Operating System Support for Embedded Real-Time Applications

Abstract

The rapid progress in processor and sensor technology combined with the expanding diversity of application fields is placing enormous demands on the facilities that an embedded operating system must provide. Embedded systems can be defined as computing systems with tightly coupled hardware and software that are designed to perform a dedicated function. The word embedded reflects the fact that these systems are usually an integral part of a larger system. We can find a large variety of applications where embedded systems play an important role, from small stand-alone systems, like a network router, to complex embedded systems supporting several operating execution environments as we can find in avionic applications. This variety of applications also implies that the properties, platforms, and techniques on which embedded systems are based can be very different. The hardware needs can sometimes be achieved with the use of general purpose processors, but in many systems specific processors are required, for instance, specific DSP devices to perform fast signal processing. Memory management capabilities are necessary in some systems to provide memory protection and virtual memory. Special purpose interfaces are also needed to support a variety of external peripheral devices, energy consumption control, and so on. Nowadays, the use of processor-based devices has increased dramatically for most of our activities, both professional and leisure. Mobile phones and PDAs are used extensively. Consumer electronics (set-top boxes, TVs, DVD players, etc.) have incorporated microprocessors as a core system component, instead of using specific hardware. This trend is expected to grow exponentially in the near future. Embedded applications have some common features such as the following.