Revisiting Time Remanence Clocks for Energy Harvesting Wireless Sensor Nodes

The intermittent operation of batteryless devices makes it difficult to have time information in order to synchronize and communicate between these devices. In this paper, we analyze time remanence clocks and compare them with real time clocks in keeping time when device looses power. We argue that the time remanence clocks can keep the time for longer period but there are several challenges the needs to be considered. In particular, high chip and board variation, coupled with a fixed, proportionally small window of time measurement inhibit the effectiveness of remanence clocks. This paper proposes the possibility of constructing small, customized SRAM-based time remanence clocks to provide an increased measurement window.