Thomas Perillo asked 5 years ago
What should the state of GPIO pins be that are not part of an uploaded sketch? I would think the pins not in use should all be LOW.
I have my ESP board (Node MCU 36 pin Board) mounted on a large breadboard. I uploaded the ‘Blinking an LED with milis()’ sketch( using pin 26). I still had the circuit on the breadboard wired for the Pulse Width Modulation Sketch (Pins 15,2,0). The LED connected to P0 is HIGH (steady at about half brightness … not fading). Is this OK or a sign of some malfunction or user error?
Rui Santos Staff answered 5 years ago
Hi Thomas,
We’ve experienced a similar behavior with our board. Basically, there are some GPIOs that are reserved for the ESP32 to work. For example, GPIO 0 is a CLK_OUT1 (it’s a Clock output 1 pin), even though it’s not being used in your sketch, it might cause some noise or do pulses. We’re not sure exactly why that happens though.