Design And Research On An Embedded Vehicle Network System

The widespread application of car electronic technology to automobile causes the smart sensor, the electronic actuator and electrically controlled unit to grow sharply, and every kind of communication equipments are applied to automobile one after another. Subsequently, more and more electrical wires as well as a variety of signal lines in automobile causes the operational reliability of system to drop, the failure rate to increase. In order to achieve each unit status information sharing, improve system reliability, a variety of network technologies have been introduced into the car, vehicle networking technology to become one of the research focus. Therefore, this paper thoroughly researched and designed embedded automotive network system.Classic CAN bus network can be a good solution to control the electronic controlled unit, the transmission rate of which is less than500kbps. The rapidly developed LIN bus in recent years is a kind of bus which is designed for data transmission between simple sensors and actuators, effectively improving the utilization rate of the CAN bus. The new MOST bus is very suitable for the requirement of the vehicle media device application environment, the MOST technology has been regarded as a standard of car media system in the future by automotive industry.This paper focuses on the current widely used LIN bus, CAN bus and MOST bus, designs a vehicle network system based on the above three bus in connection with their respective requirement for application. For the three bus of this vehicle network system, their respective division of work are as follows:LIN bus is used for low-speed sensor-actuator device; CAN bus is used for automotive electronic devices requiring better real-time; the MOST bus is used for automotive electronic device requiring high-speed transmission of data.ARM-based embedded vehicle network controller is designed based on the above classification structure of vehicle bus. The hardware platform of this system consists of the following parts:core processor S3C2440, extended memory SDRAM, NAND-Flash, the LIN bus drive MC33661, CAN bus controller SJA1000, transceiver PCA82C250, MOST bus controller OS8104and optic fiber transceiver MIT401/ MIR401.Bottom divers of various parts of hardware in this system are completed according to the general method of software design of the embedded system as well as hardware circuitry. The transplantation of embedded Linux kernel, production of Yaffs root file system, LCD display driver, the realizing method of driver of LIN bus, CAN bus and MOST bus are discussed in detail.In connection with the three network bus in vehicle network, the realization of these bus application software is discussed, the formulation of the bus data frame format, realization of some important functions as well as debugging remote diagnosis program are emphasized.