Expand Compatibility List

[Jeija]

I was concerned that my Comfee MDDF-20DEN7 dehumidifier (the one with the black top), which comes without WiFi support and does not have a WiFi button, would not be compatible with this project.
But, to my relief, you can connect the ESP-01 to the JST connector which is labeled as "WIFI" on the silkscreen and it will just work.

Add Comfee MDDF-20DEN7 to the compatibility list, so people can just buy the cheaper non-WiFi humidifier and upgrade it later.

[Hypfer]

How do you reset WiFi on that machine if it doesn't have the WiFi button?
That might be something worthy of a sidenote

[Jeija]

Well, that's the downside, you can't, except by re-flashing the firmware.

Technically the PCB inside the dehumidifier has space for a WiFi button (and even the black top has a hidden cutout for the
WiFi button and a WiFi LED), but the button on the PCB is not populated. I haven't checked if I could just solder in that button + some diode and an LED to fully upgrade it...

(My guess is that the firmware on MDDF-20DEN7 and MDDF-20DEN7-WF might be the same, so the MDDF-20DEN7 might just accept the new button)

[Hypfer]

Thanks for testing and reporting back!

[Hypfer]

Do you happen to also have pictures of your mod? Because the JST stuff sounds like it's different from the current guide

[Jeija]

No, not yet. I have ordered some tactile buttons which should fit; if I find the time, my plan is to also test the hardware modification and check if you can just add a WiFi button. I will take some pictures of the mod on that occasion, but it's really not that different.

[Jeija]

Okay, so here are some pictures of my mod:

• This is what the main PCB looks like in my device:
  
• The UART connector is labelled as "WiFi":
  
• Here, the ESP-01 module is plugged in. Pretty much like in the MDDF-20DEN7-WF model:
  

I also tried to add a WiFi button to my dehumidifer:

• This is the button / LED PCB before the mod:
  
• So I figured I could try to add a button / LED in the unpopulated spot:
  
• There is also an unpopulated footprint for some diode at the bottom, I soldered in some generic diode that I had lying around:
  
• But all to no avail. The LED is now glowing continuously, but pressing the button does not have any effect, regardless of how long I press it, at I didn't notice anything. I wouldn't exclude that maybe the button press leads to some kind of UART message to the ESP-01, but at least it didn't lead to a WiFi reset (and I don't really care enough about the reset functionality to spend more time debugging). So re-flashing the ESP-01 is currently still the only way to reset the WiFi interface of my MDDF-20DEN7.

[Meins321]

So any of these Midea Units can be upgraded to use wifi as long as the mainboard is replaced?

The mainboard starts 171201.. and then there a different versions availible :-O

control board 17120100002572

[Meins321]

[homberger]

Well, that's the downside, you can't, except by re-flashing the firmware.

How do you disable wifi on devices with a button for wifi/wireless (DF-20DEN7-WF)? It's not possible, is it?

[atrejut]

FWIW: I can also confirm this for the MDDP-50DEN7

And if, like me, you're easily confused: be wary of the pin order. The JST has Vcc and Ground on the outside, and Rx and Tx on the inside. (And disconnected both Rx and Tx are high...)