stopped to work!

[mbdrlp]

Hi,

I have an issue with my setup and I am not able to to resolve it.
I was able to configure an ESP32 mini and to communicate with my heat pump through the CN105 connector. I added a pull up resistor of 10k to 5V0 on RX and TX signals.
It worked for month. But one day it decided to stop to work for whatever reason. I was not able to send command or to receive a status.
I tried to program again my ESP32, but it didn't change anything.

My conclusion was my ESP32 was dead, or at least IO I use to communicate with the heat pump. Maybe to use a with 3.3V level...

I have a Mitsubishi WIFI device, so I tested my heat pump with it, and it worked well. It confirms that the issue is my ESP32, not the heat pump itself.

I bought a new ESP32 mini (same model), and configured it with the same yaml file. but this time, instead of using pull up resistors, I used a small level shifter board made with a mosfet transistor and a resistor on the drain, and on the source.
But it doesn't work.

Unfortunately I don't have a oscilloscope so I am not able to probe the signals on the wire. But it's really wired that it doesn't work with a second ESP32 mini.

• Does somebody already had this kind of issue?
• Does the ESP32 is able to receive status is the command link doesn't work?