Research And Development Of Wireless Vehicle Data Transmission System Based On CAN And GPRS

With the development of automotive electronics technology and network commu-nication technology, and the increasing growth of social requirement for safety, pollu-tion, reliability and cost, automotive communication technology is developing rapidly.There are two basic aspects: (1) the vehicle internal network connecting distributedelectronic device within; and (2) the external network which implements communica-tion between individual vehicle and other vehicles or outside fixed network via wirelesscommunication. Currently, CAN and GPRS wireless network can meet requirement ofthose systems respectively. Considering whole vehicle data transmission system, vehi-cle internal network communication and communication between internal network andexternal network have become key technologies and they are also the main topics ofthis thesis.The general vehicle data transmission system is designed and analysed in this dis-sertation from three aspects: the vehicle internal network configuration, the CAN/GPRSgateway implementation and the remote Internet monitoring server design.Firstly, the vehicle internal network is built. Hardware of CAN network nodes isdesigned and low level hardware drivers are programmed. Basic protocol stack accord-ing to vehicle internal network standard SAE J1939 is developed, including messagereceiving module, message sending module and timer module in the protocol stack.Secondly, GPRS wireless communication is implemented. Hardware of CAN/GPRSwireless gateway is built, ARM-Linux operating system is transplanted, drivers of theoperating system are programmed and GPRS wirelessly accessing Internet is realized.In order to transmitting wireless vehicle data, protocol is converted between vehicle ap-plication protocol and TCP protocol or UDP protocol. The heartbeat program whichdetects wireless communication abnormity is programmed.Thirdly, the remote Internet monitoring server and the database server are con-structed based on distributed architecture. Multithread wireless communication be-tween vehicle terminals and server is implemented through ARM-Linux Socket andWindows Socket. The software of database server is programmed using stored proce-dures and the operation of distributed database is realized by using ADO technology.Finally, the tests of vehicle network communication on CAN network platformand GPRS wireless communication of gateway are conducted respectively. The com-munication system containing vehicle internal network, protocol stack, CAN/GPRSwireless gateway and server is integrated and tested. The experiment result shows thatthe communication system can meet the requirement of vehicle data transmission.