Local Interconnect Network Training. Local Interconnect Network Training. Overview

Transcription

1 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

2 History and expectation Local Interconnect Network Training Time 200x Growth expectations: 3 10 LIN nodes per vehicle 1.2 billion LIN nodes per year world-wide Current specification LIN Specification Package V1.2 (Nov 17, 2000) LIN Consortium initiated (5 car manufacturers, 1 semiconductor supplier, 1 tool provider) First specification draft released

3 Typical example for LIN in automobiles (1)

4 Typical example for LIN in automobiles (2)

5 Comparison of automotive bus systems

6 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

7 Technical features (1) Sub-bus as an extension to CAN to provide connection to local network clusters Low-cost single-wire implementation (less expensive than CAN but not as reliable as CAN) Low-cost silicon implementation based on common UART/SCI interface hardware (almost any microcontroller has necessary hardware on chip) Single-master / Multiple-slave concept (no arbitration is necessary)

8 Technical features (2) Self-synchronization without quartz or ceramics resonators in the slave node (significant cost reduction of hardware platform) Data rates of up to 20 kbit/sec (limited by the EMI of single-wire transmission) Recommended Bit Rates: Slow : bit/sec Medium: bit/sec Fast : bit/sec Guaranteed latency times for signal transmission Hot plug-in / plug-out

9 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

10 The ISO/OSI reference model (1) Local Interconnect Network Training Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer All People Seem To Need Data Processing

11 The ISO/OSI reference model (2) Local Interconnect Network Training Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer Applications, operating system Conversion of data formats Task synchronization, buffers, connection setup and monitoring, access rights control Address conversion, routing, segmentation Setup of logical connection, transport protocol Transmission security, frame setup, error management Electrical / mechanical characteristics: Transmission medium, wiring, connectors, encoding, signals

12 The ISO/OSI reference model and LIN Local Interconnect Network Training 2 Data Link Layer 1 LLC- Logical Link Control is concerning with Message Filtering and Recovery Management MAC - Medium Access Control is supervised by a management entity called Fault Confinement Physical Layer Acceptance Filtering, Recovery Management, Time Base Synchronization, Message Validation Data Encapsulation / Decapsulation, Error Detection, Error Signaling, Serialization / Deserialization Bit Timing, Bit synchronization, Line Driver / Receiver

13 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

14 Frames (1) Frame: Envelope for transmission data 3 different frame types : Message Frame: used for transmission of regular data Command Frame: used for software updates, network configuration and diagnostic purposes Extended Frame: allows the embedding of user-defined message formats and future LIN formats into the current LIN protocol without violating the LIN specification

15 Frames (2) Frame Format Header Response Byte Field Format: transmission with LSB first 0 8 Data Bits 1 Start Bit Stop Bit

16 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

17 Message Frames: Header (1) Local Interconnect Network Training Synchronization Break field Synch Break Synch ID identifies the start of a message frame consists of 2 parts: dominant bus level with a minimum duration of T SYNBRK (13 bits) recessive bus level with a minimum duration of T SYNDEL (1bit)

18 Message Frames: Header (2) Local Interconnect Network Training Synchronization field Synch Break Synch ID contains the information for clock synchronization consists of the pattern 0x55

19 Message Frames: Header (3) Local Interconnect Network Training Identifier field (1) Synch Break Synch ID contains the identifier, length and parity of the frame 0 ID0 ID1 ID2 ID3 ID4 ID5 P0 P1 1 Identifier bits Length control ID parity bits

20 Message Frames: Header (4) Local Interconnect Network Training Identifier field (2) ID0 - ID5 64 (2 6 ) identifiers divided into 4 subsets of 16 identifiers with 2, 4 or 8 data bytes P0 - P1 are the parity check bits of identifier

21 Message Frames: Response Local Interconnect Network Training Response Response contains the data field and the checksum data field consists of 2, 4 or 8 bytes checksum field (1 byte) contains the inverted modulo-256 sum across all data bytes calculated using add with carry

22 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

23 LIN communication concept: Master task vs. Slave tasks Master task vs. Slave tasks master control unit master task slave control unit slave control unit slave task slave task slave task LIN bus only the master control unit contains a master task slave tasks are contained in all control units

24 LIN communication concept: Frame timing Synch Break 13 bit (min) Synch Field 1 byte Identifier Field 1 byte next Synch Break Master Task In-frame Space Data Field 2, 4 or 8 bytes Checksum Field 1 byte Inter-frame space / break t Slave Task t

25 LIN communication concept: Master Task Master Task has the control over the whole bus communication serves as the reference for synchronization sets the schedule sends the header of each message monitors the data bytes and the checksum byte receives the wake-up signal from a slave node when the bus is in Sleep Mode

26 LIN communication concept: Slave Task Slave Task waits for the Synch Break Field synchronizes on the Synch Field depending on ID sent by the Master Task, sends response (publisher), receives response (subscriber), or does none of both sends wake-up signal when bus is in Sleep Mode and it needs to transmit data

27 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

28 Command Frames Command Frames (1) are regular 8-byte Message Frames are used to broadcast general command requests for service purposes from the master to all bus participants 2 types of Command Frames: Master request frame (ID-Field = 0x3C): to send commands and data from the master to the slave node Slave response frame (ID-Field = 0x7D): to trigger one slave node to send data to the master node

29 Command Frames / Sleep Mode Command Command Frames (2) type of command is specified in the first data byte of a command frame values of 0x00 to 0x7F for command type are reserved Example: Sleep Mode Command (command type 0x00): Master Request Frame which is used to broadcast the request for transition to sleep mode to all bus nodes

30 Extended Frames Extended Frames allow the embedding of user-defined message formats and future LIN formats into the LIN protocol without violating the current LIN specification 2 types of extended frames: User-defined extended frame (ID-Field = 0xFE) Frame reserved for future LIN extension (ID-Field = 0xBF) the identifier can be followed by an arbitrary number of LIN bytes fields

31 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

32 Transition to and from Sleep Mode Local Interconnect Network Training Transition to and from Sleep Mode Slave nodes go to Sleep Mode after: reception of a Sleep Mode Command from the master node or a time-out (T TIME_OUT = T BIT ) in the case that the sleep command message was corrupted Sleep mode can be terminated by the slave task of any node by sending a Wake-Up Signal: T WUSIG Bus Sleep T UDEL Wake-up delimiter

33 Wake-up procedure Wake-up procedure Sleep Mode slave task sends wake-up signal Waiting for frame from master task master task sends first frame time-out T TOBRK slave task repeats wake-up signal max. 2 times no response to 3 wake-up signals Bus Awake Transmission of wake-up signals suspended for T T3BRK

34 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

35 Error types Possible error types Bit Error Checksum Error Identifier-Parity Error Slave-Not-Responding Error Inconsistent-Synch Field Error

36 Bit Error Bit Error Error description The bit on the bus is different from the one that was transmitted. Method of detection Sending unit monitors the bus while transmitting. Fault confinement This error is detected by: - the master task in the master node, - the slave task in the slave node while reading back their own transmissions.

37 Checksum Error Checksum Error Error description The checksum calculated over all received data bytes does not match the received checksum byte. Method of detection The sum of the inverted modulo-256 sum over all received data bytes and the checksum byte does not result in 0xFF. Fault confinement This error is detected by: - the slave task in the master node when reading data from the bus, - the slave task in the slave node while reading data from the bus.

38 Identifier-Parity Error Identifier-Parity Error Error description The parity identifier bits do not match the calculated values. Method of detection Calculation of parity bits from received identifier and comparation to received parity bits. Fault confinement This error is detected by: - the master task in the master node while reading back its own transmission, - the slave task in the slave node while reading from the bus.

39 Slave-Not-Responding Error Local Interconnect Network Training Slave-Not-Responding Error Error description The transmission of a LIN frame is not fully completed within the time frame specified in the schedule. Method of detection This error is detected while reading from the bus when a slave task expects data to be transmitted. Fault confinement This error is detected by: - the slave task in the master node when expecting or reading data from the bus, - the slave task in the slave node while reading from the bus only when this slave expects a message from another slave.

40 Inconsistent-Synch-Field Error Local Interconnect Network Training Inconsistent-Synch-Field Error Error description Synch field is different from the pattern 0x55. Method of detection Slave task detects the edges of the Synch Field outside the given tolerance. Fault confinement This error can only be detected by the slave task in the slave node.

41 Error causes Error causes Local disturbance of ground potential Local disturbance of supply voltage Global electric disturbance of the bus signal Unsynchronized time base

42 Overview Local Interconnect Network Training History and introduction Technical features The ISO/OSI reference model and LIN Frames Message Frames Communication concept of LIN Command Frames and Extended Frames Sleep mode and wake-up signal Error and exception handling CAN vs. LIN

43 Warning LIN low-cost CAN!!!

44 CAN vs. LIN (1) Data rate max. 1 MBaud max. 20 kbaud Master/Slave multi-master master/slave Data security CRC code simple checksum Acknowledgement yes no Node number up to 100 up to 16

45 CAN vs. LIN (2) Latency time not guaranteed deterministic Frame scheduling no yes Tx on event yes no Error correction retransmission none Error prevention bus-off mechanism none

46 CAN vs. LIN (3) Upper SW layers e.g. OSEK COM LIN API Protocol in HW yes no Bus length max. 1000m max. 40m Number of wires 2 (or 1) 1 ISO standard ISO / no