Power Management in Real-Time Embedded Systems

With the improvement of the computer science and electronic tecnologies, nowadays, it’s possibile to realize devices very small, with extraordinary computation capabilities and with a good cost for unit. Hi-tech products are everywhere around us and in the future we’ll be immersed in a world where everything will be electronic. In this scenario, it’s born the issue of the energy saving, especially in real-time systems, with an high level of integration in the monitored environment and a not infinite power supply. It means to try to reduce the waste of energy, with a smart organization of the jobs and resources, allowing the satisfation all requirements (e.g.: time, few resources, shared resources). In this thesis, a software module will be proposed, between the operating system and user applications, to obtain those targets, with a set of devices such as the CPU, radio modules and servomechanisms. Servo motors are the muscles of many devices and from their analysis the best updating period can be extracted to reduce the energy according to the applied torque. About radio modules, the system makes that they fall asleep when they aren’t used and wakes up them just in time to be ready when they are required. The CPU manager is the core of the discussion and implements three inter-task reclaiming algorithms. Results are compared with a DPM approach, to investigate trade-offs. Algorithms were studied for hard real-time systems, so they respect always the time constraints of tasks and devices