Microcomputer-Analog Converter Software and Hardware Interfacing ISBN 0-672-21540-1

292 Pages·2015·17.99 MB·English

~
21540
1J
TM
-MICROCOMPUTER
ANALOG CONVERTER
SOFTWARE & HARDWARE INTERFACING
rhe Blacksburg Continuing Education Series TM of books provide a laboratory - or experiment-oriented ap
iroach to electronic topics. Present and forthcoming titles in this series include the following:
• The 8080A Bugbook® : Mkrocomputer Interfacing and Programming
• DBUG: An 8080 Interpretive Debugger
• Design of Op-Amp Circuits, With Experiments
• 555 Timer Applications Sourcebook, With Experiments
• Design of Active Filters, With Experiments
• 808018085 Software Design
• Logic & Memory Experiments Using TTL Integrated Circuits (2 Volumes)
• Design of Phase-Locked Loop Circuits. With Experiments
• Interfacing and Scientific Data Communication Experiments
• NCR Data Processing Concepts Course
• NCR Data Communications Concepts
• NCR Basic Electronics Course. With Experiments
• Introductory Experiments in Digital Electronics and 8080A Microcomputer Programming
Interfacing (2 Volumes)
In most cases. thses books provide both text material and experiments. which permit one to demonstrate
and explore the concepts that are covered in the book. These books remain among the very few that pro
vide step-by-step instructions concerning how to learn basic electronic concepts. wire actual circuits. test
microcomputer interfaces. and program computers based upon the popular 8080-type microprocessor
chip. We have found that the books are very useful to the electronic novice who desires to join the "elec·
Ironies revolution." with minimum time and effort.
It is our pleasure to introduce this new book which covers interfacing AID and D/A to microcomputers as
well as the software that is required to control them. Complete hardware schematic diagrams and complete
ly assembled program examples have been included. We have not tried to describe all of the analog/digital
conversion techniques and how they operate. but rather we have concentrated upon the use of
analog/digital converters. in small computer systems. We have chosen commercially available modules and
integrated circuits for use in the examples and in the experiments. The topics of data acquisition systems.
sample-and-hold devices and multiplexer circuits are also covered. The book is aimed at the microcomputer
user~ who is interested in interfacing his computer to "real-world" analog signals for data acquisition. con
trol. display, plotting, etc.
Our books have been well accepted in the United States and abroad. Selected books are now being
translated into German. Italian. Chinese. and Japanese. If you are interested in further details concerning
these translations. contact the series editors. Both domestic and foreign short courses are available in con
junction with the Extension Division at Virginia Polytechnic Institute and State University. Plese write or call
Dr. Linda Leffel, Continuing Education Center. VPI & SU. Blacksburg, VA 24061. Phone [phone].
Short courses on microcomputer interfacing and microcomputer software development are given by
Tychon. Inc .. Blacksburg, VA 24060. For more information on these courses. write or call Dr. Christopher
Titus. at Tychon, phone [phone].
We continue to be interested in identifying other authors who could contribute books to this series. If you
have an interest in writing or publishing such a text. please contact one of the series editors.
Jonathan A. Titus. Christopher A. Titus. David G. Larsen
and Peter R. Rony
"The Blacksburg Group"
Bu1 symbol trademark Nanotnn. Inc .. Blacksbur1. VA 24060
Bqbook is a rqistmd trademark of E & l Instruments. Inc .. Derby, CT 06418
·Microcomputer-Analog
Converter Software
And Hardware Interfacing
by
Jonathan A. Titus Christopher A. Titus
Peter R. Rony David G. Larsen
Originally Published as
Microcomputer-Analog Converter
Software and Hardware Interfacing
With Experiments for 8080A/Z80/8085 Systems
by E&L Instruments, Inc.
Howard W. Sams. & Co., Inc.
4300 WEST 62NO ST. INDIANAPOLIS, INDIANA 46268 USA
Copyright © 1978 by Jonathan A. Titus,. Christopher A.
Titus, Peter R.. Rony, and David G. Larsen
FIRST EDITION
FIRST PRINTING-1978
All rights reserved. Reproduction or use, without
·express permission, of editorial or pictorial content,
in any manner, is prohibited. No patent liability is
assumed with respect to the use of the information
contained herein. While every precaution has been
taken in the preparation of this book, the publisher
assumes no responsibility for errors or omissions.
Neither is any liability assumed for damages resulting
from the use of the information contained herein.
International Standard Book Number: 0-672-21540-1
Library of Congress Catalog Card Number: 78-57201
Printed in the United.states of America.
Preface
Our purpose in writing this book has been to introduce you to the
concepts and techniques of interfacing digital computers to analog
electronic devices. Actually, the ideas presented in this book can
probably be extended to interfaces and programs for many types of
computers. We have concentrated upon interfacing analog-to-digital
and digital-to-analog converters to an 8080/8085-based microcom
puter. The designs and programs are equally applicable to all of the
8080-type microcomputers, the 8080A, 8085, Z80, etc. It has not
been our purpose to detail the inner workings of the analog and
digital converter modules, but rather, to treat them the way we now
treat the integrated-circuit digital electronic devices such as those in
the SN7400 transistor-transistor logic (ITL) family or the CD4000
complementary metal-oxide semiconductor (CMOS) family.
You will not learn how to build analog-to-digital or digital-to
analog converters in this book. We have chosen, instead, to show
you how to use the modules and devices that are already commercially
available. We present many examples of converter interfacing with
complete hardware schematic diagrams and program listings. Perhaps
one of these designs will answer one of your needs with little addi
tional work on your part. H you require something special, we hope
that you will find that the concepts presented are applicable to your
work. H so, we have done our job.
We have assumed that you will be able to condition (amplify, fil
ter, etc.) your analog signals so that they ate compatible with the
A/D converters that we present in the examples, and that you will
be able to use the voltages that are output by the .D/ A converters that
we have used. The topics of signal conditioning, filters, noise, ground
loops, and amplifiers are beyond the scope of this book. We are look
ing forward to presenting thes~ topics in future books.
If you are interested in the internal operation of A/D and DI A
converters, there are two good references available which will help
you understand how they work. These are:
Analog-Digital Converter Notes, D. H. Sheingold, ed.,
Analog Devices, Inc., Norwood, MA 02062, 1977.
Data Conversion Handbook, Donald B. Bruck, Hybrid
Systems Corporation, Burlington, MA 01803, 1974.
In all of the examples, we have tried to use commercially available
converter modules or integrated circuits (chips). There are dozens of
analog/ digital module and device manufacturers, some of whom are
mentioned in the following units or in the appendices. Our choices of
specific manufacturers, or specific modules, were made at random, but
with an eye toward presenting those modules which are easy to use
and which provide a number of interfacing schemes. "
The choke of specific modules does not imply our endorsement
and it should not be taken to mean that these modules may neces
sarily be the best ones for your specific applications.
We have assumed that you have had some experience programming
microcomputers at the assembly language level, and ~hat you are
familiar with the 8080's internal registers and I/0 operations. Both
the memory-mapped and the accumulator I/0 techniques will be dis
cussed, although we tend to favor the accumulator I/O technique be
cause of its simplicity. You should be familiar with the use of latches
at output ports, the use of three-state buffers at input ports, and the
use of various decoder circuits for device address decoding. All of the
examples and experiments assume the use of an 8080-based micro
computer with an uninverted, bidirectional data bus.
The program examples in the text and in the experiments are shown
in the byte-:per-line output that is produced by the Tychon EditorI
Assembler (TEA) that was written by Dr. Christopher A. Titus.
We find that it is much easier to read and interpret than the instruc
tion-per"'.line outputs of other assemblers. Although we favor the octal
numbering system, along with the Heath Company and others, the
TEA program can also provide a hexadecimal format. Write to Chris
if you would like more information about TEA.
We have found wide acceptance of our books in formal classes as
well as by individual users, worldwide. Selected books are being
translated into German, Japanese, French, Italian, Chinese and Ma
laysian. If you are interested in further details concerning these trans
lations, or in translating the books into other languages, please con
tact us.
The Blacksburg Continuing Education Series™ continues to ex
pand with additional titles being added in the past few months. A
list of the current series is given inside the front cover of this book.
We continue to be interested in identifying and working with authors
who think that their book ideas would fit into the Blacksburg Continu
ing Education Series. If you have an idea that you are interested in
working on, please contact us here in Blacksburg.
Many of the concepts ·that are presented in this book have been
incorporated into the material taught at seminars that are presented
by Tychon here in Blacksburg. Three courses are currently being
taught: Microprocessor Interfacing (628), Introduction to Assembly
Language Programming for 8080/8085 Processors (685), and Inter
mediate Assembly Language Programming for 8080 I 8085 Processors
( 687). If you are interested in these courses, write to The Course
Director, Tychon, Inc., Box 242, Blacksburg, VA 24060. Courses
are also provided through the Center for Continuing Education and
the Extension Division at Virginia Polytechnic Institute and State
University, Blacksburg, VA. Call Dr. Linda Leffel at [phone]
for further information.
We have received assistance from a number of companies that have
provided information, technical assistance, and permission to repro
duce information from their data sheets and books. We would like to
acknowledge the assistance of ADAC Corporation, Analog Devices,
Inc., Burr-Brown Research Corporation, Data Translation, Inc.,
Datel Systems, Inc., National Semiconductor Corporation, Signetics
Corporation, and Siliconix.
We also greatly appreciate the efforts of Mr. Murray Gallant,
president of E&L Instruments, Inc., and his continuing support in
this writing.
JONATHAN A. TITus, CHRISTOPHER A. TITUS, PETER R. RoNY,
AND DAVID G. LARSEN

Contents
UNIT ·1
INTERFACING DIGITAL-TO-ANALOG CoNVERTERS 9
Introduction to this Unit - Objectives - DIA Converter Outputs
- Generating Analog Outputs - Generating a Voltage Ramp -
Complex Ramp Outputs - Triangular Wave Outputs - Square
Waves and Other Outputs - Data Displays and Outputs - High
Speed CRT Displays With D/A Converters - Interfacing .a lO~Bit
DIA Converter - Memory-Mapped I/O Techniques and D/A Con
verters - Other Digital-to-Analog Converters
UNIT 2
INTERFACING ANALOG-TO-DIGITAL CONVERTERS 47
Introduction to This Unit - Objectives - Analog-to-Digital Con
verters - Software AID Conversion Techniques - Interfacing
AID Converter Modules - Using A/D Converters for Data Acqui
sition - Data-Acquisition Timing - Using the Data - Closing
the Loop-Control Applications
UNIT 3
DuAL-SLOPE ANALOG-TO-DIGITAL CONVERTERS AND
DIGITAL PANEL METERS . 90
Introduction to this Unit - Dual-Slope Analog-to-Digital Con
verters - Digital Panel Meters - Binary-Coded-Decimal Number
ing - Digital Panel Meter Considerations - Digital Panel Meter
Interfacing - Handling BCD Data.-Decimal-Point Detection -
Message Software - Software Modifications
UNIT 4
MISCELLANEOUS CoNVERSION TECHNIQUES 11 'i
Introduction to This Unit - Voltage-to-Frequency Converters -
Flash Converters . ·
UNIT. 5
SAMPLE-AND-HOLD CIRCUITS AND MULTIPLEXER DEVICES 125
Introduction to This Unit - Sample-and-Hold Circuits - Using
Sample-and-Hold Devices - Multiplexers - Semiconductor Ana
log Multiplexer Considerations - Miltiplexer Signal Inputs - Mul
tiplexer Applications - Multiplexer Interfacing - Multiplexers and
Sample-and-Hold Systems - Signal Processing - References
UNIT 6
. OF BITS, BOARDS, AND BLACK·BOXES 149
Introduction to this Unit - Black Boxes-Data-Acquisition Modules
-Data-Acquisition Software - Other Data-Acquisition Modules
-Boards: Plug-In Analog-Input and Output - Bits ... and Things
UNIT 7
EXPERIMENTS WITH DIGITAL-TO-ANALOG AND ANALOG-
TO-DIGITAL CONVERTERS . 164
Introduction to the Experiments - Interfacing a 10-Bit Digital-to
Analog Converter - Complex Digital-to-Analog Converter Outputs
- Software-Controlled Ramp AID Converter - A Software-Con
trolled Successive-Approximation AID Converter - A Small Data
Acquisition System - Gate Threshold Measurements Using a DIA
Converter - Using Two 8-Bit DIA Converters; the Burr-Brown
MP-10 Module - Using Two DIA Converters for a Y vs. T Dis
play - Using Two DIA Converters for an X vs. Y Display - Part
Requirements for the Experiments
APPENDIX A. . 226
APPENDIX B . . 235
INDEX. . 284