Probably either an issue with the hardware or an unsupported protocol. What’s the model number of your indoor unit? What are the first few messages the controller receives after power on?
Thanks for your quick response! I have the PC09ST. It also has the green JST connector, so figured it should also work with this unit, but I might be wrong.
I will check this evening for the first messages.
The PC09ST should be compatible. It’s most likely an issue with the hardware. Double check the wiring and maybe try a different PCB if you have one.
Hi everyone!
Could someone please explain why a 1 kΩ resistor (R5) is used in this schematic?
I understand that this value comes from the TJA1027 datasheet. However, in the case of LG air conditioners and their CN_REMO hardware implementation, it seems like a 1 kΩ resistor might not be ideal?
If you look at the schematic on the right, the LG unit includes a 12 kΩ pull-down resistor (R02K) — in some models it’s even 4.7 kΩ.
So when the controller on the LG PCB drives its Tx line low, the LIN bus ends up connected through a voltage divider consisting of 1 kΩ and 12 kΩ resistors. In this case, the bus voltage drops from 12V to only about 11V.
But that doesn’t seem to be a valid logic low level according to the LIN protocol specs?
Am I misunderstanding how this works? Or is it that the ESP32 never actually receives data from the LG controller, and only sends commands?
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Another example can be seen in a schematic from a different LG service manual. On the left side is a part of the main board, and on the right side — a part of the wired remote control board.
In this case, there is no doubt that signal transmission works correctly in both directions. Ideally, in my opinion, the ESP32 side should use the same level-shifting circuit with four transistors that LG employs on their PCB. That way, we could not only send commands to the air conditioner but also receive data from it.
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In my LG S09EQR air conditioner, the place for the CN_REMO connector exists, but the connector itself is missing — as is the surrounding circuitry. However, all the PCB traces are present. I decided to take the risk and solder the missing components. I also ran a cable from the control board for a wired controller, similar to the original one with the green connector I’ve seen in photos.
While I’m waiting for the ESP32 module to arrive by mail, I decided to try pulling the Signal line up to +12 V through a 1 kΩ resistor and check with an oscilloscope to see if the controller sends any data on its own. Unfortunately, the line is completely silent.
It seems the manufacturer may have not only omitted the connector but also disabled the UART used for CN_REMO. That significantly reduces my chances of success 
Or maybe the controller only starts transmitting data in response to packets from the ESP32? Does anyone have any information about this?
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Someone interested in a tiny pcb? Would sell some of mine I had to order on top of my personal requirement.
I would be very much interested
Yes, I am interested.
Hi, I would be interested in a pcb if it works with my requirements. I’m still looking into it just came across this thread
Nope, I have P12EN and it does not have Wifi, not even as an option. only possibility is to use WiFi → IR, though I’m yet to disassemble my unit, to see how PCB looks.
This I’ve found online (no CN-OPTION):
While on my unit there is this sticker (CN-OPTION is here):
EDIT:
Okay I’ve made my way into the PCB - my model is LG P12EN, the indoor unit PCB is EAX35907208 / EBR359365 / kb-3151c /
It seems that all connectors are populated on it, despite the catalogue saying that it’s not compatbile with PREMTB001 or any other controller.
Pic here:
I’ve found better pic online (not the same board but very similar):
Sory to ping but @JanM321 is there a simple way to test weather the CN-REMOTE is functional or not?
If someone has a PCB and is able to ship to Poland - please DM me
I need it as well so if you find more people we can order it and split costs. I do not have experience in ordering such boards, so nice if someone can order it.
I am also from Poland (Slask).
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I should have soon few of them
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Little more tinkering with my P12EN:
There is 12V (12.14V actually) at the CN-REMO header. Between GND and LIN there is ~11.85V, so I guess there is still a chance that this will work 
Hi guys!
Could you please help me test this PR?
It’s an improvement to lg_ir_climate (docs) component in ESPHome - currently (at least for my unit):
- HEAT/COOL mode would misbehave
- also swing control would not work
- other commands (jet/time,display-toggle) would be interpreted as off
all changes should need alternative_mode: true so it would not break anything for users (i’m not sure if things that i’ve pointed above are bugs, or just device-specific behaviour) - that’s why I need more users with different AC units to test
to test you need following config (example):
external_components: # please also test without this PR
- source: github://pr#10875
components: [climate_ir_lg]
refresh: 1h
remote_receiver:
id: rcvr
pin:
number: GPIO10
inverted: true
mode:
input: true
pullup: true
dump:
- lg
climate:
- platform: climate_ir_lg
name: "Living Room AC"
receiver_id: rcvr
header_high: 3265us
header_low: 9856us
alternative_mode: true # please test with true and false
Any feedback is highly appreciated
hello, im interested too. Im living near Piaseczno. Will you have any free pcbs?
Im wondering will be a problem to use this module:
aliexpress.com/item/1005009763126443.html
or better this one:
aliexpress.com/item/1005009567065183.html
instead of ordering 5 boards from jlcpcb/pcbway
what do you think?
1 Like
Also curious about this one, have you found out already?
No yet. ordered the first one, but seller just send it after 10! days after purchase. so still waiting for shipment.