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DS90UB941AS-Q1: Splitter mode sample code

Jiawei Hu1
Expert 6345 points

Part Number: DS90UB941AS-Q1

Hi team,

My customer use 941 to drive two displays, attached are the datasheet of displays. The input is like below, could you kindly help generate the sample code? Thanks!

仪表屏规格书：VL-FS-COG-VLBJT075-01 REV.C（长安回签版）_20210714.pdf京瓷张家港3.1寸规格书64877AAe2020.2.24(1).pdf

BR

Jiawei

  • 0
    TI__Expert 4160 points

    Dear Jiawei,

    Thank you for your question! I'd like to follow up with you with these questions. 

    Output port 1: 1920 x  720

    Output port 2: 800 x 480

    1. The picture that you have provided from the datasheet displays that the customer is attempting to superframe the two inputs into one input in order to use one input port. Is this correct?

    2. After reading over the datasheet, we noticed that this may not be possible. Please verify that the blanking times on the datasheet are correct.

     

    ^ Above is the vertical timing of their smaller screen. The vertical blanking time is only 10 for this screen. We need a minimum vertical blanking of 240 to match the larger screen.

    ^ Above is the horizontal timing of their smaller screen. The horizontal blanking time is only 230 for this screen. We need a minimum horizontal blanking of 1120 to match the larger screen.

    3. A solution to their issue is to do 2:2 ( 2 independent inputs to match 2 independent outputs. For this, they would need to set it up like below:

    Please let me know if this is a possible solutions for them. Otherwise, we will recommend upgrading to a 98X unit. 

    Very Respectfully,

    William Yi

  • 0 in reply to William Yi
    TI__Expert 6345 points

    Hi William,

    Thanks for your reply! Customer only have single DSI port, so they can't use 2:2 mode. For splitter mode, does the 941 need two same total resolution displays? Can't 941 do some cropping? Thanks!

    BR
    Jiawei

  • 0 in reply to Jiawei Hu1
    TI__Expert 4160 points

    Dear Jiawei, 

    Thank your for your reply!

    1. Splitter mode means that the two input images must have the same resolution. In this case, the second image is superframed with additional padding to have the same resolution as the first image.

    2. Cropping an input video on the 941AS is achieved by taking the input video and getting a smaller active output resolution by putting the rest of the resolution into blanking. This does not eliminate the need of blanking. 

    3. As shown from above, Horizontal front and back porch may be eliminated with an offset. In order to achieve the bottom diagram where the horizontal blanking is reduced, you would need to use 2x independent REFCLKs to the 941AS so that the PCLK rate of the smaller video can be reduced and this will cause the 941AS to strip pixels from the horizontal blanking.

    4. Vertical front and back porch cannot be eliminated from the vertical blanking with an offset. 

    Unfortunately, it seems that the 941 will not be able to handle their needs. We may recommend upgrading to a 98X unit to better format the output resolution.

    Very Respectfully,

    William Yi