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Timing of the input trigger of DLP0.55XGA Chipset

Seishin
Genius 4135 points
Other Parts Discussed in Thread: DLPC200

Hello,

I have a question from our cusomer.

(Problem)

The pattern projected before appears as an afterimage in the pattern to project.

　 ・The lighting start of LED and the exposure start of a camera are operated

      from the external using an input trigger of DLPC200.

      (PORT1_Trig_in and PORT2_Trig_in)

   ・External hardware trigger

   ・Start of the trigger of these two is the same timing

　 ・Pattern Sequence Mode


(Question)  

Is it necessary to delay the start of exposure of the camera?

Should I delay how long the exposure start from the LED lighting start?


Best regards,
Seishin

  • 0
    TI__Mastermind 30875 points

    Hello Seishin,

    Yes, you can delay start of the camera exposure.

    Yes, you have the option to select the exposure start wrt LED enable signal.

    I am guessing we are missing something here, 

    Could you please provide more details about the pattern sequence setting? Like, Pattern Sequence Mode - 1-bit or 8-bit? What is the pattern exposure selected? Number of patterns.

    Regards,

    Sanjeev

  • 0 in reply to Sanjeev
    Genius 4135 points

    Hello Sanjeev,

    It is made to work with the following settings:

    DMD = XGA

    MODE = SL

    Display Pattern Frm Rate = 185 Hz

    Exposure Time = 5000μsec

    Exposure Time/Firm period = 0.92500

    Num BPP: = 8

    Real-time input source = false

    Active LEDs = RLED GLED BLED


    The exposure start of a camera is performed by HW trigger from another control board,

    without using SYNC OUT of DLPC200.

    The change of the pattern stored in the flash memory is performed in the external HW

    trigger with a cycle of 185 Hz from input port PORT1_TRIG_IN of DLPC200.

    I will start with LED_EN signal of DLPC200 lighting of LED.

    The number of patterns is 80 in all.

    The afterimage disappears when I change the exposure start time for camera from 0 to 350μsec.

    Best Regards,
    Seishin

  • 0 in reply to Seishin
    TI__Mastermind 30875 points

    Seishin,


    Camera trigger un-synchronized to DLPC200 could be the reason why you are seeing the effect.

    The exposure start of a camera is performed by HW trigger from another control board, without using SYNC OUT of DLPC200.

    [Sanjeev] Was there any reason for you to not using SYNC O/P for from DLPC200? With reference to your description, 'another control board' , is it the same system sending HW_trigger to DLPC200 for pattern display? if it is so then I think you are okay, otherwise, we recommend you using the DLPC200 SYNC O/P, the sync signal has anyway Delay and Pulse width adjustment function you can derive the signal however you like, add 350us delay to this sync signal also.

    Regards,
    Sanjeev