The Raspberry Pi has 26 GPIO pins. What are the names, functions, and important limitations of each?

  • 1
    It might be a good idea to start reading this page, it has a lot of information. Too much to just sum up in a moment.
    – ikku
    Oct 27, 2012 at 2:07
  • @icarus74 Thanks, I was hoping someone would create an answer in a reference form. Most SE sites encourage answers to be useable even if links go dead, i.e., include the key information directly as part of the answer. I'll give it a bit more time (although may be offline for a while due to the impending storm)
    – TomG
    Oct 28, 2012 at 0:34
  • @TomG, the problem of creating an answer in reference form, for a rather new and evolving board, is that there is no guarantee for the reference would remain current. There has already been some discussion on RasPi forums regarding repurposing some of the GPIO pins, which had a future-use associated. BTW, good luck with the storm, may it pass over safely.
    – bdutta74
    Oct 28, 2012 at 5:18

2 Answers 2


The GPIO pins can be used as digital inputs or outputs. Additionally some of them can have alternative purpose like UART or I2C. Afaik the naming is from GPIO 0 to 31. Some of the GPIO pins can not be found on connector P1 and serve different purposes like switching onboard LED (GPIO 16) or HDMI Hotplug (GPIO 46). These can normally not be used for other things. Other GPIO pins can be found on different connectors e.g. P5 (GPIO 28-31).

For more information you can read this Wikipage or take a look at the RasPI schematics.


To make working with the GPIO pins easier, check out PiCrust. http://picru.st/ Its an open source add-on board which breaks out the pins in an organised sense. The site links to a page where you can order it, and it comes to about $14 for 3, plus the headers that would need to be soldered on by you. Makes the pi more friendly to newbs like us I'd say.

  • Sadly PI-Crust does not add any protection. That's what would be even more friendly... It's better to solder a small breakout board with at least Zener-Diode protection circuits.
    – Mose
    Oct 28, 2012 at 6:28

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