I am an electrician and have little programming ability at the moment but am trying to learn. I was wanting to know how many gpio pins can I switch and are the only certain ones that will be positive and some negative (ground) or can you make them to either.

1 Answer 1


The number of pins you can control will depend on which model Pi you have (17 user controllable pins on 26 pin Pis and 26 on 40 pin models). There are several ground pins, and at least two dedicated power pins (5v and 3.3v, 40 pin models also have 2 DNC -do not connect- pins) the remaining pins are user controllable and can be set to high (nominally 3.3v) or low (0v).

Note in electronics, unlike in residential/industrial wiring, we don't generally use the term negative as a synonym for ground.

  • Im using a b+ i was mainly asking because i would like to make an led cube and did not no weather i could do it from the pi or would have to use an arduino and micro controller like i have seen people do on youtube
    – mark
    Mar 30, 2015 at 9:02
  • You can do it from the Pi as well. This may help you get started google.com/… Mar 30, 2015 at 9:07
  • Oh nice thanks for your help saves me getting the other bits then.
    – mark
    Mar 30, 2015 at 9:09
  • Which pins are DNC on the 40-pin? I've never seen that indicated anywhere before, except with regard to the rev. 1 boards.
    – goldilocks
    Mar 30, 2015 at 14:41
  • @goldilocks they may only be labeled dnc on the B+ on the pi2 they are the eprom pins I believe raspi.tv/2014/… Mar 30, 2015 at 21:15

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