LG PQRCUDS0 compatible ESPHome Component
This repository contains the source code and the EAGLE design files for using ESPHome to control a LG air conditioning unit that uses the PQRCUDS0 control panel.
The source code and an example configuration package are in the esphome/
directory, while the eagle/ directory has the PCB design files.
Note that this project is neither endorsed, nor sponsored, by either of LG or the ESPHome project.
You can find details of the implementation and some of the choices made in the design on my blog: https://flameeyes.blog/tag/lg/
See also:
- Python utilities to emulate the panel and engine at https://github.com/Flameeyes/lg-PQRCUDS0-emu
- Saleae Logic high-level analyzer for the protocol, at https://github.com/Flameeyes/saleae-extension-LG-PQRCUDS0
Features
The custom component needs Home Assistant, to provide a reference temperature, as it does not provide its own temperature sensor.
Once provided a reference temperature sensor, the component supports the following features, tested on my flat's HVAC system (LG ARNU07GB1G2):
-
Cool, heat, fan-only, dehumidifer, and heat-cool modes, with two-point set temperature.
-
Fan speed selection (low/medium/high), including "off" speed for idling in heat-cool mode.
Board Revision History
Rev 1
Original production design. It provided support to host the panel to the side for going back to the panel on request, with a cutoff switch.
The cutoff had problems with holding the HVAC unit and the panel in sync when switching away from the ESP32, so it never really worked.
The other reason to keep te panel powered up would have been to maintain a readout of the temperature from the panel's on-board temperature sensor, but it does not appear to be very reliable or useful, being able to report only between 18C and 30C.
Rev 2
A size- and cost-reduced variant of the original board, with the same logic design, but without the secondary bus (and related components), and replacing the cutoff switch with a pushbutton that turns off the whole board.
The bus connector is now on the back of the board, to make it easier to access from the wall itself.
License
Both the custom component and the EAGLE design files are released under the permissive 0BSD license. This means you can reuse them pretty much as you may want to.
Do note that ESPHome libraries are licensed under GNU GPLv3, so combining them with logic in the components is still subject to the full license.
Boxes
The boxes/ directory contains 3D printable files for a box compatible with
the rev2 board.
Since this is literally my first 3D design, take it with a grain of salt, it particularly suffers from the following minor issues:
- The cover vents on the top are not shaped to keep into consideration the registration corners.
- The central screw is unnecessary as (at least with Nylon SLS print) it is perfectly possible to keep the box closed by friction-fitting it.
- There should be a little more clearance for the ESP32 module, by raising the top of the cover.
- There's no compatible cap to fit into the pushbutton. A different strategy should be pursued.
- The keyholes should be more tolerant, as screws are often not quite aligned as they should be.