Minimizing CAN response-time jitter by message manipulation

Delay variations (jitter) in computations and communications cause degradation of performance in applications such as control. There are many sources of jitter, including variations in execution time and bus contention. This paper presents methods to reduce the variation of frame (message) transmission time caused by the bit-stuffing mechanism in a controller area network (CAN). By introducing restrictions, such as a small reduction of available frame priorities, we are able to reduce the number of stuff-bits in the worst case. We also combine this with some of our previous work that reduces the number of stuff-bits in the data part of the frame. We show the actual penalty introduced by forbidding priorities, and show the overall improvement obtained by using these techniques together in a small case study.