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Synchronize clocks on two I2S source mixes

Anthony Yoo68
Expert 1320 points
Part Number: TLV320AIC3268

Hi!

My customer wants to mix two I2S sources to get one digital output.

Is the Clcok of the two I2S sources synchronized with each other?

If two I2S sources are not synchronized, can bit noise be generated in the mixed signal?

We of course both I2S sources have the same sampling frequency (44.1khz)

When we mix the I2S sources from two different ICs and reproduce the digital output as an amplifier, noise is occurring.

Or is it possible to improve this by synchronizing the Mclk of the two I2S source ICs with the Mclk of the 3268 CODEC?

Please check it.

Thank you

Best Regards

From Anthony

  • 0
    TI__Mastermind 30120 points

    Anthony, 

    The MCLK of the AIC3268 should always be synchronous with the I2S sources. 

    can you share with me your process flow?

    best regards,

    -STeve Wilson

  • 0
    Expert 1320 points

    Hi Steve

    My digital mix flow is as follows.Then output bit clock and word clock from ASI3 and connect it to amp.

    Our purepath flow chart and BLOCK configuration are shown below.

    I have run the CODE GEN. From PUREPATH GDE in the following flow chart, and then I have been testing it to get the desired DIGITAL MIX output by executing the following additional settings with PUREPATH CONSOLE2.
    The following REGISTER setting is executed for ASI3 CLOCK output.

    w 30 00 04
    w 30 2b 04
    w 30 2c 81
    w 30 2e 43
    w 30 56 56
    w 30 57 52


    Please advise about tips to reduce clock noise of mixed data.

    Thank you.

    Best Regards.

    From Anthony.

  • 0 in reply to Anthony Yoo68
    TI__Mastermind 30120 points

    Anthony, 

    lets try a few things, 

    first,  Change the I2S output from ASI2 to ASI3.   You'll need to configure GPIO4 

    on page 4

    w 30 59 74

    If that doesn't resolve the issue,  then go into the process flow and add some switches on the I2S inputs.  listen to them each individually and listen to them mixed.  

    is one of them always noisy?  or are they only noisy after being mixed?

    best regards, 

    -Steve Wilson

  • 0 in reply to Steve-Wilson
    TI__Mastermind 30120 points

    Anthony, 

    I haven't heard back from you.  Did this resolve your issue?  Please let me know if you need further assistance.

    best regards,

    -Steve Wilson

  • 0 in reply to Steve-Wilson
    Expert 1320 points

    Dear Steave,

    Thank you so much for your help.

    I am testing with my customer for your advice, and now my customer is building a new board,We will be testing.

    I will contact you again if I need your help.

    Thanks again for your help.

    best regards.

    From anthony