VU8C Backlight On/Off Control by Monitor Status

This wiki page describes the way how to control vu8c backlight on/off when monitor status is triggered by controlling the related GPIO ports.
So far, Ubuntu is available with the following scheme and we're investigating it on Android platform now.

On Ubuntu, monitor standby time can be set using Power Management Preferences menu.
You can refer to the section, [Set standby time to enter monitor off using power management setting menu] in the following wiki page.
http://odroid.com/dokuwiki/doku.php?id=en:c2_turn_off_monitor

Add the following lines into “/etc/rc.local”

(1) ODROID-C2

path="/sys/class/gpio"

echo 234 > $path/export
echo 214 > $path/export

echo out > $path/gpio234/direction
echo out > $path/gpio214/direction
echo 0 > $path/gpio234/value
echo 0 > $path/gpio214/value

chown odroid $path/gpio234/value
chown odroid $path/gpio214/value

(2) ODROID-C1/C1+

# vi /etc/rc.local
path="/sys/class/gpio"

echo 97 > $path/export
echo 108 > $path/export

echo out > $path/gpio97/direction
echo out > $path/gpio108/direction
echo 0 > $path/gpio97/value
echo 0 > $path/gpio108/value

chown odroid $path/gpio97/value
chown odroid $path/gpio108/value

Now you need to add a startup task to run the shell script that controls vu8c backlight ports.

First, download the script file in the path /usr/local/bin/.
And then set the mode as a+x.

(Download one of following shell script)
# mv ~/Download/vu8c_backlight_c2.sh /usr/local/bin/
# chmod a+x /usr/local/bin/vu8c_backlight_c2.sh

(1) ODROID-C2

vu8c_backlight_c2.sh

#!/bin/bash
# VU8C backlight control
 
path="/sys/class/gpio"
cur_stat="On"
 
while true
do
sleep 1
stat=$(xset -q|sed -ne 's/^[ ]*Monitor is //p')
 
if [ "$stat" == "Off" -a "$cur_stat" == "On" ]; then
        echo "monitor goes to Off"
        # backlight off first 
        echo 1 > $path/gpio214/value
        echo 1 > $path/gpio234/value
        cur_stat=$stat
elif [ "$stat" == "On" -a "$cur_stat" == "Off" ]; then
        echo "monitor turns back On"
        echo 0 > $path/gpio234/value
        # backlight on later
        echo 0 > $path/gpio214/value
        cur_stat=$stat
fi
done

(2) ODROID-C1/C1+

vu8c_backlight_c1.sh

#!/bin/bash
# VU8C backlight control
 
path="/sys/class/gpio"
cur_stat="On"
 
while true
do
sleep 1
stat=$(xset -q|sed -ne 's/^[ ]*Monitor is //p')
 
if [ "$stat" == "Off" -a "$cur_stat" == "On" ]; then
        echo "monitor goes to Off"
        echo 1 > $path/gpio97/value
        echo 1 > $path/gpio108/value
        cur_stat=$stat
elif [ "$stat" == "On" -a "$cur_stat" == "Off" ]; then
        echo "monitor turns back On"
        echo 0 > $path/gpio108/value
        echo 0 > $path/gpio97/value
        cur_stat=$stat
fi
done

Because this script includes the X server utility, xset, you need to add it using Startup Application menu to run it automatically.

Open the application Startup Applications, under System → Preference → Personal.

Click Add button and find the script file in /usr/local/bin by entering Browse button.
And then complete with Add button as described the 3rd picture.

After reboot, you can find the script in ps list.

odroid@odroid64:~$ sudo ps aux | grep vu8c

odroid    1521  0.1  0.0   5836  1396 ?        S    11:28   0:00 /bin/bash /usr/local/bin/vu8c_backlight_c2.sh
odroid    1757  0.5  0.0   5564   904 ttyS0    S+   11:28   0:00 grep --color=auto vu8c

On Android, we are investigating how to control and run auto control scheme.
As soon as it's done, we will make the instruction guide here.

(UNDER CONSTRUCTION!!!)

vu8c_backlight_c2_android.sh

#!/system/bin/sh
 
path="/sys/class/gpio"
 
echo 234 > $path/export
echo 214 > $path/export
 
echo out > $path/gpio234/direction
echo out > $path/gpio214/direction
echo 0 > $path/gpio234/value
echo 0 > $path/gpio214/value
 
chown system system $path/gpio234/value
chown system system $path/gpio214/value
 
cur_stat="On"
 
while [ 1 ]; do
 
sleep 1
 
screen_info=`dumpsys power | grep "Display Power"`
 
if [[ $screen_info == *"OFF"* && $cur_stat == "On" ]]; then
	echo "monitor goes to Off"
	# backlight off first
	echo 1 > $path/gpio214/value
	echo 1 > $path/gpio234/value
	cur_stat="Off"
elif [[ $screen_info == *"ON"* && $cur_stat == "Off" ]]; then
	echo "monitor turns back On"
	echo 0 > $path/gpio234/value
	# backlight on later
	echo 0 > $path/gpio214/value
	cur_stat="On"
fi
done

Add the following in the end point of /system/init.odroid.board.rc

# vi /system/init.odroid.board.rc

.....
.....
service vu8c /system/bin/vu8c.sh              
    class main                                
    user root                                 
    group root                                
    oneshot