FLEXRAY AND ITS APPLICATIONS

Transcription

1 FLEXRAY AND ITS APPLICATIONS

2 FLEXRAY AND ITS APPLICATIONS REAL TIME MULTIPLEXED NETWORK Dominique Paret dp-consulting, Paris, France Translated by Bill Chilcott Fellow of the Institute of Translation and Interpreting Claygate, Esher, UK A John Wiley & Sons, Ltd., Publication

3 This edition first published John Wiley & Sons, Ltd., The original French version published 2011 by Dunod, Paris Registered office John Wiley & Sons Ltd., The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at The rights of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Vector Informatik Gmbh Stuttgart, Vector France SAS Paris and NXP Semiconductors own the copyright to their images in this book. Illustrations by Alain and Ursula Bouteveille-Sanders and Raphaēlle Danet Library of Congress Cataloging-in-Publication Data Paret, Dominique. [FlexRay et ses applications. English] FlexRay and its applications : real time multiplexed network / Dominique Paret. p. cm. Includes bibliographical references and index. ISBN (hardback) 1. FlexRay (Computer network protocol) 2. Motor vehicles Electronic equipment. 3. Motor vehicles Automatic control. 4. Automotive computers. 5. Adaptive control systems. I. Title. TL P dc A catalogue record for this book is available from the British Library. Print ISBN: Typeset in 10/12pt Times-Roman by Laserwords Private Limited, Chennai, India

4 Contents Preface List of Abbreviations xiii xvii Part A SECURE REAL TIME APPLICATIONS 1 Reminders about the CAN Protocol The Limitations of CAN Event-Triggered and Time-Triggered Aspects The Probabilistic Side of CAN The Deterministic Side of Applications 5 2 The TTCAN Protocol TTCAN ISO Session Layer Principle of Operation of TTCAN 8 3 Emergence of X-by-Wire Systems High Throughput and X-by-Wire Redundancy High-Level Application Requirements The Number of Communication Systems is Growing The Electronic Architecture Must be Common to Several Vehicle Platforms Some Things the Architecture of the Communication Network and the Nodes Must Allow High-Level Functional Requirements Speed of Communication Physical Layer Access to and Management of the Medium Synchronisation Method Network Topologies Requirements at System Level 16

5 vi Contents Part B THE FLEXRAY CONCEPT AND ITS COMMUNICATION PROTOCOL 4 The Genesis of FlexRay The TTP/C Protocol FlexRay The Genesis of FlexRay The FlexRay Consortium The Aim of FlexRay A Flex(ible) Configuration Solutions 23 5 FlexRay and Real Time Physical Time Local Time Local Clock Clock Tick and Microticks In Practice Global View at Network Level Global Time Concept of Global Time Macrotick (MT) And the Bit Time What s Happening to it Inside There? Summarising: Time and its Hierarchies in FlexRay 36 6 The FlexRay Protocol History General Channels, Cycles, Segments and Slots Philosophy of the Protocol Hierarchy and Overall Form of FlexRay Communication Channels and Cycles Communication Channel(s) Communication Cycle Segments A Little Philosophy about Static and Dynamic Segments and Their Purposes Slots and Minislots Static Segments and Slots Dynamic Segments and Minislots Summary Communication Frames Overview of Frames Common Constituent Parts of Static and Dynamic Frames Encapsulation and Coding of Frames of Logical Data in Slots and Minislots for Frames which are Transported during Static and Dynamic Segments 64

6 Contents vii 6.6 SW Symbol Window Segment NIT Network Idle Time Segment 76 7 Access to the Physical Layer Definition of Tasks Execution of the Communication Cycle Frame ID (11 Bits) Arbitration Grid Level Basic Concepts Policy for Access to the Medium Conditions of Transmission and Access to the Medium during the Static Segment Conditions of Transmission and Access to the Medium during the Dynamic Segment Access to the Medium during the Dynamic Segment Example Particular, Difficult Choice of Hierarchy of Frame ID Example Similarity of the Use of the Dynamic Segment to the Network Access of the CAN Protocol Some Additions in the Case of FlexRay Being Used with Two Channels 89 Appendices of Part B 91 Appendix B1 Examples of Applications 93 The BMW X5 (Development Code L6) 93 A Little Strategy 93 Global View of the Parameters of the FlexRay System 95 Desired Functional Parameters 96 Static Segment 96 Dynamic Segment 97 Description and Justification of the Implemented Choice 97 General Composition of the FlexRay Communication Cycle 97 Details of the Parameters of the FlexRay System under Consideration 97 Appendix B2 Scheduling Problems Application of the FlexRay Protocol to Static and Dynamic Segments 103 Introduction 103 Problems of Real Time Systems 104 Concepts of Reactive Systems and Time Constraints 104 Real Time Systems and Their Classification 104 Complexity of Distributed Real Time Systems 106 Characteristics and Advantages of Distributed Systems 106 Heterogeneity in Distributed Real Time Systems 106 FlexRay 108

7 viii Contents Scheduling Real Time Systems 109 Scheduling and Analysis of Schedulability 109 Class of a Scheduling Problem 110 Different Approaches to Real Time Scheduling 113 Clock-Driven Scheduling 114 Round Robin Scheduling 114 Scheduling Based on Priorities 114 Workload Requested by a Synchronous Task T i 115 Scheduling in Single-Processor Systems 116 Clock-Driven Scheduling 116 Algorithms Based on Priorities 116 Algorithms with Fixed Priorities 116 Worst-Case Scenarios and Feasibility Tests in Non-Preemptive FP Scheduling 117 Algorithms with Dynamic Priorities 119 Scheduling Communications in Distributed Systems 120 Problem of Task Allocation in a Distributed System 121 Scheduling Communications 121 Clock-Driven Approach in Communications 122 Approach Based on Fixed Priorities in Communications 124 Scheduling Communications in FlexRay 125 Policy of Assigning Priorities 126 Class of Scheduling Problem 127 Scheduling Algorithm 128 Conclusion 129 Part C THE FLEXRAY PHYSICAL LAYER 8 Creation and Transmission (Tx) of the FlexRay Signal Creation of the Signal Bit Encoding Bit Rate The Communication Controller (CC) Physical Representation of Bits Differential Voltage on the Medium Line Driver Tx Rise Time/Fall Time Impedance Matching Ringing EMC Filtering Electrostatic Discharge (ESD) Protection Medium, Topology and Transport of the FlexRay Signal Medium General 143

8 Contents ix Conventional Propagation of the Signal on the Network Total Distances Used or Wanted on the Network or between Nodes Effects Linked to Propagation Propagation Delay Time Symmetrical Effects Reflection, Matching Topologies and Consequences for Network Performance First, a Little Light on the Obscurity of the Vocabulary Effects and Consequences of the Topology of a Network on its Performance Distances between Two Elements Distances between Several Nodes Relationships between Topologies, Electromagnetic Compatibility (EMC) and Electrostatic Discharge (ESD) Integrity of the Signal Single-Channel, Dual-Channel and Multi-Channel Communication Topologies Topology of Systems of Single-Channel Type Topology of Systems of Dual-Channel Type The FlexRay Topologies Point-to-Point Link Link Using a Passive Linear Bus Link Using a Passive Linear Bus with Stubs A Star is Born!... Linkage by Star Examples of Topologies Example of Application for a Brake-by-Wire Solution Reception of the FlexRay Signal Signal Reception Stage Triggering Threshold Unique Effects at the Start of Transmission and/or Reception of Frames Summary of the Effects of Truncation of the Complete ChainfromTxtoRx Processing of the Received Signal by the Communication Controller Acquisition of the Binary Flow Suppression of Disturbance/Noise Binary Alignment The Bit Error Rate (BER) Integrity of Signal and BER Eye Diagram Brief Reminder Jitter 176

9 x Contents 11.3 Relationship between the Integrity of the Signal, the Eye Diagram and the BER BER Calculating the BER Bathtub Curve and BER Modelling and Simulating the Performance of a Network Modelling and Simulating the Performance of a Network and its Topology Modelling the Elements of the Network Simulation Models The Line Driver/Transceiver The Communication Line The EMC Filtering Dual Inductors Back to Reality Simulation Visit Monte Carlo, its Rock, its Casino and its Method Examples of Performance and Recommended Topologies Summary on the Physical Layer of FlexRay 193 Part D SYNCHRONISATION AND GLOBAL TIME 14 Communication Cycle, Macrotick and Microtick The FlexRay Time Hierarchy Communication Cycle Macrotick Synchronisation in a Network of TDMA FlexRay Type Statement of the Problem and Requirements to be Satisfied Requirements to be Met Proposed Solution to the Problem Introduction: Forewarned is Almost Cured Description of the Chosen Method of Ensuring Time Synchronisation of the Nodes of the Network All in One Measurement Calculating the Corrective Values of Offset and Rate Application and Implementation of Corrective Values Offset and Offset Correction Rate and Rate Correction Where, When, How to Apply the Corrections? Summary Supplementary Note: Example of Time Hierarchy Network Wakeup, Network Startup and Error Management Network Wakeup Phase Node Wakeup Procedure 223

10 Contents xi Wakeup Frame Wakeup Pattern WUP Network Startup Phase Error Management Never Give Up Strategy Error Management States of the Protocol Errors on the Channels and Communication Frames FlexRay v Protocol Enhancements TT-L Time-Triggered Local Master Synchronisation TT-E Time-Triggered External Synchronisation Physical Layer Enhancements From Network Implementation to Signal Integrity Focus Signal Integrity Improvements Timing Improvements Wakeup During Operation Interoperability of Different EPL Versions FlexRay and ISO FlexRay in Other Industries 240 Part E ARCHITECTURE OF A NODE, COMPONENTS AND DEVELOPMENT AID TOOLS 17 Architecture of a FlexRay Node The Major Components of a Node Architecture of the Processor and Protocol Manager Electronic Components for the FlexRay Network The Component Range FlexRay Protocol Manager Line Drivers and Active Stars EMC and EMC Measurements Protection from ESD Conformity Tests Bus Guardian Tools for Development, Integration, Analysis and Testing The V-Shaped Development Cycle DaVinci Network Designer (Point 1 of the V Cycle) CANoe.FlexRay Modelling, Simulation (Point 2 of the V Cycle) Integration (Point 4 of the V Cycle) FlexRay CANalyzer (Covers Points 2, 4 and 5 of the V Cycle) Test and Diagnostics (Point 6 of the V Cycle) Features of the FlexRay Protocol 278

11 xii Contents 19.7 Communication Interface CANoe Real Time FlexRayStress CANape FlexRay Implementation of FlexRay Communication in Automotive Logic Controllers FlexRay and AUTOSAR The AUTOSAR Partnership Communication in an AUTOSAR System Functional Analysis, Virtual Function Bus Passing from Virtual to Real AUTOSAR FlexRay Communication Stack 287 Appendix of Part E Conclusion 297 Appendix 1 The Official Documents 299 Appendix 2 Principal Parameters of the FlexRay Protocol 301 Bibliography 311 Index 313

12 Preface Why this book now? Today, protocols for multiplexed industrial networks such as CAN, LIN and others are relatively mature, and only a few aspects such as Time-Triggered Protocol and X-by-Wire systems continue to evolve. On the two latter subjects, little information or technical training is available to engineers, technicians or students. We hope that this book will at least partly fill this gap. I waited for a long time before again dipping my pen into the inkwell of my PC(!). I preferred to wait until there were no announcements of the free shave tomorrow... type in sight. Which, of course, as usual, took a long time... Version 2.1, revision A of FlexRay was delivered officially to the public in March 2005, then some minor modifications and additions (conformity tests) called rev. 2.1 A and B were added in November 2006, and finally, at the end of 2010, there was 3.0, which clarified some points of detail. Above all, this book is not intended to give a literal translation of the standard, the original version of which can be downloaded free from the official website of the FlexRay Consortium ( Instead, its aim is to act as an introduction and a detailed teaching presentation of the technical principles and operation of the FlexRay protocol. It is also aimed at giving newcomers an overall view of the concepts and applications. The aims which FlexRay was intended to achieve (speed and security of communication, flexibility in operation, real time, distributed intelligence, network topologies, and so on) made it necessary to design the structure of the communication protocol so that it is directly related to the physical performance of the physical layer. When you read this book, always keep in mind the concerns generated by the physical layer (the medium and its management). Ideally, just as in music (see below), it would be necessary to present the communication protocol and the physical layer and their interactions simultaneously and in parallel... which is mechanically difficult for a publisher, however experienced! Something else you should know is that the content of the FlexRay protocol is dense, and includes numerous technical concepts which collide with each other, become confused with each other and intersect with each other, which makes it difficult to choose a plan for presenting the various chapters. Author s note To cover this subject of multiplexed networks correctly, this book describes many patented technical principles which are subject to the operation of licences and their associated rights (bit coding, communication techniques, and so on), and which have already been published in official, professional technical texts or communications, or

13 xiv Preface during public conferences or seminars but above all, which must be used according to the legal rules in force. How to read this book In a previous book (Multiplexed Networks for Embedded Systems: CAN, LIN, FlexRay, Safe-by-Wire), we provided an overview, which was complete at the time, of this evolving field, using long technical introductions on these subjects. Today, this book, which is entirely about FlexRay, is dense because virtually all the real subjects principles, components, applications, security, and so on are approached in practical terms. Also, to avoid discouraging the reader who is trying to understand these devices, we have put great stress on teaching so that the link between theoretical, technological, economic and so on aspects can be constantly established. The challenge is therefore to present everything in the clearest, most suitable manner. After long reflection and long oscillations, 1 it has been necessary to choose a comprehensive presentation so that you, the Reader, can find your way easily through the maze of all these emerging communication principles and new protocols. We also advise you, before approaching the technical details which will be explained in the following chapters, to take the trouble to read the next few lines, which are intended to explain the why and how of the plan of this book and how to use it. The aim of the introduction is to make your mouth water by giving a general survey of the applications which daily affect the motor vehicle and embedded systems of all types. Obviously, everything we have written in this book can be generalised to industrial applications of all kinds (control of machine tools and production lines, avionics, rail transport, building automation, transport of digital images, and so on). The first part (A) is a reminder of the CAN protocol, a quick mention of the operation and contents of the TTCAN protocol and a review of the latest applications of Xby-Wire type. We will briefly discuss the functional and application limits of CAN, and we will consider event-triggered and time-triggered communication systems, and all the implications which that consideration generates for so-called secure real time applications. In the second part (B) we will present, progressively, FlexRay and its protocol, in terms of communication cycles, decomposition of cycles into frames, format and content of frames, omitting any consideration of clock synchronisation between nodes. Then, in the third part (C), we will go on to the analysis of the physical layer and the basic concepts of bit coding, propagation and topologies which can be used, and their effects. The problems of network synchronisation in operation and during the wakeup and startup phases are the subject of the fourth part (D). We will consider the architecture of a node, components of a FlexRay network, AUTOSAR and the range of associated hardware and software tools for providing support for development simulations, verification stages, production, maintenance, and so on in the fifth and final part (E). 1 All (1 Ɣ 2 ) and (voltage) standing wave ratios included (naturellement).

14 Preface xv A little music in this brutal world Let us finish this introduction on a lighter (musical) note. Very serious discussions with some friends and FlexRay designers one day led us to the conclusion that a FlexRay system could be seen as a little like a musical score. The protocol description represents the melody in a treble key, and the physical layer represents the accompaniment in a bass key. In fact, with FlexRay as for reading a musical score, it is necessary to succeed in following the score not only by reading the two horizontal staves simultaneously, but also by reading the score vertically, to recreate the whole correctly. Additionally, like any well-informed musician, it is necessary to read ahead while playing! Welcome to FlexRay for musicians and future musicians! I wish you good and productive reading throughout the pages of this book above all, enjoy it, because I didn t write it for myself but for you! If there is still a shadow of a doubt about the subject and form of this book, your (constructive ) comments, remarks, questions and so on are always welcome by to my address, dp-consulting@orange.fr. Thanks The subject of multiplexed communication systems and networks is growing day by day, and very many skilled people are working in these fields. Luckily, I have had the opportunity to meet many of them, and consequently it is very difficult for me to thank everyone individually. Nevertheless, I must address some special thanks to several groups of people: To numerous colleagues and friends of Philips/NXP Semiconductors of Nijmegen (Netherlands) and Hamburg (Germany), with whom I have had the pleasure of working for long years on these subjects, and, taking the risk of making some people jealous, more particularly Messrs Hannes Wolff, Bernd Elend, Thomas Shuermann, Peter Bürhing, Peter Hank, Burkhard Bauer, Karsten Penno, Patrick Heuts, Matthias Muth, the numerous Hans and other colleagues in the Netherlands, and the numerous Peters and other colleagues in Germany. To the long-standing international friends in the field of multiplexed buses in motor vehicles, Messrs Florian Hartwich, Bernd Müller, Thomas Führer of the R. Bosch company, Florian Bogenberger of Motorola/Freescale and Wolfhard Lawrenz of C&S. It would be ungrateful not to thank also the numerous colleagues in the profession, and motor vehicle and equipment manufacturers, whom I meet regularly either at working meetings or at ISO, for their remarks and comments about the editing of this book, thanks to whom we all hope that this subject of multiplexed buses will blossom as it deserves. Finally, I am very glad to thank Ms Manuela Philipsen of the Marcom team of NXP Semiconductors in Eindhoven, for the numerous documents and photographs which she has been kind enough to supply to me for years to illustrate these books. Even more finally, I am also immensely grateful to the Vector Informatik GmbH company of

15 xvi Preface Stuttgart (Mr Uwe Kimmerley and the whole FlexRay team) and Vector France SAS of Paris (Mr Henri Belda, Mr Jean-Philippe Dehaene, Ms Hassina Rebaïne and Ms Rim Guernazi) for their technical and logistical support, their participation in the editing of certain chapters and for having had the kindness to agree to supply numerous very fine educational illustrations to enrich this book. In fact, this type and quality of teaching aid is fundamental to good distribution of knowledge, and in Vector s case is part of very rich support for professional training which is useful for spreading a technique and a technology. Setting up such support requires a large investment in time and money, and authorisation to publish them even in part really deserves to be welcomed as much as the quality of their content. So a big thank you for having done and authorised that. Dominique Paret dp-consulting@orange.fr

16 List of Abbreviations ABS ADC AP Autosar BD BER BSS CAN CAPL CAS CC CDD CDF CHI CID CPU CPU/ECU CRC CSEV CSS DLC DLL DPI DTS ECC ECU EMB EMC EPL EPLAN ESD FES FIFO anti braking system analogue to digital conversion action point automotive open system architecture bus driver bit error rate byte start sequence controller area network Communication Access Programming Language collision avoidance symbol communication controller CANdela Data Diagnostic cumulative distribution function controller-host interface channel idle delimiter central processing unit central processing unit/electronic control unit cyclic redundancy check channel status error vector clock synchronization startup data length coding dynamic link library direct power injection dynamic trailing sequence error correction code electronic control unit electromechanical braking electromagnetic compatibility electrical physical layer electrical physical layer application notes electrostatic discharge frame end sequence first in, first out

17 xviii List of Abbreviations FSEV FSS FTDMA GTDMA HIL LIN MTs MTS NIT NRZ OEM OS OSI OSI/ISO PDF PDUs PLL PS RF RTE SBCs SD SHF SOC ST SW SWCs TDMA TRP TSL TSS TTCAN TT-E TT-L TTP/C Tx UHF VDR VFB WCET WUP WUS frame status error vector frame start sequence flexible time division multiple access global time division multiple access hardware in the loop local interconnect network macroticks media access test symbol network idle time no return to zero original equipment manufacturer operating systems open systems interconnection open systems interconnection/international Standard Organisation probability density function protocol data units phase locked loop protocol specification radio frequency run time environment system basic chips dynamic segment super high frequency start of cycle static segment symbol window software components time division multiple access time reference point test set library transmission start sequence time-triggered communication on CAN time-triggered external time-triggered local Time Triggered Protocol Class C transmission ultra high frequency voltage-dependent resistors virtual functional bus worst case execution time wakeup pattern wakeup symbol