This document will outline a shell script to enable GPIO on a Raspberry Pi. Mainly so I dont forget about the settle command.
echo 12 > /sys/class/gpio/export
udevadm settle
echo out > /sys/class/gpio/gpio12/direction
Turn on and off:
echo 0 > /sys/class/gpio/gpio12/value
echo 1 > /sys/class/gpio/gpio12/value
echo 7 > /sys/class/gpio/export
udevadm settle
echo in > /sys/class/gpio/gpio7/direction
Check value:
cat /sys/class/gpio/gpio7/value
Simple shell script to enable all PINs:
#!/bin/bash
# Input PINs
for i in {7,8}
do
echo $i > /sys/class/gpio/export
udevadm settle
echo in > /sys/class/gpio/gpio$i/direction
done
# Output PINs
for i in {12,16,20,21}
do
echo $i > /sys/class/gpio/export
udevadm settle
# Default high - https://www.kernel.org/doc/Documentation/gpio/sysfs.txt
echo high > /sys/class/gpio/gpio$i/direction
done