This repository contains the fw for the bike beacon. It is a personnal project that aims to address multiples issues I have had with bike lights until now, namely:
- forgetting to turn the light off, and thus draining the battery
- forgetting the light on the bike, and thus losing it
- having to change the batteries every 2 weeks (or less)
With this beacon, I hope to address these issues by:
- having a light that turns off automatically after a certain amount of time with no movement
- having the light embedded in the seatpost of the bike, so that it is always with the bike and cannot be removed easily
- having enough battery life to last much much more than 2 weeks.
The hardware is based on the following components:
- STM32l052 (ARM Cortex M0+, low power)
- LIS3DH (3 axis accelerometer)
- MAX17048G (fuel gauge)
- MC34673 charger for Li-ion battery
The hardware is designed in KiCad, and the schematics are available in the bike-beacon-hw repository.
The board is intended to be used in an emptied-out Lightskin seatpost (https://www.lightskin.org/#specs-post). The board is designed to fit in the seatpost, and the battery is placed in the seatpost tube towards the pedals. Under the saddle is a magnetic connector to allow charging without removing the seatpost. image: 
when off, the system consumes 70uA on the battery, allowing for long battery life. depending on the light pattern used, it consumes between 2.5 mA and 7.5 mA.