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PCM1808: No Data out

John Dusing
Prodigy 200 points

Part Number: PCM1808

Following Typical Application diagram on data sheet pg19.

Using this part in slave mode, pins 10-12 left as NC so internal pull-downs work (I2S 24 bit Slave).

SCKI is 12MHz.

All voltages are present.

VinR is from a condenser microphone.

VinL is not connected.

I can generate an oscilloscope waveform if you can tell me how to attach it. 

I am getting no data on DOUT.

  • 0
    TI__Guru 57800 points

    Hi, John,

    This device should stream digital data as soon as valid power supplies and clocks are provided. Can you please provide the frequency of the I²S clocks provided to this device?. A 12MHz clock for SCKI is not supported as the system clock should be a multiplier of the sampling rate. Also, you mention you are using a mic as the input source, this part does not have an internal PGA, so an external mic-pre-amplifier stage may be required to condition the mic signal to a proper line level.  

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0
    Prodigy 200 points
    What is the best way to send you an oscilloscope screen picture?
    SCKI is 12MHz
    LRCK is 48KHz
    BCK is 3.41MHz
  • 0 in reply to John Dusing
    Prodigy 200 points

    With Fs=48KHz and SCKI=256*Fs, that give 12MHz which is what I am supplying (see table 1 on page 15).

  • 0 in reply to John Dusing
    TI__Guru 57800 points

    HI, John, 

    You can include pictures in your reply by clicking on "Insert Code, Attach Files and more..." and then dragging to the text area the pictures you want to include. 

    Regarding your clock information, if 48KHz sampling rate is selected, bit clock should be 64×Fs (3.072MHz), while MCLK should be 12.288MHz. I assume these are the clocks you are providing to the device, otherwise a clock error could be happening. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer