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TLV320AIC3104EVM-K: External Microphone Capture via Screw Terminals

Tay Barrett
Prodigy 60 points
Part Number: TLV320AIC3104EVM-K


Hi,

I am new to audio engineering and struggling with audio capture using screw terminals.

I have a TLV320AIC3104EVM-K board set up with the EVM GUI. Using 3.5mm jacks I am able to capture and listen to audio on different headsets using the following commands:

w 30 01 80
w 30 07 80
w 30 19 80
w 30 08 20
w 30 25 E0 
w 30 26 10
w 30 2E 80 
w 30 3F 80
w 30 41 0D
w 30 33 0D
w 30 0F 2B
w 30 10 2B

I am currently trying to wire an aviation grade headset onto the EVM using the 6 wires that correspond to COMM L, COMM R, MIC HI, MIC LO, VIN and GND. Connecting GND, COMM L and COMM R to the positive HPLOUT and HPROUT terminals respectively provides audio.

What I am unable to get working is wiring the MIC HI and MIC LO pins to a terminal that produces output.

All jumpers are set in their default positions.

The microphone has a bias operating range of 8-16VDC which I have attempted to supply via the voltage wire from the headset.

What typically happens is straight noise with no audio capture, or the on-board microphone takes over.

Any advice on what terminals to use and commands would be very helpful.

Thank you.

  • 0
    TI__Mastermind 47745 points

    Hi Tay,

    Can you confirm for me that you can playback audio through the EVM to your headset but you can't record from your mic? However the 3.5mm jack works for both playback and record paths?

    Which terminal are you trying to connect your Mic lines to? Are you using MICBIAS to supply your microphone?

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 60 points

    Hi Jeff,

    Yes, 3.5mm jack works to record and playback but can only achieve playback with the screw terminals.

    I have the MICBIAS (JMP10) connected at position 2-3, and have it enabled in the commands.

    I have tried to connect the mic lines to L and R terminals of IN2 (J7), as well as + and - terminals for both IN1R (J14) and IN1L (J6). I have also tried the mic lines in both the + terminals of IN1R and IN1L and both the - terminals, to no avail.

    I did not change any of the commands from what I listed above whilst trying the different terminals.

    Thank you,

    Tay

  • +1 in reply to Tay Barrett
    TI__Mastermind 47745 points

    Hi Tay,

    I loaded up your script as is, and connected to the EVM as shown below. I was able to see the signal from the input on the HPL output and have attached a pic of my analyzer. Double check your jumpers against mine and see if something is misaligned.

    Something I noticed was that the headset connector has a micbias connection to it, but the screw terminals don't. You mentioned in the original post that the noise is coming through but no tone. Your signal path is correct, but your mic may not be getting power unless I'm misunderstanding something about your setup.

    If none of that works I'd also recommend removing the headset from the equation right now and using test equipment to verify your connections and signal path.

  • 0 in reply to Jeff McPherson
    Prodigy 60 points

    Thanks Jeff,

    I checked my jumpers against yours and our set up matched. I added a mic bias of 8V to my mic wire (connected IN2L). I also realised I had the MIC Lo wire plugged in to IN2R instead of grounded and it fixed my problem.

    Regards,

    Tay