What can cause GPIO input pin dead

[Minimoa]

Hi,

I have a WeMos Mini D1, which worked perfectly for more than 8 months. It controls heatpump + gas boiler.

So the problem is, that there is an ESBE motor valve, which has az AUX switch what signals the state of the valve. (Valve ON = closed, valve OFF = open)

I connected this AUX switch to GND and to the GPIO5/D1 pin.
I programmed GPIO5 pin to internal pullup.

Code: Select all

#define DHW_SW D1 
pinMode(DHW_SW, INPUT_PULLUP);

It worked fine, until I realized, that this input pin is stucked internally low.
I tried it with external pullup resistor, but didn't changed anything.

All other pins are working correct.

I am curious what can cause an input pin's death, which is connected to GND or left floating (switch is open).