Arduino Pro Mini connected to 2 power supplies

I currently have a 7.2v battery running through a voltage regulator, powering the Arduino pro mini 5v. I also have this battery powering a servo motor. I would like to do some debugging of my code, which requires the pro mini to also be plugged into my computer (usb). Basically, both the computer and the battery are supplying power to the Arduino. I was wondering if this is a dangerous set up, and if so how might I fix it. Thanks.

Do not connect Vcc of the serial adapter to the Vcc pin of the Pro Mini, and you'll be fine.

You should not connect two power sources to the 5v pin simultaneously.


Indeed don’t connect the USB 5V. It’ll mess up things. Or, if it’s always connected to the computer: use the USB to power the Arduino, and do away with the regulator, letting the battery power the motor only (do connect the ground of the battery to the Arduino).

The bare minimum connections you need to communicate between the Pro Micro and the computer (via your USB adapter) is Tx, Rx and GND.