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DLPC150: sequencer i2c question

Kivanc Hedili
Prodigy 230 points
Part Number: DLPC150
Other Parts Discussed in Thread: TFP401

Hi,

We are trying to program the DLPC150 through its I2C port. So far we were able to switch between internally generated test patterns, now we are trying to display external patterns through its 24 bit parallel port. We are confused about the sequencer that is discussed in section 2.4 of the programmer's guide. What we understand is the sequencer manages the switching of the data between the DMD buffer and the pattern on the DMD. In all example I2C sequences throughout the guide, the sequencer is stopped at the beginning but how its set is never shown. The commands are not even listed in the reference summary of all I2C commands at the end of the guide.  Shouldn't we enable it for streaming data through its parallel port? If yes, what is the correct order of the I2C commands? 

Thanks,

Kıvanç Hedili 

  • 0
    TI__Genius 9971 points

    Hello Kıvanç Hedili ,

    Welcome to TI E2E forums and thanks for showing interest in the DLP technology. Kindly refer to section 2.5.3/2.5.4 of the Programmer's Guide to get to know about the I2C commands needed to display external patterns through 24bit parallel port. There is no need to run sequencer commands in order to display external patterns. 

    Regards,

    Mayank

  • 0 in reply to Mayank Khandelwal
    Prodigy 230 points

    Thank you Mayank, we are able to show parallel data on the DMD now. The current problem is the image is not stationary. We send the patterns through HDMI and convert it to parallel 24 bit data using TFP401. Do you have any suggestions?

  • 0 in reply to Kivanc Hedili
    TI__Genius 9971 points

    Kıvanç,

    Can you check if the Vsync signal coming out of TFP401 stable or not?

    Regards,

    Mayank

  • 0 in reply to Mayank Khandelwal
    Prodigy 230 points

    Mayank,

    Yes its quite stable at 60.2Hz. We tried our TFP401 circuit with an LCD display that takes 24bit parallel input, we didn't observe such behavior. 

    Regards,

    Kıvanç

  • 0 in reply to Kivanc Hedili
    TI__Genius 9971 points

    Can you please try to display some test pattern using the Test Pattern Generator mode and check if the display is stable. This help us narrow down where in further debugging.

    Regards,

    Mayank

  • 0 in reply to Mayank Khandelwal
    Prodigy 230 points

    No problems with the test patterns.

  • 0 in reply to Kivanc Hedili
    TI__Mastermind 28005 points

    Kivanc,

    Based on the above it would seem that there is some kind of video timing issue with your source generation.  You may want to ensure that your selection of pixel clock, vertical blanking, and horizontal blanking setup is good. If necessary, it may be a good idea to reduce incoming pixel clock until the issue is resolved.

    Regards,

    Philippe

  • 0 in reply to Philippe Dollo
    Prodigy 230 points

    Thank you Philippe. I have been trying different blanking parameters for a day now. It has improved a lot but still not good enough. 

    The parameters I used for 854x480 resolution:

    Clock freq = 27MHz

    Horizontal blanking = 46

    Horizontal front porch = 12

    HSYNC width = 12

    Vertical blanking = 20

    Vertical front porch = 8

    VSYNC width = 4

    Line rate = 30kHz

    FPS = 60

     Regards,

    Kıvanç Hedili

  • +1 in reply to Kivanc Hedili
    TI__Mastermind 28005 points

    Kivanc,

    Thanks for your feedback. Does the issue appear more or less with different kinds of content? For example, you could try low-frequency content such as a solid field to see if that behaves better (indicating a signal integrity issue).

    It's very likely your video source has a problem in this case, given that adjusting the video timings helped.

    Best Regards,

    Philippe Dollo