Is the level of ground at GPIO Pins 9 et al. the same as ground of the micro USB input?

I am building an application where multiple GPIO pins will output voltage, and I do not want to send the current of multiple GPIO pins through one ground GPIO pin.

  • It is unlikely that the device can source more current than a single ground return pin can handle. And cabling over to the USB would be even higher impedance. Commented Nov 29, 2012 at 21:44
  • I will not use a standard USB cable but use a fixed voltage regulator connected to USB plus and ground.
    – Residuum
    Commented Nov 30, 2012 at 23:12
  • Doesn't really matter. The lowest impedance at high frequency would be the physically closest connection, so for a GPIO signal that would be the GPIO ground reference. In terms of DC supply limits, the input PTC fuse is the greater limitation than the physical header pin. Not running the supply for a high current peripheral through the pi at all would however be a potential improvement. Commented Nov 30, 2012 at 23:27
  • I am trying to close several relays with drivers, i.e. using circuits of a BC337 transistor, a 270 Ohm resitor and a 1N4148 diode (mikrocontroller.net/articles/…). The question was about simplifying ground connections of the circuits, so I do not have to connect them back to the GPIO ground.
    – Residuum
    Commented Dec 1, 2012 at 12:34
  • I'd misread and through you were going to pull power from the USB output. At any rate, you don't really want the relay power running through the pi board at all, but rather separately connected to the same power supply - or to a different supply, with the GPIO ground furnishing the common reference (though at the low frequencies involved in your case, any of the grounds on the board should be fine for reference purposes). Commented Dec 1, 2012 at 15:58

1 Answer 1


They are the same ground as you can see here:

The Micro USB input:


The GPIO Output:


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