Enabling Ultra-Low Power Operation in High-End Wireless Sensor Networks Nodes

This paper presents a prototype hardware/software architecture for minimizing energy consumption on high-end microcontrollers, while simplifying the development of applications providing a general-purpose-like programming environment. The key features enabling this twofold goal are operating system support to processes, optimized sensing and hibernation of the system state. To balance performance offered by high-end microcontrollers with the need for ultra-low power operation—especially required by WSNs— it is essential to minimize the duty cycle by keeping the microcontroller in a low-power state as long as possible, without affecting the performance required by the appli- cation. To cope with the increasing leakage current observed in today’s microcontrollers a software-based hibernation mechanism has been implemented to transparently save the memory of processes in a non-volatile memory, allowing to completely switch off the microcontroller. To further avoid costly process loading overheads during the sleeping periods, we devised a smart sensing mechanism capable of gathering data from peripherals without restoring the state of processes. Preliminary results show that the lifetime of the proposed node architecture is of the same order of mag- nitude of that of ultra low-power nodes and significantly better than that of high-end ones.