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DS90UB947-Q1: I2C error

Colt Zhang
Expert 4985 points
Part Number: DS90UB947-Q1

Tool/software:

hi expert,

my customer use DS90UB947 pair with DS90UB948, now they find the I2C communication fail problem.

below is the test scope ：

in normal condition, I2C work normal, MCU(948 side) can reply the ACK, after 130us, SOC will get the ACK(947 side)

first and second  channel is 947 I2C side

third and fourth channel is local MCU and 948  I2C side 

in abnormal condition:

Local MCU can get the ACK and reply, but after 250ms ,SOC don't get the ACK and time out , so the I2C fail.

 

first and second  channel is 947 I2C side

third and fourth channel is local MCU and 948  I2C side 

  • 0
    TI__Mastermind 29355 points

    Hey Colt,

    Colt Zhang said:
    my customer use DS90UB947 pair with DS90UB948, now they find the I2C communication fail problem.
    1. How many systems are experiencing this issue?
    2. How often does this failure occur? example 1/1000 power cycles, etc. ?
    3. Does this happen across all customer systems or only a single system?
    4. Can you provide a register dump of 947 and 948 on a good run vs a bad run?
    5. What I2C speed is the 947 set to?
    6. What I2C speed is the 948 set to?
    7. Can you send 947 and 948 schematic for review?
    8. The I2C controller built into the 947 automatically supports clock stretching. The SoC for your system must support I2C clock stretching as well, can you confirm that ?

    Colt Zhang said:
    Local MCU can get the ACK and reply, but after 250ms ,SOC don't get the ACK and time out , so the I2C fail.

    Could you provide more information as to when this issue is occurring? More specifically, is it during the bring up process? Have both the SER and DES been initialized? Is I2C communication stopped immediately after some registers are set? in addition, does the customer observe LOCK loss at any point?

    Also, what exactly is happening in the 2nd scope capture, is MCU on Des side trying to write to the SoC through back channel?

    Or Is the SoC on Ser side trying to read some register status from the MCU through the forward channel?

    Regards,
    Fadi A.

  • 0 in reply to Fadi Abdulhameed
    TI__Expert 4985 points

    hi Fadi,

    sorry too late to reply you. To clear this problem, the problem is SOC can't get the MCU data, customer find mcu pass the data to 948 but don't see the ack in the 947side. 

    below is the feed back from customer based your question:

    1 all the 947 have this problem

    2 the probability of occurrence is 10%, 

    3 a single system 

    4 947 config(0X03,0XDA) (0X17, 0X9E) 948 config(0X02, 0X80) (0X03, 0XF8)(0X05,0X9E)

    5 947 set is 100k

    6 948 set is 76K

      

  • 0 in reply to Colt Zhang
    TI__Mastermind 33395 points

    Hi Colt,

    I will follow up with you on the other thread.

    Best,

    Jack