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Original question:

DLPC3433: Setup for Qualcomm DSI host

DLPC3433: Inquiries about DSI PHY Timing parameters.

yeon.lee
Prodigy 30 points
Part Number: DLPC3433

Hi,

Qualcomm provides an Excel sheet for DSI timing calculation.
However, it is difficult to understand how the parameters appearing there are related to the contents of the ti dlpc3433 datasheet.
Please let me know what name to look for when looking for each item below in the dlpc3433 datasheet.

T_CLK_ZERO
T_CLK_PREPARE
T_CLK_TRAIL
T_HS_EXIT
T_HS_ZERO
T_HS_PREPARE
T_HS_TRAIL
T_HS_RQST
T_TA_SURE, T_TA_GO
T_TA_GET
T_CLK_PRE
T_CLK_POST

Thanks.
Yeon.

  • 0
    TI__Genius 9971 points

    Hello Yeon, 

    The team will get back to you with more information soon.

    Regards,

    Mayank

  • 0 in reply to Mayank Khandelwal
    TI__Genius 12785 points

    Hello Yeon,

    Please refer to the DSI Setup and Debugging Guide page. Page 8 of the guide in particular should be of use to you.

    Regards,

    Austin 

  • 0 in reply to Austin Snyder
    Prodigy 30 points

    Hi Austin,

    I have already read the document.
    But I didn't understand how each element was calculated.
    So, I would like to ask questions one by one about the parts I do not understand.

    1. What is Line Time and how I can calculate it?

    2. DSI Lane clock is HS clock?

    3. How can I know T_HS_Prepare is 76ns or T_HS_Zero is 400ns?
        According to dlpc3433's datasheet, the only information in the DSI host timing requirements is T_HS_Prepare + T_HS_Zero >= 465ns
         (if HS clock is 210Mhz), so you need to know the T_HS_Prepare or T_HS_Zero value first to get the rest, but I don't know how to do that.

    4. How can I know Clock edge is dual?
       According to the "7167.DSI-HSClock.xlsx" file posted by Cody Smith at
       DLPC3433: Setup for Qualcomm DSI host - DLP products forum - DLP®︎ products - TI E2E support forums.
       Clock edge is dual. I couldn't find it explicitly in the datasheet. What can I infer?

    5. I wonder how I can calculate or find other HS and clk related values.
        If you answer the questions above, I will ask you the following questions in turn.

    Best Regards.
    Yeon.
      

  • 0 in reply to yeon.lee
    TI__Expert 3905 points

    Hello Yeon,

    Thank you for your questions. We will get back to you within the next few days with our responses. We thank you for your patience.

    Best,

    Maxine

  • 0 in reply to Maxine Cabrasawan
    TI__Expert 5565 points

    Hello Yeon,

    To answer your questions:

    1. Line time is the period of your pixel clock. 

    2. Yes, DSI Lane Clock is the HS clock.

    3.These timings are set by the host sending data over DSI. You should be able to configure these timings such that they are meet the controller's minimum specifications. 

    4.The clock edge should always be dual when configuring for the dlpc.

    5.I have attached an excel sheet that allows you to calculate new timings, this should help you make sure any new timing configurations do not violate any minimum or maximums.

    Best,

    Maximus

     5482.DSI-HSClock.xlsx

  • 0 in reply to Maximus Rusi
    Prodigy 30 points

    Hi Maximus,

    Thank you for the detailed explanation.

    I have read the document you shared.
    The blank values(HPW, HBP, HFP, VPW, VBP, VFP) and T HS Prepare, T HS Zero, T SH Settle were written by human, NOT calculated.
    So I would like to know how to determine those values.

    In other words, there are active width(840), height(480), and blank values in the DSI Setup and Debugging Guide v1.0.pdf file. When using different widths (1280)and heights(720), how should the blank values be determined, and how should the values related to T HS be determined? I wonder if they do it.

    Best,
    Yeon.

  • 0 in reply to yeon.lee
    TI__Expert 5565 points

    Hello Yeon,

    I think there may be some confusion here. You would configure the DSI host (what is sending the DSI data) to follow certain timings. These timings must also be compatible with the DLP controller (hence the min/max throughout the excel sheet). As you change each of the yellow boxes in the excel sheet this will calculate your DSI HS Clock which you need to program into the DLP controller. Then based on the DSI HS clock you can test different Dphy timings and make sure they are also okay.

    Best,

    Maximus

  • 0 in reply to Maximus Rusi
    Prodigy 30 points

    Hi Maximus,

    What you're saying is that I just need to set the yellow cell to a value that doesn't exceed the specifications in the data sheet and then assign the DSI HS clock calculated there to the dsi transmitter and receiver together?

    Best Regards.
    Yeon.

  • 0 in reply to yeon.lee
    TI__Expert 5565 points

    Hi Yeon,

    Essentially yes, you want to configure the dsi transmitter with each of the settings shown in Figures 9,10, and 11 from the DSI Setup and Debugging Guide. The calculator I sent allows you to quickly test and calculate new timings by changing each of the yellow cells. Each of the yellow cells will be the timings the DSI transmitter uses to send video. The DSI HS Clock is then calculated from those timings and that is the clock the DLP Controller will use to receive data.

    Best,

    Maximus

  • 0 in reply to Maximus Rusi
    Prodigy 30 points

    Hi Maximus,

    Yes, I'll check it.

    Best.

    Yeon.