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DS90UB954-Q1: I2C issue with 933

CHICHANG HUANG
Prodigy 10 points
Part Number: DS90UB954-Q1
Other Parts Discussed in Thread: ALP

Hi Expert,

We use 933 in combination with 954, but we have an I2C issue. As below:

Our tool connects with 954, the tool sends I2C to 954/933. We find I2C signals are normally in 954, but we find I2C signals are sometimes abnormally in 933.

I2C signals are terminated in 933. We can see byte 1, byte 2, ... byte n in 933, but no byte (n+1) in 933.

We read the 933 register "CRC Errors" (Addr. 0x0A and 0x0B), the value is increment till it reaches 0xFFFF.

We use ALP to do Margin Analysis, the result is OK.

We don't find the root cause, currently. Could you please help to give some suggestions to debug this issue? Thanks in advance.

BR

ChiChang

 

 

 

  • 0
    TI__Guru** 107740 points

    Hello Chi,

    This is happening because of the CRC errors. Please check your link quality by measuring the Insertion Loss and Return Loss specially for the lower frequency range, where the Back Channel is. Also, you may try to test without your PoC Filter, if using one. Just power your camera externally and disconnect the PoC physically from both sides.