Worst-Case Time Analysis of CAN Messages
Designers of CAN-based systems are of course interested in being able to predict the time performance of the messages exchanged over the network. The CAN protocol adopts a collision detection and resolution scheme, where the message to be transmitted is chosen according to its identifier. When multiple nodes need to transmit over the bus, the lowest identifier message is selected for transmission. The CAN MAC arbitration protocol encodes the message priority into the identifier field and implements priority-based real-time scheduling of periodic and aperiodic messages. Predictable scheduling of real-time messages on the CAN bus is then made possible by adapting existing real-time scheduling algorithms to the MAC arbitration protocol or by superimposing a higher-level scheduler designed purposely.