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DLP3010EVM-LC: 4710 and 3010 EVM external streaming from GPU: frequency and timing

Mark Wexler
Intellectual 480 points
Part Number: DLP3010EVM-LC
Other Parts Discussed in Thread: DLP4710EVM-LC, DLPDLCR4710EVM-G2

I posted this as a follow-up question on another recent thread, but it's really a separate question. Since I didn't get a reply, I'm posting it in a separate thread.

I want to use the 3010 or 4710 as high-frequency monochrome projectors, driven by a GPU over HDMI. I would settle for 1440 Hz output at 1 bit, but anything higher would be better.

1. The 3010 has a mode with 200 µs - 399 µs exposure time and 202 µs of pre- and post-exposure total dark time. At 200 µs exposure time, that works out to about 2488 Hz output frequency, and -- assuming you squeeze the 24 images into the 24 RGB bit planes -- 103.6 Hz input frequency. I assume that a 103.6 Hz output over HDMI isn't achievable. If we want an integer input frequency, we can try for 103 Hz, which would correspond to an output frequency of 2472 Hz and an image duration of 202.5 µs; or if we like round numbers, then we could try for 100 Hz input frequency, which would give an output frequency of 2400 Hz and an image duration of 214.7 µs.

Are these assumptions correct -- is that how you would have to drive the 3010 EVM to get the highest possible 1-bit output frequencies, by varying the input frequency of the HDMI signal? If so, do you know if that's achievable using GPUs over HDMI outputs? The Wikipedia article on HDMI states that versions 1.0 and 1.1 of HDMI were restricted to certain refresh rates, like 60 Hz, but starting with version 1.2 arbitrary refresh rates became possible. Have you or any of your customers been able to achieve these high refresh rates using HDMI output from GPUs at refresh rates like 100 or 103 Hz?

2. The 4710 can output at 1440 Hz at 1 bit depth in external streaming mode, right? If so, can I drive it using a 60 Hz signal from a GPU, squeezing 24 frames into the 24 bit planes of each frame?

3. Question about the different colored LEDs: in the 2488 Hz mode of the 3010, or the 1440 Hz mode of the 4710, can one have the 3 LEDs turned on simultaneously to get true white (rather than cycling through the red, green and blue LEDs through successive frames)?

Thank you very much for your help.

Mark Wexler

  • 0
    TI__Mastermind 20045 points

    Hi Mark,

    For your first two questions you are correct - one such way to achieve the maximum display rate is to vary the GPU input frame rate. For the DLP3010EVM-LC that would mean ~103Hz as you indicated. As you mentioned I am not sure if most graphics cards have such precise frame rate control.

    Another possibility is to input at a standard 120Hz frame rate and only display the first 20 patterns. Each pattern could use the minimum pre-exposure, exposure, and post-exposure times. If you display 20 patterns, those patterns will be displayed in 8.04ms ((171us+200us+31us)*20). The input frame rate will occur every 8.333ms. Therefore, the last 0.293ms (8.333ms - 8.04ms) of each input frame will be dark time. Your effective frame rate would be slightly less than maximum; however ,it would still be fairly close while using standard input frame rates.

    I would recommend playing around with various input frame rates and various display periods. As long as the total pattern display period is less than the total frame period it should work. Some combinations may allow you to achieve closer to the maximum available display rate. 

    Thanks,

    Kyle

  • 0 in reply to Kyle Rakos
    Intellectual 480 points
    Thank you, Kyle, for your reply. So if I go the 20 frames at 120 Hz route, in order to eliminate that extra 0.293 ms, I suppose I could use an exposure time of 0.214 ms (rather than 0.200 ms). Because 20 x (0.171 + 0.214 + 0.031) = 8.320 ms, the extra darkness at the end of each 20 frames would be reduced to 0.013 ms.

    What about by last question, about control of the LEDs? In the 2488 Hz mode of the 3010, or the 1440 Hz mode of the 4710, can one have the 3 LEDs turned on simultaneously on every frame?

    Thank you,
    Mark
  • 0 in reply to Mark Wexler
    TI__Mastermind 20045 points
    Hello Mark,

    That is correct!

    And sorry, I forgot to answer that. Unfortunately you can only have one LED turned on at a time. There are hardware limitations in the PMIC that prevent multiple LEDs from turning on at once.

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    Intellectual 480 points
    One last question, if I may. I'm confused about the difference between the DLP4710EVM-LC and the DLPDLCR4710EVM-G2. Can they both go to 1440 Hz?
  • 0 in reply to Mark Wexler
    TI__Mastermind 20045 points
    Hello Mark,

    The DLPDLCR4710EVM-G2 is only intended for display. Therefore, it is unable to reach the higher framerates at reduced bit depths. The DLP4710EVM-LC can do these higher frame rate light control patterns along with display applications.

    Thanks,
    Kyle