Research Of Embedded Scheduling Algorithm Based On CAN Bus

Nowadays field bus network control has been the main trend in the development of industrial control. CAN bus has become the most widely applied one in the existing field bus with its outstanding characteristics-simple structure, low cost, high reliability,high flexibility and strong anti-jamming capability. The node in CAN bus network control system is an embedded system. It tends to be more complex in the network control system, which needs to handle various tasks and has great differences in time characteristics such as periodic and aperiodic, real-time and non real-time. Meanwhile,processing resources in the completion of task are also different. For example, the non-communication task involves only CPU resources while the communication task also involves a CAN bus processing resources. Based on the diverse characteristics of the embedded task, experts put forward many hierarchical scheduling strategies of the combined task scheduling algorithm and achieved good scheduling results.This research introduces the CAN bus network control system and its structure and model, CAN bus communication protocol, embedded real-time system and its system structure and task management mechanism. Besides, it also explains the scheduling strategy and scheduling algorithm of the CAN bus and the embedded real-time system(RTOS) task and illustrates the principle of several typical scheduling algorithms. Based on the analysis of time resources characteristics and classification scheduling principles of CAN bus embedded tasks, it classifies embedded tasks and puts forward the structure mode of grading scheduling in the CAN bus embedded tasks. In order to solve the asymmetry of the task processing resources, it also puts forward the dynamic priority scheduling algorithm of shrinking proportion. Thus, this research expounds the definition of the task, records hierarchical scheduling process and its algorithm and analyzes the algorithm from the two aspects of scheduling and task delay.Finally, with the help of Simulink and Stateflow toolbox in the MATLAB software, this researcher constructs a CAN bus communication model, node model and the scheduling algorithm model, and simulates the RM scheduling algorithm and simulates the EDF scheduling algorithm and hierarchical scheduling algorithm. The simulation results show that hierarchical scheduling algorithm can improve the utilization of the network, relatively shorten the delay of message transmission andimprove the fairness of task scheduling.