Home // International Journal On Advances in Software, volume 2, number 4, 2009 // View article

Extending a Time-Triggered System by Event-Triggered Activities

Authors:
Josef Templ
Johannes Pletzer
Wolfgang Pree
Peter Hintenaus
Andreas Naderlinger

Keywords: Lock-free; Synchronization; Time-triggered; Event-triggered; Synchronous; Asynchronous; Activity; TDL

Abstract:
Time-triggered execution of periodic tasks provides the cornerstone of dependable real-time systems. In addition, there is often a need for executing event-triggered activities while the system would be otherwise idle. We first present the foundation of a time-triggered system based on the Timing Definition Language (TDL). Then we introduce eventtriggered activities as an extension of the purely time-triggered programming model. If time-triggered and event-triggered activities exchange information among each other, the data flow must be synchronized such that reading unfinished output data is avoided. The paper describes a lock-free solution for these synchronization issues that is based exclusively on memory load and store operations and can be implemented efficiently on embedded systems without any operating system support. We also discuss the implications of our synchronization approach for the semantics of combined time-triggered and event-triggered execution in a dependable real-time system. A case study of an Inertial Navigation System (INS) illustrates these extensions.

Pages: 313 to 322

Copyright: Copyright (c) to authors, 2009. Used with permission.

Publication date: March 17, 2010

Published in: journal

ISSN: 1942-2628