EE382C Embedded Software Systems - Guest Lecture

Synchronous/Reactive Systems

Stephen A. Edwards

Synopsys, Inc.,
Mountain View, CA


In this talk, I discuss the synchronous approach to designing reactive embedded systems. Reactive systems must run at the speed of their environment, and when something happens in these systems is often as important as what happens. For this reason, the synchronous approach has been developed, allowing control over system timing to be as precise as control over system function. This approach relies on the synchrony hypothesis, which assumes a system runs infinitely fast. This breaks time into a sequence of discrete instants and provides global synchronization.

After reviewing the synchronous approach, I present a new system description scheme that combines synchrony with heterogeneity. I formally present the semantics, which are complicated by the possibility of zero-delay feedback loops, and present an efficient, predictable execution scheme based on chaotic iteration, along with results that show it practical for medium-sized examples.

Updated 03/22/00.