Experiment And Research On Vehicle CAN—Bus Extension For Telematics

With the economic development, the rapid growth in the number of cars makes transportation a growing problem. How to get through information technology for making cars with electronic intelligence capabilities to ease traffic congestion has become a hot industry research. In this process, the concept of intelligent transportation systems(ITS) have come into being, which is an important means of achieving vehicle networking.The element of Telematics is a car, and with sensor technology, information collection technology, access technology, transmission technology, networking technology and so on it congests pedestrians, vehicles, roadside facilities and roads into traffic management network, mobile network and back-up network. It serves for vehicle safety, traffic control, information services, users’ access applications network. It aims at establishing improve traffic conditions, improving travel efficiency and expanding information exchange in the form of intelligent integrated network system.The vehicle network is an important part of Telematics. In this paper the author draw on existing CAN bus network and judged that only introducting new backbone network could greatly enhance the transmission speed and reduce costs for achieving the popularity of automotive networking integration. The Ethernet has a lot of advantanges, such as a large bandwidth, low cost, widely used, mature technology. Besides that the Industrial Ethernet has got a greatly progress of improving resistance to electromagnetic interference, resistance to high temperature and humidity, and improving real-time and achieved considerable progress, so it embodies great practical value and development potential. Therefore, the author proposed an Ethernet + CAN + Wi-Fi + GPRS gateway as a design goal of this paper.In this paper, the author introduced the definition and role of Telematics, and then went focus of this study- the vehicle network. Through the performance comparison between major automotive bus and Ethernet, learning Ethernet networking technology is more suitable for future vehicle requirements for on-board the bus, explicitly Ethernet as the main object of this article protocol conversion. Then the author introduced some background knowledge and agreement of Ethernet, CAN bus, Wi-Fi, GPRS and SCI bus.Getting use of eCAN modules and serial peripherals, the author chose TMS320F2812 DSP chip as the core to realize communication of CAN bus, Wi-Fi and GPRS and then used the data and address buses with RTL8019 AS for Ethernet protocol conversion. Entire hardware circuit includes a microcontroller module, Ethernet module, CAN bus transceiver module, serial module and so on.On the basis of hardware design, the author proposed the system design requirements flowchart software, and then used TI’s DSP program —CCS3.3 to execute the programming. Software program is divided into initialization, Ethernet procedures, peripheral interrupt entry, CAN bus and serial interruptions five parts.After the software and hardware design, the authors maked use of LabVIEW program for three peripherals and Ethernet protocol conversion; On the basis of this success, built system platform for systematical debugging. During the test, the author has come across many difficulties. With the help of teachers and classmates, the author analyzed and succeeded to solve problems, so complete the design goals finally.On this basis, the author of further detailed analysis, Ethernet OSI model and other protocol conversion, and discuss protocol conversion process data flow diagram for protocol conversion software programming and hardware chip and circuit design choices for the preparatory work.Completed the softwore and hardware design, the author chose NI’s LabVIEW program as a test program, using its powerful features to complete the data generated, sent, received, stored and compared, and timing control, peripheral drivers, etc. to simply and efficiently complete the test of three peripherals and Ethernet protocol conversion; on the basis of this success, an increase of a router and two computers set up to vehicle network system platform for uniting test. During the test, the author has come across several difficulties. With the help of teachers and classmates, the author went through the analysis succeeded to solving the problem, completing the design goal, to verify the correctness and usefulness of the gateway system.