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TLC2543 Evaluation Module
User's Guide
1999
Mixed-Signal Products
SLAU002A
IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ("CRITICAL APPLICATIONS"). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER'S RISK. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI's publication of information regarding any third party's products or services does not constitute TI's approval, warranty or endorsement thereof.
Copyright (c) 1999, Texas Instruments Incorporated
How to Use This Manual
Preface
Read This First
About This Manual
This user's guide provides descriptive information about the hardware and software comprising the TLC2543 evaluation module (EVM). The evaluation module includes a TLC2543 12-bit analog-to-digital converter (ADC) and can be used to assist managers and hardware and software engineers in developing 12-bit ADC applications.
How to Use This Manual
This document contains the following chapters:
Chapter 1
Overview
Provides a general description of the TLC2543 EVM
Chapter 2
Hardware Description and Operation
Describes the features of the TLC2543 EVM hardware and provides operating specifications, schematic diagram, connections, layout, and parts
Chapter 3
Board Layout
Contains illustrations of the board layout and layers
Chapter 4
Part Descriptions
Lists and describes the TLC2543 EVM parts.
Chapter 5
Software Program and Flow Charts
Describes the TLC2543 EVM software program and program flowcharts
Read This First
iii
Notational Conventions
Notational Conventions
This document uses the following conventions.
-
Program listings, program examples, and interactive displays are shown in a special typeface similar to a typewriter's. Examples use a bold version of the special typeface for emphasis; interactive displays use a bold version of the special typeface to distinguish commands that you enter from items that the system displays (such as prompts, command output, error messages, etc.). Here is a sample program listing:
0011 0012 0013 0014 0005 0005 0005 0006 0001 0003 0006 .field .field .field .even 1, 2 3, 4 6, 3
Here is an example of a system prompt and a command that you might enter:
C: csr -a /user/ti/simuboard/utilities
-
In syntax descriptions, the instruction, command, or directive is in a bold typeface font and parameters are in an italic typeface. Portions of a syntax that are in bold should be entered as shown; portions of a syntax that are in italics describe the type of information that should be entered. Here is an example of a directive syntax: .asect "section name", address .asect is the directive. This directive has two parameters, indicated by section name and address. When you use .asect, the first parameter must be an actual section name, enclosed in double quotes; the second parameter must be an address.
-
Square brackets ( [ and ] ) identify an optional parameter. If you use an optional parameter, you specify the information within the brackets; you don't enter the brackets themselves. Here's an example of an instruction that has an optional parameter: LALK 16-bit constant [, shift] The LALK instruction has two parameters. The first parameter, 16-bit constant, is required. The second parameter, shift, is optional. As this syntax shows, if you use the optional second parameter, you must precede it with a comma. Square brackets are also used as part of the pathname specification for VMS pathnames; in this case, the brackets are actually part of the pathname (they are not optional).
-
Braces ( { and } ) indicate a list. The symbol | (read as or) separates items within the list. Here's an example of a list: { * | *+ | *- } This provides three choices: *, *+, or *-.
iv
Information About Cautions and Warnings / Related Documentation From Texas Instruments
Unless the list is enclosed in square brackets, you must choose one item from the list.
-
Some directives can have a varying number of parameters. For example, the .byte directive can have up to 100 parameters. The syntax for this directive is: .byte value1 [, ... , valuen ] This syntax shows that .byte must have at least one value parameter, but you have the option of supplying additional value parameters, separated by commas.
Information About Cautions and Warnings
This book may contain cautions and warnings. This is an example of a caution statement. A caution statement describes a situation that could potentially damage your software or equipment.
This is an example of a warning statement. A warning statement describes a situation that could potentially cause harm to you.
The information in a caution or a warning is provided for your protection. Please read each caution and warning carefully.
Related Documentation From Texas Instruments
TLC2543C, TLC2543I 12-Bit Analog-to-Digital Converters With Serial Control and 11 Analog Inputs data sheet (literature number SLAS079C) is included in Appendix A of this book. It contains electrical specifications, available temperature options, general overview of the device, and application information. Microcontroller-Based Data Acquisition Using the TLC2543 12-Bit Serial-Out ADC Application Report (literature number SLAA012) Data Acquisition Circuits Data Book (literature number SLAD001) TSL250, TSL251, TSL252 Light-to-Voltage Optical Sensors data sheet (literature number SOES004C) TLC226x, TLC226xA, TCL226xY Advanced LinCMOS Rail-to-Rail Operational Amplifiers data sheet (literature number SLOS177)
Read This First
v
Running Title--Attribute Reference
TL7726C, TL7726I, TL7726Q Hex Clamping Circuits data sheet (literature number SLAS078B) TL7702B, TL7702Y, TL7705B, TL7705Y Supply Voltage Supervisors data sheet (literature number SLVS037E) CDT Addendum to the TMS370 Family C Source Debugger User's Guide (literature number SPRU133) TMS370 Family EPROM/EEPROM Programming Tool Getting Started Guide (literature number SPNU128) CDT370 Addendum to the TMS370 Family C Source Debugger User's Guide (literature number DB197A) TL1431C, TL1431Q, TL1431Y Precision Programmable References (literature number SLVS062B) TIL311 Hexadecimal Display With Logic (literature number SODS001D)
FCC Warning
This equipment is intended for use in a laboratory test environment only. It generates, uses, and can radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to subpart J of part 15 of FCC rules. This device has been tested and found to comply with the limits for a CISPRII Group 1 and the following directives: EMC Directive 89/336/ECC amending directive 92/31/ECC and 93/68/ECC as per ENV50204: 1995, EN55011: 1995 Class A, EN61000-4-4: 1995, and EN61000-4-3:1994. Operation of this equipment in other environments may cause interference with radio communications, in which case the user at his own expense will be required to take whatever measures may be required to correct this interference.
vi
Running Title--Attribute Reference
Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.1 12-Bit Analog-to-Digital Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.2 Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.3 User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.4 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1-2 1-3 1-4 1-4 1-5 1-5
2
Hardware Description and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 Setup and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.1.1 Power Supply Terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2.1.2 Input/Output Select Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2.1.3 Input Select Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2.1.4 Interface Connector Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 2.2 Microcontroller and Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2.2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2.2.2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 2.2.3 Power Supply Supervisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8 2.3 Sensor Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 2.3.1 Optical Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 2.3.2 Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 2.3.3 Voltage Variable Input (Potentiometer) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 2.3.4 Buffered User Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 2.3.5 Unbuffered Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 2.3.6 Input Voltage Clamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 2.4 Input Reference Voltage Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12 2.4.1 Ratiometric Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12 2.4.2 Absolute Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12 2.5 Grounding Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 2.5.1 Grounding Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 2.5.2 Using a Single Ground Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 2.5.3 A Practical Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 2.6 Power Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15 2.7 Driving the Input of a Switched-Capacitor ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16 Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.2 Board Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Part Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
3
4
Table of Contents
vii
Running Title--Attribute Reference
5
Software Program and Flow Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.1 Software Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 5.2 Flow Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
Figures
1-1 2-1 2-2 2-3 3-1 3-2 3-3 3-4 3-5 5-1 5-2 5-3 5-4 5-5 5-6 Evaluation Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 EVM Board Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Interface Connector Hole Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 Equivalent Input Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16 TLC2543EVM Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solder Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Layer 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Layer 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drill Template . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3-3 3-3 3-4 3-4
Main Program Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8 Initialization Subroutine Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9 Read Input Switch Subroutine Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10 Analog-to-Digital Convert Subroutine Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 Display Subroutine Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13 Delay Subroutine Flow Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-14
Tables
2-1 2-2 2-3 2-4 4-1 EVM Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 Input Select Switch Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Interface Connector Hole Pattern Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 Buffered User Input Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 Part Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
viii
Chapter 1
Overview
The TLC2543 evaluation module (EVM) provides a platform for evaluating the TLC2543 analog-to-digital converter (ADC). For ease of evaluation, the EVM provides for TLC2543 ADC evaluations using an optical sensor, temperature sensor, and variable voltage as inputs. Provisions are available for the user to configure the additional EVM inputs and the system configuration to accommodate other evaluations. This section includes the following topics.
Topic
1.1 1.2
Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Chapter Title--Attribute Reference
1-1
Introduction
1.1 Introduction
The TLC2543 evaluation module (TLC2543EVM) consists of a TLC2543 12-bit ADC interface with a TSL250 optical sensor, a transistor-based temperature sensor, a TL1431 voltage reference, a TLC2264 quad op-amp to provide four analog signal buffers, a TL7726 hex clamping circuit for signal over-voltage protection, a TMS370C712 microcontroller, and three TIL311 hex display characters. The microcontroller reads the user programmed dip switches and communicates with the TLC2543 to select the desired analog input, initiate the conversion process, and transfer the converted data back to the microcontroller. The microcontroller then transforms the data into hex form and transfers the result to the three TIL311 displays. A 74HC244 octal buffer is used as a buffer between the microcontroller and the displays. A TL7705 power supply voltage monitor provides the reset for the processor at power-on or if the power supply voltage drops below the proper operating level. Jumper provisions are made to connect the TLC2543 reference voltage to 5-V power for ratiometric measurements or to an absolute voltage provided by a TL1431 voltage reference device. A connector pattern provides for a user installed interface connector and an uncommitted breadboard area. An external 5-V power supply (4.75 V to 5.25 V at 0.5 A) is required for operation. The TL7726 hex clamping circuit (VZ1) is connected to inputs IN3 through IN8. The TL7726 clamps an input signal voltage in excess of the power supply voltage level to prevent damage to the semiconductor inputs. Signal voltages below 0 V (ground) are clamped to ground. Signal inputs between 5 V and ground are not affected. The TL7726 provides protection for inputs from incidental transients due to static discharge, excessive signals, etc. Transient current protection is limited to 25 mA.
1-2
Description
1.2 Description
This section describes the EVM. A block diagram of the EVM is shown in Figure 1-1.
Figure 1-1.
Evaluation Module Block Diagram
Controller Input Select TL7705B Power Supply Supervisor 4
12-Bit ADC TSL250 Optical Sensor 2N222A Temperature Sensor TLC2264 Voltage Variable Sensor Buffered Inputs Unbuffered Inputs 5V 3 5 3 2 Power GND
1 2
Display TMS370C712 Microcontroller 8 3 5 Buffers 2 Crystal TIL311 Hexadecimal Display
10 kW Potentiometer User Interface (16-Pin) 3 Connector Footprint
5
1
2
TLC2543 12-Bit ADC 2
Reference Select Jumper
Precision Programmable Reference
2 Power
SIG GND NC
5V
Power GND
The EVM consists of the following:
-
12-bit analog-to-digital converter with: Dedicated optical, temperature, and voltage variable inputs Eight user-configurable inputs User-selectable output for ratiometric or absolute voltage measurements Controller with input select and power supply supervisor Three-digit hexadecimal display User-configurable interface
J J J
The EVM functions are described in the following sections.
Overview
1-3
Description
1.2.1
12-Bit Analog-to-Digital Converter
The TLC2543 is a 12-bit, switched-capacitor, successive-approximation ADC. The device has three control inputs, a chip select, an input-output clock, and a serial data in address input that are interconnected to the microcontroller. The TLC2543 has an on-chip 14-channel multiplexer that can select any one of 11 inputs or any one of three internal self-test voltages. At the end of conversion, the end-of-conversion (EOC) output goes high indicating to the microcontroller that the conversion is complete. The microcontroller supplies the serial data address to, and reads the serial digital data from, the TLC2543 ADC.
1.2.1.1
Outputs
At the ADC REF+ and REF- inputs, jumper provisions are made to connect the TLC2543 ADC reference voltage to the 5-V power source that produces ratiometric measurements, or measurements can be made with respect to an absolute voltage provided by a TL1431 voltage reference device.
1.2.1.2
Inputs
The 11 EVM inputs are configured to provide access to the ADC for the following types of conversions:
-
Three dedicated inputs that include: An optical sensor A temperature sensor A variable resistor
J J J J J
Eight additional user-configurable analog inputs: Three buffered inputs by using the TLC2264 operational amplifiers. Five inputs are unbuffered and grounded.
Provisions are made for attaching the eight additional signal lines to the usersupplied interface connector.
1.2.2
Controller
The controller consists of the following:
-
The TMS370C712 microcontroller and crystal The TL7705B power supply voltage monitor The input select switches
1-4
Description
1.2.2.1
Microcontroller and Crystal
The microcontroller reads the user-programmed DIP switches and communicates with the TLC2543 to select the desired analog input, initiates the conversion process, and transfers the converted data back to the microcontroller. The microcontroller then transforms the data into hex form and transfers the result to the display. The crystal generates the clock input for the microcontroller. The microcontroller supplies the TLC2543 ADC clock and the TIL311 display strobes.
1.2.2.2
Power Supply Voltage Monitor
The TL7705B power supply voltage monitor provides a reset for the processor at power-on or when the power supply voltage drops below the proper operating level.
1.2.3
User Interface
Provisions are available for the user to configure the additional EVM inputs and the system configuration to accommodate other evaluations. A connector pattern is provided for the user to install a 16-pin interface connector. A breadboard area is also available on the EVM. The following input and power/ground options are available at the connector interface:
-
Three buffered ADC inputs Five unbuffered ADC inputs Three EVM 5-V power connections Two EVM power ground connections One EVM signal ground connection
Terminals for an external 5-V power supply are provided. An external 5-V power supply (4.75 V to 5.25 V at 0.5 A) is required for operation.
1.2.4
Display
The microcontroller decodes the 12-bit ADC data into hexadecimal three-digit values which activate the three hexadecimal displays. Buffers are used between the microcontroller and the display data input ports and blanking inputs. The three display latch strobes are driven directly from the microcontroller I/O port.
Overview
1-5
1-6
Chapter 2
Hardware Description and Operation
This chapter contains descriptions of the hardware and operation of the TLC2543EVM. This chapter includes the following topics:
Topic
2.1 2.2 2.3 2.4 2.5 2.6 2.7
Page
Setup and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 Sensor Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 Sensor Output Reference Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12 Grounding Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 Power Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15 Driving the Input of a Switched-Capacitor ADC . . . . . . . . . . . . . . . . 2-16
Chapter Title--Attribute Reference
2-1
Setup and Operation
2.1 Setup and Operation
Figure 2-1, a schematic diagram of the EVM, identifies the EVM components and the setup and operating procedures.
Figure 2-1. EVM Board Schematic
5V J1 1 IN3 IN5 IN7 IN9 5V 3 5 7 9 11 13 15 2 4 6 8 10 12 14 16 IN4 IN6 IN8 IN10 2 U1 TSL250 Optical Sensor 3
_ +
TP2
5V 1 1 R9 4.99 k 1 R7 49.9 k 2 2 TP 7 1 2 C5 0.1 F
5V
1
R10 10 k
1 2 5V U2A TLC2264 1 11 1 2 R11 10 k R12 10 k U2B TLC2264 4 TP5 7 11 2 U2C TLC2264 1 2 TP6
R8 49.9 k 2 Temperature Sensor
Q1 2N2222A 1 C4 0.1 F 2 1 2 3 4 5 6 7 8 9 11 12 2 2 AIN0 AIN1 AIN2 AIN3 AIN4 AIN5 AIN6 AIN7 AIN8 AIN9 AIN10
R13 10 k Pot AIN2 Voltage Adjust
3 2
4
+ _
IN6 IN7 IN8 IN9 IN10 VZ1C VZ1A VZ1B 2 2 2
1
1X Input
IN3 5 1 R14 10 k
5 6
+ _
1
1
1
1
1
VZ1D TL7726
1
TL7726
JP1 JP2 JP3 JP12 JP11
2X Input
IN4 6 1 R16 10 k 2
10 9 1 2
4
TP 4 8 1
+ _
11 2 R20 10 k
VZ1E TL7726
1
1
R12 10 k
5V U2D TLC2264 Power Supply Terminals GND
J2 1 2 1 C1 2 100 F
5V
2X Input
IN5 6 1 R17 10 k 2
12 13 1 2
+ _
4 14 11 2
TP5 1 Power GND SI GND
TP1 GND
VZ1F TL7726
1
R15 10 k R16 10 k
C16 C3 C2 C6 C7 C8 C9 C18 0.1 F 0.1 F 0.1 F 10 F 0.1 F 0.1 F 10 F 0.1 F 5V 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2
1
2-2
Setup and Operation
Figure 2-1. EVM Board Schematic (Continued)
5V 5V U5 TL7705B 7 R6 4.99 k 11 C15 0.1 F 5V 20 VCC CS I/O CLK DIN DOUT EOC 15 16 17 18 19 1 1 1 1 1 2 JP9 2 JP5 2 JP6 2 JP7 2 JP4 2 C13 0.1 F 2 3 21 1 2 VCC SENSE 5 RESIN RESET 6 CT RESET REF GND 4 U6 74HC244 7 13 1 C21 2 47 pF R24 1 k 5V 1 R9 4.9 k 2 5V 4 VCC 18 INT3 17 INT2 16 INT1 22 TXXX/CR 21 TXXX 20 TXXX 24 SPICLK 23 SPISIMO 25 SPISOMI 27 RESET 19 NC 5 1 1 C10 2 15 pF 5V 11 U3 TLC2543 1 5V R21 1 k JP10 1 1 2 3 1 3 1 2 2 R22 6.34 k 8 1 C11 2 15 pF 6 A7 A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 3 7 8 9 10 11 13 14 2 1 15 26 28 1 A1 1 A2 4 A3 XTAL1 VSS 12 A4 8 1 12 1 9 BI Y4 6 16 1 14 Y3 Y2 2 18 Y1 U4 TMS370C712 MSB 1 2 3 4 Input Select
8
7
6
5 S1 LSB
1
1
1
1
R1 R1 R1 R1 10 k 210 k 210 k 210 k 2
REF + REF - GND 10
14 13 2 C20 10 F 1 2
Y1 12 MHz
XTAL2/CLKIN
VOC REF V REF Select
U6 74HC244
2
D1 TL1431ACLP
R23 10 k 2
5V 1 VCC
5V 14 VCC
U7 TIL311
5V 1 VCC
5V 14 VCC
U8 TIL311
5V 1 VCC
5V 14 VCC
U9 TIL311
7 4
GND LDP A BCD 3 2 11 12
B1 RDP ST 5
8 10
7 4
GND LDP A BCD 3 2 11 12
B1 RDP ST 5
8 10
7 4
GND LDP A BCD 3 2 11 12
B1 RDP ST 5
8 10
C17 C12 C14 C19 0.1 F 0.1 F 0.1 F 0.1 F 1 2 1 2 1 2 1 2
Y1 Y2 Y3 Y4
BI
Y1 Y2 Y3 Y4
BI
Y1 Y2 Y3 Y4
BI
Hardware Description and Operation
2-3
Setup and Operation
2.1.1
Power Supply Terminals
The power supply terminals (J2) on the EVM, see Figure 2-1, should be connected to a regulated 4.75-V to 5.25-V power supply capable of providing at least 0.5 A.
This evaluation module is designed to have power supplied from an external regulated 5-V power supply. No form of power supply regulation is included on the EVM. Damage to the components can and probably will occur if the voltage exceeds the maximum specified level. Under voltage can cause improper operation.
When the power supply is switched on, the microcontroller is initialized and the displays flash to indicate proper operation. The displays then show the 2- or 3- digit hex value of the voltage generated by the TSL250 optical sensor. The value on the displays varies with the intensity of the light striking the TSL250 sensor (see section 2.3.1, Optical Sensor).
2.1.2
Input/Output Select Switches
The INPUT SELECT switch (S1) sets the binary address (LSB on the right) which selects the desired TLC2543 input (see subsection 2.1.3, Input Select Switch). The EVM is shipped with the settings listed in Table 2-1:
Table 2-1. EVM Default Settings
Function Input select switch (S1) Reference select jumper (JP9) Input jumpers (JP1, JP2, JP3, JP11, JP12) Output jumpers (JP4, JP5, JP6, JP7, JP8) REF- jumper (JP10) Setting 0000 hex (optical sensor selected) REF V Ground Shorted Shorted
Note: The input and output jumpers and the REF- jumper on the EVM are formed by a top-side copper trace on the PCB between two plated through-holes. If desired, the trace can be carefully cut to remove the jumper. The twothrough-holes allow the user to restore the jumper with a wire or connector.
2.1.3
Input Select Switch
The four-position DIP switch (S1) labeled INPUT SELECT allows the user to select the desired analog input of the TLC2543 ADC. The software program then uses the onboard SPI interface to communicate with the TLC2543 and make the hexadecimal conversions.
2-4
Microcontroller
2.1.3.1
Binary-to-Hexadecimal Conversion
The bits are read into the processor and output on the three LED displays approximately every 0.5 second. The switch is treated as a hex address command (MSB on left, LSB on right) as listed in Table 2-2:
Table 2-2. Input Select Switch Descriptions
Hex 0h 1h 2h 3h 4h 5h 6h-Ah Bh Ch Dh Eh Fh
Note:
Binary 0000 0001 0010 0011 0100 0101 0110-1010 1011 1100 1101 1110 1111
Function Selected Optical sensor input Temperature sensor input Potentiometer input IN3 buffer input IN4 buffer input IN5 buffer input IN6 through IN10 inputs (Vref input)/2 test -Vref input (ground) test Vref input test Enter power-down mode Fast conversion rate on IN4 input
Typical Response User-controlled light intensity 588h + temperature change User adjusted 000h or user input 000h or user input 000h or user input 000h or user input 800h 000h FFFh Display blank User input
Inputs IN3 through IN10 are made available to a user-supplied connector (see section 2.1.4, Interface Connector Provisions).
2.1.3.2
Fast Conversion Rate
When the INPUT SELECT switch is set to Fh, the EVM operates in a fast conversion rate mode. In this mode, the conversion rate is approximately 30k conversions per second from the IN4 input. The displays are updated once every 20 conversions.
Hardware Description and Operation
2-5
Setup and Operation
2.1.4
Interface Connector Provisions
A PCB footprint is provided for a user-supplied connector to allow easy application of external analog signals. The hole pattern interface connector provided at J1, see Figure 2-2, accepts a standard 8-by-2 set of header posts (such as an AMP 87215-5 or MOLEX 10-89-1161) that can be soldered in place. This arrangement accommodates several different styles of connectors so the user can select the one that best satisfies the system requirements.
Figure 2-2. Interface Connector Hole Pattern
2 J1 1 3 5 7 9 11 13 15 4 6 8 10 12 14 16
Table 2-3 describes the hole-pattern mapping to circuit functions.
Table 2-3. Interface Connector Hole Pattern Descriptions
Hole 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Note:
Circuit Function NC NC IN3 input (buffered with 1 gain) IN4 input (buffered with 2 gain) IN5 input (buffered with 2 gain) IN6 input IN7 input IN8 input IN9 input IN10 input 5V Signal ground (see Note) 5V Power ground 5V Power ground
Hole 12 can be used as a signal ground return to avoid the higher current ground return paths that are associated with a power supply ground.
2-6
Microcontroller
2.2 Microcontroller and Interface
This section provides an overview and describes the operation of the microcontroller and interface function.
2.2.1
Overview
The TLC2543EVM uses a TI TMS370C712 microcontroller to interface with the TLC2543 ADC. The program reads the four-position INPUT SELECT DIP switch to determine which input is selected to be digitized. The program then uses the serial peripheral interface (SPI) to communicate with the TLC2543. Sixteen bits of data (12 significant bits and 4 fill bits) are read into the processor and output on the three LED displays approximately every 0.5 second. A fast mode can also be selected with the INPUT SELECT switch. In this mode, channel four is selected as input and 20 samples are taken at about a 30-kHz rate, data is converted and displayed, and the process is repeated until another input is selected with the switch. A power-down mode, which places the TLC2543 in a power-down mode and blanks the display, can also be selected.
2.2.2
Operation
The TMS370C712 microcontroller (U4) samples the status of the INPUT SELECT switch on ports A4-A7. This sample data, which is sent to the TLC2543 ADC through the SPI ports (SPICLK, SPISIM0, and SPISOMI) determines the specific multiplexer input that is converted. The microcontroller then reads back the converted 12 bits and decodes the data into hexadecimal three-digit values. The hexadecimal data is transferred to the three hexaecimal displays, U7, U8, and U9. Five sections of the 74HC244 octal buffer are used to drive the common-bused TTL inputs of the displays. For all INPUT SELECT positions except Fh, the microcontroller instructs the TLC2543 ADC to perform the analog-to-digital conversions and display the results at a rate of approximately 2 conversions per second. When the INPUT SELECT position is Fh, the microcontroller selects input IN4 and the conversions from the ADC are at a rate of approximately 30-k conversions per second (see section 2.1.3.2, Fast Conversion Rate).
Notes: The following information applies to the TMS370C712 SPI protocol to the TLC2543. The TLC2543 strobes in the command data bits from the microcontroller on the DIN port at the rising edge of the clock pulse on the I/O CLK terminal. The TMS370C712 generates a clock rising edge on the SPICLK port, and at that time while conforming to the SPI interface requirements, the data output on the SPISIM0 port changes to reflect the next serial bit to be transferred.
Overview
2-7
Microcontroller
Notes: Continued Therefore, if the SPICLK output is connected directly to the TLC2543 ADC I/O CLK input, the required data setup time for the data to be present before a rising clock edge is applied cannot be less than 100 ns (see the TLC2543 data sheet). To solve this race condition, a resistor (R24) and capacitor (C21) are provided to delay the rising clock edge. One buffer section of the 74HC244 octal buffer (U6) is used to buffer the delayed clock signal. If only one TLC2543 ADC is being used (as with this EVM), the buffer is not usually required. However, if several TLC2543 devices are being driven in a bus configuration, this buffer is required to provide a proper clock signal into the additional capacitance.
2.2.3
Power Supply Supervisor
The TL7705 power supply supervisor, U5, (see Figure 2-1) monitors the power supply voltage. When power is first applied, a microprocessor reset is held until the power supply voltage exceeds 4.55 V (nominal). The reset is then released and the microprocessor begins operation. If the power supply voltage falls below 4.55 V during normal operation, a reset is activated.
2-8
Sensor Inputs
2.3 Sensor Inputs
The EVM inputs are configured to provide access to the ADC as outlined in Section 1.2.1.2. These inputs are discussed in more detail below.
2.3.1
Optical Sensor
The TSL250 (U1) optical sensor is connected to the AIN0 multiplexer analog input port of the TLC2543 ADC. This sensor converts light intensity to an output voltage ranging from less than 10 mV (dark) to about 3.5 V (at 2 mW/sq cm illumination intensity). The output of the optical sensor can be varied by placing an object such as a dark-colored plastic marker pen cap over the sensor. A practical application such as sorting can be demonstrated by holding similar objects of differing shades within the optical viewing range of the sensor (under a uniform intensity light) and noting the displayed values. A simple optical hood to mask ambient light (e.g., drill a hole in the side of the marker pen cap) provides more uniform results. Note: Office light generated by typical artificial lighting contains high ac line frequency intensity variations not usually perceived by the human eye. These variations are detected by the optical sensor. Since the ADC is commanded to make measurements at random times with respect to the ac line frequency, the converted values appear to be unstable in the lower order bits, even though each individual measurement is accurate. This line frequency light intensity variation can be minimized by using dc power to drive the dominate light source (light-emitting diodes work well) in addition to shielding the sensor from the ac-driven room lighting. An extension of the sorting concept yields a simple color-sorting sensor system. This system requires three optical sensors, each masked by a red, blue, or green optical filter. The individual readings from the three sensors can then be calibrated to the specific color of the object to be identified. For repeatable results, the intensity and color content of the illuminating light source must be uniform.
2.3.2
Temperature Sensor
When a single transistor and the 12-bit A/D conversion range of the TLC2543 ADC are used, the following occurs:
-
A simple temperature sensor is generated The textbook temperature variation of a transistor base-emitter junction The dc temperature instability of a simple 1-transistor amplifier
The 2N2222A transistor (Q1) is connected in a classic feedback amplifier configuration that forces the collector voltage to a base-emitter junction voltage of 2 Vbe. The base-emitter junction (essentially a forward-biased diode) voltage is about 0.7 V at room temperature (25 C) and has a temperature
Hardware Description and Operation
2-9
Sensor Inputs
variation of about -2.2 mV/C. Therefore, at room temperature the collector voltage is approximately 1.4 V with a decrease of approximately 4.4 mV for each degree of temperature increase. If the REF SELECT jumper is set to the onboard reference (REF V) position, the conversion reference is set to approximately 4096 mV or 4.1 V. This setting allows the display to decrement approximately 1 count for each mV or about 4 counts per C of temperature increase. If the ambient room temperature is approximately 25C and human body temperature is approximately 38C, the display should reduce about 52 counts when the transistor is held firmly between two fingers. (For an exact analysis, exact transistor characteristics, absolute reference voltage levels, and exact room and finger temperatures would have to be taken into account.)
2.3.3
Voltage Variable Input (Potentiometer)
The IN2 input is controlled by a potentiometer (R13). One section of the TLC2264 (U2) serves as a buffer/amplifier for the AIN2 TLC2543 input port. When the potentiometer is adjusted over its range, the input voltage changes from 0 V to VCC/2. Since the buffer/amplifier has a gain of 2, the input to the TLC2543 ADC port varies from 0 V to VCC. For ratiometric measurements, the REF SELECT jumper should be set to the VCC position. Then the TLC2543 ADC reference becomes VCC and all A/D conversions are made relative to the value of VCC. The potentiometer output voltage, due to its connection, is also relative to VCC. An A/D conversion of that voltage yields a value proportional to the setting of the potentiometer and independent of the power supply voltage.
2.3.4
Buffered User Inputs
The IN3 input is connected to the TLC2543 input port through unity gain configured buffer/amplifier (one section of the TLC2264, U2). Although providing unity gain (gain = 1), the input signal can only be within approximately 1.5 V (see the common-mode input-voltage range specifications of the TLC2264 ADC) of the power supply voltage to maintain predictable operation. As long as the power supply voltage to the TLC2264 remains at 5 V, this restricts the usable signal input voltage range from 0 V to 3.5 V; however, this range can be acceptable for some input level requirements. The input impedance is dictated by the 10-k value of resistor R14 and can be changed to almost any suitable value due to the extremely high input impedance of the TLC2264. Inputs IN4 and IN5 are connected to the TLC2543 ADC input ports, each through a buffer stage of the TLC2264, and each with a gain of 2. The full output voltage swing of 0 V to 5 V to the ADC inputs is achieved with signal inputs of 0 V to 2.5 V as listed in 2-4.
2-10
Sensor Inputs
Table 2-4. Buffered User Input Descriptions
Input IN3 IN4 IN5 IN6 IN7 IN8 IN9 IN10 Gain
1 2 2
Unbuffered N N N Y Y Y Y Y
Input Range 0 V - 3.5 V (input to ADC is 3.5/5 of full scale) 0 V - 2.5 V 0 V - 2.5 V 0V-5V 0V-5V 0V-5V 0V-5V 0V-5V
2.3.5
Unbuffered Inputs
The IN6-IN10 inputs are connected to ground by the top-side circuit board etch jumpers, JP1, JP2, JP3, JP12, and JP11, respectively. Any etch jumper can be removed by carefully cutting the copper trace between the feedthrough holes at the JP marking, allowing that input to be connected to an external signal. When these unbuffered inputs are used, the TLC2543 ADC requires a low source impedance (see Section 2.7, Driving the Input of a Switched-Capacitor ADC) and input voltage range of 0 V to 5 V to produce a zero-to-full-scale digital output. Ensure that the signal grounds are not improperly connected to the high-current power supply grounds (see Section 2.5, Grounding Considerations).
2.3.6
Input Voltage Clamp
The TL7726 hex clamping circuit (VZ1) is connected to inputs IN3 through IN8. The TL7726 clamps an input signal voltage in excess of the power supply voltage level to prevent damage to the semiconductor inputs. Signal voltages below 0 V (ground) are clamped to ground. Signal inputs between 5 V and ground are not affected. The TL7726 provides protection for inputs from incidental transients due to static discharge, excessive signals, etc. Transient current protection is limited to 25 mA.
Hardware Description and Operation
2-11
Sensor Output Reference Select
2.4 Input Reference Voltage Select
The REF SELECT jumper allows ratiometric measurements (jumper set to VCC) or allows absolute measurements (jumper set to REF V) relative to a voltage reference established by the TL1431 (D1). This voltage reference is programmed by resistors R22 and R23 to a voltage level of approximately 4.1 V.
2.4.1
Ratiometric Measurements
Ratiometric measurements are measurements made relative to the 5-V power supply voltage. If a sensor or input signal voltage is used that varies proportionally to the 5-V power supply voltage (such as the potentiometer R13), then the signal becomes a ratio of the absolute value of the power supply voltage. Therefore, when the reference voltage is connected to 5 V (REF SELECT jumper position at VCC), the TLC2543 tracks the power supply voltage and provides a converted result independent of the power supply voltage variations.
2.4.2
Absolute Measurements
Absolute measurements are required when the input analog signal does not change with the power supply voltage. The optical and temperature sensors are in this category. For these sensors, the REF SELECT jumper is set to the REF V position.
2-12
Grounding Considerations
2.5 Grounding Considerations
This section explains the grounding techniques that should be considered when designing or configuring systems using analog devices such as the ADC.
2.5.1
Grounding Problems
When designing analog circuits that share a ground with digital and high current power supplies, the voltage drop along the high current paths must be taken into account. This voltage drop is a result of the current flowing through the greater-than-zero resistance of the current path, and/or high frequency current transients flowing through the greater-than-zero inductance of a current path. If the signal ground is connected to the power supply ground at a location where excessive power currents may flow through the analog ground, the voltage drop is injected into the signal ground and appears as part of the signal, thus causing an error.
2.5.2
Using a Single Ground Point
For low frequency circuits, usually below 100 kHz, the solution is to establish a single ground point on the PC board and connect all grounds individually to that point (the EVM single ground point is at the GND terminal of the power supply connector). By using this method, currents flowing along any one path to ground do not inject error voltages in any other ground path.
2.5.3
A Practical Approach
As a practical implementation, however, it may not be reasonable to run a separate ground trace for each component that connects to ground. Therefore, the next best approach is to group the higher current grounds (such as the power supply and digital grounds) together and run them to the central PC board ground point, while still maintaining separate ground paths for the analog grounds. An analysis of current flow paths within the analog section gives an indication of which grounded components could be grouped together into a common ground path and which should be kept separate. For instance, on the EVM, it would be reasonable to use a common path for the TLC2543 REF- terminal, the TL1431 anode, and the grounded side of R23. This is because the only significant current flow is through the TL1431 (approximately 1 mA) and is not enough to cause a significant error. (A 1/2 LSB error at a reference voltage of 4.1 V would be approximately 0.5 mV, so the ground trace would have to be in excess of 0.5 to cause such an error.) If all of the input signals are low current, such as the optical sensor (approximately 2 mA), the temperature sensor (approximately 1 mA), and the potentiometer (approximately 0.25 mA), it may be reasonable to use a common ground trace. (As always, wider trace widths are desirable to keep the resistance low.) Whenever high currents are associated with any input signal, always use a separate PC board trace directly to the central ground point location.
Hardware Description and Operation
2-13
Grounding Considerations
Even though the operating current of the TLC2543 is low (2.5 mA maximum), some high speed current transients due to the internal digital switching are present and a separate ground trace is reasonable. Note: Keep the power supply decoupling capacitor as close as possible to the supply pins using a separate ground trace for the decoupling capacitor and the TLC2543 ground pin. If free area is available, or if the PC board is multilayer, a large ground plane may be acceptable to connect all of the analog side ground connections, providing that any one signal ground connection is not carrying a large current. That ground plane should be connected directly to the central ground point without touching any of the digital or power supply ground locations along its path.
2-14
Power Considerations
2.6 Power Considerations
Analyzing the distribution of the digital and analog 5-V current paths on the PCB in a similar manner to the grounds is also a good practice. The designated central power point location is the 5-V terminal of the power supply connector (J2) on the EVM board.
Overview
2-15
Driving the Input of a Switched-Capacitor ADC
2.7 Driving the Input of a Switched-Capacitor ADC
When applying an analog signal to the input of a switched-capacitor ADC such as the TLC2543, care must be taken to provide a low enough impedance to the input terminal to charge the internal capacitor (see Figure 2-3) enough for an accurate conversion during the sampling phase of the converter. The sampling time depends on the period of the I/O clock rate being used to drive the converter and the number of transfer bits commanded. With the maximum I/O clock frequency of 4.1 MHz and a 12-bit transfer mode, the TLC2543 uses eight clock cycles (or approximately 2 s) for the sampling time.
Figure 2-3. Equivalent Input Circuit
Driving Source RS TLC2543 Equivalent Input Circuit R1 VC 1 k VS C1 60 pF (max)
The input equivalent circuit of the TLC2543 looks like a series resistance and a capacitor to ground during sampling and an open circuit during conversion. For accurate operation the input capacitor must be charged to the required accuracy of 1/2 LSB (or more, depending on the required system error budget) during the sampling phase of the ADC cycle. The voltage on capacitor C1 is given by: VC
+ VS 1-e*t TC
(1)
Where: TC = the time constant C1(RS+R1) The final voltage value of VC within 1/2 LSB of VS is given by: V C 1 2 LSB Where: n = the resolution of the converter. Equating equation 1 to equation 2, then: VS
+ VS * VS 2n ) 1
(2)
* VS 2n)1 + VS 1 * e *t TC + TC ln 2n)1
(3)
Therefore, the charging time in terms of the circuit time constants is: t 1 2 LSB (4)
For a 12-bit converter, this would be: tS
+ TC x ln(8192) + 9TC
(5)
The internal capacitance for the TLC2543 is 60 pF maximum and the internal series resistance is 1 k. Therefore, with an I/O clock at 4.1 MHz and a 12-bit
2-16
Driving the Input of a Switched-Capacitor ADC
transfer mode (sample period = 2 s), the time constant should be no more than: 19x2 Therefore, C1(RS So, (RS
ms
+ 0.22 ms
(6)
) R1) + 0.22 ms
(7)
) R1) + 3.67 KW
(8)
Since RS = 1 kW, the source impedance should be less than 2.67 k to stay within 1/2 LSB error. Good design practice dictates that the source impedance be as low as possible, such as the output of an op-amp. However, in an application where fast conversion time is not critical, slow I/O clock rates can allow the driving source impedance to be relatively large.
Hardware Description and Operation
2-17
2-18
Chapter 3
Board Layout
This chapter contains illustrations of the board layout and layers.
Topic
3.1 3.2
Page
Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 Board Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Chapter Title--Attribute Reference
3-1
Board Layout
3.1 Board Layout
Figure 3-1. TLC2543EVM Board Layout
3-2
Board Layers
3.2 Board Layers
Figure 3-2. Solder Mask
Figure 3-3. Layer 1
Hardware Description and Operation
3-3
Board Layers
Figure 3-4. Layer 2 (Bottom Side)
Figure 3-5. Drill Template
3-4
Chapter 4
Part Descriptions
Table 4-1 lists and describes the TLC2543 EVM parts.
Chapter Title--Attribute Reference
4-1
Part Descriptions
Table 4-1. Part Descriptions
Description Capacitors Reference C1 C2, C3, C4, C5, C7, C8, C12, C13, C14, C15, C16, C17, C18, C19 C6, C9, C10, C11 Precision programmable reference Power supply terminals Header and shorting jumper D1 J2 JP9 Quantity 1 14 Value/Type Number 100 F, 16 V aluminum 0.1 F ceramic, Z5U, 0.2-inch
2 2 1 1 1 1 1 16
10 F, 10 V tantalum, 0.2-inch 15 pF ceramic, NPO, 0.2-inch TL1431CLP Terminal block, 2-pos, 5-mm, side entry (OST ED1601) 3-pin header 2-pin jumper 2N2222A (T0-18 metal can) 10 k, 1%, 0.25-W
Temperature sensor Resistors
Q1 R1, R2, R3, R4, R5, R10, R11, R12, R14, R15, R16, R17, R18, R19, R20, R23 R6 R7, R8 R9 R21 R22 R13
1 2 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1
499 49.9 k 4.99 k 1 k 6.34 k 10 k potentiometer, single turn, top adj, 3/8-inch sq (Bourns 3386 P) DIP, 4-pos, gold TSL251 TLC2264 TLC2543 TMS370C712 TL7705B 74HC244 TIL311 TL7726 12 MHz, HC-49/s TLC2543 EVM
Input select switch Optical sensor Rail-to-rail operational amplifiers 12-bit analog-to-digital converter Microcontroller Supply voltage supervisor Octal buffer Hexadecimal display with logic Hex clamping circuits Crystal PCB
S1 U1 U2 U3 U4 U5 U6 U7, U8, U9 VZ1 Y1
4-2
Chapter 5
Software Program and Flow Charts
This chapter lists the software program and provides flow charts for the program and each of the programs subroutines. The following topics are covered:
Topic
5.1 5.2
Page
Software Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 Flow Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
Chapter Title--Attribute Reference
5-1
Software Program
5.1 Software Program
TMS370 Macro Assembler Copyright (c) 1986-1995 adc_evm.asm 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 ;;;;;;;;;;;;;;;;;;;;;;;; ; ; TLC2543 EVALUATION MODULE PROGRAM ; ; VERSION 1.2 8/17/95 ; ; THIS PROGRAM READS A FOUR-POSITION DIP ; SWITCH WHICH IS USED TO SELECT THE INPUT ; SIGNAL CHANNEL TO THE ADC. THE PROGRAM ; THEN SELECTS THIS CHANNEL ON THE ADC AND ; CONVERTS THE ANALOG INPUT TO A 12-BIT ; HEX NUMBER AND OUTPUTS THE RESULTS ON ; 3 7-SEGMENT DISPLAYS. POSITIONS ARE ALSO ; PROVIDED TO PUT THE ADC IN A POWER-DOWN ; MODE AND A FAST MODE (APPROX 26 kHz RATE). ; ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;; ; ; SYSTEM EQUATES ; ;;;;;;;;;;;;;;;;;;;;;;;; ; ; SERIAL PERIPHERAL INTERFACE (SPI) REGISTERS ; SPICCR .EQU P030 ;SPI CONFIG REG SPICTL .EQU P031 ;SPI OPERATION CONTROL REG SPIBUF .EQU P037 ;SPI INPUT BUFFER SPIDAT .EQU P039 ;SPI SERIAL DATA REG SPIPC1 .EQU P03D ;SPI PORT CONTROL REG1 SPIPC2 .EQU P03E ;SPI PORT CONTROL REG2 SPIPRI .EQU P03F ;SPI INTERRUPT CONTROL REG ; ; PORT A AND D REGISTERS ; APORT2 .EQU P021 ;PORT A CONTROL REG ADATA .EQU P022 ;PORT A DATA ADIR .EQU P023 ;PORT A DIRECTION DPORT1 .EQU P02C ;PORT D CONTROL REG1 DPORT2 .EQU P02D ;PORT D CONTROL REG 2 DDATA .EQU P02E ;PORT D DATA DDIR .EQU P02F ;PORT D DIRECTION ; ; TIMER 1 DEFINITIONS ; T1CNTR1 .EQU P040 ;MSB OF COUNTER T1CNTR2 .EQU P041 ;LSB OF COUNTER TC11 .EQU P042 ;MSB OF COMPARE REGISTER TC12 .EQU P043 ;LSB OF COMPARE REGISTER T1CTL1 .EQU P049 ;TIMER 1 CONTROL REG 1 T1CTL2 .EQU P04A ;TIMER 1 CONTROL REG 2 T1CTL3 .EQU P04B ;TIMER 1 CONTROL REG 3 ; ; BIT DEFINITIONS ; Version 5.20 Thu Aug 17 17:20:54 1995 Texas Instruments Incorporated PAGE 1
0030 0031 0037 0039 003d 003e 003f
0021 0022 0023 002c 002d 002e 002f
0040 0041 0042 0043 0049 004a 004b
5-2
Software Program
TMS370 Macro Assembler Copyright (c) 1986-1995 adc_evm.asm 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 2e 31 2e 2e 2e 2e 4a 4b Version 5.20 Thu Aug 17 17:20:54 1995 Texas Instruments Incorporated PAGE 2
6000
6000 6002 6003 6006 6009 600c 600f 6012
5260 fd '8e6014 '8e6056 '8e60ed '8e614d '8e6126 '00f2
6014 6017 601a 601d 6020 6023 6026 6029 602c 602f 6032
f70021 f70f23 f7002c f7002d f7f82f f78030 f70730 f7033d f7223e 720019 72001d
6035 6038
720314 2208
CSBIT .DBIT 3,DDATA ;ADC CHIP SELECT BIT SPIF .DBIT 6,SPICTL ;SPI INTR FLAF DOUT1 .DBIT 5,DDATA ;STROBE FOR DISPLAY 1 DOUT2 .DBIT 6,DDATA ;STROBE FOR DISPLAY 2 DOUT3 .DBIT 7,DDATA ;STROBE FOR DISPLAY 3 DBLANK .DBIT 4,DDATA ;BLANK STROBE RST .DBIT 0,T1CTL2 ;SW TIMER RESET TOUT .DBIT 5,T1CTL3 ;TIMER 1 TIME OUT ; ;;;;;;;;;;;;;;;;;;;;;;;; ; .TEXT 6000H ;START OF PROGRAM ; ;;;;;;;;;;;;;;;;;;;;;;;; ; ; MAIN PROGRAM ; START MOV #60H,B LDSP ;SET STACK POINTER TO 60H CALL INIT ;INITIALIZE SYSTEM ; LOOP CALL READSW ;READ INPUT DIP SWITCH CALL ADC ;DIGITIZE INPUT CALL DISPLAY ;DISPLAY VALUE CALL DELAY ;DELAY .5 SEC JMP LOOP ; ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;; ; ; INIT ; ; THIS ROUTINE INITIALIZES PORTS A AND ; D, SETS UP THE SPI, AND INITIALIZES ; THE DISPLAYS BY FLASHING 8 AND 0 THREE ; TIMES. ; INIT MOV #0,APORT2 ;SET PORT A TO I/O MOV #0FH,ADIR ;SET A4-A7=INPUT, A0-A3 = OUTPUT MOV #0,DPORT1 ;SET PORT D TO I/O MOV #0,DPORT2 MOV #0F8H,DDIR ;SET D3-D7 OUTPUTS ; MOV #80H,SPICCR ;INIT SPI MOV #07H,SPICCR ;SET CLOCK, 8BIT CHAR LEN MOV #03H,SPIPC1 ;SET SPI CLK TO OUTPUT MOV #22H,SPIPC2 ;SET SPISOMI AND SPISIMO TO SPI DATA ; MOV #0,R25 ;CLR CHANNEL REGS MOV #0,R29 ; ; FLASH DISPLAY ; MOV #03,R20 ;SET LOOP CTR TO 3 CYCLES MOV #08H,A ;SET DISPLAY REGS TO 8
Software Program and Flow Charts
5-3
Software Program
TMS370 Macro Assembler Copyright (c) 1986-1995 adc_evm.asm 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 603a 603c 603e 6040 6043 6046 6049 604c 604f 6052 6055 d01a d01b d01c '8e614d 720218 '8e6126 a4102e '8e6126 a3ef2e 'da14eb f9 MOV MOV MOV CALL MOV CALL SBIT1 CALL SBIT0 DJNZ A,R26 A,R27 A,R28 DISPLAY #02H,R24 DELAY DBLANK DELAY DBLANK R20,LOOP1 Version 5.20 Thu Aug 17 17:20:54 1995 Texas Instruments Incorporated PAGE 3
LOOP1
;SET DELAY TO .5 SEC ;BLANK DISPLAY ;TURN OFF BLANK ;JMP BACK IF NOT DONE
6056 6058 6059 605b 605d 605f
8022 b7 230f 1d1d '0601 f9
6060 6062 6065 6068 606a 606b 606d 606f
d01d 720318 '8e6126 8022 b7 230f 1d1d '06ef
6071 6074 6076 6079 607c 607f 6082 6084 6085
7d0e1d '061b a4102e a3f72e f70631 f7ec39 8022 b7 230f
RTS ; ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;; ; ;READSW ; ; THIS ROUTINE READS THE 4 POSITION DIP ; SWITCH FOR THE CHANNEL NUMBER AND SAVES ; IT IN R29. IF 0EH IS SELECTED THE ADC ; IS PLACED IN A POWER DOWN MODE. IF 0FH ; IS SELECTED THE INPUT ON CHANNEL 4 IS ; CONVERTED IN FAST MODE. ADC CHANNEL NUMBER ; IS STORED IN R25. ; ; READSW MOV ADATA,A ;READ SWITCHES SWAP A ;SWAP NIBBLES AND #0FH,A CMP R29,A JNE READ1 ;JMP IF ADC INPUT CHANGED RTS ; ; ADC INPUT CHANGED - WAIT FOR COMPLETE ; READ1 MOV A,R29 ;SAVE IT MOV #03,R24 ;SET DELAY FLAG TO 2 SEC CALL DELAY MOV ADATA,A ;CHECK AGAIN SWAP A AND #0FH,A CMP R29,A JNE READ1 ; ;SEE IF POWER DOWM MODE ; CMP #0EH,R29 JNE READ2 ;JMP IF NOT POWER DOWN SBIT1 DBLANK ;BLANK DISPLAY SBIT0 CSBIT ;ENABLE ADC MOV #06H,SPICTL MOV #0ECH,SPIDAT READ3 MOV ADATA,A ;WAIT FOR CHANGE SWAP A AND #0FH,A
5-4
Software Program
TMS370 Macro Assembler Copyright (c) 1986-1995 adc_evm.asm 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 6087 * 4d001d 608a '02f6 608c a3ef2e 608f '00cf CMP JEQ SBIT0 JMP A,R29 READ3 DBLANK READ1 Version 5.20 Thu Aug 17 17:20:54 1995 Texas Instruments Incorporated PAGE 4
;CLEAR BLANK
6091 6094 6096 6099 609c 609e 60a1 60a4 60a6 60aa 60ad 60af 60b3 60b6 60b7 60b8 60b9 60bc 60bf 60c1 60c4 60c7 60ca 60cd 60cf 60d2 60d5
7d0f1d '0650 a3f72e 720419 224c 721414 f70631 2139 'a74031fc a21537 2139 'a74031fc a21637 ff ff ff 'da14e8 42151a d71a 730f1a 42151b 730f1b 42161c d71c 730f1c '8e614d a4082e
60d8 8022 60da b7 60db 230f 60dd * 4d001d 60e0 '02b4 60e2 *'89ff7b 60e5 f9
60e6 60e9 60ec
421d19 720218 f9
; ; SEE IF FAST MODE ; READ2 CMP #0FH,R29 ;IS IT FAST MODE JNE READ4 RLOOP1 SBIT0 CSBIT ;ENABLE ADC MOV #04H,R25 ;CHANNEL 4 - FAST MODE MOV #4CH,A ;CHANNEL 4,16BITS,MSB 1ST MOV #20,R20 ;DO 20 FAST THEN UPDATE MOV #06H,SPICTL RLOOP2 MOV A,SPIDAT RFLG1 JBIT0 SPIF,RFLG1 ;WAIT FOR DATA MOV SPIBUF,R21 MOV A,SPIDAT RFLG2 JBIT0 SPIF,RFLG2 ;WAIT FOR DATA MOV SPIBUF,R22 NOP ;GIVE TIME FOR NOP ; CONVERSION TO NOP ; COMPLETE DJNZ R20,RLOOP2 ;DISPLAY VALUE MOV R21,R26 SWAP R26 AND #0FH,R26 ;SAVE MSDIGIT IN R26 MOV R21,R27 AND #0FH,R27 ;SAVE MIDDLE DIGIT IN R27 MOV R22,R28 SWAP R28 AND #0FH,R28 ;SAVE LSDIGIT IN R28 CALL DISPLAY SBIT1 CSBIT ;DISABLE ADC ;SEE IF FAST MODE STILL SELECTED MOV ADATA,A ;WAIT FOR CHANGE SWAP A AND #0FH,A CMP A,R29 JEQ RLOOP1 JMP READ1 RTS ; ; SETUP CHANNEL # IN R25 ; READ4 MOV R29,R25 MOV #02,R24 ;SET DELAY TO .5SEC RTS ; ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;; ; ; ADC ;
Software Program and Flow Charts
5-5
Software Program
TMS370 Macro Assembler Copyright (c) 1986-1995 adc_evm.asm 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 ; ; ; ; ADC Version 5.20 Thu Aug 17 17:20:54 1995 Texas Instruments Incorporated PAGE THIS ROUTINE DIGITIZES THE INPUT ON THE CHANNEL SPECIFIED IN R25. THE RESULTS ARE PLACED IN REGISTERS R26, R27, AND R28. 5
60ed 60ef 60f0 60f2 60f4 60f7 60fa 60fc 6100 6103 6105 6109
1219 b7 23f0 240c a3f72e f70631 2139 'a74031fc a21537 2139 'a74031fc a21637
610c 610f 6111 6114 6117 611a 611d 611f 6122 6125
42151a d71a 730f1a 42151b 730f1b 42161c d71c 730f1c a4082e f9
6126 6129 612b 612c 612f 6131 6134 6137 613a 613d 6140 6144 6145
7d0118 '0601 f9 7d0218 '0614 f71642 f7e343 a40749 a4014a a3df4b 'a7204bfc f9 f75b42
MOV R25,A SWAP A AND #0F0H,A ;CHANNEL # IN MS NIBBLE OR #0CH,A ;16 BITS, MSB 1ST, BINARY SBIT0 CSBIT ;ENABLE ADC MOV #06H,SPICTL MOV A,SPIDAT ADCFLG1 JBIT0 SPIF,ADCFLG1 ;WAIT FOR DATA MOV SPIBUF,R21 ;SAVE MSBYTE MOV A,SPIDAT ADCFLG2 JBIT0 SPIF,ADCFLG2 ;WAIT FOR DATA MOV SPIBUF,R22 ;SAVE LSBYTE ; ; SAVE DATA ; MOV R21,R26 SWAP R26 AND #0FH,R26 ;SAVE MSDIGIT IN R26 MOV R21,R27 AND #0FH,R27 ;SAVE MIDDLE DIGIT IN R27 MOV R22,R28 SWAP R28 AND #0FH,R28 ;SAVE LSDIGIT IN R28 SBIT1 CSBIT ;DISABLE ADC RTS ; ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;; ; ; DELAY ; THIS ROUTINE USES TIMER 1 AS ; A GENERAL PURPOSE TIMER TO ; DELAY 0, .5, OR 2 SECONDS. ; R24 IS SET AS FOLLOWS: ; 1 = 0 SEC. ; 2 = 0.5 SEC. ; 3 = 2 SEC. ; DELAY CMP #1,R24 ;SEE IF NO DELAY JNE DELAY1 RTS DELAY1 CMP #2,R24 ;SEE IF 0.5 SEC DELAY JNE DELAY2 MOV #16H,TC11 ;0.5 SEC COMPARE VALUE MOV #0E3H,TC12 DLOOP OR #07H,T1CTL1 ;SET PRESCALER TO 256 OR #1,T1CTL2 ;START COUNTER AT ZERO SBIT0 TOUT ;CLR CMP FLAG DFLAG1 JBIT0 TOUT,DFLAG1 ;WAIT FOR TIMEOUT RTS DELAY2 MOV #5BH,TC11 ;2-SEC COMPARE VALUE
5-6
Software Program
TMS370 Macro Assembler Copyright (c) 1986-1995 adc_evm.asm 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 6148 614b f78d43 '00ea MOV JMP #8DH,TC12 DLOOP Version 5.20 Thu Aug 17 17:20:54 1995 Texas Instruments Incorporated PAGE 6
614d 614f 6152 6154 6157 615a 615c 615f 6161 6164 6167 6169 616c 616e 6171 6174 6175 6176 6177 6178 6179 617a 617b 617c 617d 617e 617f 6180 6181 6182 6183 6184
321a 'aa6175 2122 a3df2e a4202e 321b 'aa6175 2122 a3bf2e a4402e 321c 'aa6175 2122 a37f2e a4802e f9 00 08 04 0c 02 0a 06 0e 01 09 05 0d 03 0b 07 0f
7ffe 7ffe
6000
; ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;; ; ; DISPLAY ; ; THIS ROUTINE DISPLAYS THE HEX ; DIGITS STORED IN REGS R26, R27, ; AND R28. ; DISPLAY MOV R26,B ;OUTPUT LSD MOV *DTBL[B],A MOV A,ADATA SBIT0 DOUT1 ;STROBE IT SBIT1 DOUT1 MOV R27,B ;OUTPUT MIDDLE DIGIT MOV *DTBL[B],A MOV A,ADATA SBIT0 DOUT2 SBIT1 DOUT2 MOV R28,B ;OUTPUT MSD MOV *DTBL[B],A MOV A,ADATA SBIT0 DOUT3 SBIT1 DOUT3 RTS DTBL .BYTE 00H ;0 .BYTE 08H ;1 .BYTE 04H ;2 .BYTE 0CH ;3 .BYTE 02H ;4 .BYTE 0AH ;5 .BYTE 06H ;6 .BYTE 0EH ;7 .BYTE 01H ;8 .BYTE 09H ;9 .BYTE 05H ;A .BYTE 0DH ;B .BYTE 03H ;C .BYTE 0BH ;D .BYTE 07H ;E .BYTE 0FH ;F ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;; .SECT "RESET",7FFEH ;RESET VECTOR ADDR .WORD 6000H ;PROGRAM START ; .END
No Errors,
No Warnings
Software Program and Flow Charts
5-7
Flow Charts
5.2 Flow Charts
The flow charts for the TLC2543 EVM are shown in Figure 5-1 through Figure 5-6.
Figure 5-1. Main Program Flow Chart
TLC2543 EVM Version 1.1 Main Program START
Set up Stack Pointer
Call INIT
Initialization Subroutine (see Figure 5-2)
Call READSW
Read Input Switch Selection (see Figure 5-3)
Call ADC
Convert Analog Input to Digital (see Figure 5-4)
Call DISPLAY
Display Results (see Figure 5-5)
DELAY
Delay (see Figure 5-6)
5-8
Flow Charts
Figure 5-2. Initialization Subroutine Flow Chart
Initialization Subroutine START
Set up Ports, SPI, and Registers
Flash Display 3 Times
RETURN
Software Program and Flow Charts
5-9
Flow Charts
Figure 5-3. Read Input Switch Subroutine Flow Chart
Read Input Switch Selection Subroutine START
Read DIP Switch Setting
Yes Same as Before? Return
1
No
Delay 2 Seconds
Yes Any More Changes?
No
Yes Power-Down Mode Selected?
Blank Display and Power-Down ADC
No 2 Yes Power-Down Mode Still Selected?
No 1
5-10
Flow Charts
Figure 3-3. Read Input Switch Subroutine Flow Chart (Continued)
Read Input Switch Selection Subroutine (continued)
2
Fast Mode Selected?
No Save Channel Number
Yes Return Select Channel 4 and Digitize 20 Times
Display Data
Yes
Fast Mode Still Selected?
No 1
Software Program and Flow Charts
5-11
Flow Charts
Figure 5-4. Analog-to-Digital Convert Subroutine Flow Chart
Convert Analog Input to Digital Subroutine START
Get Channel Number, 16-Bit Data, and MSB First for ADC
Enable ADC
Start Serial Output (SPI)
No
Data Back From ADC?
Yes
Save Data
Start Clock Again for Last 8 Bits
No
Data Back From ADC
Save Data in R26, R27, R28 Disable ADC
Return
5-12
Flow Charts
Figure 5-5. Display Subroutine Flow Chart
Display Results Subroutine START
Get Bit Pattern for LSD
Output Data and Strobe It
Get Bit Pattern for Middle Digit
Output Data And Strobe It
Get Bit Pattern for MSD
Output Data And Strobe It
Return
Software Program and Flow Charts
5-13
Flow Charts
Figure 5-6. Delay Subroutine Flow Chart
Delay Subroutine START
No Delay Selected?
Yes
Return
No
0.5 Second Delay Selected No
Yes
Set up Timer 1 Control Register For 0.5 Second
Set up Timer 1 Control Register For 2 Seconds
No
Timer Timed Out?
Yes Return
5-14

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