Design And Implementation Of Diagnosis System Of Automobile ECU Based On CAN Protocol

Nowadays all walks of life are in rapid developing, the automobile industry also is forging ahead with the development of the times. The development has brought the modern car assembly structure increasingly complicated, which leads to car fault diagnosis more and more difficult. Presently, the automobile diagnosis technology has not only confined to after-sales maintenance, but more applied in electronically controlled unit (ECU) research and development, auto safety, vehicle emission testing, automobile production offline matches, etc. With the importance of fault diagnosis more and more obvious, the fault diagnosis technology is a growing part in the controllers. In current automobile industry, Vehicle plants or auto parts manufacturing company will diagnose the developed ECU in advance of the ECU developing process. It will improve the efficiency of ECU research and development.This paper describes a design of vehicle ECU diagnosis system based on low CAN speed.The diagnosis system includes hardware design and software design.And finally,the function test of the designed diagnosis system is carried out.In hardware design aspect, hardware circuit module mainly includes power module, reset module,oscillator module and CAN transceiver module.The chip of CAN transceiver module is MC33897.In software design aspect,software module include two sides,one part is the microcontroller CAN communication module,the function of the module including CAN data reading and sending of vehicle ECU, and the programming software language is C language.The other part is PC module,the function of this module is receiving the CAN data from microcontroller CAN communication module and indicating the data.The programming software language is VB.In system function test aspect,This paper uses a comparison test method,set the ECU sending period of 200ms,300ms,400ms,500ms,600ms and 700ms to test receive and transmit stability of the diagnosis system.and the test baud rate are 33.3kb/s and 83.3kb/s,through the experiment testing,the designed diagnosis system can receive and transmit CAN data completely and PC can display the received CAN data correctly.