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DLPLCR50XEVM: issue of video pattern mode

Satoshi Yawata
Prodigy 10 points
Part Number: DLPLCR50XEVM
Other Parts Discussed in Thread: DLPLCRC900DEVM

I'm using DLPLCR50XEVM+DLPLCRC900DEVM.

when I show the pattern with parameters shown below, some blocks have no dark period (once in 28 blocks)

 

video pattern mode

Pattern1 with G0, Exposure 500us, dark 100us

Repeat

 

with different duration for exposure or dark, frequency of trouble seems to be changed.

 

  • 0
    TI__Guru 54350 points

    Hello Yawata-san,

    Could you include a screenshot of the Video Pattern Mode setup page?  What I am looking for is whether you have a "Frame Change" included:

    If you are free running without a frame change, then every time a sync occurs the system will throw a sequence abort error and will not display as expected.

    By my calculation 28 * (500 us + 100 us) = 16.8 ms which will give about 59.5 Hz - about 1 frame.  So I think you need to define the same pattern (and color bit) 28 times at 495 us display time and 100 us dark time and put a frame change on the very first (or very last) pattern only.  You can experiment a bit with the display time to get it match your incoming video frame rate.

    Fizix

  • 0
    Prodigy 10 points

    Thanks Fizix san,

    Based on your advice, I also think my problem is related to refresh rate.

    Even with different duration, ordered pattern was shortened every 16.6~16.7msec.

    I haven't used a "Frame change"  previously.  And now I tried and found

    With "Frame change" on the very first pattern, 17 * (500us + dark500us)

    => repeated  {16* (500us + dark500us) + 500us + dark230us}

    Frame change seems to reset the pattern sequence.  And with Frame change, I can easily find when deletion occurs.

    But my goal is showing patterns repeatedly and correctly.

    Is it possible to show patterns independent of video frame rate?

  • 0 in reply to Satoshi Yawata
    TI__Guru 54350 points

    Yawata-san,

    Since the incoming data is from incoming video frames, it is not possible to show patterns independent of frame rate.  The closest you can come is to split the time up as close as possible to fill the frame without going over.  That is what the 495 us display time was trying to demonstrate.

    You are correct that the frame change causes the sequence to restart at that pattern that the frame change is in.  It is possible to have more than one frame change in your sequence of defined patterns.  In that case each sync will start at the next frame change in the sequence until no frame changes are left and then it will start back at the beginning of the sequence and look for the next frame change.  It is not required for the frame change to be on the first pattern, but it is easier to keep track of.

    You can use Pattern On-the-Fly Mode or Pre-Stored Pattern Mode, but then you are limited to what you download at the beginning of the sequence and cannot stream patterns in real time.

    Fizix

  • 0 in reply to Fizix
    Prodigy 10 points

    Fizix san

    Thank you for your kind advice.  I completely understand!