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DS90UB964-Q1: Maximum payload data rate of the CSI-2 output.

user4779049
Expert 2155 points
Part Number: DS90UB964-Q1

Dear person,

Please advise me on my questions bellows.

I consider using DS90UB964 with four DS90UB935s.

I concern that the one CSI-2 output port can support outputting the video

data transferred from four DS90UB935s.

 One XSI-2 port can run at 1.6Gbps/lane. Using four lanes, the bandwidth 

is 6.4 Gbps.

However, I there may be some overhead such as LP00-LP11 transition, inter packet gap etc.

Q1. Can you let me know how much percent of bandwidth can be allocated to the payload (video data)?

Q2. If one CSI-2 output port can not handle the maximum input data, can you use two CSI-2 output port

      to extend the output bandwidth?

Mita

  • 0
    TI__Guru* 83600 points

    Hello Mita,

    1) This is not easy to answer since it depends on the incoming resolution from each camera, the number of connected cameras, if using continuous or Non-continuous CLK mode, and the used forwarding mode ... etc.

    If you provide me with the above details, I can calculate for you if it is okay or not.

    2) Yes, you can use both CSI-2 output ports to output your data to an SoC. For example, you can forward each 2-camera-data to each CSI-2 output port.

    See figures 24, 25, 26 in the d/s.

  • 0
    Expert 2155 points

    Hamzeh-san,

    Thank you for your prompt feedback..

    In terms of answer to the Q1, it is hard to give you the details of camera I will use or use case of

    DS90UB964 forwarding mode etc. I am in early stage of my design and have not decided them.

    Q1-2    I prefer to have some magic number if the payload vs. bandwidth ratio exceeds it, CSI-2 may be the 

                 bottle neck in the signal chain. 

    Q1-3   If  four 1Mega pixel cameras in raw 12 mode run at 100 MHz, exceed the one CSI-2 output limit?

    Q1-4   If not how much margin does one CSI-2 port provide?

    Q1-5. Which forwarding mode results the lowest bandwidth?

    Regarding to the answer to the Q2, thank you for the answer. I got it.

    Mita

  • +1 in reply to user4779049
    TI__Guru* 83600 points

    Hello Mita-san,

    You may consider as approximate numbers, the CSI-2 overhead of one output port is as following:

    Continuous CLK = ~10-20%

    Non-continuous CLK = ~20-30%.

    But as said, these are approximate numbers. To calculate the exact numbers we will need the above details.

    Yes, this use case with 1Mp cameras in RAW12, is okay to be used with just one CSI-2 port.

    I hope these Info will help you at the start of your design.

  • 0 in reply to Hamzeh Jaradat
    Expert 2155 points

    Hamzeh-san,

    Thank you for the answer.

    I will pursue my design counting on your answers.

    Mita