LG ERV (Energy Recovery Ventilation) control, invalid checksum problem

[Sakab001]

I have the hardware part set up, and I can receive the packets, but due to an invalid checksum, the commands are not being sent. I need your help with this. I’ve saved multiple state changes and tried to create a test button from them, but the response still comes back with an invalid checksum.

For the received state change, I converted it using ChatGPT and created a button from it, but it doesn’t work. How can I capture the commands sent by the PREMBT100 and reproduce them exactly as button presses in Home Assistant? I at least know now that the issue occurs at the checksum verification stage.

These are the commands I was able to read after changing the state on the wall controller:

`fan speed low: 
[14:30:25.595][D][lg-controller:950]: received 03.60.80.00.00.00.00.00.00.00.00.C6.B0 (13) 
[14:30:25.602][E][lg-controller:960]: invalid checksum03.60.80.00.00.00.00.00.00.00.00.C6.B0 (13) 
[14:30:25.603][D][lg-controller:950]: received 03.60.40.00.00.00.00.00.00.00.00.06.B0 (13)
[14:30:25.604][E][lg-controller:960]: invalid checksum 03.60.40.00.00.00.00.00.00.00.00.06.B0 (13) 
[14:30:25.608][D][lg-controller:950]: received 03.60.20.00.00.00.00.00.00.00.00.66.B0 (13) 
 
  Heat Exchange:  
13.666][D][lg-controller:1358]: update 
[14:35:13.669][D][lg-controller:950]: received E0.01.00.00.01.00.27.00.20.9A.07.2B.A8 (13) 
[14:35:13.672][E][lg-controller:960]: invalid checksum E0.01.00.00.01.00.27.00.20.9A.07.2B.A8 (13) 
[14:35:13.675][D][lg-controller:950]: received 4A.00.00.80.00.81.93.00.80.04.80.DF.A8 (13) 
[14:35:13.678][E][lg-controller:960]: invalid checksum 4A.00.00.80.00.81.93.00.80.04.80.DF.A8 (13) 
[14:35:13.681][D][lg-controller:950]: received 4A.00.00.80.00.81.93.00.80.04.80.DF.AC (13) 
[14:35:13.684][E][lg-controller:960]: invalid checksum 4A.00.00.80.00.81.93.00.80.04.80.DF.AC (13) 
[14:35:13.687][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.27.00.00.86.AC (13)
 
 Auto Mode:  
49.674][D][lg-controller:1358]: update 
[14:35:49.680][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.27.00.00.86.B0 (13) 
[14:35:49.682][E][lg-controller:960]: invalid checksum 00.00.00.00.00.00.00.00.27.00.00.86.B0 (13) 
[14:35:49.684][D][lg-controller:950]: received 02.20.20.00.00.00.00.00.00.00.00.A7.B0 (13) 
[14:35:49.687][E][lg-controller:960]: invalid checksum 02.20.20.00.00.00.00.00.00.00.00.A7.B0 (13) 
[14:35:49.690][D][lg-controller:950]: received 02.20.20.00.00.00.00.00.00.00.00.A7.D0 (13) 
[14:35:49.693][E][lg-controller:960]: invalid checksum 02.20.20.00.00.00.00.00.00.00.00.A7.D0 (13) 

 Bypass (Mode 3): 
[14:36:37.693][D][lg-controller:1358]: update 
[14:36:37.694][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.27.00.00.86.AC (13) 
[14:36:37.698][E][lg-controller:960]: invalid checksum 00.00.00.00.00.00.00.00.27.00.00.86.AC (13) 
[14:36:37.700][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.27.00.00.86.AE (13) 
[14:36:37.704][E][lg-controller:960]: invalid checksum 00.00.00.00.00.00.00.00.27.00.00.86.AE (13) 
[14:36:37.707][D][lg-controller:950]: received 80.36.00.00.00.00.00.02.8E.13.03.5F.AE (13) 
[14:36:37.710][E][lg-controller:960]: invalid checksum 80.36.00.00.00.00.00.02.8E.13.03.5F.AE (13) 
[14:36:37.714][D][lg-controller:950]: received 80.36.00.00.00.00.00.02.8E.13.03.5F.B0 (13)
[14:36:37.718][E][lg-controller:960]: invalid checksum 80.36.00.00.00.00.00.02.8E.13.03.5F.B0 (13) 
    
ON: 
[14:38:19.718][D][lg-controller:1358]: update 
[14:38:19.722][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.00.00.8E.30.B0 (13) 
[14:38:19.725][E][lg-controller:960]: invalid checksum 00.00.00.00.00.00.00.00.00.00.8E.30.B0 (13) 
[14:38:19.729][D][lg-controller:950]: received 03.60.20.00.00.00.00.00.00.00.00.66.B4 (13) 
[14:38:19.732][E][lg-controller:960]: invalid checksum 03.60.20.00.00.00.00.00.00.00.00.66.B4 (13)[14:38:19.736][D][lg-controller:950]: received FF.01.00.00.01.00.27.00.40.9A.07.E8.B4 (13) [14:38:19.739][E][lg-controller:960]: invalid checksum FF.01.00.00.01.00.27.00.40.9A.07.E8.B4 (13) 

OFF:  
14:39:01.734][D][lg-controller:1358]: update 
[14:39:01.740][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.27.00.00.86.B0 (13) 
[14:39:01.740][E][lg-controller:960]: invalid checksum 00.00.00.00.00.00.00.00.27.00.00.86.B0 (13) 
[14:39:01.743][D][lg-controller:950]: received 01.60.20.00.00.00.00.00.00.00.00.64.B0 (13) 
[14:39:01.746][D][lg-controller:950]: received 01.60.20.00.00.00.00.00.00.00.00.64.B0 (13)      `

Please help, because I have no experience with UART or checksums, and I’ve been struggling with this for weeks without success.

What I can offer my assistant is 1 ready Feather-type board ordered from JLCPCB for free, with shipping within Europe :)

Devices: PREMBT100 + LG LZ-H035GBA5

[dzungpv]

The data using difference checksum algorithm, It is my first guest

[dzungpv]

[14:35:13.687][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.27.00.00.86.AC (13)
[14:35:49.680][D][lg-controller:950]: received 00.00.00.00.00.00.00.00.27.00.00.86.B0 (13)

[14:35:13.675][D][lg-controller:950]: received 4A.00.00.80.00.81.93.00.80.04.80.DF.A8 (13)
[14:35:13.681][D][lg-controller:950]: received 4A.00.00.80.00.81.93.00.80.04.80.DF.AC (13)

They are same data but with difference checksum, it is not right. May be it cause by your hardware problem.

[dzungpv]

Or this device have a difference protocol longer than 13 bytes data https://github.com/JanM321/esphome-lg-controller/blob/7d981b743822f3c9157754a2f072a3ae2e2e7ee2/esphome/components/lg_controller/lg-controller.h#L132C29-L132C35, you can try to change the code like maximum 32 byte buffer and test it