Marian Marinov/HackMan

Today I decided to play a bit with my Raspberry Pi and one of my Relay shields that I have for the Arduino.
I was surprised to see how easy it was to control and read the GPIOs on the Raspberry. So I decided to make it even easier by writing a simple bash script which I use to turn on and off relays from the shield.

This is the script:

#!/bin/bash

GPIO=11
if [ $# == 1 ]; then
        if ! [[ "$1" =~ ^[0-9]+$ ]]; then
                echo "Error: wrong pin format"
                echo "Usage: $0 [GPIO]"
                echo "GPIOs: [0-24]"
                exit
        fi
        GPIO=$1
fi

# export GPIO 11 to userspace if it isn't exported already
if [ ! -d /sys/class/gpio/gpio${GPIO} ]; then
        echo "Exporting GPIO $GPIO"
        echo $GPIO > /sys/class/gpio/export
        sleep 1
fi

if [ "$(</sys/class/gpio/gpio${GPIO}/direction)" != 'out' ]; then
        echo "Setting GPIO $GPIO to OUT"
        echo out > /sys/class/gpio/gpio${GPIO}/direction
fi

if [ "$(</sys/class/gpio/gpio${GPIO}/value)" == 1 ]; then
        echo "Set GPIO $GPIO OFF"
        echo 0 > /sys/class/gpio/gpio${GPIO}/value
else
        echo "Set GPIO $GPIO ON"
        echo 1 > /sys/class/gpio/gpio${GPIO}/value
fi

I decided to use GPIO 11 as default, because it is the closest to pin 25(ground). So it was easier to have the wires close to each other.

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