Real-time C Code Generation in Ptolemy II for the Giotto Model of Computation

Abstract

Giotto is a programming model for embedded control systems that is applicable to hard realtime specifications that are periodic and feature multi-modal behavior. Examples of such systems include fly-by-wire or brake-by-wire systems where sensor readings must be periodic and there are multiple modes of operation.Ptolemy II is a university based open source modeling and simulation framework that supports model-based design, and facilitates actor oriented and objected oriented programming. It serves as a laboratory for the modeling and simulation necessary in the design of a real-time embedded system. Ptolemy also has a C code generation framework that generates code for different targets.Ptolemy II has an implementation of the Giotto programming model, that allows the simulation of Giotto models in Ptolemy II. In this report we discuss our ability to implement Giotto semantics using code generation and a real-time operating system. We illustrate these techniques with Ptolemy II and the FreeRTOS embedded operating system. To illustrate these techniques we extend the code generation framework within Ptolemy II to generate C code for the Giotto programming model. We have implemented a C code generation adapter in Ptolemy II for the Giotto model of computation targeted to systems capable of running the FreeRTOS operating system. We present an elevator controller as an example that uses the code generation framework.2

Action-level real-time DEVS modeling and simulation

“…29 For hard real-time execution, a Giotto model of computation has been developed in Ptolemy. 39 The Giotto programming model 40 with periodic timing is developed where tasks defined in a Giotto Director coordinate the execution of the actors based on their assigned frequencies or default values. Ptolemy’s code generation capability is used to generate C code.…”

A Study on Run Time Assurance for Complex Cyber Physical Systems

“…Any code generation provided for a distributed platform is specialized to a particular network protocol (often even to a particular network device) and to specific processors. Research in this area focuses on generating code to target a more generic model of computation so that the generated code can be reused on any platform that implements that model of computation [216] •…”