LG split air conditioner did not send information

[DavidAntonin]

Hello,
I have LG Prestige split unit with 3 pin (black, yellow, red) connector. But the yellow wire is still on HI 12V and never change to zero to send some information. I have the level converter and connected the Saleae logic analyzer but there is no signal. I have no wired controller. Must be the comunication initialized by the controller? Thank you
David

[Flameeyes]

(A bit of an old issue but you never know.)

I have a different LG system than @AussieMakerGeek, and mine is indeed panel-initiated for sure. If you still have the unit you want to check, you may want to take a look at my reversing posts (https://flameeyes.blog/tag/lg/) or the emulator (https://github.com/Flameeyes/lg-PQRCUDS0-emu) and see if it works for you.

[AussieMakerGeek]

That's some great work there @Flameeyes

Just so you know, I still have 2 standard wall controllers installed and 'piggy backed' my interface onto the existing bus. So I effectively have 3 controllers. One master and two slaves. Your implementation would have great benefit because as you state, the internal temp sensors are basically useless. It is very hard to actually get proper temp control in my house. Having a better temp reference from a sensor closer to the controlled area like you have done would be a much better system.

I'm interested in what you found with the 'something changed' bit. I don't recall anything with that in my data. I still have issues with mine, almost all due to the single wire bus but it works enough for what I need.

@DavidAntonin I doubt a split will work the same. Only some of them have the ability for a wall controller but even if yours did have the option, you'd probably need one of the original ones to reverse it and it's entirely possible that nothing here will apply to what you have.

[AussieMakerGeek]

@Flameeyes Further to that, I have now got my hands on a 'Standard wall controller' which seems to have all the same features and data protocol but supports IR control.

The downside so far is that I can't seem to configure the wall controller to work with my system (but it is a qualified controller for my exact model). It uses menu options rather than switches for all of the configuration. I got it to work for standard features but it would mess with the dampers and open them all up regardless of what I did. One day I might look at it again....

[JanM321]

@DavidAntonin Your situation sounds pretty similar to mine. I have a wall unit that comes without a wired controller (but a wireless remote and ThinQ) and I created an ESP32-based wired controller for it.

@AussieMakerGeek To avoid issues with the single wire bus causing collisions, I recommend (1) monitoring the RX pin state (with digitalRead) for at least a few hundred ms (I use 500 ms) right before sending a message to ensure it's idle (2) verifying the checksum (3) checking if the message you sent was transmitted uncorrupted on the bus. I think (1) and (2) together go a long way; I haven't seen any collisions yet after more than a week (although I also don't watch the logs regularly).