A modern vehicle will typically use the OSEK Operating System as a scheduling mechanism to distribute time between functions on an ECU and the CAN network to transmit messages between ECU nodes. Both OSEK OS and CAN are event-triggered technologies, that is they respond to events or stimuli in the external environment. For example, a braking system will be triggered by the driver pressing on the brake pedal; an engine management system will be triggered by the angular rotation of the engine crankshaft etc. This paper has developed a process whereby the temporal correctness of a distributed hard real-time application can be determined. This is achieved through the use of contracts on both the nodes and network. Contracts de-couple the system components within an analyzable framework and so reduce brittleness in the event of subsequent system modification - node and network behavior can be freely changed proving the changes still satisfy the contract. The authors have introduced basic deadline monotonic analysis and shown how it can be used to validate the contracts placed on the nodes. It has also been shown how this same analysis can be applied to the priority based networking of CAN. For more information on Deadline Monotonic Analysis, schedulability analysis or developing distributed hard real-time applications.
Meeting hard real-time requirements in distributed systems
Annäherung an harte Echtzeitanforderungen in verteilt angeordneten Systemen
2004
10 Seiten, 4 Bilder, 4 Tabellen, 3 Quellen
Conference paper
English
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