Arduino Stack Exchange is a question and answer site for developers of open-source hardware and software that is compatible with Arduino. It only takes a minute to sign up.
Sign up to join this community
I have really bad eyesight, so whenever I plug in the power wire and the GND wire I always double check if I'm actually plugging in to the power port not one of the two GND ports.
Why does an Arduino UNO have two GND ports, and for what application would one use both of them?
In electronics circuits, a major point in connecting two circuits and make them "talk" together is to ensure, at the minimum, that they have a common reference of voltage (typically called GND and defined as 0V voltage).
On Arduino, GND pins can be used in 2 situations:
Having 2 distinct GND pins is, I think, just a matter of convenience when you want to build prototypes but don't necessarily have a breadboard (if you use a breadboard, you will just need to connect its power rail to Arduino GND pin and use this power rail directly).
If you are not using a shield and are directly adding components to the arduino it is nice to have 2 ground so you can attach several components without having to add a bread board.
To be precise, you have 3 ground, since the third is sitting on the left hand side of the board (looking in to the USB port)
