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DLP4500: DLP4500 - pattern mode with RGB source

Luca Zanotto
Prodigy 120 points
Part Number: DLP4500

Hello!

I am using a DLP4500 with its Evaluation Module. I am trying to send some patterns via HDMI in pattern mode.

If I understood correrctly, in this case the trigger is given by the Vsync coming from the RGB video source (I am using a laptop to control the DMD so it is 60Hz). What I would need is to send a pattern and to make sure the mirrors stay fixed in the "pattern position" for long time (0.1-1 sec), until another pattern is sent from the source.

So the questions are:

1)  does the DMD stay in the "pattern position" if this one is the same over many "trigger periods" (let's say if my pattern is the same for 300ms), or it changes to another position and goes back everytime it receives an input from the Vsync?

2) in this second case is there a easy way to change the settings to make sure the mirrors are fixed if the pattern does not change (for example changing the exposure time of the patterns), or I am forced to change the Vsync somehow?

I hope my questions are clear (I am not very experienced with this).

(I already asked a question related to this some days ago but I think I didn't fully understand my issue back then and I thought it was resolved, so I apologize for this multiple thread).

Thnk you very much!

Regards,

Luca Zanotto

  • 0
    TI__Mastermind 20045 points
    Hello Luca,

    When using the video port as the input you are correct that the Vsync acts as the input trigger. Therefore, your exposure period should be less than the Vsync period. The selected bitlplanes with the specified exposure time will be shown during each Vsync period. This will then be repeated for each new Vsync signal.

    If you need a longer exposure time you will either need to slow down your input Vsync (i.e. lower framerate) or you could look at using the internal pattern mode.

    I hope that helps. Please let us know if you have any other questions.
  • 0 in reply to Kyle Rakos
    Prodigy 120 points
    Thank you Kyle for your quick answer.
    A couple of more things:

    1) Just to be sure (maybe you alredy meant this in your previous answer): if I set the exposure time exactly equal to the Vsync time for example, and the bitplanes I send are the same in two successive Vsync periods, is there a period of time in which the DMD is in a different position (during the time in which the bitplanes are loaded maybe) or it stays fixed because the new position is the same as before?

    2) With the "internal pattern mode" you mean to store the patterns in the Flash memory?

    Thanks,
    Luca
  • 0 in reply to Luca Zanotto
    TI__Genius 10925 points
    Hi Luca,

    1. I'll get back to you on this query.
    2. Yes, you can store the patterns in the flash memory to use internal pattern mode.

    Thanks & Regards,
    Hirak.
  • 0 in reply to Hirak Biswas
    TI__Genius 10925 points
    Hi Luca,

    To answer your first question,

    Yes. The mirrors will be refreshing every time a new bitplane is loaded. So they will not remain still in the same position.
    Thanks for your interest in TI DLP Technology, have a nice day.

    Regards,
    Hirak.
  • 0 in reply to Hirak Biswas
    Prodigy 120 points

    Hi Hirak,

    thanks for your answer.

    Regards,

    Luca