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Original question:

DLPDLCR230NPEVM: 960x540@240hz displayed image is constantly wiggles

DLPDLCR230NPEVM: 960x540@240hz screen tearing issue

Kei Kim
Intellectual 275 points
Part Number: DLPDLCR230NPEVM

Hi,

I'm testing the EVM by connecting it to the Raspberry PI and setting the display mode to the 960x540@240hz.

There were several issues when setting up including the insufficient current in the GPIO pins and the FPGA misalignment with the video data.

Today, I have displayed something at 240hz on the Raspberry PI via the EVM and found another problem.

https://www.youtube.com/watch?v=LYha7v6h6U0

The reason why I recorded the video was that I felt the screen is torn even though the frame rate is set to 240hz and also reported to follow the vsync.

I used the iPhone slowmo and also the vsync-connected hardware camera : both results were the same. The screen is torn.

When we look at the captured video, we can see that the gears are torn in the middle.

I used the famous sample openGL program "glxgears" (only modifying the gear's rotation axis, to see the issue more clearly) which renders images while vsync enabled by default.

What could be the cause of this problem?

Could this be another FPGA misalignment with the video data issue—how can I fix this problem?

Thank you.

  • 0
    TI__Genius 9225 points

    Hi Kei,

    Welcome to TI E2E forums and thanks for your interested in our DLP technology.

    We'll look into your questions and get back to you in next few days. 

    Regards,

    Lori

  • 0 in reply to Lori Wang
    TI__Genius 9971 points

    Hello Kim, 

    Are you seeing similar behavior for lesser frame rates as well?

    Regards,

    Mayank

  • 0 in reply to Mayank Khandelwal
    Intellectual 275 points

    Hi,

    While trying to answer what you have just asked, changing the resolution to the 1920x1080@60 and vice versa,

    suddenly the problem seems resolved by itself—I suspect changing the resolution to another resolution and vice versa might somehow have affected the screen tearing issue.

    I will check if the problem is actually resolved by testing in a couple more days, without closing this issue.

    Thank you.

  • 0 in reply to Kei Kim
    TI__Genius 9225 points

    Hi Kei,

    Thank you for checking! We can keep the thread open until you won't see any more issues. 

    Regards,

    Lori 

  • 0 in reply to Kei Kim
    TI__Expert 3360 points

    Hi Kei,

    This seems like the EVM is not configured correctly for 960x540 input. For example, if the EVM expects to receive 1920x1080 resolution video, but there is actually 960x540, there will be a "screen tearing"-like video displayed.

    Here is the recommended steps to set up the EVM using raspberry pi for some resolution:

    # H_RESOLUTION = horizontal active pixels
# V_RESOLUTION = vertical active lines

Summary = WriteSourceSelect(Source.ExternalParallelPort, Set.Disabled)
Summary = WriteInputImageSize(H_RESOLUTION, V_RESOLUTION)

    Note that if you are using 1920x1080 resolution, you will need to ensure the actuator DAC output is enabled (which enables XPR). 

    If you are using 960x540 resolution, you will need to ensure the actuator DAC output is disabled, which you can use:

    Summary = WriteActuatorGlobalDacOutputEnable(Set.Disabled)

    Please let us know if you have any other issues.

    Thank you,

    Chris