voltage Reference (CVREF) .................... 59 Fail-Safe Clock Monitor (FSCM) ................................. 28 In-Circuit Serial Programming Connections.............. 117 Interrupt Logic ........................................................... 110 MCLR Circuit............................................................. 103 On-Chip Reset Circuit ............................................... 102 PIC16F688.................................................................... 5 RA1 Pins ..................................................................... 36 RA2 Pin....................................................................... 37 RA3 Pin....................................................................... 37 RA4 Pin....................................................................... 38 RA5 Pin....................................................................... 38 RC0 and RC1 Pins...................................................... 40 RC2 and RC3 Pins...................................................... 41 RC4 Pin....................................................................... 41 RC5 Pin....................................................................... 42 Resonator Operation................................................... 23 System Clock .............................................................. 21 Timer1......................................................................... 49
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 165
PIC16F688
D
Data EEPROM Memory ...................................................... 71 Associated Registers .................................................. 75 Reading....................................................................... 73 Writing ......................................................................... 73 Data Memory......................................................................... 7 DC Characteristics Extended and Industrial ............................................ 142 Industrial and Extended ............................................ 137 Demonstration Boards PICDEM 1 ................................................................. 132 PICDEM 17 ............................................................... 133 PICDEM 18R ............................................................ 133 PICDEM 2 Plus ......................................................... 132 PICDEM 3 ................................................................. 132 PICDEM 4 ................................................................. 132 PICDEM LIN ............................................................. 133 PICDEM USB............................................................ 133 PICDEM.net Internet/Ethernet .................................. 132 Development Support ....................................................... 129 Device Overview ................................................................... 5 CLRWDT .................................................................. 122 COMF ....................................................................... 122 DECF ........................................................................ 122 DECFSZ ................................................................... 123 GOTO ....................................................................... 123 INCF ......................................................................... 123 INCFSZ..................................................................... 123 IORLW ...................................................................... 124 IORWF...................................................................... 124 MOVF ....................................................................... 123 MOVLW .................................................................... 124 MOVWF .................................................................... 124 NOP .......................................................................... 124 RETFIE ..................................................................... 125 RETLW ..................................................................... 125 RETURN................................................................... 125 RLF ........................................................................... 126 RRF .......................................................................... 126 SLEEP ...................................................................... 126 SUBLW ..................................................................... 126 SUBWF..................................................................... 126 SWAPF ..................................................................... 127 XORLW .................................................................... 127 XORWF .................................................................... 127 Summary Table ........................................................ 120 INTCON Register................................................................ 15 Internal Oscillator Block INTOSC Specifications ................................................... 146 Internal Sampling Switch (Rss) Impedance........................ 68 Interrupts........................................................................... 109 A/D.............................................................................. 67 Associated Registers ................................................ 111 Comparators ............................................................... 58 Context Saving ......................................................... 112 Interrupt-on-Change ................................................... 33 PORTA Interrupt-on-Change .................................... 110 RA2/INT .................................................................... 110 TMR0 ........................................................................ 110 TMR1 .......................................................................... 50 INTOSC Specifications ..................................................... 146 IOCA Register..................................................................... 33
E
EEADR Register ................................................................. 72 EEADR Registers................................................................ 71 EEADRH Registers ............................................................. 71 EECON1 Register ......................................................... 71, 72 EECON2 Register ............................................................... 71 EEDAT Register.................................................................. 72 Electrical Specifications .................................................... 135 Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART)................................ 77 Errata .................................................................................... 3 Evaluation and Programming Tools .................................. 133
F
Fail-Safe Clock Monitor....................................................... 28 Fail-Safe Mode............................................................ 29 Reset and Wake-up from Sleep .................................. 29 Firmware Instructions........................................................ 119 Flash Program Memory....................................................... 71 Fuses. See Configuration Bits
G
General Purpose Register File.............................................. 7
L
Load Conditions................................................................ 144
I
I/O Ports .............................................................................. 31 ID Locations ...................................................................... 117 In-Circuit Debugger ........................................................... 118 In-Circuit Serial Programming (ICSP) ............................... 117 Indirect Addressing, INDF and FSR Registers.................... 20 Instruction Format ............................................................. 119 Instruction Set ................................................................... 119 ADDLW ..................................................................... 121 ADDWF ..................................................................... 121 ANDLW ..................................................................... 121 ANDWF ..................................................................... 121 BCF ........................................................................... 121 BSF ........................................................................... 121 BTFSC ...................................................................... 122 BTFSS ...................................................................... 121 CALL ......................................................................... 122 CLRF......................................................................... 122 CLRW ....................................................................... 122
M
MCLR................................................................................ 103 Internal...................................................................... 103 Memory Organization ........................................................... 7 Data .............................................................................. 7 Program ........................................................................ 7 Migrating from other PICmicro Devices ............................ 163 MPLAB ASM30 Assembler, Linker, Librarian ................... 130 MPLAB ICD 2 In-Circuit Debugger ................................... 131 MPLAB ICE 2000 High-Performance Universal In-Circuit Emulator ................................................... 131 MPLAB ICE 4000 High-Performance Universal In-Circuit Emulator ................................................... 131 MPLAB Integrated Development Environment Software .................................................................. 129 MPLAB PM3 Device Programmer .................................... 131 MPLINK Object Linker/MPLIB Object Librarian ................ 130
DS41203B-page 166
Preliminary
2004 Microchip Technology Inc.
PIC16F688
O
OPCODE Field Descriptions ............................................. 119 OPTION_REG Register ................................................ 14, 46 OSCCON Register ........................................................ 10, 30 Oscillator Associated Registers .................................................. 30 Oscillator Configurations ..................................................... 21 Oscillator Specifications .................................................... 145 Oscillator Start-up Timer (OST) Specifications............................................................ 149 Oscillator Switching Fail-Safe Clock Monitor............................................... 28 Two-Speed Clock Start-up.......................................... 27
R
RA3/MCLR/VPP .................................................................. 37 RCREG............................................................................... 89 RCSTA Register ................................................................. 79 SPEN Bit..................................................................... 77 Read-Modify-Write Operations ......................................... 119 Register RCREG Register ........................................................ 84 Registers ADCON0 (A/D Control 0)............................................ 66 ADCON1 (A/D Control 1)............................................ 66 ANSEL (Analog Select) .............................................. 65 BAUDCTL (Baud Rate Control).................................. 80 CALIB (Calibration Word) ......................................... 101 CMCON0 (Comparator Control 0) .............................. 53 CMCON1 (Comparator Control 1) .............................. 58 CONFIG (Configuration Word) ................................. 100 EEADR (EEPROM Address) ...................................... 72 EECON1 (EEPROM Control 1) .................................. 72 EEDAT (EEPROM Data) ............................................ 72 INTCON (Interrupt Control) ........................................ 15 IOCA (Interrupt-on-change PORTA) .......................... 33 OPTION_REG ...................................................... 14, 46 OSCCON (Oscillator Control)..................................... 30 PCON (Power Control) ............................................. 105 PIE1 (Peripheral Interrupt Enable 1) .......................... 16 PIR1 (Peripheral Interrupt Register 1) ........................ 17 PORTA ....................................................................... 31 PORTC ....................................................................... 43 RCSTA (Receive Status and Control) ........................ 79 Reset Values ............................................................ 107 Reset Values (Special Registers)............................. 108 Special Function Register Map..................................... 8 Special Register Summary ........................................... 9 Status ......................................................................... 13 T1CON (Timer1 Control) ............................................ 51 TRISA (Tri-state PORTA) ........................................... 32 TRISC (Tri-state PORTC)........................................... 43 TXSTA (Transmit Status and Control)........................ 78 VRCON (Voltage Reference Control) ......................... 61 WDTCON (Watchdog Timer Control) ....................... 114 WPUA (Weak Pull-up PORTA)................................... 32 Reset ................................................................................ 102 Revision History................................................................ 163
P
Packaging ......................................................................... 159 Marking ..................................................................... 159 PDIP Details.............................................................. 160 SOIC Details ............................................................. 161 TSSOP Details.......................................................... 162 PCL and PCLATH ............................................................... 19 Computed GOTO........................................................ 19 Stack ........................................................................... 19 PCON Register ................................................................. 105 PICkit 1 Flash Starter Kit................................................... 133 PICSTART Plus Development Programmer ..................... 132 PIE1 Register ...................................................................... 16 Pin Diagram .......................................................................... 2 Pinout Description PIC16F688.................................................................... 6 PIR1 Register...................................................................... 17 PORTA................................................................................ 31 Additional Pin Functions ............................................. 31 Interrupt-on-Change ........................................... 33 Ultra Low-Power Wake-up ............................ 31, 34 Weak Pull-up ...................................................... 31 Associated Registers .................................................. 39 Pin Descriptions and Diagrams................................... 36 RA0 ............................................................................. 36 RA1 ............................................................................. 36 RA2 ............................................................................. 37 RA4 ............................................................................. 38 RA5 ............................................................................. 38 Specifications............................................................ 147 PORTA Register ................................................................. 31 PORTC ............................................................................... 40 Associated Registers ............................................ 30, 43 PA/PB/PC/PD.See Enhanced Universal Asynchronous Receiver Transmitter (EUSART)........................................ 40 Specifications............................................................ 147 PORTC Register ................................................................. 43 Power-Down Mode (Sleep) ............................................... 115 Power-on Reset (POR) ..................................................... 103 Power-up Timer (PWRT) .................................................. 104 Specifications............................................................ 149 Precision Internal Oscillator Parameters........................... 146 Prescaler Shared WDT/Timer0 ................................................... 47 Switching Prescaler Assignment................................. 47 PRO MATE II Universal Device Programmer ................... 131 Product Identification System ........................................... 171 Program Memory .................................................................. 7 Map and Stack .............................................................. 7 Programming, Device Instructions .................................... 119
S
Software Simulator (MPLAB SIM) .................................... 130 Software Simulator (MPLAB SIM30) ................................ 130 SPBRG ............................................................................... 81 SPBRGH ............................................................................ 81 Special Function Registers ................................................... 7 Status Register ................................................................... 13
T
T1CON Register ................................................................. 51 Time-out Sequence .......................................................... 105 Timer0 Associated Registers.................................................. 47 External Clock ............................................................ 46 External Clock Requirements ................................... 150 Interrupt ...................................................................... 45 Operation.................................................................... 45 T0CKI ......................................................................... 46
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 167
PIC16F688
Timer0 Module .................................................................... 45 Timer1 Associated Registers .................................................. 52 Asynchronous Counter Mode ..................................... 52 Reading and Writing ........................................... 52 External Clock Requirements ................................... 150 Interrupt....................................................................... 50 Modes of Operations................................................... 50 Operation During Sleep .............................................. 52 Oscillator ..................................................................... 52 Prescaler ..................................................................... 50 Timer1 Gate Inverting Gate ..................................................... 50 Selecting Source........................................... 50, 58 Synchronizing C2OUT w/ Timer1 ....................... 58 TMR1H Register ......................................................... 49 TMR1L Register .......................................................... 49 Timer1 Module with Gate Control ....................................... 49 Timing Diagrams A/D Conversion ......................................................... 154 A/D Conversion (Sleep Mode) .................................. 155 Asynchronous Reception ............................................ 90 Asynchronous Transmission ....................................... 87 Asynchronous Transmission (Back to Back) .............. 87 Auto Wake-up Bit (WUE) During Sleep ...................... 91 Automatic Baud Rate Calculator ................................. 85 Auto-Wake-up Bit (WUE) During Normal Operation ... 91 Brown-out Detect (BOD) ........................................... 148 Brown-out Detect Situations ..................................... 104 CLKOUT and I/O....................................................... 147 Comparator Output ..................................................... 54 External Clock ........................................................... 145 Fail-Safe Clock Monitor (FSCM) ................................. 29 INT Pin Interrupt........................................................ 111 Reset, WDT, OST and Power-up Timer ................... 148 Send Break Character Sequence ............................... 92 Synchronous Reception (Master Mode, SREN) ......... 95 Synchronous Transmission......................................... 93 Synchronous Transmission (Through TXEN) ............. 94 Time-out Sequence................................................... 106 Case 3............................................................... 106 Timer0 and Timer1 External Clock ........................... 150 Timer1 Incrementing Edge.......................................... 50 Two Speed Start-up .................................................... 28 USART Synchronous Receive (Master/Slave) ......... 151 USART Synchronous Transmission (Master/Slave) . 151 Wake-up from Interrupt ............................................. 116 Timing Parameter Symbology........................................... 144 TMR1H Register ................................................................. 49 TMR1L Register .................................................................. 49 TRISA.................................................................................. 31 TRISA Register ................................................................... 32 TRISC Register ................................................................... 43 Two-Speed Clock Start-up Mode ........................................ 27 TXREG................................................................................ 86 TXSTA Register .................................................................. 78 BRGH Bit .................................................................... 81
U
Ultra Low-Power Wake-up........................................ 6, 31, 34 USART Asynchronous Mode ................................................... 86 12-bit BreakTransmit and Receive ..................... 92 Associated Registers, Receive........................... 90 Associated Registers, Transmit .......................... 88 Auto Wake-up on SYNC Break .......................... 91 Receiver ............................................................. 89 Setting up 9-bit Mode with Address Detect ........ 89 Baud Rate Generator (BRG) Auto Baud Rate Detect....................................... 84 Baud Rate Error, Calculating.............................. 81 Baud Rates, Asynchronous Modes .................... 82 Formulas............................................................. 81 High Baud Rate Select (BRGH Bit) .................... 81 Sampling............................................................. 81 Serial Port Enable (SPEN Bit) .................................... 77 Synchronous Master Mode......................................... 93 Associated Registers, Reception........................ 96 Associated Registers, Transmit .......................... 94 Reception ........................................................... 95 Requirements, Synchronous Receive .............. 151 Requirements, Synchronous Transmission...... 151 Timing Diagram, Synchronous Receive ........... 151 Timing Diagram, Synchronous Transmission... 151 Transmission ...................................................... 93 Synchronous Slave Mode........................................... 97 Associated Registers, Receive........................... 98 Associated Registers, Transmit .......................... 97 Reception ........................................................... 98 Transmission ...................................................... 97
V
Voltage Reference. See Comparator Voltage Reference (CVREF) VRCON Register ................................................................ 61
W
Wake-up Using Interrupts ................................................. 115 Watchdog Timer (WDT).................................................... 113 Associated Registers ................................................ 114 Clock Source ............................................................ 113 Modes ....................................................................... 113 Period ....................................................................... 113 Specifications ........................................................... 149 WDTCON Register ....................................................... 9, 114 WPUA Register................................................................... 32 WWW, On-Line Support ....................................................... 3
DS41203B-page 168
Preliminary
2004 Microchip Technology Inc.
PIC16F688
ON-LINE SUPPORT
Microchip provides on-line support on the Microchip World Wide Web site. The web site is used by Microchip as a means to make files and information easily available to customers. To view the site, the user must have access to the Internet and a web browser, such as Netscape(R) or Microsoft(R) Internet Explorer. Files are also available for FTP download from our FTP site.
SYSTEMS INFORMATION AND UPGRADE HOT LINE
The Systems Information and Upgrade Line provides system users a listing of the latest versions of all of Microchip's development systems software products. Plus, this line provides information on how customers can receive the most current upgrade kits. The Hot Line Numbers are: 1-800-755-2345 for U.S. and most of Canada, and 1-480-792-7302 for the rest of the world. 042003
Connecting to the Microchip Internet Web Site
The Microchip web site is available at the following URL: www.microchip.com The file transfer site is available by using an FTP service to connect to: ftp://ftp.microchip.com The web site and file transfer site provide a variety of services. Users may download files for the latest Development Tools, Data Sheets, Application Notes, User's Guides, Articles and Sample Programs. A variety of Microchip specific business information is also available, including listings of Microchip sales offices, distributors and factory representatives. Other data available for consideration is: * Latest Microchip Press Releases * Technical Support Section with Frequently Asked Questions * Design Tips * Device Errata * Job Postings * Microchip Consultant Program Member Listing * Links to other useful web sites related to Microchip Products * Conferences for products, Development Systems, technical information and more * Listing of seminars and events
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 169
PIC16F688
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 ________
From: Name Company Address City / State / ZIP / Country Telephone: (_______) _________ - _________ Application (optional): Would you like a reply? Device: PIC16F688 Questions: 1. What are the best features of this document? Y N Literature Number: DS41203B FAX: (______) _________ - _________
2. How does this document meet your hardware and software development needs?
3. Do you find the organization of this document easy to follow? If not, why?
4. What additions to the document do you think would enhance the structure and subject?
5. What deletions from the document could be made without affecting the overall usefulness?
6. Is there any incorrect or misleading information (what and where)?
7. How would you improve this document?
DS41203B-page 170
Preliminary
2004 Microchip Technology Inc.
PIC16F688
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 16F: Standard VDD range 16FT: (Tape and Reel) c) PIC16F688-E/P 301 = Extended Temp., PDIP package, 20 MHz, QTP pattern #301 PIC16F688-I/SO = Industrial Temp., SOIC package, 20 MHz
Temperature Range
I E
= =
-40C to +85C -40C to +125C
Package
P SL ST
= = =
PDIP SOIC (Gull wing, 150 mil body) TSSOP(4.4 mm)
Pattern
3-Digit Pattern Code for QTP (blank otherwise)
* JW Devices are UV erasable and can be programmed to any device configuration. JW Devices meet the electrical requirement of each oscillator type.
2004 Microchip Technology Inc.
Preliminary
DS41203B-page 171
WORLDWIDE SALES AND SERVICE
AMERICAS
Corporate Office
2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: 480-792-7627 Web Address: http://www.microchip.com
China - Beijing
Unit 706B Wan Tai Bei Hai Bldg. No. 6 Chaoyangmen Bei Str. Beijing, 100027, China Tel: 86-10-85282100 Fax: 86-10-85282104
Korea
168-1, Youngbo Bldg. 3 Floor Samsung-Dong, Kangnam-Ku Seoul, Korea 135-882 Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934
Singapore
200 Middle Road #07-02 Prime Centre Singapore, 188980 Tel: 65-6334-8870 Fax: 65-6334-8850
China - Chengdu
Rm. 2401-2402, 24th Floor, Ming Xing Financial Tower No. 88 TIDU Street Chengdu 610016, China Tel: 86-28-86766200 Fax: 86-28-86766599
Atlanta
3780 Mansell Road, Suite 130 Alpharetta, GA 30022 Tel: 770-640-0034 Fax: 770-640-0307
Taiwan
Kaohsiung Branch 30F - 1 No. 8 Min Chuan 2nd Road Kaohsiung 806, Taiwan Tel: 886-7-536-4818 Fax: 886-7-536-4803
Boston
2 Lan Drive, Suite 120 Westford, MA 01886 Tel: 978-692-3848 Fax: 978-692-3821
China - Fuzhou
Unit 28F, World Trade Plaza No. 71 Wusi Road Fuzhou 350001, China Tel: 86-591-7503506 Fax: 86-591-7503521
Taiwan
Taiwan Branch 11F-3, No. 207 Tung Hua North Road Taipei, 105, Taiwan Tel: 886-2-2717-7175 Fax: 886-2-2545-0139
Chicago
333 Pierce Road, Suite 180 Itasca, IL 60143 Tel: 630-285-0071 Fax: 630-285-0075
China - Hong Kong SAR
Unit 901-6, Tower 2, Metroplaza 223 Hing Fong Road Kwai Fong, N.T., Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431
Dallas
4570 Westgrove Drive, Suite 160 Addison, TX 75001 Tel: 972-818-7423 Fax: 972-818-2924
EUROPE
Austria
Durisolstrasse 2 A-4600 Wels Austria Tel: 43-7242-2244-399 Fax: 43-7242-2244-393
China - Shanghai
Room 701, Bldg. B Far East International Plaza No. 317 Xian Xia Road Shanghai, 200051 Tel: 86-21-6275-5700 Fax: 86-21-6275-5060
Detroit
Tri-Atria Office Building 32255 Northwestern Highway, Suite 190 Farmington Hills, MI 48334 Tel: 248-538-2250 Fax: 248-538-2260
Denmark
Regus Business Centre Lautrup hoj 1-3 Ballerup DK-2750 Denmark Tel: 45-4420-9895 Fax: 45-4420-9910
China - Shenzhen
Rm. 1812, 18/F, Building A, United Plaza No. 5022 Binhe Road, Futian District Shenzhen 518033, China Tel: 86-755-82901380 Fax: 86-755-8295-1393
Kokomo
2767 S. Albright Road Kokomo, IN 46902 Tel: 765-864-8360 Fax: 765-864-8387
France
Parc d'Activite du Moulin de Massy 43 Rue du Saule Trapu Batiment A - ler Etage 91300 Massy, France Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79
China - Shunde
Room 401, Hongjian Building, No. 2 Fengxiangnan Road, Ronggui Town, Shunde District, Foshan City, Guangdong 528303, China Tel: 86-757-28395507 Fax: 86-757-28395571
Los Angeles
18201 Von Karman, Suite 1090 Irvine, CA 92612 Tel: 949-263-1888 Fax: 949-263-1338
China - Qingdao
Rm. B505A, Fullhope Plaza, No. 12 Hong Kong Central Rd. Qingdao 266071, China Tel: 86-532-5027355 Fax: 86-532-5027205
Germany
Steinheilstrasse 10 D-85737 Ismaning, Germany Tel: 49-89-627-144-0 Fax: 49-89-627-144-44
San Jose
1300 Terra Bella Avenue Mountain View, CA 94043 Tel: 650-215-1444 Fax: 650-961-0286
India
Divyasree Chambers 1 Floor, Wing A (A3/A4) No. 11, O'Shaugnessey Road Bangalore, 560 025, India Tel: 91-80-22290061 Fax: 91-80-22290062
Italy
Via Quasimodo, 12 20025 Legnano (MI) Milan, Italy Tel: 39-0331-742611 Fax: 39-0331-466781
Toronto
6285 Northam Drive, Suite 108 Mississauga, Ontario L4V 1X5, Canada Tel: 905-673-0699 Fax: 905-673-6509
Japan
Benex S-1 6F 3-18-20, Shinyokohama Kohoku-Ku, Yokohama-shi Kanagawa, 222-0033, Japan Tel: 81-45-471- 6166 Fax: 81-45-471-6122
Netherlands
P. A. De Biesbosch 14 NL-5152 SC Drunen, Netherlands Tel: 31-416-690399 Fax: 31-416-690340
ASIA/PACIFIC
Australia
Suite 22, 41 Rawson Street Epping 2121, NSW Australia Tel: 61-2-9868-6733 Fax: 61-2-9868-6755
United Kingdom
505 Eskdale Road Winnersh Triangle Wokingham Berkshire, England RG41 5TU Tel: 44-118-921-5869 Fax: 44-118-921-5820
02/17/04
DS41203B-page 172
Preliminary
2004 Microchip Technology Inc.

▲Up To Search▲

Price & Availability of PIC16FT688-IST

	To Download PIC16FT688-IST Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .