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DLP4500: Question about operation in Video mode in the DLP lightcrafter 4500

Ashish Rao
Prodigy 110 points
Part Number: DLP4500
Other Parts Discussed in Thread: DLPC350

Hi,

I have been operating the DLP4500 in video mode for an experiment. In short, it projects whatever display the lightcrafter has been connected to through the HDMI port.

The question is about how the projector projects. Does it update the projection by raster scanning  (similar to a TV display) ? Or does it does it use some other scheme to update the projection? 

Thanks 

Ashish

  • 0
    TI__Mastermind 20045 points
    Hello Ashish,

    The DLP4500 DMD mirrors will flip at the same time in a global refresh. Therefore, it does not use raster scanning. You may find this app note helpful: www.ti.com/.../dlpa008b.pdf It refers to a different type of DMD but still generally explains the DMD refresh concept.

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    Prodigy 110 points

    Is there any mode where I can make the update (flipping of the mirrors) in a raster fashion rather than flipping all at once?

  • 0 in reply to Ashish Rao
    TI__Mastermind 20045 points
    Hello Ashish,

    This is not a mode we support. Could you elaborate on your application a little bit so we can perhaps understand what you are trying to achieve?

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    Prodigy 110 points

    Hello Kyle,

    I have a sensor which is able to detect fast moving objects. I am trying to get a dot to move over some area in a raster fashion really fast (need to complete a row in a few microseconds). Suppose I had a raster update scheme, projecting a white image onto the object would have achieved the same. 

    An alternative to this is to generate a video of a dot moving in a raster pattern in OpenCV or some framework. However, since the projector merely displays the screen and the refresh rate of screens are usually 60Hz, the max achievable speed would get locked onto the refresh rate of the screen. In other words, I could go only upto a 60FPS video of a dot moving in a raster fashion(when the refresh rate of the display is 60hz). This would be extremely slow (would take 4.5 minutes, compared to 1/60 secs in a raster update scheme). Being able to change the update scheme at the hardware level would allow me to achieve extremely high speeds

  • 0 in reply to Ashish Rao
    TI__Mastermind 20045 points
    Hello Ashish,

    Do you already have the Lightcrafter4500 and are you able to download the GUI? You may be able to use 1-bit patterns which allow external input frame rates up to 2880Hz. Please see the DLPC350 datasheet for more info (the DLPC350 is the controller for this EVM).

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    Prodigy 110 points

    Hello Kyle,

    Yeah I do have the Lightcrafter4500 and the GUI. I think the lightcrafter flash memory can't store 260x346 images because that's how many pixels I need to project over. I would need to run a loop of the pixel at different locations in the image to simulate raster scanning. Please correct me if I am wrong.

  • 0 in reply to Ashish Rao
    TI__Genius 10925 points
    Hi Ashish,

    Kindly note you can store upto 3 24 bit images in flash, so in effect you can have 3x24= 72 bitplanes stored in the flash.

    THanks & Regards,
    Hirak.