The Controller Area Network (CAN) protocol is widely used in distributed real-time, resource-constrained embedded systems. CAN uses “Non Return to Zero” (NRZ) coding and employs a bit-stuffing mechanism for clock synchronization. Such a mechanism causes a variation in the CAN frame length which may have a detrimental impact on the control behaviour of safety-critical systems employing this protocol. To address this issue, two techniques known as “byte-based XOR masking” and “software bit stuffing” were developed and achieved a jitter reduction of up to 20% and 40%, respectively, when employed in practical designs. This paper investigates the effectiveness of such techniques in a real-time control application; that is a simple furnace system case study based on a “hardware-in-the-loop” (HIL) testbed facility. The results show that reducing bit stuffing jitter has the potential to improve the control performance of distributed real-time systems employing CAN protocol.

jitter, bit stuffing, scheduler, time-triggered, shared-clock, furnace system, hardware-in-the-loop