I/O control over serial

[Paul_B]

@PsychodelicPenguin

I agree it is a strange order to start with D1 instead of D0. I presume it has something to do with the onboard 328P pinouts, avoiding un-nessessary via's or something to do with FTDI/PL2303 chipset, I would like to hear if someone knows the actual reason for this.

It's a stuff-up on the diagram you used, as I mentioned.

The actual names are RXO where "O" is "Output" and TXI where "I" is "Input" as indicated by the little arrows. Don't get upset about it.

The use of optocouplers in #8 above makes no sense. Transistors would be more appropriate.