3v3 pin on duo


Can someone answer the following: is the 3V3 Pin on the DUO a voltage input or voltage output pin? Thanks.


Hi pat-babbled,
3V3 is an voltage output pin and VIN is an input pin. You can refer to DUO


If you are talking abt Arduino DUE, the 3v3 pin is an OUTPUT.
More info here:



@lucian, I’d say it’s actually both, you can either draw some current @3.3V from it when powered via USB or Vin or you can power the device via 3v3 but in that case you mustnot also power via USB or Vin.

Also be aware that you have no extra safety when powering via 3v3, so you must make sure to have a reliable, clean 3.3V supply.

Check https://github.com/redbear/Duo/blob/master/docs/duo_introduction.md#3v3-pin

@rafargb, considering this is the RedBear forum and there is a RedBear Duo device, I’d assume it’s not an Arduino Due @pat-babbled is inquiring about.