No PWM signal

    According to the specs, pin 65 on J1 is a PWM signal to control the backlight intensity. But if I use that pin the screen stays dark and if I connect my scope to pin 65, there's no signal at all there. Do I need to do something to enable the PWM signal on pin 65?

    You need to specify in the display settings that the display driver should use this pin. Then it should be possible to adjust this pin with contrast commands.
    E.g:

    Code
    1. contrast get
    2. contrast set 0
    3. contrast set 0xfff


    What display are you using and what are your current display settings?


    BTW: By default this PWM signal is grinded by a small capacitor on the baseboard.

    Software developer, F&S Elektronik Systeme GmbH
    As this is an international forum, please try to post in English.
    Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.

    Using display ET035080, settings as follows:


    reg open \drivers\display\LCD
    reg create key mode100
    reg set value name string "EDT ET035080"
    reg set value BLW dword 48
    reg set value HSW dword 20
    reg set value ELW dword 20
    reg set value BFW dword 8
    reg set value VSW dword 10
    reg set value EFW dword 4
    reg set value msignal dword 0
    reg set value rows dword 240
    reg set value LPP dword 240
    reg set value width dword 115
    reg set value height dword 86
    reg set value contrastenable dword 1
    reg set value contrastvalue dword 0xfff
    contrast set 0xfff
    reg set value type dword 0x106
    reg set value config dword 0x00300000
    reg set value columns dword 320
    reg set value PPL dword 320
    reg set value bpp dword 16
    reg set value lcdclk dword 10
    reg set value EnableCursor dword 0
    display mode set 100


    Does the grounding have to be removed in order to use the PWM? Or is just to provide some filtering?

    Have you already tried to execute the contrast ndcucfg comannds?
    In my opinion they should work with this display and these settings.

    Software developer, F&S Elektronik Systeme GmbH
    As this is an international forum, please try to post in English.
    Da dies ein internationales Forum ist, bitten wir darum, Beiträge möglichst in Englisch zu verfassen.

    Yes I have used the 'contrast' commands and they do nothing. The problem is of course that you need some signal to control the display (on pin 18 if I remember correctly). Now, that signal should come from pin 65 on J1 but there's no signal there. If I put 3V DC on pin 18 then the display works but then I can't control it. So the question is not "How do I control the backlight?", the question is "Why is there no signal on pin 65 (PWM)?"