Tokenit: Designing State-Driven Embedded Systems through Tokenized Transitions

The development of resource-constrained embedded systems that are naturally state-driven is still a challenging issue, especially in industrial applications -- developed on a bare-bone style runtime system with basic programming features. This is because of the complexity of state-driven design in embedded applications, such as parallel and complicated event-based activity flows, and complicated constraints for transitioning between program states. State machines are considered a systematic approach for such needs. However, existing approaches, in this area, either do not satisfactorily address the above complexity aspects, or force the developer to write code intermingling state handling logic with the functional code. To tackle these issues, we propose TOKEN IT, a state machine-based development framework for resource-constrained embedded systems. Using TOKEN IT, the programmer models the application as a set of parallel processes, where each process consists of sequenced activities with state constraints such as delayed transitions or interdependency between the states of parallel processes. TOKEN IT, then, processes the obtained model and associates a token to each sequential flow of activities, synthesizing them and executing state transitions according to the constraints expressed in the TOKEN IT model. The evaluation results show that TOKEN IT reduces significantly the complexity of state-driven programming in embedded systems at an acceptable memory cost and with no extra processing overhead.