[addaon]

Yeah, COBS works. In my case, I can even go simpler, since messages are fixed size. But:

1) This is now part of the line code. And "uart + slip but modified" starts losing some of the "simplest thing" charm of "just do what everyone else does."

2) Looking at this without reference to previous work, it sure seems unlikely to be the simplest thing. Magic numbers everywhere -- 8N1 uses 8 bit bytes to support ~5% clock skew, which isn't reflective of the application; COBS forces sub-packets at 255-ish byte intervals, which doesn't match any inherent concept, etc. It can work, but does it make sense in isolation?