Raspberry Pi 2 Gray Code Light Blinker

blinky.sh

#!/bin/bash

BASE=/sys/class/gpio

RED=20
YELLOW=16
GREEN=12

function on() {
    echo 1 > $BASE/gpio$1/value
}

function off() {
    echo 0 > $BASE/gpio$1/value
}

function init() {
    echo Remuxing...
    echo $RED > $BASE/export
    echo $YELLOW > $BASE/export
    echo $GREEN > $BASE/export
    sleep 1
    echo Setting directions...
    echo out > $BASE/gpio$RED/direction
    echo out > $BASE/gpio$YELLOW/direction
    echo out > $BASE/gpio$GREEN/direction
    sleep 1
    echo Initializing values...
    off $RED
    off $YELLOW
    off $GREEN
}

init

function randdelay() {
    local integer=$[ $RANDOM % 2 ]
    local mantissa=
    if [ "$integer" == "1" ]; then
        mantissa=$[ $RANDOM % 50 ]
    else
        mantissa=$[ ( $RANDOM % 50 ) + 50 ]
    fi
    sleep ${integer}.${mantissa}s
}

echo Blinking\!

while true
do
    #000
    on $RED
    randdelay
    #001
    on $YELLOW
    randdelay
    #011
    off $RED
    randdelay
    #010
    on $GREEN
    randdelay
    #110
    on $RED
    randdelay
    #111
    off $YELLOW
    randdelay
    #101
    off $RED
    randdelay
    #100
    off $GREEN
    randdelay
done