threeboard VS EmbeddedProto

I tried to give a bit of an overview of this in the 'hardware design' section of the documentation [0]. It has some external links to further documentation and tutorials in it too. But the learning curve is very steep.

I'd maybe suggest looking for an electrical engineering intro book or course at a level you feel comfortable with, just to get an idea of the basics.

For the ErgoDox keyboard, the schematic is actually available on their own repo [1], but it's going to look quite intimidating initially. But I found a pretty great looking article explaining the electrical design of the ErgoDox that you might find useful [2].

[0]: https://github.com/taylorconor/threeboard/blob/master/docume...

Have you looked into Embedded Proto? https://embeddedproto.com/

For a general embedded library for safety critical applications you could look at our Embedded Proto lib. This is a data serialization lib which is checked against the MISRA coding standard guidelines. Doing so makes it possible for our customers to use it in medical applications.

That's when protobuf has your back if other formats don't.

Embedded Proto is a project aimed at using protobuf with embedded C++ code without using dynamic memory allocation. It is MISRA compatible code and build with professional use in mind.