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Slow Image Download to LightCommander

Other Parts Discussed in Thread: DLPC200

I am using the DLP_Img_DownloadBitplanePatternToExtMem() function from the DLPC200 API to download .bpp images to the LightCommander. With this method it takes over 2 minutes to download 512 images; however, it seems that with a USB 2.0 interface it should only take several seconds (.bpp images are only 96KB each). Since the image sets need to be changed frequently, a large chunk of my day is spent waiting for the image sets to download. Is this slow image download speed normal? Is there a faster way to download images to the LightCommander?

  • Hello Eric,

    Although the typical download speed of USB 2.0 is close to 300Mbit/s, the download speed using the LC is slower due to the image packets flow.  After the USB chip, the packets flow into FPGA internal buffers and are then pulled out by the MCU software 512 bytes at a time.  This buffering and processing slows down the image download.  However, I'm going to look into an alternative option using the parallel flash to determine if it could help you download the images faster.  I will post another response once I do.

    Regards,

    Raul

  • Sorry to revive such an old post, but was anyone ever able to find a work around for this issue? 

  • Hello Alex,

    If there are known set of patterns and there number is <= 960 1bit or <=120 for 8-bit patterns, then you can actually stored them into a solution, store them on the flash. 

    You can then recall them in any order or subset of the patterns to be displayed by sending commands like discussed in the this thread http://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/f/387/t/248361.aspx

    Regards,

    Sanjeev

  • Hi Sanjeev,

    Thanks for the quick reply.

    I'm aware of the ability to shuffle the sequence of patterns already in the buffer using DLP_RegIO_WriteImageOrderLUT. Unfortunately, my application requires that I rapidly display many thousand unique 1bit patterns over the course of a few minutes, so I need to repeatedly play all 960 patterns and then load the buffer with new ones.

    I have been able to improve my overall speed somewhat by loading new patterns while playing i.e. I will play patterns from the 1-480 indices while loading new patterns into 481-960. But ultimately I have not been able to load new patterns faster than 5 Hz, and this creates a difficult bottleneck for me. Is there anything else I can do to speed this up?

    Alex

  • Hello Alex,

    Unfortunately that is the maximum available when it comes to downloading patterns real time via USB interface.

    The other option is to explore driving the patterns via RGB 24-bit video port, for this you need to package 24 1bit patterns into a single video frame real time. 

    Regards,

    Sanjeev