FlexRay basics

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FlexRay basics

In recent years there has been a significant increase in the amount of electronics that have been introduced into the car, and this trend is expected to continue as car companies introduce further advances in safety, reliability and comfort.

The introduction of advanced control systems combining multiple sensors, actuators and electronic control units are beginning to place demands on the communication technology that are not currently addressed by existing communication protocols.

Additional requirements for future in-car control applications include the combination of higher data rates, deterministic behavior and the support of fault tolerance.
Flexibility in both bandwidth and system extension will also be key attributes as the need for increased functionality and on-board diagnostics also increase.

Availability, reliability and data bandwidth are the key for targeted applications in Powertrain, Chassis and Body control, and these must also be supported within the automotive environment which presents some unique challenges.

The core member companies of the FlexRay Consortium (BMW, Bosch, DaimlerChrysler, Freescale, GM, Philips and Volkswagen) have been working together in developing the requirements for an advanced communication system for future automotive applications. These seven companies have brought together their respective areas of expertise to define a communication system that is targeted to support the needs of future in-car control applications.
FlexRay is a communication system that will support the needs of future in-car control applications. At the core of the FlexRay system is the FlexRay communications protocol. The protocol provides flexibility and determinism by combining a scalable static and dynamic message transmission, incorporating the advantages of familiar synchronous and asynchronous protocols. The protocol also supports:
Fault-tolerant clock synchronization via a global time base
Collision-free bus access
Guaranteed message latency
Message oriented addressing via identifiers
Scalable system fault-tolerance via the support of either single or dual channels

A physical layer incorporating an independent Bus Guardian provides further support for error containment. The FlexRay system is targeted to support data rates of up to 10Mbit/sec with increased flexibility for easy system extension and the dynamic use of bandwidth. The 10Mbit/sec data rate is available on two channels, giving a gross data rate of up to 20Mbit/sec.

In support of FlexRay, an array of development tools for design, measurement and simulation of the communication system is also under development.

BMW and DaimlerChrysler – the first car companies to kick off the initiative - intend to use FlexRay in advanced application series-production within the next few years.

FlexRay is targeted at meeting the needs of present and future in-car control applications and the aim is to establish FlexRay as the de facto standard in the automotive industry.

Background

The FlexRay Consortium is an alliance of automotive, semiconductor and electronic systems manufacturers working together to develop a deterministic and fault-tolerant bus system with high data rates for advanced automotive control applications.

The FlexRay Consortium came about as a result of a cooperation between BMW and DaimlerChrysler after the two automobile manufacturers realized that current solutions did not meet their needs for future applications including x-by-wire. In September 2000, BMW and DaimlerChrysler joined forces with Philips and Motorola to form the FlexRay Consortium. Since then the Consortium has grown to include some of the automotive industry’s largest and most influential players, including Bosch, General Motors, and Ford among others.

The FlexRay communication system has quickly gained momentum with many new members coming on board. Industry experts are predicting that FlexRay will become the de facto standard for high-speed control applications within vehicles.

Motivation & goals

Motivation
Market need for an industry wide standard scalable communication system
Increasing number of different communication systems within vehicles
Demand for a bus system with a high data rate.
Deterministic and fault-tolerant bus system for high-speed automotive control applications.
Support from the bus system for distributed control systems.

Goals
Develop an advanced communication technology for high-speed control applications in vehicles, to increase safety, reliability and comfort.
Make the technology available in the market place for everyone.
Drive the technology as the de facto standard.
Make the technology available for new application and application domains such as active and passive safety systems, systems for consumer comfort and fuel consumption.
Mission & vision

The FlexRay Consortium was formed to drive the adoption of the FlexRay communication system as the de facto industry standard for high-speed communication networks for automotive applications.

By establishing FlexRay as the best solution for these advanced automotive applications, the Consortium intends to create an industry standard for serial communication systems to efficiently support the control of communication between electro-mechanical nodes in automotive applications. The adoption of FlexRay as the standard will afford the automotive industry many design and cost efficiencies by simplifying the manufacturing and design of vehicles, controlling the cost of the microcontrollers and electronic systems that go in them while benefiting from the advanced electronic systems that will become an integral part of new vehicles.


Key features

Synchronization
Synchronous and asynchronous data transmission (scalable).
Support of a fault tolerant synchronized global time base.
Scalable electric/electronic architectures to support different platforms
Gross data rate of 10 Mbit/sec

Protocol
Deterministic data transmission, guaranteed message latency and message jitter.
Support of redundant transmission channels.
Fault tolerant and time triggered services implemented in hardware.
Support of optical and electrical physical layers.
Arbitration free transmission.

Flexible Configuration - Physical Layer:
Support for bus, star and multiple star topologies.
Error containment on the physical layer through an independent "Bus Guardian".
Fast error detection and signalling.
Support of wake-up/sleep functionality via bus

Tool Landscape
FlexRay schedule design tool with data base interface
Adaptation to development environment for distributed systems
Software in the loop simulation
FlexRay bus monitoring for integration
Hardware in the loop simulation


Current members

Core partners
BMW
Bosch
DaimlerChrysler
Freescale Semiconductor
General Motors
Philips
Volkswagen

Premium Associate members
3SOFT
austriamicrosystems AG
c&s group
Continental AG Hannover
DECOMSYS
Delphi Corporation
Denso
Elmos Semiconductor AG
Fiat
Ford Motor Company
HONDA Motor Co.
NISSAN MOTOR CO., Ltd.
Renault
TTAutomotive Software GmbH
Tyco Electronics Corporation
TZM
Vector-Informatik

Associate members
NIPPON SEIKI CO., LTD.
ADVANCED DATA CONTROLS, CORP. (ADaC)
Agilent Technologies Inc.
Aisin Seiki
Alpine Electronics (Europe) GmbH
Analog Devices
ARC Seibersdorf research GmbH
AVL List GmbH
Berner & Mattner Systemtechnik GmbH
Bertrandt Ingenieurbüro GmbH
Calsonic Kansei Corporation
dSPACE
EPCOS AG
ESG - Elektroniksystem und Logistik-GmbH
eSOL
Esterel Technologies
ETAS
FTZ -Research and Technology Association
Fuji Heavy Industries Ltd.
Fujitsu
FUJITSU TEN Limited
G.i.N. mbH
GIGATRONIK
GÖPEL electronic GmbH
HELLA KGaA Hueck & co.
Hitachi, Ltd.
HYUNDAI KIA MOTORS
IAV GmbH
IPETRONIK GmbH &Co.KG
K2L
KEIHIN CORPORATION
Mitsubishi Electric
Movimento Automotive
NEC Electronics Corporation
Pacifica Group Technologies
Preh Gmbh
Renesas Technology Europe GmbH
RWTÜV Fahrzeug GmbH
Rücker AG
samtec
Softing AG
SUMITOMO ELECTRIC INDUSTRIES, LTD.
Sunny Giken Inc.
Suzuki Motor Corporation
Synopsys
Takata
Tata Elxsi Limited
TDK
Texas Instruments
Tokai Rika
Toyota Tsusho Electronics Corp.
TRW Conekt
WÜRTH ELEKTRONIK eiSos GmbH & Co.KG
Xilinx
Yamaha Motor Co., Ltd.
Yazaki
Yokogawa

Organization structure

Organization consortium
Working group
Structure mechanisms

Working groups


Requirements
This WG defines the requirements on the FlexRay communication system.
These requirements are captured in the requirements specification, which is the source of reference for the other technical WGs.
The requirements specification is a public document and therefore made available for download on the FlexRay homepage.
This WG discusses feedback received from outside the Consortium and works closely together with protocol WG to determine the potential impact of such feedback.

Protocol
The task of the protocol WG is the development of the FlexRay communication protocol.
The result of this work is documented in the FlexRay protocol specification.
This specification also contains information on diagnostics (on protocol level) and defines interfaces (e.g. to the bus guardian and the physical layer).
The WG collects change requests and decides on acceptance of change requests
The WG works together with WG Physical layer to ensure the interoperability of protocol controller,bus driver and bus guardian.

Physical layer
The task of the physical layer WG is the development of an electrical physical layer for the FlexRay communication system.
The results of this work is documented in two specification documents: the bus driver specification and the bus guardian specification.
The WG collects change requests and decides on acceptance of change requests.
The WG works together with the protocol WG to ensure the interoperability of bus driver, bus guardian, and protocol controller.

Protocol Conformance Test
defining and tracking protocol conformance testing
defining and tracking physical conformance testing
making available conformance tests

Safety
The safety working group focusses on the development and engineering process requirements for FlexRay as a safety relevant system.
The goal is to certify FlexRay against a minimum set of requirements that satisfy current standards and provide relevant information needed for a future automotive standard.


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