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PCM1864: PCM1864

Sue Tane
Prodigy 70 points
Part Number: PCM1864
Other Parts Discussed in Thread: EVMK2GX

Hello,

We would like to perform beamforming operations on EVMK2GX using analog microphones, so we need an ADC inbetween. On Voice Processing Tools and Software for K2G and C5517 Designs, we saw that 2 PCM1864 ADCs were being used. We were wondering how two ADCs can be made to sample and give output simultaneously since this will be crucial in our microphone array application. Also, could you explain the hardware necessary? Would it be as simple as connecting the output of mic to ADC and connecting ADC's relevant output to DSP or is there an additional circuitry involved?

Moreover, is 192 kHz max sampling rate for this ADC per channel?

Thank you.

Best regards,

Sueda

  • 0
    TI__Expert 5645 points

    Hi Sueda,

    Thanks for considering the PCM186x device for your beamforming application.

    As far as using 2 PCM186x is concerned, first off I assume you will need 8 channels. If YES, you can use 2 PCM1864/65 either in TDM or I2S mode.

    TDM mode:

    If you are using TDM mode, you can use device #1 as MASTER and provide external MCK using XTAL (for example). In this case, the device #1 will have BCKO and LRCKO as outputs.

    You can run the device #2 as SLAVE which means it will need BCK and LRCK as inputs. You can have the BCKO/LRCKO of the device #1 as inputs to device #2 which will have simultaneous outputs and your processor can choose which channel to use for beam forming.

    I2S mode:

    if you want to use I2S mode, the clocking scheme remains the same as described above...the only additional step you will need is to configure one of the GPIO as DOUT2 so that you will have ch1/ch2 on DOUT and ch3/ch4 on GPIOn pin. So you will have total 4 I2S streams that need to be handled by your processor. This is useful when your processor cannot handle TDM stream and need I2S stream instead.

    Best regards,
    Ravi