Power supply monitoring for wireless sensor platforms
Most of the portable electronic devices use a battery as a primary power source. Nowadays, when the applications are becoming smaller and smaller and more power efficient, the designer needs to concentrate more on reducing power consumption, using secondary power sources and introducing power storage devices. Multiple power source availability and a power storage device on the board will make the applications much more useful and efficient in everyday use. This thesis proposes a power supply unit (PSU) for wireless sensor platforms which is capable of supplying a sensor node with energy from multiple sources, as well as status information from the PSU. Present power storage devices, like electric double-layer capacitors (EDLCs) and batteries, have become more and more common as their characteristics have developed. The EDLCs are popular due to their ability to charge and discharge efficiently and quickly at high currents. In addition, there are no limits for the number of charge and discharge cycles. The advantage of batteries is their ability to store a larger amount of energy (with longer charging period) and their decreasing size. In this design, both battery and EDLCs are used. Batteries will be used only in critical conditions. Otherwise, the system will be powered by renewable solar energy which will charge the EDLCs at the same time. The device?s architecture contains a context- and power-aware task manager, which controls the node?s low-power modes and decides when they are activated. Its main responsibility is to schedule the moments when the energy consuming task can be dispatched. Depending on task priority and system configuration, the task can be dispatched, discarded or delayed.