I tested every pin on the Firebeetle ESP32-E with a micro-switch and they all work fine except for the following pins: 1, 35, 36, 39. Wiki says Pin 1 (TX) is Occupied when using USB power supply and serial printing so it can be expected not to work well for creating a button. However, I don't see anything in the Wiki about 35, 36 or 39 that would suggest these pins have any limitations, except for being “Used for input only”. Also 34 has the same description but works fine.

The problem that I am encountering when testing code for a button such as the one from here https://esp32io.com/tutorials/esp32-button or the Interrupt code from ESP32-E Wiki, or any other code such as for a rotary encoder, is as follows. Pins 35, 36 and 39 don't seem to work with a switch that is wired up to them, but they all respond to a touch from a finger. They are in a pressed state and when the finger touches the pin, they become released. Also if I hold my finger to the pin on the switch that is going to the pin on the ESP32-E, Serial prints that the button is released, and then when I press down on the micro-switch, Serial prints that the button is now pressed. So touching my finger to the pin on the switch this way, almost makes the switch function properly.

I don't know much about electronics. Does anyone know what's up with these particular pins? Does anyone know based on my description what I could test with these pins so that they could be used with switches or rotary encoders? Thanks.

PS. Tested with two Firebeetle ESP32-E boards and results are the same.