Development Of Automotive Fault Real-time Reminding System

With the widely development of electric technology and control technology on the vehicles, special fault diagnostic tools are used in automobile's fault diagnosis. Now, the on broad diagnostic system can monitor the systemic parameters of automotive electronic control system continuously. This kind of diagnostic system can memorize the intermittent problems. So it would be easier and faster to find out the faults. The communication protocols used by diagnostic system, the communication criterions which should be followed, and the trouble codes and how to get them are described in detail in OBD-II standard. Most of the automobile manufactures have adopted the OBD-II fault diagnostic system.The on-vehicle fault diagnostic platform is used to get diagnostic information and real-time status messages from the electronic control units. It communicates with the electronic control units through the OBD-II electrical connector, acquire trouble codes and dates. The diagnostic results will be displayed on the LCD or be transmitted on the loudspeaker.This dissertation based on in-depth study of the protocols and methods which defined by OBD-II standard. It puts forward how to design Automotive Fault real-time reminding system, completed the interface circuit and related software Procedures, voice broadcast system software and hardware development and debugging.This system which designed in this dissertation is made up of two parts: the hardware and the software. The hardware includes ECU-OBD interface, dealing with transferring the data signals of network bus to serial communication signals which ECU can identify. We also give the detailed explaining of hardware design of the OBD -ECU interfaces which bases on the ASIC special for protocol converting. The software includes acquiring and analyzing the ECU data and fault codes, dealing with sending request messages, receiving respond messages, analyzing the data and displaying the data. The software design carries out fully the principle of software engineering. It adopts the programmer method of configuration and module. Also combines some database system theories. Then achieves the integration of serial communication, data collection, data analyze and speech play.