Are my GPIO ports not working?

Question

On my Raspberry Pi, I tried to do some experiments with GPIO, without success.

Measuring the voltage between GND and GPIO11, for example, always helds a result of 0. I am using /sys/class/gpio commands to turn GPIO on and off. Between GND and 3.3V, it returns 2.2V. Te only one that seems to work is between GND and 5v.

EDIT

• Turned on the raspberry py
• Plugged in a flat cable between raspberry and a breadboard
• Measured P1-25 (GND) and P1-01 (3v3). Got 2.2 V
• Followed there instructions (https://sites.google.com/site/semilleroadt/raspberry-pi-tutorials/gpio). GPIO pin 11 didn't change voltage

Any clues?

Am I doing something wrong?

Answer 1

If you followed the instructions, this should work. I suspect that you have your cable crossed over. You say Measured P1-25 (GND) and P1-01 (3v3). Got 2.2 V This is wrong, I suspect that you are actually measuring between pin 2 (5v) and pin 26.

I suggest you install WiringPi (mentioned in the instructions). This is much easier to use, and more importantly includes a utility gpio readall which displays the state of all the pins.

Get your instructions right (as shown in the gpio readall utility) then you can work out if you have a wiring problem. NOTE this works even if nothing is connected.