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DS90UB941AS-Q1: About I2C communication

Shuji Ishiwata
Mastermind 7715 points
Part Number: DS90UB941AS-Q1

Hi All,

When CLK is not input to DSI (open state)
I2C connection to DES may not be correct in the route of CPU → Ser (DS90UB941) → Der.

Is the following method the best way to deal with this?

If there is no valid input in DSI, set Bit3 in the RESET CTL register to ‘1’.
If there is a valid input in DSI, set Bit3 of the RESET CTL register to ‘0’.


Best Regards,
Ishiwata

  • 0
    TI__Guru** 103215 points

    Hello Shuji,

    That is because the DSI clock can detect noise on the I2C line as a clock signal and attempt to switch from AON clock to DSI clock if the DSI clock is floating. So yes, it is recommended to set the RESET_CTL bit 3 to 1 to disable the DSI if DSI input is not present. Also you can switch the clock mode from continuous to non-continuous mode by setting 0x4F[7] = 0 which will prevent false detection. Of course if there is DSI data which is using continuous mode then you would want to switch the clock mode back to continuous while the DSI data is active 

    Best Regards,

    Casey