Table Of ContentIn terface Fundamen tals in Microprocessor-Controlled Systems
International Series on
MICROPROCESSOR-BASED SYSTEMS ENGINEERING
Editor
Professor S. G. TZAFEST AS, National Technical tJniversity, Athens, Greece
Editorial Advisory Board
Professor C. S. CHEN, University of Akron, Akron, Ohio, U.S.A.
Professor F. HARASHIMA, University of Tokyo, Tokyo, Japan
Professor G. MESSINA, University of Catania, Catania, Italy
Professor N. K. SINHA, McMaster University, Hamilton, Ontario, Canada
Professor D. TABAK, Ben Gurion University of the Negev, Beer Sheva, Israel
Interface Fundamentals
in Microprocessor-Controlled
Systems
by
CHRIS 1. GEORGOPOULOS
Professor ofE lectronics,
Department ofE lectrical Engineering,
University ofThrace,
Xanthi, Greece
D. REIDEL PUBLISHING COMPANY
A MEMBER OFTHE KLUWER .. ACADEMIC PUBLISHERS GROUP
DORDRECHT/BOSTON/LANCASTER/TOKYO
library of Congress Cataloging in Publication Data
Georgopoulos, Chris J., 1932-
Interface fundamentals in microprocessor-controlled systems.
(International series on microprocessor-based systems engineering)
Includes index.
1. Computer interfaces. 2. Microprocessors. I. Title.
II. Series.
TK7887.5.G46 1985 004.6'16 85-18462
ISBN-13: 978-94-010-8915-9 e-ISBN-13: 978-94-009-5470-0
DOl: 10.1007/978-94-009-5470-0
Published by D. Reidel Publishing Company,
P.O. Box 17, 3300 AA Dordrecht, Holland
Sold and distributed in the U.S.A. and Canada
by Kluwer Academic Publishers,
190 Old Derby Street, Hingham, MA 02043, U.S.A.
In all other countries, sold and distributed
by Kluwer Academic Publishers Group,
P.O. Box 322, 3300 AH Dordrecht, Holland
All Rights Reserved
© 1985 by D. Reidel Publishing Company, Dordrecht, Holland
Softcover reprint of the hardcover lst edition 1985
No part of the material protected by this copyright notice may be reproduced or utilized
in any form or by any means, electronic or mechanical, including photocopying,
recording or by any information storage and retrieval system,
without written permission from the copyright owner.
To my
w~6e Geo~g~a
and my
daughte~~
Voula and Pamela
ACKNOWLEDGEMENTS
I am indebted to many people for their advice, assistance, and sugges
tions during the development of this book. First, I wish to thank the Ed
itor of Microprocessor Based Systems Engineering Series, Prof. S. Tzafes
tas of University of Patras, Greece, and the Publisher of D. Reidel
Publishing Company, Mr. Ian Priestnall for their encouragement in under
taking the writing of this book. I wish also to express my sincere appre
ciation to several individuals of the Engineering School of the Universi
ty of Thrace, Greece, and especially to Professors D. Papadopoulos and D.
Panagiotakopoulos for their commnents and help in improving the accuracy
and the clarity of certain chapters. I am also indebted to Messrs. G.
Vaidis and V. Bakirtzis for their careful preparation of the drawings and
their general support, and to Mrs. Helen Raftopoulou-Kondili for her
skillful typing of the manuscript.
It is known that an author, writing in a language other than his
native one, is up against a difficult challenge; and in spite of all
his efforts to be linguistically accurate, some blunders in syntax and
in idiomatic structures are bound to occur. I am grateful to a number of
distinguished colleagues and friends from abroad for devoting part of
their valuable time to examine and correct the English, while at the same
time making valuable suggestions and constructive criticism on the sub
stance of the text. They are: Messrs.J. Brandenberger and G. Litsikas
(Raytheon Co.), Dr. and Mrs. D. Rogers (IBM), Mr. J. Quinn (Wang Labs),
Prof. G. Vachtsevanos (Georgia Institute of Technology), Mr. Kaplan (Mo
torola, Inc.), Mr. l.Jhit Cotten (Stromberg-Carlson), Mr. J.D. McDonald
(McGraw-Edison Company), Mrs Cynthia Christie (Christie Associates).
In addition to specific acknowledgement made throughout this book,
and to credit given for each and every source used, special thanks are
herein extended to the editors of various publications and the authors
of many excellent papers on microprocessors and related topics, who have
granted permission for using excerpts from their published work. Many
thanks go also to various manufacturers for their kind permission to re
print certain figures and other information that definitely enhance the
value of this book.
Finally, I am grateful to my wife and two daughters who not only
tolerated my long hours of manuscript work, but, also, encouraged and
assisted me in every possible way. Special thanks go to my daughter Voula,
who, although a graduate Electrical Engineering student at MIT, devoted
a considerable part of her valuable time in proofreading some special
topics of the manuscript and offering numerous suggestions for improve
ments.
PREFACE
There is nO' dDubt that the mioroprooessor (~p) revDlutiDn will cDntinue
intO' the future and many will be required to' specify and integrate mi
crDprDceSSDrs intO' prDducts Dr systems in their Dwn disciplines. There
fDre, well-designed flexible interfaoes will be required to' ensure CDm
patibility with Dther equipments and to' extend design DptiDns. AlthDugh
there are several bDDks Dn micrDcDmputers and micrDprDcessDrs, Dnly few
Df thDse devDte but a small part Dn the impDrtant aspects Df interfaces.
It was with this in mind that the present bDDk was written as a selfcDn
tained vDlume to' be part Df the mDre general series : Mioroprooessors
Based Systems Engineering. It fills an existing gap in technDIDgy, as in
terfaces are the last items to' be seriDusly cDnsidered in the race Df
new technDIDgy, and it deals with the systematic study Df micrDprDcessDr
interfaces and their applicatiDns in many diversified fields.
This bDDk is aimed at engineers in industry and engineering stu
dents whO' need to' learn hDW to' interface micrDprDcessDrs, and hence mi
crDcDmputers and Dther related equipments, to' external digital Dr analDg
devices. It is suitable fDr use as a textbDDk Dr fDr supplementary read
ing, either in an applied undergraduate CDurse in electrical engineering
Dr in the last year Df three-year-curriculum technical cDlleges.
A gDDd pDrtiDn Df this bDDk CDmes frDm the nDtes Df an undergradu
ate Dne-semester CDurse Dn Digital Systems and Mioroprooessors which has
been successfully taught by the authDr to' electrical engineering students,
fDr six years, at the University Df Thrace, Greece. It has alsO' been
taught as an in-hDuse CDurse to' design, applicatiDns, and systems engi
neers, as well as to' prDject managers bDth in EurDpe and USA. The treat
ment is kept as straightfDrward as pDssible, with emphasis Dn variDus
types Df interfacing circuits and applicatiDns examples. A minimal priDr
knDwledge in micrDprDcessDrs and Dther related areas at the undergradu
ate level is assumed, althDugh each chapter cDntains a brief review Dn its
particular tDpic(s). Questions and problems, as well as oited and general
references have been included in each chapter fDr use in a CDurse as a
means to' supplement and expand Dn the material of Dther related subjects.
All micrDprDcessDrs are nDt created equal when it CDmes to' prDvid
ing designers and users with tDDls they need fDr effective systems re
SDurce management and interface cDmpatibilities. And it is precisely here
that this bDDk CDmes as an aid by integrating a variety Df micrDprDcessDr
interface principles and applicatiDns intO' a single handy vDlume. Thevar
iDus tDpics are extensively treated and are presented in a tutDrial man-
nero
The first chapter is a review Df micrDprDcessDr basic structures
with emphasis placed Dn the need fDr special interfaces. Chapter 2 dis
cusses variDus key lDgic families and their capabilities Df interfacing
with micrDprDcessDrs. It is pDinted Dut that in many micrDprDcessDr sys
tems , using a mixture Df IDgic families, a gDDd cDmprDmise can be achieved
x PREFACE
toward obtaining the required system performance. In Chapter 3, after a
brief review of main memory types and their interface requirements, var
ious design examples are considered that can assist in achieving reli
able, efficient, and cost effective memory -UP interface hardware. ChaP
ter 4 concentrates on fundamentals of IC timing circuits and on pro
grammable time interface modules. Chapter 5 starts with a discussion on
periph~ral processors and then concentrates on IC peripheral chips, exam
ining support chips, peripheral adapters, and microprocessor speed com
patibility chips.
Chapter 6 shows how instrumentation manufacturers can develop suit
able microprocessor interfaces using experience gained from other mi
croprocessor-based systems in connection with the flexibility provided
by the IEEE-488 instruments bus • .In Chapter 7, microprocessor interfaces
are discussed in connection with communication standards and protocols,
while in Chapter 8 representative microprocessor interfaces for office
systems are presented including LANs, PABXs, workstations, as well as
peripheral and terminal equipment. Chapter 9 shows how to circumvent cer
tain performance limitations, plaguing microprocessor interfaces in typ
ical signal processing environments with AID and D/A converters, taking
into account the special requirements for compatibility of the devices
involved. Chapter 10 focuses on interfaces with the analog world in au
tomated factories, while Chapter 11 deals with various special interfaces
and bus configurations as they apply to distributed process control sys
tems. Microprocessor interfaces in energy management, heating and motor
control systems constitute the main topics of Chapter 12.
Chapter 13 addresses the importance of using microprocessors as on
board vehicle controllers and discusses various devices that act as in
terfaces between the microprocessor and the automobile's real-world va
riables. Innovative UP interfaces for both new and redesigned medical de
vices are covered in Chapter 14, while Chapter 15 emphasizes the interest
in adopting fiber optic data links to a broad spectrum of applications
including UP-based systems. Chapter 16 is dedicated to interfaces used
in UP-based security and alarm systems where both physical and logical
security are examined. Techniques for interfacing an ATE system, using
a microprocessor, to various devices, instruments, and peripherals is
the subject of Chapter 17. Finally, Chapter 18 deals with the VLSI tech
nology impact on microprocessor interfaces and suggests that UP-based
system designers and users have to consider more than just the processing
element when choosing a microprocessor. They TIllst also look at the processor,
its peripheral chips, and other interfacing elements as they are affected
by VLSI technology.
After reading thi~ book, the reader will gain an appreciation of
the problems and their solutions through a number of design and applica
tions examples in the area of microprocessor interfacing and will estab
lish a foundation for future study or work. The systematic study and
timely introduction of innovative, high performance interfaces in both
the digital and analog territories, will result in better system func
tionality, flexibility, realibility and safety, as well as in lower cost.
Xan;t;h..L, GILe.e.C.e. VIL. ChJU6 J. GeolLgopOulo-6
Au.gLUd. 1985 PM 6e .M OIL
CONTENTS
ACKNOWLEDGEMENTS vii
PREFACE ix
CHAPTER 1 MICROPROCESSOR BASIC STRUCTURES AND THEIR NEEDS
FOR SPECIAL INTERFACES 1
1.1 INTRODUCTION
1.2 SOME USEFUL DEFINITIONS
1.2.1 Definitions Related to ~omputers and Otper Classes
of Machines 2
1.2.2 Interface Definitions 3
1.3 MICROPROCESSOR ARCHITECTURES 4
1.3.1 Basic UP Architecture 4
1.3.2 The Evolution of Four Generations of UPs 5
1.3.3 4-Bit Microprocessors 5
1.3.4 8-Bit Microprocessors 8
143.5 16-Bit Microprocessors 9
1.3.6 32-Bit Microprocessors 11
1.4 MICROPROCESSOR INTERFACE REQUIREMENTS 11
1.4.1 The Importance of Interfacing 16
1.4.2 Interfaces in an Operating System With UP 16
1.4.3 MC68020 Bus Interface 18
CHAPTER 2 UP- LOGIC FAMILIES INTERFACES 23
2.1 INTRODUCTION 23
2.2 BASIC LOGIC FAMILIES AND THEIR INTERFACE CAPABILITIES 23
2.2.1 Interface Devices from TTL Logic Families 23
2.2.2 Interface Devices from ECL Logic Families 26
2.2.3 Interface Devices from NMOS and PMOS Families 26
2.2.4 Interface Devices from CMOS Logic Families 26
2.2.5 The ISO-CMOS Technology 27
2.3 COMPARISON OF CHARACTERISTICS AND CAPABILITIES OF KEY LOGIC
FAMILIES AS THEY MAY APPLY TO MICROPROCESSOR INTERFACING 27
2.3.1 A Rule of Thumb 28
2.3.2 Power Consumption and Speed Comparisons 28
xii CONTENTS
2.3.3 Noise Immunity Comparisons 30
2.4. INTERFACE CONSIDERATIONS WHEN MIXING FAMILIES 31
2.4.1 ECL and TTL Compatibility 31
2.4.2 Bipolar and CMOS Compatibility 31
2.4.3 CMOS to CMOS and Other Logic Families Interfacing 32
2.5 DESIGN AND APPLICATIONS EXAMPLES 33
2.5.1 D- Type Flip-Flop as a UP-Output Device 33
2.5.2 Emulating Co~plex MOS Chips with Shottky TTL ICs 34
CHAPTER 3 ~P- MEMORY INTERFACES 39
3 • 1 INTRODUCTION 39
3.2 BRIEF REVIEW OF MAIN MEMORY TYPES 39
3.3 INTERFACE REQUIREMENTS 40
3.3.1 Timing Requirements for Interface Between RAMs and UPs 41
3.3.2 Interfacing Fundamentals for Direct Memory Access (DMA) 42
3.4 CMOS MEMORY SYSTEM INTERFACE DESIGNS 43
3.4.1 System Timing Factors 44
3.4.2 CMOS Memory Interface 44
3.4.3 HM-6100 CMOS Memory Interface 47
3.4.4 80C48 CMOS Memory Interface 48
3.5 INTERFACING BUBBLE MEMORIES TO UP- BASED SYSTEMS 50
3.5.1 1-Mbit Bubble Memory to UP Interface 50
3.5.2 High Performance Interface Circuitry 51
CHAPTER 4 ~P-TIMING AND SYNCHRONIZATION INTERFACES 57
4.1 INTRODUCTION 57
4.2 FUNDAMENTALS OF IC TIMING CIRCUITS 57
4.2.1 Monolithic Timers 57
4.2.2 Adapted Timing Diagram Conventions 61
4.2.3 Clock Skewing Problems 65
4.3 REAL-TIME CLOCK HARDWARE AND SOFTWARE 65
4.3.1 Simple Version of Real-Time Clock 66
4.3.2 The MC146818 CMOS Real-Time Clock 68
4.4 PROGRAMMABLE TIME INTERFACE MODULES 69
4.4.1 Programmable Timer Module With Integrated Hardware
and Software Capabilities 69
4.4.2 Universal Clock Generator-Clock Stretching 72
