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Digital microphone script for TLV320AIC3204 eval board

Kevin Honeyager
Prodigy 140 points
Other Parts Discussed in Thread: TLV320AIC3204

Hello,

I'm having difficulty getting a PDM microphone (ADMP521) to work with the evaluation board for the TLV320AIC3204.  I have my clock output on MISO and my data coming in on SCLK.  The signals look OK going into the codec, but I can't get any output on the headphones.  Would anyone happen to have a working script for this eval board?  I've been waiting for over a week for tech support, but have not received any help.  Supposedly someone is looking at it, but I can't wait much longer.

I did find a script for a related part and tried it, but it still didn't work.  I'm looking for a 'if you run this script, you will hear something from the headphones' solution. I would greatly appreciate any help I can get.  I need to prove this works before proceeding with a PCB layout.

Kevin

  • 0
    TI__Guru 57800 points

    Hello Kevin,

    The configuration of the digital microphone input with the AIC3204 consists basically in setting a few registers:

    w 30 00 00 #Page 0
    w 30 01 01 #Reset

    #Digital Microphone Setting
    w 30 37 07 #MISO Pin DMIC CLK
    w 30 38 02 #SCLK Pin DMIC DATA
    w 30 51 DC #ADC ON/ DMIC Enabled
    w 30 52 00 #ADC Not Muted

    For your configuration, you need to remove the resistor connected to MISO (R18) in order to isolate the Digital Mic CLK signal from the SPI circuitry. Also you need to remove the shunt from W14 to isolate digital microphone data on SCLK.

    This configuration sends the digital microphone data to the digital audio interface by default. Now, if you want to get the digital microphone audio into the headphone output of the codec, you need to make a loopback to connect the ADC output to the DAC input (Page 0 / Register 29) and configure properly the DAC to Headphone path. Otherwise the data of the ADC will be streaming into the PC (if using the USB connection), this could be useful for testing the digital microphone using a recording tool in the PC.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 140 points

    Diego,

    Did you actually try this?  I was following your register settings, and it looks to me like the setting for #MISO Pin DMIC CLK is incorrect.  That register has a GPIO bit at D0, so shouldn't the register value be 0x0E?

    I am working my way through this. FYI, I'm not seeing any corruption of my clock or data on TP17 or TP18 of the eval codec board, so I'm wondering if the shunt and resistor really need to be removed?  I am connecting my signals on J15. Pin 5 (labelled SCLK) has my PDM_DATA connection, and pin 9 (labellsed MISO) has my PDM_CLK connection.


    Kevin

  • 0 in reply to Kevin Honeyager
    Prodigy 140 points
    There is a lot of information missing here. I cannot seem to make this work. The audio I hear is from a connected I2S microphone. It is behaving as though the I2S mic is overriding the PDM mic. I understand how to turn the digital microphone input on and tell it data is coming in on SCLK. That was never the problem, and is quite clear from looking at the Input Routing dialog.

    I can see PDM data coming in on TP17 and the PDM clock going out on TP18. These signals are getting to and from my PDM mic. The part I am missing is how to get this audio out the headphones. Isn't there any way I can get a script that will take a digital mic and route it to the headphone output? IMO, there should already be a script for this included with the EVM software. I have literally spent days trying to get this last piece to work. Please help me out.
  • 0 in reply to Diego Melendez
    Prodigy 140 points
    There is a lot of information missing here. I cannot seem to make this work. The audio I hear is from a connected I2S microphone. It is behaving as though the I2S mic is overriding the PDM mic. I understand how to turn the digital microphone input on and tell it data is coming in on SCLK. That was never the problem, and is quite clear from looking at the Input Routing dialog.

    I can see PDM data coming in on TP17 and the PDM clock going out on TP18. These signals are getting to and from my PDM mic. The part I am missing is how to get this audio out the headphones. Isn't there any way I can get a script that will take a digital mic and route it to the headphone output? IMO, there should already be a script for this included with the EVM software. I have literally spent days trying to get this last piece to work. Please help me out.
  • 0 in reply to Kevin Honeyager
    Prodigy 140 points
    Diego,

    I am still unable to get any audio output. I really need to have this resolved - I have a technical support case, but after a couple weeks of TI support giving me the runaround, they changed their story and told me I should have requested assistance here. Please, if you (or anyone reading this) can provide me a known working script that produces audio to the headphones using a PDM mic, I can complete my design. This is still my only unresolved issue. I would think this would be rather straightforward for applications engineering to provide.

    I'm writing this today because I must leave the country for three weeks, and I'm hoping to have the answer upon my return. Please help.

    Regards,
    Kevin
  • 0 in reply to Kevin Honeyager
    Prodigy 140 points

    Three weeks and no help? C'mon, TI.