Forced Speed Limit System With The Function Of Flash Boot Loader Based On CAN Bus

As the number of vehicles dramatically increases in china, traffic accidents take place more and more frequently. According to the statistics, over-speed is most serious and may lead to death. Therefore, solving this problem attracts people’s highly attention. At the same time, with the rapid development of automotive bus and intelligence technology, automobile electronic technology aiming at settling such problem has become a research hot. Under this circumstance, more and more car companies, manufacturers and research institutions begin to develop all kinds of active or passive intelligent security systems. In this paper, an active intelligent throttle control system based on the CAN(Controller Area Network) bus technology is introduced, which solves the security problems caused by over-speed effectively.Combined with the embedded technology, CAN bus technology, bluetooth technology and computer technology, the force speed limit system have the ability of controlling the auto’s speed within the safe range by using a certain proportional relationship between output and input. In addition, it adds online upgrade function called Flash BootLoader to solve the repeated disassembly problem during the development process. That is, it doesn’t need to remove the speed limiter from the car body and can update the user program via CAN bus of OBD interface directly.According to the design requirements, this paper chooses MC9S08DZ60 as the main controller of the whole system, PCA82C250 as the CAN transceiver, XM-10 as the bluetooth communication module, and then completes the designs of hardware and software of the forced speed limit system respectively. Besides, the Flash Boot Loader consists of BootLoader program guiding the download process and UI controlling the data extraction and update.Finally, the result of simulation and field tests shows that under the condition of normal communication, functions of speed limit and online upgrade are realized and the system work stably. Therefore, this forced speed limit system can not only protect the driver but also solve the over-speed problem very well.