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What is the shortest upload time from a PC to LPC 6500 EVM limited by the firm ware (not by a code or a program?)

user4724985
Prodigy 140 points
Other Parts Discussed in Thread: DLPC900

Good morning,

I would like to send an image (1 bit depth) to LPC lightcrafter 6500 EVM and would like to know how fast I can send an image. 

Is it possible to send an image (1 bit depth, I can limit the number of pixels to use if needed) from a PC to the DMD in about 10 to 50 ms?

If it is possible, what would be the required settings? And if it is not, what would be the limitation and what is the shortest time to send an image?

Thank you in advance.

  • 0
    TI__Mastermind 30600 points
    Welcome to the DLP Forums and thank you for your question!

    The interfaces that the DLP6500 has available are HDMI, DisplayPort, and USB. This EVM will accept streaming video input through HDMI or DisplayPort at up to 247Hz, which is sufficiently fast for what you're asking about. However, I don't think this is going to fit your application because it requires a continuous data stream.

    Can you describe a bit further your application and why you're interested in the PC to EVM time?

    Typically we see customers wanting to know about speed once a pattern is stored in flash on the device. With binary patterns, those are loaded onto the EVM and then pattern mode is used to display the stored pattern quickly and accurately. I recommend that you take a look at the Lightcrafter 6500 and 9000 user's guide: www.ti.com/.../dlpu028b.pdf

    Hope that helps!
    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 140 points

    Hi Paul,

    Thank you very much for your quick reply! Yes, as you guessed, the video streaming is not what I want.

    What I plan to do is a feedback process of an image. The sequence would be as follow. 

    1. Take a picture (like position of particles)

    2. Make a DMD pattern according to the picture taken in 1. 

    3. Send it to the DMD.

    It is required that the whole process is within 100 ms. 

    Since I don't know in advance the pattern to be sent in 3, I would like to shorten the upload time from PC to EVM. 

    I am using PC currently, but the PC can be replaced to FPGA if that helps.

    Thank you,

    Eunmi

  • 0 in reply to user4724985
    TI__Mastermind 30600 points
    Eunmi,

    That sounds like a cool application. What I would suggest is that you play with "Pattern-on-the-Fly" mode. This allows you to upload an image to the EVM through USB and if the image is sufficiently small and simple, the upload time should be quick. You'll have write your own code or batch file to make this happen (because clicking on the GUI is waaay too slow).

    Another approach would be to use Video Pattern mode and display black between your images if that's what you'd like to do. This would allow fairly fast times but the implementation could be tricky. It would look something like storing your camera image in one image channel, say R0 and displaying black on the others.

    Aside from the user's guide that I recommended above, I would also take a look at the DLPC900 programmer's guide: www.ti.com/.../dlpu018b.pdf

    -Paul
  • 0 in reply to Paul Goedeke
    Prodigy 140 points

    Hi Paul,

    Thanks for the answer! Actually, that is what I am currently doing - "Pattern-on-the-Fly" mode, USB connection using a Python code. It takes about 3 seconds to upload an image. I haven't optimized the code yet and I would like to know what is the best I can get before I start playing with the codes.

    One thing I found is that the speed of USB1.1 that the DCLP900 has (correct me if I'm wrong) is 12 Mbps. Since the DLP 6500 has 1920x1080 pixels, the minimum file size is about 2 Mb and it would take about 170 ms to transfer the data thru USB1.1. Is my way of thinking correct? I don't need to use the full range of the DMD but I'm not sure if I could only send partial data (for example, data for 700x700 pixels only) to the DMD. 

    The video pattern mode approach sounds good although the timing might be tricky as you said. I will also check that option. 

    Thanks a lot!

    Eunmi

  • 0 in reply to user4724985
    TI__Mastermind 30600 points
    Eunmi,

    USB 1.1 is definitely slow and your way of thinking is correct. Unfortunately with the Lightcrafter 6500 the interface options are a little bit more limited. Keep in mind as well that your image complexity will impact the transfer speed as well because of the compression that takes place. Simple binary images (vertical bars, etc.) will generally transfer faster than more complex images.

    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 140 points
    Hi Paul,

    Thanks a lot for your help! I'll play with the video mode then.

    Best,
    Eunmi
  • 0 in reply to user4724985
    Prodigy 140 points

    Hi Paul,

    Thank you very much for your advice here. We tested the video mode using both HDMI and display port and the update is fast enough that human eyes don't catch any delay.

    You told me that this EVM accepts streaming data at upto 247 Hz. Does this also mean that the video image is displayed on the DMD 4ms after the PC sends it? Or, is there more time lag inside the module?

    Thanks!

    Eunmi

  • 0 in reply to user4724985
    TI__Mastermind 30600 points
    Hi Eunmi,

    There should be no additional delay, otherwise the device won't be able to keep up with the incoming data.

    Paul