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--- en:acc:vu8 [2016/12/22 11:49]
odroid [3. Backlight control with PWM.]
+++ en:acc:vu8 [2017/01/19 14:18]
joy.cho [3. Backlight control with PWM.]
@@ Line 58: / Line 58: @@
 ==== 2. Backlight ON/OFF. ====
-Add the following line in "/etc/rc.local".\\
+=== [ Ubuntu ] ===
+Add the following lines into "/etc/rc.local".\\
 **ODROID-C2**
 <code>
@@ Line 79: / Line 81: @@
 echo 0 > $path/gpio108/value
 </code>
+=== [ Android ] ===
+In case of Android, please add the followings in "init.odroid.board.rc".\\
+First, make the filesystem writable.
+<code>
+shell@odroidc2:/ $ su
+root@odroidc2:/ # mount -o rw,remount /
+</code>
+Make or download the following shell script of the board model that you're using (C1 or C2)\\
+and copy it in **/system/bin/**.\\
+And make its permission executable.
+<code>
+# su
+# chmod 755 /system/bin/vu8c_backlight_c2_android.sh
+</code>
+**ODROID-C2**
+<file sh vu8c_backlight_c2_android.sh>
+#!/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 $path/gpio214/value
+</file>
+Now, you need to register the service to run this script automatically on boot time.\\
+Add the following lines in the end of /init.odroid.board.rc.\\
+Don't forget the root filesystem should be writable as aforementioned.
+<code>
+# su
+# vi /init.odroid.board.rc
+.....
+.....
+service vu8c_backlight /system/bin/vu8c_backlight_c2_android.sh
+    class main
+    user root
+    group root
+    oneshot
+</code>
+Then, reboot.
+<code>
+$ reboot
+</code>
+After reboot, you can confirm if the nodes are configured normally by checking "gpio214" and "gpio234".
+<code>
+$ ls /sys/class/gpio/
+export
+gpio214
+gpio234
+gpiochip122
+gpiochip136
+unexport
+</code>
+**ODROID-C1**
+<file sh vu8c_backlight_c1_android.sh>
+#!/bin/sh
+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 system system $path/gpio97/value
+chown system system $path/gpio108/value
+</file>
+Now, you need to register the service to run this script automatically on boot time.\\
+Add the following lines in the end of /init.odroid.board.rc.\\
+Don't forget the root filesystem should be writable as aforementioned.
+<code>
+# su
+# vi /init.odroid.board.rc
+.....
+.....
+service vu8c_backlight /system/bin/vu8c_backlight_c2_android.sh
+    class main
+    user root
+    group root
+    oneshot
+</code>
+Then, reboot.
+<code>
+$ reboot
+</code>
+After reboot, you can confirm if the nodes are configured normally by checking "gpio97" and "gpio108".
+<code>
+$ ls /sys/class/gpio/
+export
+gpio97
+gpio108
+......
+......
+unexport
+</code>
 ==== 3. Backlight control with PWM. ====
 === GPIO configuration ===
 == ODROID-C2 ==
-  cd /sys/class/gpio
+<code>
-  echo 214 | sudo tee export
+cd /sys/class/gpio
-  echo out | sudo tee gpio214/direction
+echo 214 | sudo tee export
-  echo 0 | sudo tee gpio214/value
+echo out | sudo tee gpio214/direction
-  echo 234 | sudo tee unexport
+echo 0 | sudo tee gpio214/value
+echo 234 | sudo tee unexport
+</code>
 == ODROID-C1+/C1/C0 ==
-  cd /sys/class/gpio
+<code>
-  echo 97 | sudo tee export
+cd /sys/class/gpio
-  echo out | sudo tee gpio97/direction
+echo 97 | sudo tee export
-  echo 0 | sudo tee gpio97/value
+echo out | sudo tee gpio97/direction
-  echo 108 | sudo tee unexport
+echo 0 | sudo tee gpio97/value
+echo 108 | sudo tee unexport
+</code>
 === PWM configuration ===
+== [Ubuntu] ==
 Load PWM driver modules.
-  sudo modprobe pwm-meson
+<code>
-  sudo modprobe pwm-ctrl
+sudo modprobe pwm-meson
+sudo modprobe pwm-ctrl
+</code>
+Ignore warning message of "pwm-ctrl pwm-ctrl: cannot export to PWM-1 : modprobe pwm-meson npwm=2" \\
+Enable PWM via sysfs. \\
+<code>
+echo 100000 | sudo tee /sys/devices/platform/pwm-ctrl/freq0
+echo 1 | sudo tee /sys/devices/platform/pwm-ctrl/enable0
+</code>
+Set duty ratio (value can be 0 to 1023. Lower is brighter)
+<code>
+echo 1023 | sudo tee /sys/devices/platform/pwm-ctrl/duty0
+</code>
+== [Android] ==
+Load PWM driver modules.
+<code>
+root@odroidc2:/ # insmod /system/lib/modules/pwm-meson.ko npwm="1"
+root@odroidc2:/ # insmod /system/lib/modules/pwm-ctrl.ko
+</code>
 Enable PWM via sysfs.
-  cd /sys/devices/platform/pwm-ctrl
-  echo 100000 | sudo tee freq0
+<code>
-  echo 1 | sudo tee enable0
+root@odroidc2:/ # cd /sys/devices/pwm-ctrl.43/
-Set duty cycle
+root@odroidc2:/sys/devices/pwm-ctrl.43 # ls
-  echo [0-1023] | sudo tee duty0
+driver
+duty0
+enable0
+freq0
+modalias
+power
+subsystem
+uevent
+root@odroidc2:/sys/devices/pwm-ctrl.43 # cat enable0
+PWM_0 : off
+root@odroidc2:/sys/devices/pwm-ctrl.43 # echo 1 > enable0
+root@odroidc2:/sys/devices/pwm-ctrl.43 # cat enable0
+PWM_0 : on
+</code>
+Set default frequency.
+<code>
+root@odroidc2:/sys/devices/pwm-ctrl.43 # echo 100000 > freq0
+</code>
+Set duty ratio.\\
+Value can be 0 to 1023 and lower value means brighter.
+<code>
+root@odroidc2:/sys/devices/pwm-ctrl.43 # cat duty0
+
+root@odroidc2:/sys/devices/pwm-ctrl.43 #echo 160 > duty0
+root@odroidc2:/sys/devices/pwm-ctrl.43 # cat duty0
+
+</code>
+==== 4.  How to Set Auto Backlight On/Off by Monitor Status ====
+Please refer to the following wiki page if you want to run auto backlight on/off control that is triggered by monitor on/off status. \\
+http://odroid.com/dokuwiki/doku.php?id=en:vu8c_backlightcontrol
 ===== Hardware assembling =====