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PCM1864-Q1: question about configuring 1864 and 1862 into TDM mode

Jiang Boqian
Intellectual 655 points

Part Number: PCM1864-Q1
Other Parts Discussed in Thread: PCM1864, PCM1862

Dear expert,

I have 5 channel audio data (three microphone, and one stereo FM), due to the limited I2S/TDM port available on my application processor, I want to use PCM1864 + PCM1862 configured as TDM.

I see on PCM1864 datasheet page 73, one PCM1864 can be configured as clock master and another can be clock slave, like the picture below.

My question is, to save a crystal on PCM186x, can I use application processor as clock master without MCLK output, and let the two PCM186x to be clock slave, so that they both generate the required MCLK from BCLK?

Thank you.

  • 0
    TI__Expert 5645 points
    Hi Jiang,
    I am not able to understand your question very clearly...

    As far as the PCM186x device go, you can either provide MCK (either via Crystal or host processor) to configure one of the PCM186x device in MASTER mode and then take BCKO and LRCKO from this device to drive the second PCM186x in SLAVE mode and you will not have issue w synchronization.

    Also, if your host processor has GPIO pins to generate LRCK & BCK, you can configure both PCM186x devices in SLAVE mode as well as the same clocks will assure synchronization. Hope this clarifies your question. If not, please let me know and we can address the same accordingly.

    Thanks.

    Best regards,
    Ravi
  • 0 in reply to Ravi Patil
    Intellectual 655 points

    Hello Ravi,

    Thank you. I want to configure PCM186x like you said latter:

    "Also, if your host processor has GPIO pins to generate LRCK & BCK, you can configure both PCM186x devices in SLAVE mode as well as the same clocks will assure synchronization. Hope this clarifies your question. If not, please let me know and we can address the same accordingly."

    So in this case, my host processor don't have to provide MCLK output, right?

  • 0 in reply to Jiang Boqian
    TI__Expert 5645 points
    Hi Jiang,
    Correct. When you do configure the PCM186x device as SLAVE, the host processor needs to provide BCK and LRCK as inputs to the PCM device and in this case, you can have the same BCK and LRCK signal tied to both devices from the host.

    Hope this clarifies your question.

    Best regards,
    Ravi