I have not been following the UART discussion, I would say one thing though, I would not bother to send out anything other than some raw data packets with some identifiers. No point having the controller do any data processing that some external device can easily do. (Guess you already knew that
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Hmm, maybe implementing a simple modbus slave type protocol. External device can write to registers to set parameters and read from registers to get any data it wants.....need to think about that for a moment..