Open Rowing Monitor Concept 2 interface

This is an interface to allow the Concept 2 model C Indoor Rower to be used with the  Open Rowing Monitor. The interface is designed to be connected to a Raspberry Pi (I'm using a Raspberry Pi Zero W v1.1). It seems to work but has not been thorougly tested.  I do not know hardware design so it probably has numerous issues.  I can add anyone that wants to make improvements to the project.

I have a couple assembled boards available if you are in USA/Canada.