Research And Realization Of Bootloader Based On CAN Bus

With rapid development of automotive ECU(Electronic Control Unit) applications, their functions are getting more powerful, and structures are becoming increasingly complex. If applications need update in the future, the traditional process requires that related parts must be removed from the vehicle, which increases workload and may cause damage to vehicle itself. However, Bootloader(boot and load) can transmit data through vehicle network, implementing online update of applications without disassembling. CAN(Controller Area Network) bus, one of the five diagnostic criteria of OBD(On-Board Diagnostics), has a high degree of flexibility to adjust, which can add nodes in the existing network platform without any modifications on hardware and software. Therefore, research on Bootloader based on CAN network is of great practical value.Firstly, both the history of vehicle network development and summary of the future trend are introduced. Based on research of CAN bus, CAN module and corresponding peripheral modules are both selected and designed. After that, the interfaces between master chips and CAN bus are implemented. On the detailed study of ISO15765 protocol, the mathematical model for STmin is established. Then state transition diagrams are described by UML and implemented by code. According to the characteristics of Bootloader, system and workflow of Bootloader are redesigned. Also, each module of Bootloader is designed and realized in detail. At last, some improvements are proposed. After implementing Bootlader, related hardware and software environment are built to test the system feasibility and stability. Finally, on the basis of the better performance proved under high bus load, some future possible functionalities are presented.The analysis of testing results attests that, this system can realize accurate application update and achieve an excellent performance under high bus load. Compared with Bootloader based on traditional serial buses and other Bootloader based on CAN bus, the proposed system proves to own higher stability, greater compatibility and better update feature. The result reveals that the major suppliers’ Bootloader system can be replaced by the proposed system to gain enormously reduced costs. The research conducted provides great theoretical basis for system designing and developing, which has strong utility and commercial significance in practical applications.