Hello, if you don't want to use battery power supply, it depends on the voltage of the device you connect, if it is 3.3V, you can choose to connect to VIN 3.3V and GND (you can also connect to VIN 5V and GND), if it is If it is 5V, it can only be connected to VIN 5V and GND (cannot be connected to VIN 3.3V), you can refer to the following figure:
