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DS90UB936-Q1: data rate compatibilty

Atul Singh
Prodigy 70 points
Part Number: DS90UB936-Q1

Tool/software:

Hi TI Team,

Below are the details for camera specification for calculation:

 

  1. Resolution:  1280*960
  2. Frame Rate: 60
  3. Input Interface (CSI2/ LVCMOS): CSI2
  4. Video Format (YUV422 / RAW/ RGB) RAW
  5. Bits per pixel: 12/16

 so,

For RAW16 at 60fps over CSI-2 with 1280x960 resolution and 15% headroom – leads to a throughput of 1.357 Gbps.

Total throughput is 1.357gbps so, 339mbps per lane.

As per the calculation for Des936 along with our imager data 339mbps per lane and min BW per csi lane is 368mbps (according to the datasheet of DS90UB936). So in this case Is 936des compatible with our system data rate speed.

Pl clarify.

 

For Headroom how much min and max we can consider for data rate calculation.

  • 0
    TI__Mastermind 26640 points

    Hello,

    Thank you for your question. Yes, with the system configuration you have provided, the total CSI payload of your imager will be 1.357 Gbps, and if 4 CSI lanes are used this will be 339 Mbps/lane. This payload is supported by a 935 serializer and 936 serializer. If the headroom/blanking of a system is not known, for estimation purposes a value from 10% to 25% can be used.

  • 0 in reply to Darrah Merillat
    Prodigy 70 points

    Hi ,

    as per the datasheet of 936 Des the min Bw of single lane is 368-1664mbps.

    In our calculation 339mbps is below min range. M i right or missing something if yes pl correct me.

    for reference pl see datasheet page no.9

  • 0 in reply to Atul Singh
    TI__Mastermind 26640 points

    In an FPD-Link system the CSI data is received directly by the serializer. For your system this will look like the below image. An imager will transmit the CSI data to the 935 serializer. The serializer will then transmit this data to the 936 deserializer over the FPD-Link protocol. The deserializer will then output the CSI data on the TX CSI ports to a display/SoC/analyzer. 

    When determining if the bandwidth of a particular imager or camera is supported it should be compared to the bandwidth of the serializer, as that is the device that will be receiving the data. The 935 serializer can support a maximum of 2.528Gbps of CSI data or 632Mbps/lane. There is no minimum data bandwidth.

    The deserializer TX CSI ports can be programmed to transmit at different frequencies. When the data sheet refers to "MIPI Data Rate" it is referencing the speed or frequency of the TX CSI ports.

  • 0 in reply to Darrah Merillat
    Prodigy 70 points

    Hi Darrah,

    for my system 339mbps is coming from image to Ser (ref above image).

    and acc to the datasheet of SER 935 below image is referred for reference.

    so, in the above image 80mbps-832mbps is range of SER935 BW and my calculation 339 mbpps per lane which is okay for the SER935

    Now, Moving towards DES Side,

    data coming from SER TO DES (339mbps) so for DES (input is coming Through FPD LINK is there any limit on RX input port BW also(4.16gbps) Am I right.

    Now moving towards the TX CSI (O/P of DES 936), In data sheet it is mentioned (368-1664) MBPS so, from our system 339mbps min is coming so is it feasible to send from des output as it is mentioned 368min for DES936. (pl correct me if any confusion)

    DES 936 image is attached for ref.

  • 0 in reply to Atul Singh
    TI__Mastermind 26640 points

    Hello,

    Yes, for your system the 935 serializer will be able to support the 339 Mbps/lane as well as transmit the data to the 936 deserializer. One note, the FPD-Link channel transmits more information between the serializer and deserializer than just the CSI data. Control data, I2C communications, GPIO information, etc. is also included in the transmission. This will not cause any issues in your system, but is just something to be aware of for understanding the functionality of the devices. For the TX ports, the CSI speed is programmable (nominal 400Mbps, 800Mbps, 1.5Gbps, or 1.6Gbps). The output speed can be programmed via registers. The default output speed is 800Mbps, which will be suitable for your system. This is only the speed of the transmitter and not a bandwidth requirement.

  • 0 in reply to Darrah Merillat
    Prodigy 70 points

    hi Darrah,

    so just need to understand in the datasheet of the DS90UB936 Deserializer what is mipi csi range.

    it is not the output range ? 

    and if we transmit 339mbps per lane from SER935 so it is ok for des 954 to take the same input data.

  • +1 in reply to Atul Singh
    TI__Mastermind 26640 points

    The DS90UB936 CSI output ports operate at nominal speeds of 400Mbps, 800Mbps, 1.5Gbps, or 1.6Gbps. The exact speed will vary based on the refclk used in the system and general part to part variation. The datasheet accounts for this by listing 368Mbps as the min (400Mbps programming) and 1664 Mbps max (1.6Gbps programming). This is the expected speed of the CSI output ports, it is important that the receiving SOC or display is able to receive data at the programmed speed.

    The imager to serializer connection is a different interface in the system than the deserializer to SOC/display connection. The serializer interface is receiving the CSI data, but the deserializer is outputting the data.