VWGoA - Ex. 1008
`Volkswagen Group of America, Inc. - Petitioner
`1
`
`

`

`
`
`AUTOMOTIVE
`
`ELECTRONICS
`
`HANDBOOK
`
`
`
`Ronald K. Jurgen Editor in Chief
`
`WAREHAM FREELInnm '
`59 mmoa ROAD
`WAREHAMMA 02521
`
`I
`
`McGraw-Hill, Inc.
`
`New York San Francisco Washington. D.C. Auckland Bogota
`Caracas Lisbon London Madrid Mexico City Milan
`Montreal New Delhi San Juan Singapore
`Sydney Tokyo Toronto
`
`2
`
`

`

`LLT
`first
`
`Library of Congress Cataloging-in-Publicalion Data
`
`Automotive electronics handbook t Ronald Jurgen, editor in chief.
`p.
`cm.
`Includes index.
`ISBN 0-07-033189-8
`
`1. Automobiles—Electronic equipment.
`TL272.5.A982
`1994
`629.25'49—dc
`
`I. Jurgen, Ronald K.
`
`94-39724
`CIP
`
`Copyright © 1995 by McGraw—Hill, Inc. All rights reserved. Printed in the
`United States of America. Except as permitted under the United States
`Copyright Act of 1976,11o part of this publication may be reproduced or dis-
`tributed in any form or by any means, or stored in a data base or retrieval
`system, without the prior written permission of the publisher.
`
`234567890 AGWAGM 9098765
`
`ISBN WOT-0331898
`
`The sponsoring editor for this book was Stephen S. Chapman, the editing
`supervisor was Virginia Carroit, and the production supervisor was
`Suzanne W B. Rapcavage. It was set in Times Roman by North Market
`Street Graphics.
`
`Printed and bound by Arcara Graphics/Martinsburg.
`
`McGraw-Hili books are available at special quantity discounts to use as pre-
`miums and sales promotions, or for use in corporate training programs For
`more information, please write to the Director of Special Sales, McGraw-
`Hill, Inn, 11 West 19th Street, New York, NY 10011. Or contact your local
`bookstore.
`
`Information contained in this work has been obtained by McGraw-
`Hill, Inc. from sources believed to be reliable. However, neither
`McGraw-Hill nor its authors guarantee the accuracy or complete-
`ness of any information published herein, and neither McGraw-
`Hill nor its authors shall be responsible for any errors, omissions,
`or damages arising out of use of this information. This work is
`published with the understanding that McGraw-Hill and its authors
`are supplying information, but are not attempting to render engi-
`neering or other professional services.
`if such services are
`required, the assistance of an appropriate professional should be
`
`sought.
`
`This book is printed on acid-free paper.
`
`‘Z’fihé‘o
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`3
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`

`

`
`
`
`
`CONTENTS
`
`Contributors
`
`xv
`
`Preiace
`
`xvii
`
`Part 1
`
`Introduction
`
`
`
`Chapter 1. Introduction Ronald K. Jargon 1.3
`
`1.1 The DawnofaNewEra I 1.3
`
`1.2 The MicrocomputerTakes Center Stage 1’ 1.4
`1.3 Looking to the Future 1 1.5
`References l 1.6
`
`Part 2 Sensors and Actuators
`
`
`
`Chapter 2. Pressure Sensors Randy Frank 2.3
`
`2.1 Automotive Pressure Measurements ! 2.3
`2.2 Automotive Applications for Pressure Sensors ;’ 2.5
`2.3 Technologies for Sensing Pressure 3‘ 2.15
`2.4 Future Pressure—Sensing Developments I 2.23
`Glossary 4" 2.24
`Bibliography 1’ 2.24
`
`
`
`Chapter 3. Linear and Angle Position Sensors Paul Nickson 3.1
`
`3.1 Introduction I 3.]
`3.2 Classification of Sensors f 3.1
`
`3.3 Position SensorTechnologies f 3.2
`3.4 Interfacing Sensors to Coutrol Systems
`Glossary ! 3.1?
`References 3' 3.17
`
`f 3.16
`
`
`
`Chapter 4. Flow Sensors Robert E. flicking 4.1
`
`4.1 Introduction I 4.!
`
`4.2 Automotive Applications of Flow Sensors f 4.1
`4.3 Basic Classification of Flow Sensors ! 4.3
`
`4.4 Applicable Flow MeasurementTechnologies f 4.4
`Glossary I 4.8
`Bibliography 1 4.9
`
`vii
`
`4
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`

`

`viii
`
`CONTENTS
`
`Chapter 5. Temperature, Heat, and Humidity Sensors Randy Frank
`
`5.1
`
`5.1 Temperature, Heat, and Humidity 1 5.1
`5.2 Automotive Temperature Measurements 1 5.5
`5.3 Humidity Sensing andVehicle Performance 1 5.12
`5.4 Sensors forTemperature 1 5.14
`5.5 Humidity Sensors 1 5.21
`5.6 Conclusions 1 5.22
`Glossary 1 5.23
`Bibliography 1 5.23
`
`Chapter 6. Exhaust Gas Sensors Hans-Martin Wiedenmann.
`6.1
`Gerhard Hfitzel, Herald Neumann, Johann Hiegel, and Helmet Weyl
`_______,—__.___———«—————
`
`6.1 Basic Concepts 1 6.1
`6.2 Principles of Exhaust Gas Sensors for Lambda Control
`6.3 Technology of Ceramic Exhaust Gas Sensors 1 6.11
`6.4 Factors Affecting the Control Characteristics of Lambda z 1 Sensors 1 6.14
`6.5 Applications 1 6.18
`6.6 Sensor Principles for Other Exhaust Gas Components 1 6.20
`Bibliography 1 6.2.2
`
`1 6.5
`
`7.1
`Chapter '1. Speed and Acceleration Sensors William C. Dunn
`___—_——_———.-———————-
`
`7.1 Introduction 1 7.1
`7.2 Speed-Sensing Devices 1 7.2
`7.3 Automotive Applications for Speed Sensing 1 7.6
`7.4 Acceleration Sensing Devices 1 7.8
`7.5 Automotive Applications for Accelerometers ( 7.18
`7.6 New Sensing Devices z' 7.22
`7.7 Future Applications 1 7.24
`7.8 Summary 1 7.26
`Glossary 1 7.27
`References 1 7.28
`
`3.1
`Chapter 8. Engine Knock Sensors William G. Wolber
`————_——__——————-
`
`8.1 Introduction 1 8.1
`8.2 The Knock Phenomenon i 8.2
`3.3 Tiechnologies for Sensing Knock 1 8.4
`8.4 Summary 1 8.9
`Glossary 1 8.9
`References 1 8.9
`
`9.1
`Chapter 9. Engine Torque Sensors William G. Wolber
`___————————
`
`9.1 Introduction 1 9.1
`9.2 Automotive Applications ofTorque Measurement
`9.3 Direct'lbrque Sensors 1 9.6
`9.4 Inferred Torque Measurement
`9.5 Summary 1 9.13
`Glossary 1 9.13
`References I 9.14
`
`1 9.8
`
`1 9.3
`
`5
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`

`

`10.1
`Chapter 10. Actuators Kraus Mfifler
`————..——________—_
`
`CONTENTS
`
`ix
`
`10.1 Preface 1 10.1
`
`10.2 Types of Electromechanical Actuators 1 10.2
`10.3 Automotive Actuators 1 10.19
`10.4 Technology for Future Application 1 10.27
`Acknowledgments 1 10.30
`Glossary 1 10.30
`Bibliography 1 10.31
`
`Part 3 Control Systems
`
`11.3
`Chapter 11. Automotive Microcontrollers David s. Boehmer
`-—__._o_—___L——_—_
`
`11.1 Microcontroller Architecture and Performance Characteristics 1 11.3 -
`11.2 Memory 1 11.24
`11.3 Low-Speed Input10utput Ports 1 11.31
`11.4 High-Speed 110 Ports 1 11.36
`11.5 Serial Communications 1 11.41
`11.6 Analog—to-Digital Converter
`1 11.45
`11.7 Failsafe Methodologies 1 11.49
`11.8 FutureTrends 1 11.51
`Glossary 1 11.54
`Bibliography 1 11.55
`
`Chapter 12. Engine Control Gary c. Hirschlieb, Gottfried Schiflei;
`12.1
`and Shari Stat-tier
`————_____——_
`
`12.1 Objectives of Electronic Engine Control Systems 1 12.1
`12.2 Spark Ignition Engines 1 12.5
`12.3 Compression Ignition Engines 1 12.32
`
`Chapter 13. Transmission Control Kurt Neutron Woifgang Bitumen
`1 3.1
`and Werner Brehm
`———+——._.—_—.—_—_—_____
`
`13.1 Introduction 1 13.1
`13.2 System Components 1 13.2
`13.3 System Functions 1 13.7
`13.4 Communications with Other Electronic Control Units
`13.5 Optimization of the Drivetrain 1 13.18
`13.6 Future Developments 1 13.19
`Glossary 1 13.20
`References 1 13.20
`
`1 13.17
`
`14.1
`Chapter 14. Cruise Control Richard Valentine
`_____—______——__
`
`14.] Cruise Control System 1 14.1
`14.2 Microcontroller Requirements for Cruise Control
`14.3 Cruise Control Software 1 14.4
`14.4 Cruise Control Design 1 14.6
`14.5 Future Cruise Concepts 1 14.7
`Glossary 1 14.8
`Bibliography 1 14.8
`
`1 14.3
`
`6
`
`

`

`1
`
`CONTENTS
`
`Chapter 15. Braking Control
`
`Jerry L. Cage
`
`15.1 Introduction 1 15.1
`15.2 Vehicle Braking Fundamentals 1 15.1
`15.3 Antiiock Systems 1 15.8
`15.4 FutureVehicle BrakingSysterns 1 15.14
`Glossary 1 15.15
`References 1 15.16
`
`Chapter 16. Traction Control Armin Czr'ncze!
`
`16.1 Introduction 1 16.1
`
`16.2 Forces Affecting Wheel Traction: Fundamental Concepts 1 16.3
`16.3 Controlled Variables 1 16.5
`16.4 Control Modes 1 16.6
`
`16.5 Traction Control Components 1 16.11
`16.6 Applications on Heavy Commercial Vehicles 1 16.13
`16.7 FutureTrends 1 16.14
`
`Glossary 1 16.14
`Bibliography 1 16.15
`
`Chapter 1'1. Suspension Control Akarsu Yohsuke
`
`17.1 Shock Absorber Control System 1 17.1
`17.2 Hydropneurnatic Suspension Control System 1 17.4
`17.3 Electronic Leveling Control System 1 17.5
`17.4 Active Suspension 1 17.8
`17.5 Conclusion 1 17.17
`
`Glossary 1 17.18
`Nomenclature 1 17.18
`
`Bibliography 1 17.18
`
`Chapter 18. Steering Control Makoro Sara
`
`18.1 Variable-Assist Steering 1 18.1
`18.2 Four—Wheel Steering Systems (4W5)
`Glossary 1 18.33
`References 1 18.33
`
`1 18.15
`
`Chapter 19. Lighting, Wipers. Air Conditioninngoating
`Richard Val'entr'ne
`
`19.1 Lighting Controls 1 19.1
`1 19.9
`19.2 Windshield Wiper Control
`19.3 Air Conditionerfl-Ieater Control
`1 19.15
`19.4 Miscellaneous Load Control Reference 1 19.20
`
`19.5 Future Load Control Concepts 1 19.25
`Glossary 1 19.26
`Bibliography 1 19.27
`
`15.1
`
`16.1
`
`17.1
`
`18.1
`
`19.1
`
`7
`
`

`

`Part 4 Displays and Information Systems
`
`20.3
`Chapter 20. Instrument Panel Displays Ronald K. Jorgen
`—_——‘——-—‘—-—————-———___.
`
`CONTENTS
`
`Ki
`
`20.1 The Evolution to Electronic Displays 1 20.3
`20.2 Vacuum Fluorescent Displays 1 20.3
`20.3 Liquid Crystal Displays 1 20.4
`20.4 Cathode-RayTube Displays 1 20.6
`20.5 Head-up Displays 1 20.6
`20.6 ElectronicAnalog Displays f 20.8
`20.7 Reconfigurable Diaplays .r‘ 20.9
`References 1 20.9
`
`21.1
`Chapter 21. Trip Computers Ronald K. Jargon
`———.—_..______—_—__
`
`21.1 Trip Computer Basics 1 21.1
`21.2 Specific'Irip Computer Designs 1 21.2
`21.3 Conclusion 1' 21.4
`References f 21.6
`
`Chapter 22. On- and Off-Board Diagnostics Wolfgang Bremen
`22.1
`Frieder Heintz, and Robert Huge!
`———E__——_
`
`22.1 Why Diagnostics? l 22.]
`22.2 Orr-Board Diagnostics 1 22.6
`22.3 Off-Board Diagnostics 1 22.7
`22.4 Legislation and Standardization I 22.8
`22.5 Future Diagnostic Concepts 1 22.15
`Glossary 1 22.18
`References 1 22.19
`
`Part 5 Safety, Convenience, Entertainment,
`and Other Systems
`
`
`
`Chapter 23. Passenger Safety and Convenience Bernhard K. Matias 23.3
`
`23.1 Passenger Safety Systems 1 23.3
`23.2 Passenger Convenience Systems 1 23.11
`Glossary 1 23.13
`Bibliography l 23.13
`
`
`
`Chapter 24. Antitheft Systems Shlnlchl Karo 24.1
`
`24.1 Vehicle'I'ireft Circumstances 1 24.1
`24.2 Overview of Antitheft Regulations l 24.2
`24.3 ABasic Antitheft System 1’ 24.3
`
`8
`
`

`

`xii
`
`CONTENTS
`
`Chapter 25. Entertainment Products
`
`Tom Chrapkiewicz
`
`25.1
`
`25.1 Fundamentals ofAudio Systems 1 25.1
`25 .2 A Brief History of Automotive Entertainment
`25.3 Contemporary Audio Systems I 25.5
`25.4 Future'Ircnds 1 25.12
`
`1 25.4
`
`Glossary 1 25.17
`References I 25.18
`
`Chapter 26. Multiplex Wiring Systems Fred Miesterfeld
`
`26.1
`
`26.1 Vehicle Multiplexing 1 26.1
`26.2 EncodingTechniques 1 26.9
`26.3 Protocols 1 26.23
`
`26.4 Summary and Conclusions 1 26.53
`Glossary 1 26.56
`References l 26.64
`
`Part 6 Electromagnetic Interference and Compatibility
`
`Chapter 27. Electromagnetic Standards and Interference
`James R Muccioli
`
`27.3
`
`27.1 SAE Automotive EMC Standards 1 27.3
`27.2 IEEE Standards Related to BMC 1 27.11
`
`2?.3 The Electromagnetic Environment of an Automobile Electronic System I 27.13
`Bibliography 1 27.18
`
`Chapter 28. Electromagnetic Compatibility James P. Muccioli
`
`28.1
`
`28.1 Noise Propagation Modes 1 28.1
`28.2 Cabling f 28.2
`28.3 Components 1 28.4
`28.4 Printed Circuit Board EMC Checklist
`
`1 28.9
`
`28.5 Integrated Circuit Decoupling—A Key Automotive EMI Concern 1 28.10
`28.6 IC Process Size Affects EMC 1 28.14
`
`Bibliography 1 28.19
`
`Part 7 Emerging Technologies
`
`Chapter 29. Navigation Aids and Intelligent Vehicle-Highway Systems Robert L.
`29.3
`French
`
`29.1 Background 1 29.3
`I 29.4
`29.2 Automobile Navigation "Ibchnologies
`29.3 Examples of Navigation Systems I 29.10
`29.4 Other IVHS Systems and Services 1 29.15
`References 1 29.18
`
`9
`
`

`

`Chapter 30. Electric and Hybrid Vehicles George G. Karady, Tracy Blake.
`30.1
`Raymond S. Hobbs, and Donald B. Kamer
`—__.—_—_____—__
`
`CONTENTS
`
`xiii
`
`30.1 Introduction 1' 30.1
`
`30.2 System Description i 30.5
`30.3 Charger and Protection System I 30.6
`30.4 Motor Drive System i 30.8
`30.5 Battery a“ 30.17
`30.6 Vehicle Control and Auxiliary Systems
`30.? Infrastructure 1 30.21
`30.8 Hybrid Vehicles 1 30.23
`Glossary 1 30.24
`References l 30.25
`
`2' 30.19
`
`31.1
`Jeffrey N. Denenberg
`Chapter 31. Noise Cancellation Systems
`——_—___—_——__
`
`31.] Noise Sources 1 31.1
`
`31.2 Applications 1 31.5
`Glossary 2’ 31.10
`Bibliography 1 31.10
`
`32.1
`Chapter 32. Future Vehicle Electronics Randy Frank and Salim Mamie
`——_—_—___—_—__
`
`32.1 Retrospective ! 32.1
`32.2 IC Technology a“ 32.1
`32.3 Other SemiconductorTechnologies I 32.5
`32.4 Enabling the Future ! 32.11
`32.5 Impact on Future Automotive Electronics l 32.15
`32.6 Conclusions 1 32.20
`Glossary 1 32.21
`Bibliography 1' 32.23
`
`Index 1
`
`[.1
`
`1O
`
`10
`
`

`

`
`
`
`
`CONTRIBUTORS
`
`Robert E. Bioking HoneyWeii. Micro Switch Di vision (CHAR 4)
`
`Tracy Blake Arizona State University (CHAR 30)
`
`David S. Boehmer
`
`Intel Corporation (CHAR 1])
`
`Werner Brehm Robert Bosch Gran (CHAR13)
`
`Wolfgang Bramer Robert Bosch GmbH (CHAR 22)
`
`Wolfgang Bullmer Robert Bosch GmbH (CHAR 13)
`
`Jerry L. Cage Aiiied Signal, Inc. (CHAR. 15)
`
`Tom Chrapkiawicz Phiiips Semiconductor (CHAR 25)
`
`Armin Czinozel Robert Bosch GmbH (CHAR 16)
`
`Jeffrey N. Denenberg Noise Canceiiation Technologies, inc. (CHAR 31)
`
`William C. Dunn Motorota Semiconductor Products (CHAR 7)
`
`Randy Frank Motorola Semiconductor Products (CHAPS. 2, 5. 32)
`
`Robert L. French R. L. French &Associates (CHAR 29)
`
`Friedar Heintz Robert Bosch GmbH (CHAR 22)
`
`Gary C. Hirschlieb Robert Bosch GmbH (CHAR 12)
`
`Raymond S. Hobbs Arizona Pubiic Service Company (CHAR 30)
`
`Glrhal'd H6tzel Robert Bosch GmbH (CRAP. 6)
`
`Robert Hugel Robert Bosch GmbH (CHAR 22)
`
`Ronald K. Jurgan Editor (CHAPS. 1. 20. 21)
`
`George G. Kan-adv Arizona State Univeristy (CHAR 30)
`
`Donald B. Karner Electric Transportation Appiication (CHAR. 30)
`
`Shinichi Kata Nissan Motor Co. Ltd. (CHAR 24)
`
`'
`
`Bernhard K. Mattes Robert Bosch GmbH (CHAR 23)
`
`Fred Miestarfeld Chrysler Corporation (CHAR 26)
`
`Salim Momin Motorola Semiconductor Products (CHAR 32)
`
`James P. Muccioli
`
`JASTECH (CHAPS. 27, 28)
`
`Klaus Miiller Robert Bosch Gran (CHAR '10)
`
`Kurt Neuffer Robert Bosch GmbH (CHAR 13)
`
`Harald Neumann Robert Bosch GmbH (CHAR 6)
`
`Paul Niokson Anaiog Devices, Inc. (CHAR 3)
`
`Johann Riegal Robert Bosch Gnth (CHAR 6)
`
`XV
`
`11
`
`11
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`

`

`XVI
`
`CONTRIBUTORS
`
`Makato Sate Honda R&D Co., Ltd. (CHAR 18)
`
`Gottfried Schiller Robert Bosch GmbH (CHAR 12)
`
`Shari Siottlar Robert Bosch GmbH (CHAR 12)
`
`Richard Valantirle Motorola Inc. (CHAPS. 14, 19)
`
`Helmut Weyl Robert Bosch GmbH (CHAR 6)
`
`Halls-Martin Wiedenmann Robert Bosch GmbH (CHAR 6)
`
`William G. Wolber Cummins Electronics Co., Inc. (CHAPS. 8. 9)
`
`Akatsu Yohaulce Nissan Motor Co, Ltd. (CHAR 17)
`
`12
`
`12
`
`

`

`
`
`
`
`PREFACE
`
`Automotive electronics as we know it today encompasses a wide variety of devices and sysv
`terns. Key to them all. and those yet to come, is the ability to sense and measure accurately
`automotive parameters. Equally important at the output is the ability to initiate control
`actions accurately in responSe to commands. In other words, sensors and actuators are the
`heart of any automotive electronics application'l'har is why they have been placed first in this
`handbook where they are described in technical depth. in other chapters, applicationspecific
`discussions of sensors and actuators can be found.
`
`The importance of sensors and actuators cannot be overemphasized. The future growth of
`automotive electronics is arguably more dependent on sufficiently accurate and low-cost sen—
`sors and actuators than on computers, controls, displays, and other technologies. Yet it is those
`nonsensor, nonactuator technologies that are to many engineers the more “glamorous" and
`exciting areas of automotive electronics.
`In the section on control systems, a key in-depth chapter deals with automotive microcon~
`trailers. Without them, all of the controls described in the chapters that follow in that sec—
`tion—engine. transmission, cruise, braking. traction, suspension, steering, fighting, windshield
`wipers, air conditioner/heater-would not be possible. Those controls of course, are key to car
`operation and they have made cars over the years more drivable, safe, and reliable.
`Displays. trip computers, and on- and off-board diagnostics are described in another sec-
`tion, as are systems for passenger safety and convenience, antitheft. entertainment, and multi-
`plex wiring. Displays and trip computers enable the driver to readily obtain valuable
`information about the car’s operation and anticipated trip time. On— and off-board diagnostics
`have of necessity become highly sophisticated to keep up with highly sophisticated electronic
`controls Passenger safety and convenience items and antithef‘t deVices add much to the feel—
`ing of security and pleasure in owning an automobile. Entertainment products are what got
`automotive electronics started and they continue to be in high demand by car buyers And
`multiplex wiring, off to a modest start in production cars, holds great promise for the future in
`reducing the cum bersomc wiring harnesses presently used.
`The section on electromagnetic interference and compatibility emphasizes that interfer—
`ence from a variety of sources, it not carefully taken into account early on. can raise havoc
`with what otherwise would be elegant automotive electronic designs And automotive systems
`themselves, if not properly designed. can cause interference both inside and outside the auto-
`mobile.
`
`In the final section on emerging technologies, some key newer areas are presented:
`
`I Navigation aids and intelligent vehicle—highway systems are of high interest worldwide
`since they hold promise to alleviate many of vehicle-caused problems and frustrations in
`our society.
`
`I While it may be argued that electric vehicles are not an emerging technology, since they
`have been around for many years it certainly is true that they have yet to come into their
`own in any really meaningful way.
`
`I Electronic noise cancellation is getting increasing attention from automobile designers
`seeking an edge over their competitors
`
`xvii
`
`
`
`13
`
`

`

`
`
`xvii]
`
`PREFACE
`
`The final chapter on future vehicle electronics is an umbrella discussion that runs the
`gamut of trends in future automotive electronics hardware and software. It identifies poten-
`tial technology developments and trends for future Systems.
`Nearly every chapter contains its own glossary of terms. This approach. rather than one
`overall unified glossary, has the advantage of allowing terms to be defined in a more applica-
`tion-specific mannerr—tn the context of the subject of each chapter. It should also be noted
`that there has been no attempt in this handbook to cover. except peripherally. purely mechan—
`ical and electrical devices and systems. To do so would have restricted the number of pages
`available for automotive electronics discussions
`Finally, the editor would like to thank all contributors to the handbook and particularly
`two individuals: Otto Holzinger of Robert Bosch (3th in Stuttgart, Germany and Randy
`Frank of Motorola Semiconductor Products in Phoenix, Arizona. Holzinger organized the
`many contributions to this handbook from his company. Frank, in addition to contributing
`two chapters himself and cocontiibuting a third, organized the other contributions from
`Motorola. Without their help. this handbook would not have been possible.
`
`Ronald K. Jurgen
`
`
`
`14
`
`

`

`Fred Miesterfeld
`Chrysler Corporation
`
`
`
`
`
`
`
`
`
`
`CHAPTER 26
`MULTIPLEX WIRING SYSTEMS
`
`
`
`
`
`
`
`
`the same or similar form in a conventionally wired vehicle.
`Class B. A potential multiplex svstem u.
`
`
`
`
`transferred between nodes to eliminate redundant sensors and other system elements The
`nodes in this form of a multiplex systern typically already existed as standalone modules
`
`
`in a conventionally wired vehicle.
`Class C. A potential multiplex system usage where hi
`gh data rate signals, typically asso-
`ciated with real-time control systems, such as eng
`ine controls and antiloek brakes, are sent
`
`
`over the signal bus to facilitate distributed contr
`
`
`0! and to further reduce vehicle wiring.
`
`26.? VEHICLE MULTIPLEXING
`
`‘;
`
`work design can be applied while delivering functional improvements 3
`then this design is the most likely network design to be aCcepted.
`The SAE Vehicle Network for Multi
`plexing and Data Communications (Multiplex) Com~
`mittee has defined‘ three classes of veh
`icle data communication networks:
`
`ta system-cost saving.
`
`‘
`
`i;
`l 2:
`; '- -
`
`
`The Class B network is intended to be
`Class B bus mu
`
`
`
`
`15
`
`

`

`25.2
`
`SAFETY, CONVENIENCE, ENTERTAMTENT.AND OTHER SYSTEMS
`
`26.1.1 Background of Vehicle Network Architectures
`
`A wide variety of network topologies: can be envisioned by network designers, The message
`structure described in this section is very flexible and useful in exchanging information
`between network nodes. The following discussion describes two network architectures which
`are likely configurations that can use this message definition set: a single—network architec—
`ture and a multiple—network architecture.
`The selection would be application—specific and, thus, it is the system designer’s choice as
`to which network architectures to use. It should be noted that the hardware that supports
`these two message structures is generally not interchangeable. It is recommended that care be
`taken in choosing which message definition to use, because the selection is generally irre-
`versible because of hardware limitations.
`
`1. Header for Functional Message Frames
`
`
`I:
`
`ID
`
`Target
`
`Data 1
`
`I
`
`.
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`.
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`.
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`2. Header for Physical Message Frames
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`FIGURE 26.1 Single-byte header protocol.
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`Header Selection. The header field (header) is a one-, two-, or three-byte field within a
`frame and contains information about the message priority, message source, target address,
`message type, and in—frame response. The multiple network architecture is usually associated
`with the single-byte header protocol. Figure 26.1 (1) illustrates the header byte as the message
`identifier (ID), which is primarily used for functional “broadcast”-type messages and implic-
`itly defines all the required information about the message. It is unnecessary to specify the
`source or destination of functional—type messages. Reception becomes the exclusive responsi—
`bility of the receiving node. Figure 26.1 (2) also illustrates header bytes, which are primarily
`used for physical—type messages, and has two bytes: the first is the ID and the second is the tar-
`get address.
`'
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`working for more information on Class A multiplexing considerations.
`
`The single—network architecture is usually associated with the multiple-byte header proto-
`col,shown in Fig. 26.2. The first byte of the frame defines the priority and message types, func-
`tional or physical.
`
`Eriority/Type ‘ Target
`Source
`1 Data 1
`l
`.
`
`.
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`.
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`FIGURE 26.2 Multiple—byte header protocol.
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`Architecture Selection. Consideration must be given by the network designer as to whether
`a single—network architecture or a multiple—network architecture is preferable for an applica-
`tion. For example, a multiple—network architecture could be based on one network optimized
`around data communication (Class B) protocol requirements, and another network opti-
`mized around sensor type (Class A) multiplexing requirements. The Class B network may be
`characterized such that low latency is a significant requirement of the protocol and where the
`short functional type of messages can most effectively be used. A Class A network could han-
`dle the vehicle’s event-driven multiplexing requirements. See the next section on Class A net-
`
`16
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`age
`ion
`ich
`ee—
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`[0-
`JC-
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`MULI‘IPLEX WIRING SYSTEMS
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`25.3
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`Without regard to either the header or architecture selection, in Class B communications
`the network consists of the interconnection of intelligent nodes such as an engine controller.
`a body computer, a vehicle instrument cluster, and other modules. Such a network normally
`does not significantly reduce the base vehicle wiring but provides an intermodule data com~
`munications capability for distributed proceSsing. The data shared between modules may be
`repetitive in nature and sometimes requires handshaking between modules or acknowledg—
`ment of data reception. As a result of handling the repetitive data and response-type data, a
`network can be optimized around functional addressing. Functional addressing sends data on
`the network, which can be received by one or more nodes without regard to the physical loca-
`tion of the module but only by their “interest” in those specific functions. In general, the trans—
`mitting node does not care which, if any, nodes receive the data it is sending. When physical
`addressing is required in a data communications network (Class B), it is usually for vehicle
`maintenance purposes and can be easily handled without reducing network bandwidth.
`The nature of Class A multiplexing requires the interconnection of limited intelligence
`nodes, often simply sensors or actuators. These Class A networks can significantly reduce the
`base vehicle wiring as well as potentially remove redundant sensors from the vehicle. The data
`shared between nodes in this case are generally event—driven in nature. In most vehicles, the
`number of eventalriven signals predominates, but they are only needed infrequently. The
`message to “turn headlamps on," for example, can be easily seen as event-driven. Because
`these messages are infrequent (only sent once when the signal changes} they gen'erally
`require acknowledgment, either within the same message or a separate handshakelresponse
`message.
`The single-network architecture carries both the Class A and Class B messages on one net-
`work and the multiple-byte header has the advantage of having more bits available for use‘in
`assigning message identifiers, priorities, message types, etc. The characteristics of both time—
`critical and event-driven messages must be acconunodated on a message—by-message basis. in
`general, this level of complexity will need the flexibility of the multiple-byte header structure.
`It should be clear that both network architectures must be cost effective for the application
`and the specific nodes on each network.
`The multiple network architecture tends to separate the Clans A messages from the Class
`B messages and optimize each network and node interface for the specific characteristics of
`each network class. The time—critical messages could be exchanged on one network, while the
`event-driven messages are sent on another. For example, the data communication {Class B)
`repetitive messages can be handled on one network and the sensor and control (Class A) mul—
`tiplexing requirements on another network.'l'his architecture requires both networks to work
`together to achieve the total vehicle network requirements. If information is needed between
`the multiple networks, care must be exercised to meet the needs of each of the networks. This
`concept of multiple networks is not limited to two, but can be extended to several separate
`networks if desired.
`
`ClassA Newark. Class A multiplexingr3 is most appropriate for low-speed body wiring and
`control functions. The example most often used to illustrate the benefits of Class A multi-
`plexing is the base exterior lighting circuit. HoWever, this example is the hardest function to
`cost—justify. The base exterior lighting system is extremely simple and very low cost. A multi—
`plex network applied to this lighting system could result in increased wiring complexity and
`cost. Data integrity in the lighting system can he a stringent requirement for Class A multi-
`plexing; e.g., a single—bit error that results in headlights “off“ when they should be “on.” Ade-
`quate data integrity in a Class A multiplex network is a constraint and bit-error checking may
`be required.
`In the future, the results could change if new features, such as low—current switching or
`lamp—outage warning, became a requirement or new lamp technology, such as smart bulbs,
`became a reality. in general, the addition of new features will play a major role as to when and
`how multiplexing will become a cost—effective solution.
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`17
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`26.4
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`SAFETY. CONVENIENCE, ENTERTAINMENT, AND OTHER SYSTEMS
`
`Other Driving Forces The design of vehicles to minimize manufacturing complexity is a
`major force that will lead to architecture partitioning development. The properly developed
`multiplex architecture can be very effective in reducing the number of parts in the assembly
`plants and built-in testability can substantially reduce vehicle build test time.
`Example ClassA Systems. To illustrate how a Class A multiplex network could be used
`to simplify the vehicle wiring situation, consider the vehicle theft alarm system shown in Fig.
`26.3. Although this example does not represent the epitome in theft alarm features, it does
`illustrate the uonmultiplexed condition. The horn actuator and the sensor switches are all
`wired directly to the theft alarm module. The module is then armed by activating the dash arm
`switch. The module can be disarmed by either the driver door key switch, paSsenger door key
`switch, or the trunk key switch. When the module is armed, the horn is sounded when the
`hood, door, or trunk is tampered with.
`
`DRIVER DOOR
`PASSENGER DOOR
`Door Switch
`Door Switch
`
`Key Switch F
`4K9)? Swing-l1
`
`LEFT REAR DOOR
`RIGHT REAR DOOR
`113001: switch
`
`
`olTr-unx Switch
`_
`olTrunk Kay switch
`
`Door Switch I.
`v
`Hood switch I.
`Dash Arm
`I
`switch
`I.
`
`
`
`
`
`_,._'.\..-.-_4.._.._....
`
`'-1
`-.'l.l
`75.
`:‘l
`
`
`
`
`
`FIGURE 26.3 Vehicle theft alarm system.
`
`The vehicle theft alarm system shown in Fig. 26.4 illustrates a near-optimal configuration
`of a Class A network. The sensors and actuators are integrated with the multiplexing elec-
`tronics so that they can communicate over a single wire to the theft alarm module. The inte-
`gration of electronics into the sensors and actuator improve sensor diagnostics because the
`sensor status and condition can be reported back to the controlling module. The integrity of
`the sensor status and condition can be linked to the mechanical operation of the sensor. This
`level of switch integrity cannot be achieved with normal switch—biasing methods. In a theft
`alarm system, there is an added benefit: the sensor condition can be used to set off the alarm
`and foil the tampering of a would—be thief.
`The U0 requirements support T—tap connections. which can be highly automated in the
`production of wiring harnesses, reducing the wire bundle size and eliminating dual comps.
`The configuration also supports the concept of adding sensors or actuators as the option
`requires without changing the theft alarm module configuration to support the optional fea-
`tures. This expandability feature allows the cost of the option to drive the system cost.
`To show how this configuration is flexible and easily expandable, consider the example
`condition in which some versions of theft alarms are built as originally described, but an
`upscaled version is offered as an option in which the unit is armed by the driver locking the
`doors. To support this option, the dash arm switch would be eliminated and the driver door
`lock switch would be configured with the integrated switch multiplex at a different address.
`The same theft alarm module’s software could then reconfigure itself without hardware mod-
`ificattons
`
`There are approximately seven sensors to every actuator in a real vehicle body system.
`This theft alarm system is typical with '10 sensors (switches) to one actuator (horn).
`
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`18
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`

`

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`Doua- Switch
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`MULTIPLEX WIRING SYSTEMS
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`23.5
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`DOOI‘ Switch
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`Kay Sui tch
`
`' arous- Rean noon
`Door Sui bah
`
`
`
`FIGURE 26.4 Multiplexed vehicle theft alarm system.
`
`The sensors and multiplexing electronics can be integrated into the switch corngonent.
`This configuration eliminates separate wiring and mounting of the multiplex module. Some
`component manufacturers have even been working on two wire (signal and ground) sensors
`in which the power to run the sensor has been supplied by the multiplex signal. For an exam—
`ple component, see Sec. 26.3.7. These sensors have been designed to include the multiplex cir—
`cuit integrated with the Hall effect device in the same T092 size package. The multiplexer
`portion is very small and requires approximately 300 logic gates.
`The actuator driver and multiplexer can similarly be integrated into the horn or motor.
`This configuration also reduces wiring and mounting complexity. Actuators normally require
`more powar then sensors and usually require three wires; signal, power, and ground. How-
`ever, some manufacturers are developing a method to eliminate one of these wires by placing
`the signal on the povver wire.
`
`
`
`Class B Data Communications. The vehicle system designer now has many architecture
`partitioning options A prime example is when to integrate many features into a module or
`when to employ a dedicated node. Care must be taken or the partitioning strategy may not
`achieve optimal results. The. issue is mu