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PCM1864: TDM mode for PCM1864

yoshiki hasebe
Mastermind 6385 points
Part Number: PCM1864


Dear Sirs,

My customer asked us about TDM mode for PCM1864.

He is planning to use it with 4ch ADC. In that case, he thinks that PCM1864  can only select TDM as the data transfer method.
However, he thinks the content is compatible with the TDM format of the PCM1864 and the customer's microcomputer side.

The microcomputer side only supports the mode that sets only the first 1 word to H.
If PCM 1864 is used under this condition (In the mode to set only the first 1 bit to H and input the following SSIWS to LRCK), will it still operate normally?

Please let us know above question.

Best Regards,

Y.Hasebe

  • 0
    TI__Expert 5645 points

    Hello Hasebe-san,

    First off, PCM1864 can operate in I2S mode or TDM mode.

    If I understand the question & terminology correctly, I assume you are referring to LRCK duty cycle in TDM mode. If this is the case, you can configure the part to operate w LRCK duty cycle as 50% or 1/256 of LRCK. This can be configured using the below listed register.

    Below is the representation of the clocks for TDM mode -

    If TDM_LRCK_MODE='1', the LRCK/Frame sync is HIGH for 1 cycle of BCK as shown above.

    Best regards,
    Ravi 

  • 0 in reply to Ravi Patil
    Mastermind 6385 points

    Hello Ravi-san,

    Thank you for your reply.

    From your comments,
    As the customer's microprocessor format is high only for the first 1ch (System Word 1), I think that PCM 1864 does not support it.
    Is this correct?

    Best Regards,

    Y,Hasebe

  • 0 in reply to yoshiki hasebe
    Mastermind 6385 points

    Hello Ravi-san,

    Please reply to me the answer to the question of the day before yesterday 

    As the customer's microprocessor format is high only for the first 1ch (System Word 1), I think that PCM1864 does not support it.

    Is this correct?

    (Please reply as to whether you support the format of the customer.)

    Best Regards

    Y.Hasebe

  • 0 in reply to yoshiki hasebe
    TI__Expert 5645 points

    Hi Hasebe-san,

    Typically when interfacing PCM186x in DSP mode (TDM), only the rising edge on the first bit of data of the frame is required. Hence PCM1864 will support the customer's microprocessor foramt of LRCK HIGH for first channel as shown in the diagram.


    Hope this clarifies your question.

    Best regards,
    Ravi