Enhancement of Controller Area Network (CAN) Bus Arbitration Mechanism

Abstract

FlexRay protocol includes a static time-triggered and a dynamic event-triggered segment, where the static segment enabling a guaranteed real-time transmission of critical data, while the dynamic segment (optional) for low-priority and event-triggered data. FlexRay is operated in a synchronous fashion. Based on the CAN (Controller Area Network) bus arbitration mechanism, this study takes the most significant bit (MSB), D10, of the identifier to assign the messages to be either static-like or dynamic-like, where the static-like type has higher priority than the dynamic-like type. Both types are operated in an asynchronous fashion as the conventional CAN protocol. With the designers\' experience with good schedulability, the above assignment can ensure that all critical messages be sent out before their deadline and no one message type hugs the bus. However, the salient feature is achieved at the cost of losing one bit for the identifier.