can通訊協(xié)議介紹ppt課件-資料下載頁
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【正文】 called “Suspend Transmission” field ? Bus off nodes: no influence on the bus Intrepid Control Systems, Inc. Fault Confinement Error Counters TEC: 000 REC: 000 Error Active Error Active 01: 0020010030020040041011018026029509731129033185042204723351256Error Counters TEC: 000 REC: 000 : 000 : Error Counters TEC: 000 REC: 000 : 001 : 000 : 002022022000? 3 Error States: Error Active, Error Passive, Bus Off CAN Node 1 CAN Node 2 CAN Node 3 Error Active Err Passive BUS OFF Intrepid Control Systems, Inc. 50 Receive Error Counter ? If receiver sends an error frame: REC+1 ? If receiver was first to start an error frame: REC+8 ? If receiver monitors a BIT ERROR while sending an error frame: REC+8 ? After successfully receiving a message: REC1 Intrepid Control Systems, Inc. 51 Transmit Error Counter ? If transmitter sends an error frame: TEC+8 ? If transmitter monitors a BIT ERROR while sending an error frame: TEC+8 ? After successfully transmitting a message: TEC1 ? If TEC reaches 127: Cannot send Error Frames, but can Tx/Rx Intrepid Control Systems, Inc. 52 Lab 3: Objectives ? Get familiar with Vehicle Spy software ? Create a message that is sent periodically ? Put that message into the 2nd node on the EVB ? Find our message amongst all the messages Intrepid Control Systems, Inc. 53 Quiz 4 1. Overload frame is sent when receiver requires a delay. (True or False)? 2. Under what conditions does a form error occur? 3. Stuff bits are inserted only if there are 5 consecutive bits of the same state on the bus. (True or False)? Intrepid Control Systems, Inc. 57 CAN Bit Timing Issues ? All nodes must receive TX waveform “simultaneously” for arbitration ? Varying Delays for different nodes ? Resynchronization: no mon clock between nodes Intrepid Control Systems, Inc. 58 CAN Bit Timing Issues ? Each bit has four parts and the sampling point ? Each part of the bit consists of a number of time quantas ? Sample point at 7080% of bit SYNC_SEG PROP_SEG PHASE_SEG1 PHASE_SEG2 1 bit in CAN frame Sample point Intrepid Control Systems, Inc. 59 High Level Protocols ? Examples: Ford SCP is a HLP to J1850 and so is Class 2 ? CAN HLP: J1939, GMLAN are on top of CAN ? CAN HLP: CAN Calibration Protocol (CCP)? ? CAN HLP: DeviceNet Intrepid Control Systems, Inc. 60 DBC Files ? Industry standard DBC file format ? DBC files describe the structure for signals that CAN frames could contain ? Vehicle Spy supports DBC files for message decoding Intrepid Control Systems, Inc. 62 Quiz 5 1. CAN frame arbitration takes into account frame ID and frame data bytes. (True of False)? 2. During CAN arbitration a dominant bit (logical 0) always wins arbitration vs a recessive bit (logical 1) (True or False)? 3. What is bit sampling point? Can we change it? Intrepid Control Systems, Inc. 63 Thank you for your attention Questions?
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