The Study Of Automobile Digital Instrument On The Base Of CAN Bus

The automobile instrument is the main interface through which the driver can communicate messages with the automobile. The traditional automobile instrument requires a large number of wiring harnesses. The design will increase the difficulty of wiring distribution and EMI among the wiring harnesses, which can result in low system reliability. With the latest development of the bus technology and the increment of car electronic equipments, the traditional automobile instrument faces a big challenge. The digital-based CAN bus automobile instrument will replace the traditional automobile instrument. CAN bus can be an excellent implementation of data exchange among automobile equipments. CAN bus has a lot of excellent advantages, such as the high communication speed, strong reliability, easy connection, simple and cost-effective communication protocol. CAN bus has become a standard vehicle bus for communication among electronic control units, and it has been widely used in vehicle distributed control systems.Based on the principle of CAN bus protocol and the relevant features of automobile instrument, the relevant CAN bus technology of automobile instrument has been researched and analysed in the dissertation. On the base of CAN bus digital automobile instrument, a hardware system is proposed. This system uses the STC90C52 as the core processor, SJA1000 as the CAN bus controller, PCA82C250 as the CAN bus transceiver and uses LCD to display data.In the architecture of systematic software, a modular programming method, which matches the system function modules, is proposed in the dissertation. It has a great help for developing and debugging that modularize each function and parameterize each interface among functions.A sub-system, which is used for debugging and validating digital instrument, is proposed, and the topology between the digital automobile instrument and the debugging-validating sub-system is proposed in the dissertation. It provides a great help for early development and later debugging of the system. For optimizing performance of CAN bus controller, the principle of the acceptance filter in SJA1000 is deeply analysed and experimentally implemented in the dissertation.