Please mention the module name and WinCE version you are using in your queries.
I think you are using our Colibri T20 Module.
To automatically power off the backlight, you need to set it in the power settings. The Display timeout does not work.
Microsoft has once changed the concept but NVidia did not port it.
You can do it by setting the Power Properties. (Control Panel → Power > Schemes > Power Scheme : AC Power, Swtich state to System Idle)
The minimum timeout you can set there is 1 minute. If you want to set timeout less than 1 minute, set this in the below registry path.
By default we use SODIMM Pin no. 71 as backlight enable pin. You can change this pin and its polarity as per your hardware configuration through below display driver registry entry :
“BL_GPIO”=dword: x (where x = GPIO No. of SODIMM Pin you want to use)
“BL_POL”=dword:0 or 1
“DISP_POL”=dword:0 or 1
Please refer to the below link and module’s datasheet to get the GPIO No. of the SODIMM Pin.
Further, you can also use PWM to control the brightness of the LCD backlight.
Feed the PWM signal to backlight LED driver of your display to control the display brightness.
PWM reference codes are available on our developer webpage both in C as well as C# :
There are 4 standard PWMs available on our Colibri Modules.