andrewm@268: #!/bin/bash
andrewm@268: #
andrewm@268: # shutdown_switch.sh: script for gracefully halting the BeagleBone Black
andrewm@268: # when an onboard button is pressed. 
andrewm@268: #
andrewm@268: # (c) 2016 Andrew McPherson, C4DM, QMUL
andrewm@268: # Developed for Bela: http://bela.io
andrewm@268: 
andrewm@268: 
andrewm@268: # Prepare P9.27 as input (will be configured with pullup)
andrewm@268: # via BB-BONE-PRU-BELA overlay
andrewm@268: 
andrewm@268: BUTTON_PIN=115
andrewm@268: 
andrewm@268: echo $BUTTON_PIN > /sys/class/gpio/export
andrewm@268: echo in > /sys/class/gpio/gpio"$BUTTON_PIN"/direction
andrewm@268: 
andrewm@268: if [ ! -r /sys/class/gpio/gpio"$BUTTON_PIN"/value ]
andrewm@268: then
andrewm@268: 	echo "$(basename $0): Unable to read GPIO pin $BUTTON_PIN for shutdown button."
andrewm@268: 	exit
andrewm@268: fi
andrewm@268: 
andrewm@268: # First, wait for pin to go high. If it starts at 0, that's more
andrewm@268: # likely that the GPIO is not set correctly, so do not treat this
andrewm@268: # as a button press
andrewm@268: 
andrewm@268: while [ $(cat /sys/class/gpio/gpio"$BUTTON_PIN"/value) -ne 1 ]; do
andrewm@268: 	# Keep checking pin is readable in case it gets unexported
andrewm@268: 	if [ ! -r /sys/class/gpio/gpio"$BUTTON_PIN"/value ]
andrewm@268: 	then
andrewm@268: 		echo "$(basename $0): Unable to read GPIO pin $BUTTON_PIN for shutdown button."
andrewm@268: 		exit
andrewm@268: 	fi
andrewm@268: 	sleep 0.5
andrewm@268: done
andrewm@268: 
andrewm@268: # Now for button press. Make sure the button is held at least
andrewm@268: # 1 second before shutting down
andrewm@268: 
andrewm@268: PRESS_COUNT=0
andrewm@268: 
andrewm@268: while true; do
andrewm@268:   # Keep checking pin is readable in case it gets unexported
andrewm@268:   if [ ! -r /sys/class/gpio/gpio"$BUTTON_PIN"/value ]
andrewm@268:   then
andrewm@268:     echo "$(basename $0): Unable to read GPIO pin $BUTTON_PIN for shutdown button."
andrewm@268: 	exit
andrewm@268:   fi
andrewm@268: 	
andrewm@268:   # Button pressed? (pressed = low)
andrewm@268:   if [ $(cat /sys/class/gpio/gpio"$BUTTON_PIN"/value) -eq 0 ]
andrewm@268:   then
andrewm@268:     PRESS_COUNT=$((PRESS_COUNT+1))
andrewm@268: 	if [ "$PRESS_COUNT" -ge 4 ]
andrewm@268: 	then
andrewm@268:     	echo "$(basename $0): Shutdown button pressed. Halting system..."
andrewm@268: 		halt
andrewm@268: 		exit 1
andrewm@268: 	fi
andrewm@268:   else
andrewm@268:     PRESS_COUNT=0
andrewm@268:   fi
andrewm@268:   sleep 0.5
andrewm@268: done