shutdown_script

#!/bin/bash

#title           :shutdown_script
#description     :This script runs on Raspberry Pi equipped with the Juice4Halt module.
#author		 :Nelectra s.r.o.
#date            :20150812
#version         :1.0    
#usage		 :copy this file to /home/pi/juice4halt/bin/
#		  and make it executable: sudo chmod 755 shutdown_script 	
#notes           :www.juice4halt.com
#copyright	 :GNU GPL v3.0	
#==============================================================================

#create directory for working with GPIO and wait
echo "25" > /sys/class/gpio/export
sleep 0.2s
 
# use the pin as an open-drain output, send a short LOW pulse (means: message "Booting finished, shutdown_script runs")
# after that change to input and listen
# when a LOW occurs sent from J4H start with shutdown
 
# set GPIO25 as output and set output to LOW
echo "out" > /sys/class/gpio/gpio25/direction
echo "0" > /sys/class/gpio/gpio25/value
sleep 0.1s
echo "in" > /sys/class/gpio/gpio25/direction
 
#wait until pin rises to HI
sleep 0.1s
 
pinval="1"
 
while [ "$pinval" !=  "0" ]
do
        #reading the value of the input pin
        pinval=$(cat /sys/class/gpio/gpio25/value)
       
        #wait
        sleep 0.2s
 
done
 
#juice4halt firmware needs another reading from I2C bus for acknowledging
pinval=$(cat /sys/class/gpio/gpio25/value)
 
 
# set GPIO25 as output and set output to LOW
echo "out" > /sys/class/gpio/gpio25/direction
echo "0" > /sys/class/gpio/gpio25/value
 
# wait for system halt
# after system halted the pin will be automatically switched to input and the level will be pulled up to HI
# a LOW to HI transition signals to the J4H to turn the power off

echo ""
echo "Juice4halt: Power failure, RPi will now shut down."
sudo halt