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DS90UB925Q-Q1: 948/925 I2C communication is much slower than 948/949

Amelie Zheng
Genius 10865 points
Part Number: DS90UB925Q-Q1

hi Team,

My customer now use 948 and 925/949.

When they open pass through in 948/925 and 948/949 by 0x03->0xda,0x17->0xde.

Customer can visit 949 and 925 by I2C in 948. The speed of 949 is normal ;but the speed of 925 is very slow, and has affected the boot and normal communication.

Based on 925 datasheet, 0x03->0xfa,0x17->0xde (change 5bit  from 0 to 1), the 948/925 communication speed is not change but it shows that communication is fail...

  • 0
    TI__Mastermind 18755 points

    Hello Amelie,

    Can you clarify what you mean by is very slow?  Is the I2C frequency lowered or is it not responding?  It appears you may be writing a reserved bit in register 0x03 which should be avoided.

    Also, setting bit 0x03[5] for auto acknowledge will not make the I2C communicate faster.  It makes the device not wait for an acknowledge which may show as I2C errors.

    Regards,

    Nick

  • 0 in reply to Nicholas Darash
    TI__Genius 10865 points

    Hi Nick,

    I draw a diagram in order to describe customer's question more clear.

    When 949 is connected with 948, it can communicate normally.

    When 925 is connected with 948:

    If 0x03->0xda,0x17->0xde: 925 can visit Touch IC or 948 address; 927 visit Touch IC very slow and impact communication.

    If 0x03->0xfa,0x17->0xde: 925 can’t visit Touch IC or 948 address;927 can visit Touch IC normally

  • 0 in reply to Amelie Zheng
    TI__Mastermind 18755 points

    Amelie,

    Does the system work if only one device is connected at a time?  For example take the 925 out of the system and try to communicate with the deserializer and display.  I would like to know if the 925 and 927 are interfering with each others communication.   Try this with both settings enabled and see how they respond.

    Regards,

    Nick