Research And Realization Of Communication Module Of Automotive Electronic Control System

With the development of Auto industry and electronic technology, automotive electronic control system is becoming more and more complex. In order to transfer information among these ECUs (Electronic Control Unit), CAN is introduced in most automotive electronic control system. With the increasingly strict exhaust regulation, malfunction diagnosis is necessary. So it is very significant to develop a communication module between PC and CAN for online development of ECUs and read of malfunction code. There are two main ways to accomplish this task before. One is to connect PC from COM port, the other is by extended card of PCI bus or ISA bus. The communication module used in motor's ECUs ask for convenience, high exchange speed, low resource's occupying , and self power .But the current product can not meet these demands at the same time, a new CAN/USB/RS-232 communication solution was presented in this paper.On the basis of the research of automotive ECU, OBD system and communication protocol of CAN/USB/RS-232, the design project is given. The main chip of communication module is Motorola's MC68HC908AZ60A, which has integrated MSCAN (Motorola Scalable Controller Area Network) and SCI (Serial Communication Interface); USB interface chip is Philips's PDIUSBD12, which has integrated USB SIE (Serial Interface Engine); The voltage conversion chip of RS-232 is TI's MAX3222I; CAN high-speed transceiver is Philips's TJA1040. The firmware of module is written in C and assembly language under CodeWarrior IDE (Integrated Development Environment); WDM driver of Windows 2000 is accomplished with DDK and DriverStudio, and application program with Win32 API under Visual C++ 6.0 IDE. At the end of this paper, problems in debugging of hardware and software are also discussed.This communication module has accomplished the high-speed communication between CAN bus and USB. And based on the module, read of malfunction diagnosis code and development online of ECU has realized. In addition, protocol conversions between RS-232 and USB, RS-232 and CAN are realized respectively. Furthermore, some parameters such as baud rate of RS-232, baud rate and ID of CAN can be modified by PC program, thereby the module's application has been extended.This communication module possesses the following characters: small size, easy to use, multifunction, portability, none of external power. Now this communication module has been applied to products of JiangKui's ECU.