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LCD display lost sync problem

maik maa
Intellectual 400 points
Other Parts Discussed in Thread: TVP5158

Hi, 

    I'm using 814x with DVRRDK McFW demo example,

I modified the example to display image(capture from tvp5158) to QVGA(320x240) LCD(via DVO2),

the result like the following pictures. 

the output resolution seems correct(as 4ch mode via swms link),

but the image will be shift(both vertical and horizontal) and twinkling,

i guess it's Hsync, Vsync issue like polarity, timing or pulse width,

but it doesn't work when i change the config.

any suggestions? thanks. 

  • 0
    TI__Mastermind 43875 points

    Check if this is a display issue or a capture issue by stopping the capture process and then fill the frame buffer with an image.

    If the image is displayed correctly then this is a capture issue. If the display still shifts/sparkles then it is a display issue.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Intellectual 400 points

    Thanks for the reply,

    I'm sure the capture process is correct, 

    Is there any example to show how to configure

    LCD(320x240) by using McFW?

    it needs custom define in several API(swms, vpss...),

    it's seems very complex and  hard to debug, thanks.

  • 0 in reply to maik maa
    TI__Mastermind 43875 points

    Check the HDVPSS software documentation.

    Configuring the output video timings and format can be changed through sysfs entries.

    Search for 'timings' here...

    http://processors.wiki.ti.com/index.php/DM814X_AM387X_VPSS_Video_Driver_User_Guide

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Guru 20755 points

    Hi,

    I hope someonce can give an advise...

    I have similiar problem with LCD 240x320.
    When displaying an image to framebuffer, the image is shifted vertical and start from a random line (after boot).
    Only if I weep the framebuffer as following:
    dd if=/dev/zero of=/dev/fb0
    And then start to display, it will display correctly from first line on screen.
    I do not understand why this solve the issue, but then on trying to display video with the demo, I got the video image shifted on line.
    Each stop, and start will show the image from a different line (and the rest of screen is blank).
    Is it a timing issue ?

    The timing I use is:

    echo 6500,240/1/100/14,512/1/1/10,1 > /sys/devices/platform/vpss/display1/timings

    Since I use height 512 (instead of 320), I suspect that this value might explain the shifting problem.

    Unfortunately, I could not find parameters to stable the image with height 320....


    Regards,
    Ran

  • 0 in reply to ranchu
    Guru 20755 points
    Hi,

    fbdev is configured as following:
    fbset -fb /dev/fb0 -xres 240 -yres 320 -vxres 240 -vyres 320
    So I'm not sure why dd command:
    dd if=/dev/zero of=/dev/fb0
    seems to resolve this issue . Maybe the timing issue actually is still not resolved ?

    Regards,
    Ran