ESP32-POE-ISO GPIO3 & POE

[Tritu]

Got a small project going with an ESP32-POE-ISO. Just 4 touchless buttons that send UDP commands, nothing fancy. But now i bumped into the following issue. The button connected to GPIO3 seemed to work when the ESP-POE-ISO was powered over USB and connected to Ethernet without POE but not when powered over POE. I am probably overlooking something. But does anyone have a explanation? The other 3 buttons are connected to GPIO2, GPIO4 and GPIO5.

[LubOlimex]

Umm, looking at the schematic it seems GPIO3 is also connected to the USB-serial converter CH340T (second function U0RXD). So when you have USB connected probably the pull up (R19) is making your button work. When no USB is present, there is no pull up and it is not clear what is the state of that wire GPIO3/U0RXD.

My advice is to use another pin instead of GPIO3. You can use other pins for example GPIO16 is a good pin.