The Research And Application Of CAN Bus Static Scheduling Platform On S12

CAN bus is a serial data bus that supports priority based message arbitration and non-pre-emptive message transmission. With the characteristic of simple structure, high efficiency, stable transmission, CAN bus is widely used in the field of automotive electronics, medical instruments, mechanical manufactures, etc. Along with the development of modern industrial design, the real-time data on the CAN bus will be improved continuously, the non-pre-emptive arbitration mode of CAN bus will inevitably affect transmission time of the actual message, so the analysis of message time on CAN bus is indispensable. The schedulability of message on CAN bus will affect the real-time and stability of the whole system, so the schedulability analysis of message on CAN bus is also imperative.This paper primitively introduces the development of CAN bus and the research of CAN bus scheduling. Because of CAN bus which is triggered by events, this paper introduces static scheduling method on CAN bus in detail according to the characteristic of CAN bus protocol. Based on the requirement of the program, this paper proposes a set of optimization schemes on CAN bus static scheduling platform, and also designs static scheduling system platform on this scheme. The author chooses S12series microcontroller as the core unit to construct CAN bus static scheduling hardware environment, and respectively makes the analysis of static scheduling theory model, software simulation and system test on this system platform. In the analysis of static scheduling theory model, the author compares two static scheduling theory models which are widely used, finds out the drawback of Tindell scheduling theory model, improves and introduces Davis scheduling theory model. Based on Davis scheduling model, the author improves the common algorithm of CAN bus static scheduling. By use of Stateflow software simulation tools, this paper simulates the improved algorithm. It also identifies the availability of the improved algorithm according to two common assessment standards which are the schedulability of system and the utilization of CAN bus. Finally, this paper completes the test and analysis of CAN bus static scheduling platform. The author uses Visual C++software development tools to realize the software of improved scheduling algorithm and designs CAN bus static scheduling software platform. The author also uses the actual transmission example on CAN bus to test the static scheduling platform. According to the static scheduling software platform, this paper schedules CAN bus nodes and analyzes real-time message parameters of CAN bus nodes in order to realize the schedulability of CAN bus system. This paper sufficiently validates the availability and reliability of CAN bus static scheduling platform. The research of this program not only provides the effective technical support to the research project, but also supplies important reference value to the theory research of real-time communication system.