Distributed Real-Time Systems (TI-DRTS) Track 3

Transcription

1 Distributed Real-Time Systems (TI-DRTS) Track 3 The Communication Systems for advanced automotive control applications Version:

2 Abstract The FlexRay protocol provides flexibility and determinism by combining a scalable static and dynamic message transmission, incorporating the advantages of familiar synchronous and asynchronous protocols Sources: FlexRay Requirements Specification, Version 2.1, 19-dec-2005 (115 pages). FlexRay Protocol Specification, Version 2.1.Rev.A, 15-dec-2005 (243 pages). Slide 2

3 Context Demand for a bus system with high data rate for automotive applications Deterministic and fault-tolerant bus system for advanced automotive control applications Support from the bus system for distributed control systems Limited number of different communication systems within vehicles Slide 3

4 FlexRay Consortium Goals Develop an advanced communication technology for high-speed control applications in vehicles Make the technology available in the market place for everyone Drive the technology as a defacto standard Slide 4

5 FlexRay Architecture Example CAN Slide 5

6 FlexRay Core Partners The seven FlexRay Consortium Core Partners: BMW Daimler Volkswagen General Motors Bosch Freescale (Motorola) NXP (Philips) Semiconductors have agreed on continuation agreements for the time frame from January 1, 2009, until December 31, Slide 6

7 FlexRay History Source: Slide 7

8 Freescale s FlexRay Roadmap Slide 8

9 Slide 9

10 FlexRay News BMW X5 Slide 10

11 BMW X5 first FlexRay Car AdaptiveDrive an optional chassis package: AdaptiveDrive, uses sensors that constantly monitor and calculate data on the road speed of the vehicle, its steering angle, straight-line and lateral acceleration, body and wheel acceleration, as well as height levels. Then, based on this information, the system controls both the swivel motors on the anti-roll bars and the electromagnetic shock absorber valves, controlling body roll and dampening as required at all times. Simply by pressing a button, the driver can choose either a sporting or a more comfortable basic setting of AdaptiveDrive. BMW X5 is based on Freescale's 32-bit FlexRay MCUs. Freescale is currently the only semiconductor supplier that has FlexRay microcontrollers (MCUs) in a production-ready automobile. The new BMW X5 will be launched in North America at the end of November It will be available in other markets worldwide in spring Slide 11

12 FlexRay News (2006) Slide 12

13 General FlexRay Requirements One or two channel solutions must be supported An electrical and optical physical layer must be supported Redundant physical links is optional. A mix of non-redundant and redundant physical links must be supported Wake-up of nodes and stars via the communication system A baud-rate from 500 Kbit/s up to 10 Mbit/s Slide 13

14 Basic Features Synchronous and asynchronous data transmission High net data rate of up to 10 Mbit/sec Deterministic data transmission, guaranteed message latency and message jitter Support of redundant transmission channels Fault tolerant and time triggered services implemented in hardware Fast error detection and signaling Support of a fault tolerant synchronized global time base Error containment on the physical layer through an independent "Bus Guardian" Support of optical and electrical physical layer Support for bus, star and multiple star topologies Slide 14

15 Use Cases for the FlexRay Communication System Source: FlexRay Req. spec. Slide 15

16 FlexRay Node Architecture (1) ECU= Electronic Control Unit Slide 16

17 FlexRay Node Architecture (2) Bus Driver Slide 17

18 Host Processor Inteface Slide 18

19 FlexRay Communication Controller Slide 19

20 E-Ray FlexRay Controller Block Diagram PRT A: Protocol Communication Controller (Protocol Finit State Machine) TBF A: Transient Buffer RAM IBF: Input Buffer OBF: Output Buffer Source: Slide 20

21 State Model of a Communication Module Source: FlexRay Req. spec. Slide 21

22 Topologies - Bus & Star Bus passive medium no active components within the channel most automotive experience automotive costs Star best suited technology for high speed networks different degrees of intelligence possible with/without protocol knowledge can protect against concurrent media access limits the error domain of not correctly working sub networks Slide 22

23 Passive Bus Topology Slide 23

24 Active Star Toplogy Slide 24

25 Active Star Component A branch has to be deactivated if a faulty signal is detected A deactivated branch shall be fail-silent and should be reactivated if the fail condition is no longer available Slide 25

26 Hybrid Topology Slide 26

27 Static and Dynamic Segments Static message segment state message semantic deterministic communication behavior periodic statically scheduled message transfer is a benefit for automotive applications, especially distributed control loops with replication required support for distributed control and closedloop control functions Dynamic message segment spontaneous (event) message transfer e.g. for burst transmissions for diagnostic information for ad hoc messages in general Slide 27

28 FlexRay Configurations Slide 28

29 Frame Transfer Cycles consisting of two segment Static: Divided in timeslots (TDMA) The slot length is defined off-line and therefore fixed during runtime Dynamic: Has a start delimiter: Start of cycle SOC Dynamic frame length Media is accessed via timers and priorities Slide 29

30 FlexRay Communication Cycle Slide 30

31 Communication Scheme Slide 31

32 Topology Example A node can either be connected to both channels or only to one of the channels Slide 32

33 Frame Transfer (1) Communication cycle with both static and dynamic segments A,D,C,E A,B,C,E Slide 33

34 Frame Transfer (2) Communication cycle in a pure dynamic system Start of Cycle Slide 34

35 Timing Hierarchy Within one communication cycle FlexRay offers the choice of two media access schemes. These are a static time division multiple access (TDMA) scheme, and a dynamic mini-slotting based scheme. Slide 35

36 Static Part Characteristics (1) Slide 36

37 Static Part Characteristics (2) Slide 37

38 Dynamic Part Minislotting (1) Slide 38

39 Dynamic Part Minislotting (2) Slide 39

40 Dynamic Characteristics (1) Slide 40

41 Dynamic Characteristics (2) Slide 41

42 FlexRay Frame Format (1) 254 bytes payload Payload length Frame ID (11 bits): The frame ID defines the slot in which the frame should be transmitted. A frame ID is used no more than once on each channel in a communication cycle. Slide 42

43 FlexRay Frame Format (2) Network Management Vector The message ID is an application determinable number that identifies the contents of the data segment Slide 43

44 AUTOSAR TTAutomotive Joins AUTOSAR, Vienna, Austria November 29, 2005 AUTOSAR is the acronym for AUTomotive Open System ARchitecture. TTAutomotive, TTTech s subsidiary for FlexRayTM solutions, has joined the AUTOSAR development partnership as a premium member. TTAutomotive will focus on FlexRay software modules that comply with AUTOSAR specifications to advance FlexRay-based Time-Triggered Architecture (TTA) in the automotive industry. The development partnership s mission is to establish an industrial standard for off-the-shelf software components, in order to provide costoptimized, best-in-class solutions to the automotive industry. The architecture is characterized by standardized, non-proprietary, and clearly defined interfaces. Slide 44

45 AUTOSAR FlexRay Communication Stack Task: - Provide a uniform interface to the FlexRay network - Hide protocol and message properties from the application Slide 45

46 Summary FlexRay is the de facto standard for high performance bus systems for the automotive market FlexRay supports both static and dynamic communication Future for car makers: the AUTOSAR initiative (supporting CAN, LIN, FlexRay) Slide 46

47 [FlexRay2005] References FlexRay Requirements Specification, Version 2.1, 19-dec [FlexRay2005] FlexRay Communications System, Protocol Specification Version 2.1. Rev.A, 15-dec [FlexRay] FlexRay Consortium home page: [FlexRay-tools] [Autosar] Slide 47