[Non-NASA] F3 F4 serial bus

[Foggy2]

Hello @lanwin

First of all thanks for putting this together and sharing it on GitHub. It is exactly what I have been looking for.

I am wondering if you have considered adding in support for the non-nasa F3 F4 (wall controller <-> indoor unit) serial bus? I ask as it is much easier for me (I assume others too) to connect to the cabling behind the wall controller than to connect to the outdoor unit or the indoor unit in the roof space.

I realise that this wouldn't be a minor change to your codebase. To this end I have been experimenting with adapting your existing code to function based off of the specifications shared by DannyDeGaspari. I have reached a point now where I am able to reliably send commands and have them accepted.

Temperature and On/Off works. I have a ducted system with a 3rd party ventilation system so am unable to test for fan speed/blade positions.

Mode does not appear to be working but I note that other non-nasa users are reporting the same on the F1F2 serial bus. So this is a work in progress.

I would submit a PR myself but this is my first time using c++ and I only understand how all the code fits together at a basic level. I fear that I would not be able to produce something of good enough quality myself so instead I wish to point out my repo here where you can see the changes that I have made to reach this point.

I am more than happy to keep working on this on my own repo for myself but in the event that you are happy to explore the F3 F4 serial bus further I would be happy to help where I can.

Thanks!