• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 29 subscribers
  • Views 430 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PCM1865 digital mic

Jordi Duat
Prodigy 20 points
Other Parts Discussed in Thread: PCM1865

HI everybody,

I'm currently setting a system using the PCM1865 where I need to use 4 digital mics. The problem is I can'¡t really see how to send the data from the mics over I2S to a DSP. In the registers I can see how to setup TDM mode for the 4 analog channels but nothing about the digital outputs.

Thanks in advance!

  • 0
    TI__Genius 9175 points

    Hello,

    The digital output will be on a single I2S bus on pins 16, 17 and 18. The PDM signal form the 4 microphones will share 2 digital datelines (as 2 stereo pairs of microphones per data line). One data line for mic pair 1 and a second data line for mic pair 2.

     See pg. 23 in the datasheet HERE for an illustration.

    For routing, the mic input GPIOs must be routed into the decimation filter, and then mixing functions were the two channels can be mixed together. See Fig 22 on pg 20.

    If you use fig 18 on pg 17, starting with GPIO 1 and 2 on the left side of the page, you can trace the signal path through the different features of the part in order to convert the input GPIOs to I2S. Every block in the signal path will have to be configured by changing specific I2C registers.

    Regards,

    Matt

     

  • 0 in reply to Matthew Beardsworth
    Prodigy 20 points

    Hi Matt,

    Thank you so much. I found now the register to select the digital mics.

    One more thing, so as the mic pair is always in a dateline, i can have 2x(mic pair) + 2 analog channels on I2S, am I right?

    Thanks again,

    Regards,

    Jordi

  • 0 in reply to Jordi Duat
    TI__Genius 9175 points

    Hi Jordi,

    That should be no problem as long as you TDM and or mix the different sources accordingly for the number of channels want.

    Regards,

    Matt