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DS90UB941AS-Q1: Porch signal question

Zirui Su
Expert 5340 points
Part Number: DS90UB941AS-Q1

How is the timing of the blanking data of the two DOUT output ports handled in the following working mode of 941?
1: Are the blanking signals of the two DOUT output ports the same?
2: Are the blanking signals of the two DOUT output ports the same as the blanking signals of DSI0 input?

To put it simply, when the 941 uses the super frame, is the porch data of the two out ports the same or half of the porch data of the super frame? Thank you!

 

  • 0
    TI__Guru** 103215 points

    Hello Zirui,

    941AS takes all video timing from the input DSI interface. The blanking components are determined by the timing between HSS/HSE VSS/VSE from the MIPI packets 

    By default, when using a superframe splitter mode on the 941AS, the resultant horizontal timings for each component of the blanking is 1/2 the superframe timing. So if the superframe back porch is 64 pixels, then the back porch for each video will be 32 pixels. There are ways to change the horizontal blanking components through a combination of overrides and PCLK fine tuning, but that becomes quite complex, especially if the two output videos are asymmetrical. If there is a special case where this is needed, then we could help to check if it is possible, but in general if it is possible to use the default it is much easier. 

    For the vertical timing, the blankings for each component are the same from the superframe to the resultant split videos (not 1/2). 

    If you crop the superframes (asymmetrical splitting), then cropped components will turn into blanking - either front or back porch depending on how the video is cropped. 

    Best Regards,

    Casey