Communication systems for vehicle electronics Communication systems for vehicle electronics Presentation overview Background automotive electronics as an application area for real-time communication Real time protocols LIN – Local Interconnection Network CAN – Controller Area Network TTCAN - Time Triggered CAN (based on CAN) CAN FD – CAN with Flexible Data-rate FlexRay , based on BMW’s “ByteFlight” TTE - Time Triggered Ethernet Hybrid scheduling 1 combining static scheduling with fixed priority scheduling analysis 1 Roger Johansson/ 2015
Communication systems for vehicle electronics A premium passenger car is controlled and managed by 80+ Embedded Systems Infotainment: Comfort Electronics: Telematics Solutions Thermal Management Car PC Chassis Control Wireless Connectivity Parking Assistant Car-to-car communication Floating Car Data Powertrain: Safety: Engine Management Predictive Safety Systems Transmission Control 2 Driver Assistance Systems Power Management Adaptive Cruise Control Electric Power Steering Courtesy of Daimler, Bosch 2 Roger Johansson/ 2015
Communication systems for vehicle electronics Virtual differentiation between variants Entertainment configuration Variant 1 A All variants of a specific model are physically identical and differ only in Motor configuration their individual software A configuration Entertainment The various included configuration physical components can be F activated or deactivated by Motor the software configuration B Variant 2 3 Roger Johansson/ 2015
Communication systems for vehicle electronics Example of the electrical system complexity 1927-1997 54 54 1200 1200 No. of No. of meters of meters of No. of fuses electric electric wires wires 27 27 575 575 16 Wiring diagram, Volvo ÖV4 (“Jacob”) 1927 16 283 9 283 9 7 7 183 183 5 5 83 4 83 4 50 50 30 30 1927 1927 1944 1944 1956 1956 1966 1966 1975 1975 1982 1982 1997 1997 4 Roger Johansson/ 2015
Communication systems for vehicle electronics The evolution of functional requirements on the electrical system Features Power production and distribution 450 Architecture Simple Optimisation on many 400 components levels 350 Standardised interfaces 300 # of More complex functions 250 functions stand-alone systems 200 ABS, Airbag 150 # of 100 Integration of systems integrated functions 50 Optimisation of information Common data busses 0 1930 1940 1950 1960 1970 1980 1990 1995 2000 2005 1970 1980 1990 2000 2010 5 Roger Johansson/ 2015
Communication systems for vehicle electronics Automotive electronics roadmap 6 Roger Johansson/ 2015
Communication systems for vehicle electronics Multiplex Networks Conventional Network Data Identifier Control Command system Engine Control Module Driver Information Control units Automatic Transmission Central Module 7 Roger Johansson/ 2015
Communication systems for vehicle electronics Evolution of protocols MOST TT Ethernet Byteflight FlexRay TTP/C CAN FD TTCAN CAN CAN 2.0 VAN J1850 LIN 2010 2015 1990 1995 1985 2000 2005 8 Roger Johansson/ 2015
Communication systems for vehicle electronics Example of the electrical system… Mirror Lock Lock Window lift Power Train Seat Seat Heating Instruments Heating Central body Roof Infotainment control Roof Trunk systems Heating Climate Seat Seat Seat Seat Heating Steering wheel panel Interior lights Universal motor Very high performance Lock Lock Lock Lock High performance Universal panel Mirror Medium performance Mirror Low end performance 9 Roger Johansson/ 2015
Communication systems for vehicle electronics The LIN protocol, started in 1998 LIN Local Interconnection network predecessor: VOLCANO Lite Cooperation between partners: Freescale, VOLVO CAR, BMW, AUDI, Volkswagen, Daimler-Chrysler Mentor Graphics (former: Volcano Communication Technology) Objectives: Low cost, modest performance and safety requirements, flexible system architecture 10 Roger Johansson/ 2015
Communication systems for vehicle electronics LIN target applications Steering Wheel: (very many controls are going to be Roof: positioned on the steering wheel) (high amount of wiring) Cruise Control, Wiper, Turning Light, … Rain Sensor, Light Sensor, Light Control, Sun Roof … Optional: Climate Control, Radio, (Rain Sensor needs to be Telephone, etc. interrogated every 10-20ms) Seat: many Seat Position Motors, Occupancy Sensor, Control Panel Door/window/seat: Climate: Mirror,Central ECU, many Small Motors Mirror, Switch, Window Lift, Control Panel Seat Control Switch, Door Lock, etc. 11 Roger Johansson/ 2015
Communication systems for vehicle electronics LIN protocol features – Bus topology – Master-slave protocol, no arbitration required – UART protocol, 10 bits (uses “sync break” facility) – 8 bits of data in a block – 2-8 blocks of data per frame – Single wire – Maximum 20 kbits/s 12 Roger Johansson/ 2015
Communication systems for vehicle electronics LIN bus communication master control unit slave control unit slave control unit polling master task slave task slave task slave task inter-frame spacing next synch field synch Identifier field Master Task time 1 byte 2 byte block parity data Response spacing Slave Task time 13 Roger Johansson/ 2015
Communication systems for vehicle electronics CAN – Controller Area Network – Bus topology – CSMA/CR (Carrier sense, Multiple ARB Arbitration ( identifier ) Access/ Collision Resolution) CTRL Control information – Error detection capabilities DATA 0-8 bytes – Supports “atomic broadcast” CRC Checksum ACK – 0-64 bytes of data per frame Acknowledge EOF End of frame – Twisted pair – Maximum 1 Mbit/s MESSAGE FRAME SOF ARB CTRL DATA CRC ACK EOF 14 Roger Johansson/ 2015
Communication systems for vehicle electronics Bus collission detection Bus transceivers ”Open collector” Bus level: Recessive (bit) ”1” Idle bus (recessive level) Dominant (bit) ”0” +5V R Bus level 1 1 NodeA Node B 15 Roger Johansson/ 2015
Communication systems for vehicle electronics Bus arbitration Two nodes transmitting same level (1) transmit 1 receive 1 +5V transmit 1 I R = 0 receive 1 Bus level 1 1 1 1 1 1 I A = 0 I B = 0 Node A Node B 16 Roger Johansson/ 2015
Communication systems for vehicle electronics Collission Resolution transmit 1 receive 0 +5V transmit 0 I R =I A R receive 0 Bus level: 0V Node A Node B 0 0 1 1 0 0 1 1 I A I B =0 Node B aborts transmission since the received bit differs from the transmitted bit 17 Roger Johansson/ 2015
Communication systems for vehicle electronics Three messages collide... Arbitration field (identifier with priority) Nodes ”own” specific message identifiers. EXAMPLE: Three nodes start simultaneously Node A transmits: $257 (0010 0101 0111) Node B transmits: $360 (0011 0110 0000) Node C transmits: $25F (0010 0101 1111) Bit number SOF 1 2 3 4 5 6 7 8 9 10 11 12 13 Bus level D D D R D D R D R D R R R R Node A 0 0 0 1 0 0 1 0 1 0 1 1 1 1 Node B 0 0 0 1 1 Aborts Node C 0 0 0 1 0 0 1 0 1 1 Aborts 18 Roger Johansson/ 2015
Communication systems for vehicle electronics Standard/Extended CAN drawback.... – Protocol bus arbitration, acknowledge and error handling slow down bitrate ( maximum 1 Mbits/s) – Solution: New CAN FD specification CAN Flexible Data-rate 19 Roger Johansson/ 2015
Communication systems for vehicle electronics By-wire control Electronic information carrier Hydraulic information carrier The F-8 Digital Fly-By-Wire (DFBW) flight research project validated the principal concepts of all-electric flight control systems now used on nearly all modern high-performance aircraft and on military and civilian transports. The first flight of 20 the 13-year project was on May 25, 1972. Courtesy of Dryden Flight Research Center 20 Roger Johansson/ 2015
Communication systems for vehicle electronics Control system implementation strategies Local control Local information processing Independent control objects Centralized global control Local and central information processing Interconnected control objects Distributed global control Local and distributed information processing Interconnected control objects 21 Roger Johansson/ 2015
Communication systems for vehicle electronics Non-functional requirements System life Maintainability time Extendability Interoperability Changeability Portability Safety Testability Restructuring Performance/ Usability Efficiency System Security Availability Architecture Robustness Cost-effectiveness Reliability Fault tolerance Produceability Understandability Timeliness Variability (variants, configurations) Conceptual integrity 22 Roger Johansson/ 2015
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