Can I connect an external 3.3V power to the 3V3 pin?

General
5

I see, thanks.

However:

  1. pin 3V3 is not a general I/O pin;
  2. the VIN pad on the back, which you highlighted, is directly connected to the 5V pin and hence to the voltage regulator 5V->3.3V input, so it makes no sense to connect 3.3V power supply there.

Thank you, anyway.