I just starting with Raspberry PI and I have first problem with understanding what's happen with GPIO. I have installed wiringPI and after call readall GPIO. 7 is set to 1 and I can't change it to 0 by gpio write 7 0.

Here is the screenshoot: enter image description here

Changing value via Pigs also doesn't work: enter image description here

  • Have you tried it with sudo? Feb 8 '15 at 16:20
  • Yes, I tried. I tried with different pins and it doesn't work with wPi 0 too. But works with wPi: 2 and 3 (without sudo). Feb 8 '15 at 16:21
  • What does pigs report? (sudo pigpiod then pigs w 4 0 r 4 w 4 1 r 4)
    – joan
    Feb 8 '15 at 16:38
  • @joan - I'm unable to install pigs. After calling make it hang on this: gcc -03 -Wall -c -o pigpio.o pigpio.c. Feb 8 '15 at 16:58
  • It probably isn't hanging. The compilation of pigpio.c takes three minutes on a Pi. Be patient.
    – joan
    Feb 8 '15 at 17:02


su root

You will need the root password. sudo alone is a PITA for the next few steps because of redirection.

cd /sys/class/gpio

If you see a gpio7 directory there already, skip the next step.

echo 7 > export

There should now be a gpio7 directory.

cd gpio7
echo out > direction
echo 0 > value
cat value

The last command should report 0. If not, as joan says, something mysterious is going on with the hardware.

  • wiringPi has been updated and should now work on a Pi 2. pigpio does not currently work on a Pi 2 (in fact it will hang the machine).
    – joan
    Feb 8 '15 at 17:51

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