Enabling Component-Based Design For Embedded Real-Time Software

The increasing complexity of embedded software calls for a new, more efficient design approach. A natural choice is to use well-established component-based design; however, its adoption to design of embedded software has been slow and riddled with difficulties. It can be argued that these problems are due to the following peculiarities of embedded systems. Firstly, the tight integration between hardware and software, typical for embedded systems, makes it virtually impossible to model and implement software separately from hardware. Secondly, it is difficult to express timing requirements, an intrinsic part of functionality of many embedded systems, in dataflow abstractions traditionally used in component-based design.We propose to overcome these difficulties by introducing a uniform, consistent modeling of both hardware and software and by integrating timing requirements into the model. We present a modeling framework based on the notions of reactive objects and time-constrained reactions, which enables component-based design of embedded real-time systems. Within this framework, functionality of both hardware and software components is defined in terms of reactions to discrete external events, and timing requirements are specified for each reaction relative to the event that triggered it. We also present a detailed software design methodology for embedded real-time systems based on our modeling framework.