Can I power my board from the 3V3 pin?

Yes, you can power an Unexpected Maker board using the 3V3 pin if you have an external 3V3 power supply available. However, there are important restrictions.

The 3V3 pin functions as either input or output depending on the power source. You must use an external 3V3 power supply connected directly to this pin, and the board cannot simultaneously receive power from USB, 5V, or VBAT sources.

You cannot connect the USB cable to the board to flash it or get serial output when you also have a 3V3 source connected to the pin.

You can absolutely NOT connect any voltage higher than 3V3 to the 3V3 pin.

Do not connect a 3V3 source to the VBAT pin, as it has a charge IC connected to it, that could interfere with the source voltage.

It is recommended to add one or two capacitors near the power source before the pin, since powering through 3V3 bypasses a lot of the existing decoupling capacitors already on the board.