The 3v3 gpio pins and all of the numbered pins are not providing any voltage. Or rather, very little voltage. I used a voltmeter to check the voltage difference between 3v3 and ground and the needle moves very, very slightly.

I tested the diff between the 5v0 gpio pins and ground as well and they correctly provided 5 volts.

I think it may be short circuiting or something but I don't know how to test for that. It is also unlikely to be short circuiting in my breadboard as I am using an adafruit breakout board and I have nothing connected to any of the gpio pins.

If it is useful I have my RPi connected to a macbook with an ethernet cable and the main power is being supplied by a wall outlet - 5v micro usb.

(I have a RPi model B)

3 Answers 3


If your Pi is functioning then 3V3 must be available. It will not work without 3V3.

Look at Is my Pi's GPIO damaged? for a method of testing the gpios.


The problem is not because of a short circuit. A short circuit will bring down the whole pi until you restart it.

To test if the GPIOs are working correctly, try gpiotest


I figured it out. The problem had nothing to do with my RPi or my python code.

The problem was in the adafruit t-cobbler. When I took it off the gpio pins and tested the voltmeter directly on them, I got the expected results.

  • Quite a few posters have inserted the cables into the cobbler incorrectly. I understand the cables are not "keyed" so it is not surprising that many are connected incorrectly. Might be worth rechecking your connections.
    – joan
    Dec 22, 2014 at 9:47

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