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DS90UB936-Q1: The 936 is paired with the 933 camera module and has no image output

Cherry Zhou
Mastermind 22235 points
Part Number: DS90UB936-Q1


Hi Team,

Host-side deserializer: DS90UB936

Camera-side serializer: DS90UB933

There is no image output when the camera is connected to the host computer. Measured MIPI-CSI for 936 does not have clock. However, the camera is OK to connect to other hosts of the same model/batch, meaning there is no problem with the camera itself. The registers for the working host and 936 on the host side that cannot output images are different as follows: 

      936 register      Register values - working master      register values-the master without output
0x22 0x01 0x00
0x35 0x03 0x01
0x4F 0x25 0x1a
0x50 0x20 0x03
0x73 0x74 0x75 0x03 0xc0 0x0a 0x00 0x00 0x00
0xd3 0x05 0x27
0xd7 0x00 0x03

When this problem occurs, the Rx port input stream is out of sync and the FPD-Link III Receiver receives a different frequency and does not solve the video frames and lines. However, at this point 0x4D = 0x03, which means pass and lock are valid. Here is a screenshot of all the registers: 

（Left part is the working setting）

Could you please help check this case? Thanks.

Best Regards,

Cherry

  • 0
    TI__Mastermind 24415 points

    Hello Cherry,

    Thank you for reaching out with your question. Reviewing the registers listed as being different, I see the AEQ value selected changes from 0x05 to 0x27. Do both set ups have the same hardware settings and use the same cables? Would you be able to run MAP tool on the two conditions currently shared? 

    Best,

    Zoe 

  • 0 in reply to Zoe Bison
    TI__Mastermind 22235 points

    Hello Zoe,

    Thank you for the support.

    Zoe Bison said:
    Do both set ups have the same hardware settings and use the same cables?

    Yes.

    Zoe Bison said:
    Would you be able to run MAP tool on the two conditions currently shared? 

    Would you help tell how to get start with MAP tool? 

    Also, the customer measured 936 CSI and 933 DIN without any problems when the plot was not available. Lock_STS=1 and port_pass=1 from 4D register of 936, i.e. FPD-link is lock state. However, FWD_SYNC0 = 0 in register 0x22, TX_port_sync = 0 in register 0x35, and registers 0x73–0x75 are 0, that is, 936 did not receive a valid video frame.

    1) The signal quality of FPD-link may be critical, is there a way to monitor the signal quality?

    2) The customer tried to restart the Aeq with Aeq_restart=1 and still cannot figure out.

    3) Is there a way to improve the quality of the FPD-link signal? 

    Thanks and regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Mastermind 24415 points

    Hello Cherry,

    MAP tool is an acronym for Margin Analysis Program which is used to observe the link margin from the deserializer. The tool can be found in the Analog LaunchPAD GUI.

    While MAP tool is being used, the deserializer will test the link at various AEQ and strobe positions. For step by step instructions, a User's Guide is available here: FPD-Link Margin Analysis Program (MAP) user's guide

    The AEQ settings can also be restarted with a digital reset, 0x1[0]. Both DIGITAL_RESET0 and AEQ_RESTART restart bits are self-clearing. How is the customer determining the AEQ restart is not occurring? 

    Beyond the AEQ and strobe position settings, the quality of the FPD-Link signal may be impacted by the design of the PCB.

    Kindly, 

    Zoe

  • +1 in reply to Zoe Bison
    TI__Mastermind 24415 points

    Hi Cherry, 

    Please let me know if there are any remaining questions. 

    Best,

    Zoe