Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

Audio CODEC help

Hi,

I am a newbie and am trying to get the ADC working on the DE2 board. So far, I am using the MICIN input and I used the ADCDAT to get out the bits serially. I have been reading up on the WM8731 Audio CODEC and had a few questions:

1) How do I change the sample rate, word length etc? It says I can use "software control" but I really am not sure what this means. can someone please provide some sort of an example.

2) How do i output the bits from the ADCDAT to a text file? I need to convert the serial output of the bits to parallel and then I would like to output these bits to a text file and use a small plotting code to ensure that the ADC module is working correctly. Or is there an easier way to do this?

3) The datasheet for the WM8731 says that ADCDAT contains the left and right channels multiplexed? I would like to disable the LINEIN input and just use the MICIN. would there still be two channels? I am very confused about this part.

Any help is greatly appreciated. I am doing a project where I am building a digital controller for a DC/DC converter on the FPGA but am having problems with the ADC part.

Thanks

Sagar

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    16 years ago

    Hello,

    1) You need to look up the datasheet for this.

    There is an I2C interface which is used to set the internal registers.

    R7 and R8 do this -- see the register map.

    2) This is complex. I imagine you would set up a jtag interface

    then use a tcl function to read data from a register, then write that to a file.

    3) Yes- left and right channels are muxed in ADCDAT.

    Bit 2 of R4 is the INSEL analogue switch which selects either stereo line in or mono mic in (which goes to both channels) for the two adc's.

    This doesn't affect the ADCDAT output.

    Best

    jt