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RTOS/TDA3XEVM: control of RGB gain , contrast of display from TDA3xx

Part Number: TDA3XEVM

Tool/software: TI-RTOS

Hi Everyone ,

I like to know is there any possible ways to control the RGB gain, brightness / contrast of the display from the TDA3x . I like to know whether these parameters can be controlled through software .

Thanks & Regards ,

V.B.Surendar

  • Hi Surendar,

    It is not supported as of now. HW natively does not support it. But there is some support in the ISP links. So Are you using ISP link in your data path?

    Regards,
    Brijesh
  • In reply to Brijesh Jadav:

    Hi Brijesh,

    We are trying to alter the DSS parameters which will affect all the usecases in common if I am not wrong . Now we are working on the DISPC VIDEO PORT OUTPUT which we found in TRM , using these registers we could enable GAMMA but color phase rotation unit is not taking any effect .

    Kindly suggest whether is it a right place to alter the RGB gain .Basically our problem is we are getting some bright yellow color on the display which we are trying to adjust it now .
  • In reply to Surendar V B:

    Hi Surendar,

    To enable CPR module, you require to enable it first in the config register. Please enable it, it will work.

    Rgds,
    Brijesh
  • In reply to Brijesh Jadav:

    Hi Brijesh ,

    I have enabled 15th bit of config register to one for CPR, still I couldn't see any changes in the display . I have also changed the coefficients of RGB separately still I couldn't see any changes

    .In between can we reduce the yellow over exposure on the display by controlling this parameter ?
  • In reply to Surendar V B:

    Surendar,

    What is the output interface that you are using? This module cannot be used for BT output interface.
    If you are using video pipeline, there is one more CPR in the video pipeline. Probably you could use this one to control yellow color while converting YUV to RGB.

    Rgds,
    Brijesh
  • In reply to Brijesh Jadav:

    Hi Brijesh ,

    We are using parallel LCD interface and not BT interface . Can you kindly help us to find the other CPR in the video pipeline . I could also check that .
  • In reply to Surendar V B:

    Surendar,

    The coefficients for this YUV to RGB conversion are configured in DISPC_VID_CONV_COEF0,1 and 2 registers. You could try changing values in these registers.

    Rgds,
    Brijesh
  • In reply to Brijesh Jadav:

    Hi Brijesh ,

    I have enabled the above mentioned register and tried , but I could not see the image on the display . I tried with different coefficients value still I could not adjust the RGB gain of the display.


    Kindly help us on this and also let me know if I have missed anything.

  • In reply to Surendar V B:

    Hi Surendar,

    What is your input format? which display pipeline you are using?

    The CSC module will be definitely used if your input format is YUV and you are doing some blending operation. It is not possible that change does not take any effect if it is getting used.  You must be using either using difference pipeline or your input format is not YUV.

    It is even strange that CPR is not working. I have used CPR and it works fine. Are you enabling CPR for the correct output? TDA2x supports multiple outputs, so if you are not enabling it in correct output, you will not see its effect. Check the overlay manager and LCD output that you are using and enable CPR accordingly. 

    Rgds,

    Brijesh

  • In reply to Brijesh Jadav:

    Hi Brijesh ,

    We are not sure about the following things :

    1) Input format
    2) Display pipeline

    We are currently using rear view panorama usecase on TDA3x platform and the output is VIP LCD display . The observations which we found is we could enable Gamma output whereas the CPR even after enabling we couldnt see changes in the display . I also like to know whether you are referring to TDA2x platform.

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