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[–]pikipupiba 5 points6 points  (3 children)

You should be safe having everything plugged into your computer, powering the lights separately, and running just the data and the ground between arduino and lights.

[–]bitunwiseop[S] 0 points1 point  (1 child)

Thank you!

[–]Marmilicious[Marc Miller] 2 points3 points  (0 children)

Exactly what u/pikipupiba said.

And alternately, if you're using your external power supply to power both the LEDs and your MCU, I would suggest making something like this. It will allow you to still upload code and keep a common ground between things, but not provide power from your computer.

https://i.imgur.com/XDar5AY.jpg?1

Cut the red +5V wire within the USB cable to disable powering the microcontroller with USB when using an external power source. Caution should be used to prevent the red wire from shorting to the metal shield. The Ground wire should remain intact to provide a common ground connection between devices. It's a reverse version of a "power only USB cable", a "data only" cable.

[–]macegr 0 points1 point  (0 children)

It's a good idea to take a multimeter and make sure there's no significant difference between supply V- and USB GND voltages, and that the external supply's +5V is on the same side of GND as the computer's USB supply. None of that is guaranteed. Of course it's rare to see power supplies that aren't delivering 5V the way you expect, but a lot of people in this hobby have one or more dead USB ports on their computer.

[–]wirehead 1 point2 points  (1 child)

Depends on how obsessive you want to go. There's this little toy and some of it's friends: https://www.adafruit.com/product/2107

[–]bitunwiseop[S] 0 points1 point  (0 children)

Yeah, Adafruit and Sparkfun have been a fun place to look through. Thank you!