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DS90UB936-Q1: DS90UB936 read-only register clear fail on ESD test

Imelda Zhang
Expert 5025 points
Part Number: DS90UB936-Q1

Hi expert,

Customer do the ESD test to DS90UB936-Q1.

Background:

1) When ESD test is carried out on 936, interrupt would happen and GPIO3/INTB would be low. 

2)SOC would receive the interrupt and clear interrupt on 934, then GPIO3/INTB would be high. 

Question：

When the ESD test is carried for 10 times, the read-only register 0X7A and 0X7B cannot be cleared by reading.  GPIO3/INTB would be high and interrupt cannot happen.

Would you mind helping me to verify that why we cannot clear the read-only register?

Kind Regards

Imelda

  • 0
    TI__Mastermind 24861 points

    Hi Imelda,

    Thanks for your question. Do you have any details on the ESD test done? Questions below would be helpful:

    • What serializer is used here?
    • Is this contact or air discharge?
    • What is the contact point for ESD testing?
    • Can we monitor lock status on the GPIO pin during ESD test?

    Registers 0x7A & 0x7B are related to CSI error counters. It looks like we've checked register 0x4d, and it continuously reads 0x13. If this is correct, it would mean that that lock is not stable, with errors potentially accumulating in the CSI status registers. Could you confirm if lock is stable after the ESD test?

    Best,

    Thomas

  • 0 in reply to Thomas Bejin
    TI__Expert 5025 points
    Thomas Bejin said:
    • What serializer is used here?
    • Is this contact or air discharge?
    • What is the contact point for ESD testing?
    • Can we monitor lock status on the GPIO pin during ESD test?

      1) DS90UB935

      2)Air discharge ±8kV

      3) Yes，we can. We would monitor lock status in the future test.

      4)Lock is stable. We checked lock pin ,and found it remaining high while 0x4d read 0x13. 

  • 0 in reply to Imelda Zhang
    TI__Mastermind 24861 points

    Hi Imelda,

    Could you confirm on the lock pin? 0x4D = 0x13 has bit 4 asserted, which is the lock lost flag. If reads here always read 0x13, this indicates that lock is stable when read, but there are lock drops which are occuring.

    Best,

    Thomas