So I picked up this Pro Micro device from EBAY. Seems to be a copy of the Sparkfun Pro Micro. I am running it from the Micro USB cable and it seems to be working predictably. As I study the device, I see there is a place to mark 3.3v or 5v on the bottom. On my device, neither is marked. I read fu…

Pro Micro Power - 3.3 or 5 and What's this J1 ?

MarkDerbyshire February 12, 2018, 4:22pm 2

On the genuine Arduino J1 just bypasses the inbuilt regulator which is VCC. Are you sure you are not measuring UVCC which is the USB pin

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