Can I hook up power and usb cable to arduino?

Hey guys,

When I'm using my arduino, (plugged into my Mac via USB) my mac just randomly shuts off. Is it because I'm pulling to much out of the USB? Can I hook up my 9v into the DC plug and hook up the USB or will combine the input and fry the board?

quatch4 years ago
what version of arduino? Some (older or third party) had special jumpers to set the power source.

Sounds more like you have a ground fault. Ensure there is something insulative under the board so it doesnt short circuit.

An easy (but not good idea) test is to just try again with only USB power.

USB ports (esp on newer macs) have resettable fuses. Mine pops up an error box if you draw too much current.

Try using a multimeter on the board with external power to measure the current draw. USB will only want to supply 500mA.
HavocRC (author)  quatch4 years ago
Well I have the official UNO.
No, what I'm saying is I have NOT tried using both power supplies. I want to know if I CAN use the USB and the DC jack at the same time.

LOL I dunno how to use a multimeter like that :D
Mebbe you could tell me?
Yes you can have both plugged in but it will draw power from the DC jack and not from the USB plug. Make sue you have no shorts that could be causing problems with your PC.
HavocRC (author)  mpilchfamily4 years ago
Ok thanks mPilch! Oh, my MAC only shut off twice over the course of two weeks. The second time I got a little worried. Maybe because I had my arduino board on top of a some resistors? Lolz, just like me to do that!

Thanks!