Design and energetic analysis of a self-powered Bluetooth low energy speed sensor
Luca Buccolini, Paola Pierleoni, Massimo Conti · 2016
Most of the speedometers on bicycles uses batteries. Batteries are polluting materials and they must be replaced. This paper presents an implementation of a self-powered speed sensor that uses energy harvesting to power itself, it measures the speed and transmits the data using Bluetooth Low Energy (BLE) to external devices such as smartphones. The energy harvester is a coil that acts as sensor, too. A prototype of the sensor has been built and a voltage regulation circuit has been simulated by using a SPICE simulator. Furthermore, a custom firmware has been designed using a Bluetooth Low Energy nRF51822 SoC by Nordic Semiconductor and the parameters of the BLE connection has been accurately chosen to obtain low energy consumptions. Finally, the energy balance between the harvested energy by the coil and the used energy by the SoC has been accomplished. The results demonstrate the technical feasibility of the self-powered BLE speed sensor for bicycles.