Midea A/C via local XYE

ESPHome
41

Yeah my unit seems to have 2 separate buses, both electrically RS485:

  • CN9 XYE “to CCM comm. bus”
  • CN40 to “wire controller”, optionally daisy chained via WiFi adaptor

I got some photos of the terminals and the wiring diagram inside the unit, which is the complete version from Midea rather than the “sanitised” version from Actron Air in my case.

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IMG_53042079×2504 1.53 MB

IMG_5305
IMG_53054032×3024 1.98 MB

IMG_5306
IMG_53064032×3024 1.81 MB

I’m guessing that the CN20 link from indoor to outdoor unit is also electrically RS485. Now I am also tempted to sniff this and see if it reveals some interesting data (e.g. outdoor fan speed, compressor speed, EEV opening angle).

42

Ah hah. Ok.
My RS485 connector I’m using, which you call CN40, is labeled CN14 on my unit. (Name not visible in this pic, but I saw it in another - it’s the one on the bottom right with the red connector)

Conn_Names
Conn_Names1920×2550 343 KB

And here’s my circuit diagram for reference:

Circuit_Diagram
Circuit_Diagram1920×1446 383 KB

So your CN9 would be my CN3. And you’ve tested both sets of wiring and you get different results on the CN9… Interesting.

I’m not sure how mine is, and I’m kinda feeling a bit lazy haha. Whatever the case is, my plan is to keep using the extended functionality - I don’t think C6 will work on your CN9 if C4 errors out, as they seem “releated”

Having the compressor duty cyle or speed would be fine, but I can infer that from the output temps too. Now the unit does a LOT less work than it was before using the 24V setup and it’s just as nice if not nicer in here.

-Matt

43

I am happy to see you progressing this.

I have a ducted minisplit that is senville branded. I have spent an unbelievable amount of time working on this myself. My home had an addition that was not ducted with the main central heat pump, so we had a mini split installed. The thermostat is on the same wall our fireplace is on, and the addition is all windows, so it gets very cold in the winter towards the back of the addition where we sit. I wanted to do a remote mounted temp sensor (which i use to control our fireplace) to control the minisplit to make everything work in sync and provide interlocks so someone isn’t turning on the main unit heat, and running ac out in the addition.

There are a LOT of threads out there about the midea communications. My unit had a wall thermostat that was 5 wire. Most of the threads talk about the 4 wire thermostats. My unit has multiple communication busses. I have tried to switch to the 4 wire thermostat and an esp32 connected to the remote unit in the crawl space that is connected to the older 5 wire thermostat. I removed the Tsop from that board and hard wired the esp32 to send IR follow me commands, then using the uart through a level shifter to set the temp, control on and off, and such, however I don’t fully feel its working properly. The unit never actually shuts the fan down. It does ramp, I do have it regulating temp, but the fan never shuts down when the fan is set to “auto”

Now knowing what I do now and understanding how the follow me commands work, I should have just removed the temp sensor from the internal board, used a digital pot to control the temp remotely. It probably would have been a lot easier.

The issue I have is once I switched to the 4 wire thermostat, it will only display Celsius. I have contacted Senville, they sent me a second thermostat for free saying that it should display Fahrenheit but it doesn’t. I spent a lot of time on the phone with the tech support about it and it was never resolved.

It also seems as though the uart is expecting *C where as the IR commands are sent to the receiver board as *F and displays *F

I have not found a way to do the follow me commands with UART that completely bypasses any IR commands. I can’t use the 5 wire thermostat because it doesn’t update when the esp32 changes the the set temp via uart because it does not have 2 way communication it appears.

I would like to dig into the rs485 side of things because it seems as though that is the only communication protocol that does everything. I don’t understand the logic of all of these different communications especially when they do not all talk to each other.

My board has RS485 marked on it, and its been a little while but I believe it says xye as well somewhere. I will continue to follow this thread!