Design and Implementation of TinyGALS: A Programming Model for Event-Driven Embedded Systems

Elaine Cheong

Memorandum No. UCB/ERL M03/14
23 May 2003
Electronics Research Laboratory
College of Engineering
University of California, Berkeley 94720

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ABSTRACT

TinyGALS is a globally asynchronous, locally synchronous model for programming event-driven embedded systems. At the local level, software components communicate with each other synchronously via method calls. Components are composed to form modules. At the global level, modules communicate with each other asynchronously via message passing, which separates the flow of control between modules. TinyGUYS is a guarded yet synchronous model designed to allow thread-safe sharing of global state between modules without explicitly passing messages. This programming model is structured such that code for all intermodule communication, module triggering mechanisms, and access to guarded global variables can be automatically generated from a high level specification. We present language constructs for this specification, as well as a detailed description of the semantics of this programming model. We also discuss issues of determinacy that result from the event-driven nature of the target application domain.

We have implemented the programming model and tools for code generation on a wireless sensor network platform known as the Berkeley motes. We present details of the code generation process, which is designed to be compatible with components written for TinyOS, a component-based runtime environment for the motes. We describe a redesign of a multi-hop ad hoc communication protocol using the TinyGALS model.