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DS90UB954-Q1: MIPI test fail

Amy Luo
Expert 6895 points
Part Number: DS90UB954-Q1

Hi team,

This is a problem one of our customers is experiencing,  could you please provide some troubleshooting suggestions?

DS90UB954-Q1 sends the image data to the cpu via the mipi interface. The cpu module is a black box for us and can only test the MIPI signal quality on the carrier board intermediate link. Some items are always fail after actual testing, and it was not possible to confirm whether the end could not be detected or whether there was a problem with the board hardware.

The customer wants to know if there is any other way to verify the reliability of this link? And does the 954 have some registers that can adjust the mipi parameter?

The signal test points are as follows 

The signal clk0 and data0 are observed directly with an oscilloscope, the upper part is clk0 and the lower part is data0. Data0 doesn't look good. 

Best Regards,

Amy Luo

  • 0
    TI__Genius 11315 points

    Hi Amy,

    Our devices have been validated to comply with MIPI D-PHY specs, and we provide layout guidelines to help the customer design meet the D-PHY specification. We typically do not recommend adding test points to the CSI-2 traces since they can affect the trace impedance. If they decide to add test points on the CSI-2 traces, they must make sure that it does not cause an impedance discontinuity. Have they verified the impedance in their design along with the other CSI-2 layout best practices? 

    Regards,

    Cindy