LCD Backlight Error => Solved

eschoi@huvitz.c

I am working with AIO-3399J and DM-M10R800
I compiled with rk3399-firefly-aio-linux-lvds.dts
and  I checked lcd_pwr_en is high , VDD-CORE is 1.2V , lcd_rst is high, 1.8V
and I checked LCD Board VGH =>5.59V ,  VGL=>-5.6V
AVDD=>11.2V ,VCC_LCD=>3.2V, LED+ => 4.97V, LED- =>0.0V
But LCD backlight is not working. tured off.
what position should I check?
I want to turn on LCD

eschoi@huvitz.c

<Solved>
1.edit rk3399-firefly-aio-linux-lvds.dts
        backlight: backlight {
                status = "okay";
                compatible = "pwm-backlight";
                pwms = <&pwm0 0 25000 1>;
                brightness-levels = </*
                          0   1   2   3   4   5   6   7
                           <SKIP>
                        248 249 250 251 252 253 254 255>;
                default-brightness-level = <200>;  => default-brightness-level = <100>;  
2.check LED+ of LCD Board
LED+ voltalge should be higher than 11v
when  default-brightness-level is 200,  78% duty, LED+ voltage is 4.9v  => backlight turned off
but   if default-brightness-level is 100,  40% duty,LED+ voltage is 11.4v  => backlight turned on

Success!!!!!!!!

permature

Have you fixed it yet? I was playing Chill Guy Clicker and my computer had the same problem as yours. Please help me.

barkerxavierr

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JamesLunt

LCD backlight error, solved! A common issue with a simple fix, often involving replacing the inverter or checking connections. Celebrate the win with a game of Wordle Unlimited to sharpen your deduction skills. Now, enjoy that perfectly illuminated display.

cocacola89

I appreciate your work. Your posts are very interesting and I must say you have done an amazing job. I think this is one of the most positive blogs I have come across. fireboy and watergirl

neaac88

Make sure the data lines (MIPI, LVDS, etc.) that connect the AIO-3399J to the DM-M10R800 are not broken and are properly linked wordle hint. Look at the connecting pins to see if there are any loose connections or shorts.

EthanWalker

Great technical breakdown — you’ve clearly done thorough voltage checks on the AIO-3399J setup. It reminds me of how Remark Construction approaches troubleshooting: methodical and precise. Maybe double-check the backlight enable signal or PWM control line; that’s often the missing piece when all the voltages look right but the LCD stays dark.