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DS90UB953-Q1: Algorithm question

AJ Cheng
Genius 3615 points

Part Number: DS90UB953-Q1

Hello.

We currently need to evaluate the 953 transmission speed,

I would like to ask if the calculation method below is correct. If it is wrong, please correct it.

1. Sensor 3.1M 60FPS 12bit

2. 953 Currently know that the bandwidth is 4.16 Gps and can support 2.3MP 60 FPS.

Algorithm 1 : bandwidth 4.16Gps

1Frame size is 3.1M (piexl) One image = 3.1*12 = 37.2M

4.16 Gbps = 4160 Mbps

UB953 maximum reception can reach 4160 / 37.2 = 111.82

Algorithm 2 : 953 : 2.3MP * 60fps * 12bit = 1656M

         Sensor: 3.1*12 bit=37.2M

                1656/37.2 = 44.51

If both algorithms are wrong. Please kindly help provide the correct algorithm. Thanks for help~

  • 0
    TI__Genius 11340 points
    Hi AJ,

    Your forward channel rate from the UB953 to UB954 is independent of your video input rate and is determined by the equation (Gbps): REF_CLK (MHz)* 80 * 2, so if your REF_CLK to the UB954 is 25MHz, your forward channel rate would be 4Gbps.

    Your total CSI bandwidth is calculated using the equation (Gbps): # pixels per frame* # bits per pixel * frame rate * 25% overhead. For your 3.1MP imager this would come out to be ~2.7Gbps.

    Since your CSI bandwidth is lower than your forward channel rate, the 953 would work.

    Best,
    Jiashow
  • 0 in reply to Jiashow Ho
    Genius 3615 points
    Dear Jiashow.
    Good day.
    Some questions are as follows. Thank you.
    1. forward channel rate (4Gbps) v.s CSI bandwidth (2.7Gps) <= What is the difference between the two?
    2. REF_CLK (MHz)* 80 * 2 <= 80 *2 What is it?
    3. For your 3.1MP imager this would come out to be ~2.7Gbps <= We use TI's formula to evaluate 3MP's throughput as follows
    Total Horizontal Samples = 2880, Total Vertical Lines = 1080
    Pixel Clock Frequency = 2800 x 1080 x 60Hz = 186.624 MHz
    Bandwidth (Total Data Rate) = 186.624 MHz * 12-bit = 2.799 Gbps

    In summary, UB953 should be work for 3MP@60fps RAW12. is it correct?
  • 0 in reply to AJ Cheng
    TI__Genius 11340 points
    Hi AJ,

    The forward channel rate is the FPD-Link rate, which is fixed and calculated using the equation REF_CLK * 80 * 2. The 80 * 2 is simply our PLL multiplier to derive the forward channel rate from the reference clock to the UB954 (REF_CLK).

    The CSI bandwidth is the rate at which your CSI camera outputs to the 953. So if your forward channel rate is greater than your CSI bandwidth, then your sensor would work.

    In summary, yes, your sensor would work for our 953-954 link.

    Best,
    Jiashow
  • 0 in reply to Jiashow Ho
    Genius 3615 points

    Dear Jiashow.

    Good day.

    May I confirm with you again whether the following Sensor specifications can support UB953? Thanks for kindly help~

  • 0 in reply to AJ Cheng
    TI__Genius 11340 points
    Hi AJ,

    What frame rate are you planning to run at? How many bits per pixels?

    Best,
    Jiashow
  • 0 in reply to Jiashow Ho
    Genius 3615 points

    Dear Jiashow.

    Good day.

    Frame rate is 2880 x 1080 @ 60Hz.

    About how many bits per pixels? Do you want to ask the following picture? Thanks for kindly help~

  • 0 in reply to AJ Cheng
    TI__Genius 11340 points

    Hi AJ,

    With your resolution and frame rate, you should be able to run MIPI CSI-2 12bit or 14bit mode.

    Best,

    Jiashow

  • 0 in reply to Jiashow Ho
    Genius 3615 points
    Dear Jiashow.
    I got it. Thanks for kindly help~