PWM signal for LCD contrast in WinCE

  • Hello,
    after using during sometime NetDCU14, we'd like to be able to modify PWM signal for LCD contrast.
    Documentation says this CPU has 2 PWM signal outputs: one for LCD contrast, one generic.


    For LCD it seems that this PWM signal is in pin J12- 25 (LVDS connector), but the question is:


    Is the same pin available (hardwired) to any connector of the CPU? we are using not LVDS CPU and we don't see in the documentation.


    Which value and hard pin is then modified with ndcucfg command/s contrast++(--) and so on in NetDCU14??

  • Hello,


    using the RGB version you will find this voltage (smoothed) on pin J3.24 (Veek=0...3V DC. 4096 steps (0=3.3V, 4096=0V)).


    Note. activate the Veek control by HKLM\display\LCD\<yourmode>\ContrastEnable=Dword:1

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  • OK,


    but then pin J12.25 (PWM for LVDS) and pin J3.24 (Veek) are differents:
    J12.25: allows to modify duty cycle with command "contrast++/--"
    J3.24: seems to modify only amplitude of signal from 0.0V and 3.3V but not frequency and not duty. (both pins tested with a scope)


    Pin J12.25 is not available to my carrier board ?


    Is this correct ?


    I need to fix frequency (i.e: 500hz) and then modify duty for my dimming PWM Led backlight RGB LCD . How can I do that ? which pins/register values I must use?

  • Yes,
    pin J12.25 (PWM for LVDS) and pin J3.24 (Veek) are different!
    Between these two pins is a RC filter which smoothes the PWM.
    And yes, pin J12.25 is not available on another connector.


    Please contact our sales office. Maybe it is possible to NOT assemble the RC filter (custom HW).

    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.

  • Thank you for information.


    So, without this RC filter, functionality of both pins are the same ?


    As suggestion, your HW team can consider in the future to route J12.25 to any of the J3 pins currenlty not used (there is several ones NC) in next HW revision of NetDCU14, it can be usefull for any LCD PWM dimming RGB display, and I was told F&S is making maybe some redesign to current CPU to allow 2 USB ports as host....


    For my current CPU HW, I can only use J4.15 (general PWM output), can you tell me the values to modify in the register for this output? after that, PWM will start automatically or I have to write a program, and any example in C# for it?

  • Hello,

    Quote

    So, without this RC filter, functionality of both pins are the same ?

    Yes.


    Quote

    For my current CPU HW, I can only use J4.15

    Sorry i missunderstood. I thought j3.24 is "ok" for your purpose, when we do not assemble RC filter. I will check state for "second" pwm driver and will answer you again.

    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.

  • You will find pwm driver in the latest beta kernel (V1.04) and all following releases.
    You can also usesd attached DLL and register:

    Code
    1. [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\NetDCU14\PWM]
    2. "Prefix"="PWM"
    3. "Dll"="fs_pwm.dll"
    4. "Order"=dword:99
    5. "Index"=dword:1
    6. "Channel"=dword:1
    7. "FriendlyName"="PWM driver for NetDCU14"

    Files

    • fs_pwm.zip

      (3.87 kB, downloaded 154 times, last: )

    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.