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Linux/DS90UB953-Q1: UB953 and UB954 paired with MIPI CSI port betwwen sensor and ISP

shaobo ren
Prodigy 60 points
Part Number: DS90UB953-Q1


Tool/software: Linux

Hello there , 

here question  UB953 and UB954 paired together, regarding mode configuration.

a.  UB953 set DVP mode , 

b. UB954 set RAW12 HF mode. 

[Note, imager sensor output port supported MIPI with raw data 12]

there one imager sensor connect to UB953,  don't know what's the problem there caused UB954 CSI output port didn't measured CSI signal when imager sensor worked well.     would please let me know which UB953 and UB954 register setting should look at and  be corrected ?

thanks and waiting your suggestion.

Shaobo 

  • 0
    TI__Guru** 103215 points

    Hello Shaobo,

    When you pair 953 with 954 you should use CSI-2 mode since both sides are CSI-2. DVP and RAW modes are reserved for backwards compatibility with older devices. Please use CSI-2 mode on both sides. RAW12 can be contained within CSI-2 which is what your imager is outputting. 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 60 points

    Hello Casey,  

    thanks for you hints for CSI-2 mode my question.     recently UB954 CSI-2 port can measured  Clock and Data. 

    unfortunately ,  still not have same MIPI data signal  like  UB953 CSI input ( come from imager sensor ) .   copied  UB953 side imager sensor CSI  DATA0 measured scope . 

    would you mind can have some suggestion,  which  register setting will impact  UB954 CSI-2 port can repeat and generate exactly  same as imager sensor  output data signal ? 

    we are stop here several days ...  so far still trying to find the configuration , hoping can have some hints again..   

    Note:   imager sensor  output MIPI clock is 250MHz,  4 x LANE.

    also have a question regards  I2C controller question.       ISP is I2C host at UB954 side,  imager is slave at UB953 side . host side I2C bus is 400KHz .  if ISP not support I2C sketching ,  how to configure UB953 and UB954 to allow ISP configure imager sensor ?   some special register ?

    have a nice day ! 

    Shaobo 

  • 0 in reply to shaobo ren
    TI__Guru** 103215 points

    Hello Shaobo,

    For 954, the CSI-2 output speeds are discrete and selectable as 400, 800, 1200, or 1600Mbps/lane. You can not generate exactly the same speed (500Mbps/lane = 250MHz clock) that the imager is outputting at the serializer side. Is this the main problem? For 954 to 953 communication over the back channel I2C clock stretching is a requirement, Unfortunately there is no work around available. 

    Best Regards,
    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 60 points

    Hello Casey ,

    thanks .that's my main problem ... I would like to get same clock speed and data lane from UB954 that the imager generate . if can't get 500Mbps CSI-2 output from UB954 , that's so bad news for me.   could you have some suggestion  on this ,   I go thought  the data sheet ,  the data rate range from 368Mbps to 1664Mbps.     

    Pleas advice on that ... thanks for your time. 

    Shaobo 

  • 0 in reply to shaobo ren
    TI__Guru** 103215 points

    Hello Shaobo,

    The CSI transmitter frequencies are shown in table 13 of the 954 datasheet. As you can see, the speed can be varied slightly by changing the REFCLK frequency, but the range of REFCLK is 23-26MHz. You will not be able to get 500Mbps exactly. 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Guru** 103215 points

    Hello Shaobo,

    Is there any other help I could provide here? Unfortunately the device can only output those discrete rates as mentioned above but are there any other configurations you need assistance with?

    Best Regards,

    Casey  

  • 0 in reply to Casey McCrea
    Prodigy 60 points

    Hello Casey , 

    appreciated  so much ..   could you have some hints to me ,   how UB953 and UB954 handle unbalance bandwidth  between  imager  sensor  CSI-2 output and UB954 CSI-2 output.  or my means  the bandwidth is difference  after though  UB953 and UB954 ?    I would like to see how to recover or re-generate same bandwidth what come out from Sensor CSI-2 data after UB954 .

    thanks

    Shaobo 

  • 0 in reply to shaobo ren
    TI__Guru** 103215 points

    Shaobo,

    Unfortunately I do not understand the question at all. Can you please try explaining a different way?

    Thanks,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 60 points

    Hello Casey , 

    yes ....  imager sensor output data bandwidth :  500Mbps x 4 lane = 2Gbps  ( MIPI clock 250Mhz)

    those 2Gpbs bandwidth data follow into UB953 , and then follow out UB954 .   but  UB954 only supported 400Mbps , 800Mbps  or 1.6Gpbs per lane . 

    if select  400Mbps  ,   the total throughput 400Mpbs x 4 =1.6Gpbs . looks like will lost some data .

    if select 800Mbps ,     the total  throughput 800Mbps x 4 =3.2Gbps , looks like bandwidth is too larger . 

    consider above scenarios ,   would to know UB953 and UB954 to handle the bandwidth mismatch between sensor and UB954  output ...   hoping this time you can understand  my question.

    Thanks 

    Shaobo

  • 0 in reply to shaobo ren
    TI__Guru** 103215 points

    Shaobo,

    I understand now. Consider the two use cases:

    if select  400Mbps  ,   the total throughput 400Mpbs x 4 =1.6Gpbs . looks like will lost some data.

    This is not a valid use case since the bandwidth on the receiver side is too small and it will causes FIFO overflow errors. 

    if select 800Mbps ,     the total  throughput 800Mbps x 4 =3.2Gbps , looks like bandwidth is too larger.

    In this case, then the data output will basically just be time compressed in bursts and there will be LP (low power) states for idle time to buffer the difference in bandwidth. 

    Best Regards,

    Casey