An Analytical Model of the CAN Bus for Online Schedulability Test
Abstract
Controller area network (CAN) is a prioritybased
bus that supports real-time communication. Existing
schedulability analysis for the CAN bus is peformed at the
design stage, by assuming that all message information is
known in advance. However, in pratice, the CAN bus may
run in a dynamic environment, where complete specifications
may not be available at the design stage and operational
requirements may change at system run-time. In this paper,
we develop an analytical model that describes the dynamics of
message transmission on the CAN bus. Based on this analytical
timing model, we then propose an online test that effectively
checks the schedulability of the CAN bus, in the presence of
online adjustments of message streams. Simulations show that
the online test can accurately report the loss of scheduability
on the CAN bus.