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DVI Display Issue on DM3730 EVM

Jeffrey Vertosick
Intellectual 310 points
Other Parts Discussed in Thread: DM3730

I am using DVSDK 4.02 with a DM3730 EVM.  I am attempting to use the DVI output to pass 24-bit data from the DM3730 to an external FPGA.  The data I am passing consists of 16-bits of YUV data + 8-bits of additional data.  So I am copying the Y values into the R bytes of frame buffer fb0, the U/V data into the G bytes, and the 8-bit additional data into the B bytes.  I have the DVI settings such that the data is passed through from the frame buffer to the DVI.  However, whenever I send a value of (R,G,B) = (16,anynumber,0) the FPGA is receiving a value of (16,anynumber,2).  Similarly, an (R,G,B) = (16,anynumber,1) the FPGA is receiving a value of (16,anynumber,3) and (R,G,B) = (16,anynumber,4) the FPGA is receiving a value of (16,anynumber,6).  If I vary the R value the B values are transmitted properly.

Is there any type of color correction performed in the omap2 display that could be causing this effect?

  • 0
    TI__Expert 8180 points

    I am not quite sure if I understand your problem clearly, and also information is not sufficient. I need to understand, how are you configuring DSS for this usecase (like pixel format, etc...).

     

    Thanks,

    Vaibhav

  • 0 in reply to Vaibhav Hiremath
    Intellectual 310 points

    In uboot I am passing the boot arg 'omapfb.mode=dvi:1152x864' to setup the DVI output and resolution.  The framebuffer is 32-bit RGBA.  Overlay0 is the only enabled overlay.

    Another way of framing the problem is by setting pixels in the framebuffer based on the table below.  It seems that the 2nd bit of the Blue value is always being set in certain cases.  The numbers in the table below are not the only values that produce this effect, I tried a loop that incremented the R value with each line of the display while holding B at 0 and the results was periodic horizontal stripes alternating between B of 0 and B of 2. 

    Framebuffer Value                                              Actual Value on DVI

    (R,G,B)                                                                  (R,G,B)

    (16, 128, 0)                                                           (16, 128, 2)

    (16, 128, 1)                                                           (16, 128, 3)

    (16, 128, 4)                                                           (16, 128, 6)

    (34, 128, 0)                                                           (34, 128, 0)

    (34, 128, 1)                                                           (34, 128, 1)

    (34, 128, 4)                                                           (34, 128, 4)