Deterministic Execution of Ptides Programs

This paper discusses the use of the Ptides model of computation as a coordination language for the design of deterministic, event-driven, real-time, distributed embedded systems. Specifically, the paper shows how the use of synchronized clocks in the context of Ptides enables explicit, platform independent specification of functionality and timing. From this specification, we generate code for two target platforms: Renesas and XMOS. The generated code includes a lightweight operating system which performs scheduling, I/O and network handling as well as application specific tasks. Ptides models are developed in Ptolemy, a design and simulation environment for heterogeneous systems. This framework also contains a code generation framework which is leveraged to derive Ptides implementations from the models. We illustrate our approach by designing a simple Ptides application, a small component in a printing press responsible for on-the-fly changeover between paper rolls. We demonstrate the design process and show that the generated code exhibits identical timing at the cyber-physical boundary on multiple implementation platforms. 1