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This page will explain you how to configure and use the Linux driver controlling the BackLight of your LCD


Backlight control is done through the i.MX integrated backlight PWM (inside LCDC module). The output signal of this PWM is redirected to the CONTRAST pin of your LCD connector.

In short the driver is mainly exporting a /sys interface to user space, allowing you to change the Duty Cycle of the PWM output signal and so the backlight intensity of the LCD.


This driver is now installed by default on the standard Armadeus rootfs.


On your APF, load the module (not needed on APF6 and OPOS6UL):

 # modprobe imx_bl
 i.MX Backlight driver v0.X initialized.
  • Depending on your platform, backlight interface may have a different name, so let's define an envt variable to ease further instructions:
APF27/51/28 APF6 OPOS6UL
export BACK_IF=imx-bl
export BACK_IF=backlight_lcd
export BACK_IF=lcd_backlight

All backlight controls are done through the /sys interface:

 # ls /sys/class/backlight/$BACK_IF/
 actual_brightness  max_brightness     subsystem
 brightness         power              uevent
  • To see the actual brightness:
 # cat /sys/class/backlight/$BACK_IF/actual_brightness
  • To see the max allowed brightness:
 # cat /sys/class/backlight/$BACK_IF/max_brightness
  • To change the brightness (X depends on previous allowed brightnesses):
 # echo X > /sys/class/backlight/$BACK_IF/brightness


  • There is a small test script (shell) in target/linux/modules/backlight/test/
  • For a C/SDL example, take a look at target/demos/backlight_control/