To be clear, this doesn’t currently exist, but the premise was that everyone agrees to switch to something else. (Which is an unlikely premise, but maybe if som

To be clear, this doesn’t currently exist, but the premise was that everyone agrees to switch to something else. (Which is an unlikely premise, but maybe if something got momentum…) Microcontrollers do have their own proprietary serial debug protocols. ARM SWD, for example, has been around for almost 15 years. It’s “proprietary”, but being ARM that means it’s in billions of chips from many manufacturers. It does require a clock line, though. https://www.ti.com/lit/wp/spmy004/spmy004.pdf https://www.ti.com/lit/wp/spmy004/spmy004.pdf I’m suggesting something much simpler though, just keep the UARTs and stick a Manchester encoder/decoder in between.