Abstract

Abstract-The analysis of the real-time properties of an embedded communication system relies on finding upper bounds on the Worst-Case Response Time (WCRT) of the messages that are exchanged among the nodes on the network. The classical WCRT analysis of Controller Area Network (CAN) implicitly assumes that at any given time, each node is able to enter its highest priority ready message into arbitration. However, in reality, CAN controllers may have some characteristics, such as nonabortable transmit buffers, which may break this assumption. This paper provides analysis for networks that contain nodes with non-abortable transmit buffers, as well as nodes that meet the requirements of the classical analysis. The impact on message WCRTs due to a limited number of transmission buffers with non-abortable behaviour is examined via two case-studies.

No abstract

In distributed real-time systems it is crucial to ensure the temporal validity of the data exchanged among the nodes. Classically, the frame Worst Case Response Time (WCRT) analyses, and the software tools which implement them, do not take into account the aperiodic traffic. One of the main reasons for this is that the aperiodic traffic is generally very difficult to characterize (i.e., the arrival patterns of the aperiodic frames). The consequence of this is that one tends to underestimate the WCRT, which may have an impact on the overall safety of the system. In this paper, we propose a probabilistic approach to model the aperiodic traffic and integrate it into response time analysis. The approach allows the system designer to choose the safety level of the analysis based on the system's dependability requirements. Compared to existing deterministic approaches the approach leads to more realistic WCRT evaluation and thus to a better dimensioning of the hardware platform. * Jörn MIGGE was with PSA Peugeot-Citroën at the time the study was undertaken.