Software Engineering for Embedded Systems: Chapter 5. Real-Time Building Blocks: Events and Triggers

The previous chapter approaches embedded systems from a higher level of abstraction; from the system design architecture and how to apply design patterns for the implementation. This chapter introduces two fundamental concepts and design patterns in real-time systems: (a) the ability to set asynchronous event flags (events) and (b) the ability to have things triggered in a timely fashion (triggers). These two concepts are used both in systems with a real-time operating system (RTOS) and in systems not using an RTOS. The chapter starts with use cases and then develops different ways to implement events and triggers. It presents different implementation details and discusses the advantages and disadvantages. The sources for both event and trigger implementation are provided at the end of the chapter.