[Updated, see end of article]
Since my last post I’ve improved the Arduino speedo code to respond to requests and also tweaked the gear ration to be a bit closer to my road bike. I’ve also implemented a simple speedo interface using Unity.

The Unity application also automatically searches the COM ports on the machine until it finds the Arduino speedo, it’s a bit hacky but works and means I don’t have to implement a COM port selection UI.
I’m going to add functionality to save off the readings to CSV log files too, at a later date I’ll add some kind of analysis in but getting the data saved is the important thing for now.
Update: CSV functionality has been added and I’ve tweaked the interface too.

For the Arduino portion of this weekend long hack, see here.