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THS8135 Picture is not displaying

samantula bhaskarrao
Intellectual 785 points
Other Parts Discussed in Thread: THS8135, DA8XX, AM3359, THS8200

Hai to all !!!

We have designed a new PCB for THS8135 based on THS8135 EVM .

We interfaced with the TI-AM3359 ( Phytec phyCORE-AM335x).

We have added the support in Board file and timing parameters in Driver.

In Board file :

***********************************

 }, {
 .manu_name = "vga_vesa",
 .controller_data = &lcd_cfg,
 .type = "VGA_Monitor",
 },

*************************************

In drivers/video/da8xx-fb.c

****************************************

[10] = {
 .name = "VGA_Monitor",
 .width = 640,
 .height = 480,
 .hfp = 16,
 .hbp = 81,
 .hsw = 63,
 .vfp = 10,
 .vbp = 33,
 .vsw = 3,
 .pxl_clk = 25000000,
 .invert_pxl_clk = 0,
 },

************************

While booting kernel the display parameters got detected and we are getting the resolution values(640x480@60HZ) on Monitor.

******************

            [    0.227722] da8xx_lcdc da8xx_lcdc.0: GLCD: Found VGA_Monitor panel
            [    0.245910] Console: switching to colour frame buffer device 80x30

******************

But the screen remains blank.

For your Ref :  LCD is Working good on same board.

Please Help me to resolve this.

Thanks in Advance

~

Bhaskar 

  • 0
    Intellectual 785 points

    Happy to discuss, After changing some Hardware settings,

    Now "VGA" is working fine.

    But once maximize the image or scroll the image right side corner of monitor,it suddenly change to black color.

    Here I am attaching the files for your reference.

    In Minimize condition, the picture is like below.

    If I shift the window to left, The picture is looks like in above only.

    But If I shifted the Windows to right by using mouse, the picture is like below.

    If I Maximize the window, the picture is like below.

    Please Help me the find out the issue, Project dead lines are very near.

    Thanks in advance.

    ~

    Bhaskar

  • 0 in reply to samantula bhaskarrao
    TI__Mastermind 43875 points

    I believe there is an issue with the AM3359 in that it does not correctly zero the video databus at the end of each video line. This is an issue for generic video DACs since it means that the blanking level is not correctly set to black, i.e. digital video code R=G=B=0.

    One possible fix is to configure the AM3359 display driver so that there is always a black pixel on the right hand edge of the screen. This may be possible to do with the display controller so that the actual frame buffer is still  640x480.

    alternatively you might be able to configure the THS8135 to use the DE signal as a blanking control but I don't know enough about the THS8135 to be much help there.

    Finally, I know the THS8200 has an internal timing mode which allows it to generate its own internal blanking signal.

    As a test to see if this is the issue try adding a single black pixel to the right hand edge of the frame buffer data and see if the issue goes away.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Intellectual 785 points

    Thanks Steve.
    By connecting DE with Blank signal, The VGA Starts Working Good now.

    Thank you very much

    Regards,
    ~ Bhaskar

  • 0 in reply to samantula bhaskarrao
    TI__Mastermind 43875 points
    Glad you are now working.