I have spent a bit of time producing a write up of this project, not least for my own benefit so that when I look back in a few months time I can remember how everything works. The write up is availalble in the ZIP folder attached to this project (along with all of the other files) and also on GitHub here.

I have also taken a few photos of the soldered boards. Ideally I would like to make the bracelet board a little smaller. The limiting factor is the size of the coin battery holder on the rear. The size of each board is around 4cm squared (c. 1.5 inches).

Bracelet board

Sensor board