On Sat, 19 May 2018 18:54:26 GMT, Jan Panteltje 
declaimed the following:


>then MAYBE I would xor ptlrc output bytes with 0xff and same for input bytes
to force the invert ;-)

 Unless you are bit-banging a GPIO, that won't work... 8-bit data is
sent as 10+ bits by a UART.

1 start bit
8 data bits
1+ stop bit (some devices required up to two bit times before they could
handle a new start bit.

 You'd be inverting the 8 data bits, but not the start/stop bits. Stop
bits are whatever the protocol considers as an idle state (pull up or pull
down, so when the UART is not doing anything, the line shows a stop bit.
Start bit is the inverse of a stop bit -- basically a forced level
transition to wake up the receiver UART, since the first data bit could be
the same state as a stop bit.


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 Wulfraed                 Dennis Lee Bieber         AF6VN
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