Schedulability Analysis for Controller Area Network (CAN) with FIFO Queues Priority Queues and Gateways

Controller Area Network (CAN) is widely used in automotive applications. Existing schedulability analysis for CAN is based on the assumption that the highest priority message ready for transmission at each node on the network will be entered into arbitration on the bus. However, in practice, some CAN device drivers implement FIFO rather than priority-based queues invalidating this assumption. In this paper, we introduce response time analysis and optimal priority assignment policies for CAN messages in networks where some nodes use FIFO queues while other nodes use priority queues. We show, via a case study and experimental evaluation, the detrimental impact that FIFO queues have on the real-time performance of CAN. Further, we show that in gateway applications, if it is not possible to implement a priority queue, then it is preferable to use multiple FIFO queues each allocated a small number of messages with similar transmission deadlines.