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Linux/TLV320AIC3106: Audio codec

pranav prakash55
Intellectual 620 points
Part Number: TLV320AIC3106


Tool/software: Linux

Hey Team ,

we have designed a audio system the issue which i am getting is when mic is coming close to speaker a humming noise start to come and that keep of intensifying till we power off.I am using LINE1L+ as input and HPROUT as output in tlv320aic3x as the driver for my codec (tlv320auc3106).Rest all other input and output channels i had disabled .Is there any codec settings which i have to do or i have to modify something in the hardware mic section .

Kindly  show me some way to resolve this issue.

With Regards ,

Pranav

  • 0
    TI__Mastermind 30220 points
    Pranav,

    Can you be more specific on the hum? what is the frequency and amplitude? Is the mic signal routed to the output? could it just be positive feedback?
    Does it go away if you mute the mic, or mute the DAC output?

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Intellectual 620 points

    The frequency goes on increasing its like a howling noise.No, Mic signal of codec is muted .
    I dont have much idea how to assure about that positive feedback ?
    Yes when i speek something that frequency is going off and it also goes off if i mute the mic .while going through the datasheet i got something like noise threshold but how to utilise that to minimise the noise value when speech is not there.

    And one more observation which i am getting is when i am placing the mic parellel to speaker and the placement is very close then the humming noise gets intensified,comparative to the position when they are distant.

    Below is the script i am using to provide the path :-

    amixer cset numid=14 90% > /dev/null //pcm
    amixer cset numid=30 90% > /dev/null //dac vol
    amixer cset numid=51 DAC_R2 //Right DAC Mux
    amixer cset numid=94 0//Left HPCOM Mixer DACL1
    amixer cset numid=90 0 //Right HP Mixer DACR1
    amixer cset numid=102 0 //Right HPCOM Mixer DACR1 Switch
    amixer cset numid=63 0 //Right PGA Mixer Line1R
    amixer cset numid=52 single-ended //Right HPCOM Mux
    amixer cset numid=50 single-ended //left HPCOM MUX
    amixer cset numid=43 1 //De-emphasis Switch
    amixer cset numid=13 0 //mono playback switch

    And here if i enable AGC gain control the noise gets increase .

    With regards ,
    Pranav

  • 0 in reply to pranav prakash55
    TI__Mastermind 30220 points
    Pranav,

    What is the De-emphasis switch? does ti change the De-emphasis filter? or what is that doing?

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Intellectual 620 points
    Hello Steve !

    Thanks for the response ,That switch is corresponding to reg 12(Audio Codec Digital Filter Control Register) and the value corresponding to it after on is 0x05 which is enabling left and right DAC de-emphasis filter.

    with regards ,
    Pranav
  • 0 in reply to pranav prakash55
    TI__Mastermind 30220 points
    Pranav,

    can you record the sound? even a simple recording made with your phone would help.

    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Intellectual 620 points

    Hey Steve ,

    I am able to record the the sound properly. The problem is coming when i am streaming RTP packets on other device .

    And one more issue I am facing is now i start using push to talk mic so that the mic should record only when we push and start to talk but that is not happening . The mic is on and is recording in either states i.e even the switch is pressed or not that is not making any difference on the record .

    Can you please give me some pointer about this issue.Where should i look either in the driver or in my hardware.

    With Regards,
    Pranav

  • 0 in reply to pranav prakash55
    TI__Mastermind 30220 points

    Pranav,

    "I am able to record the the sound properly. The problem is coming when i am streaming RTP packets on other device ."

    I'm not sure I understand.  you can record audio without hum, but when you stream it to another device you have hum?

    Regarding the microphone,  can you explain how you are connecting the push to talk mic?   Can you share a schematic? 

    There isn't any automatic push to talk functionality on the Audio codec.  so I imagine that this push to talk function is connected to a GPIO which reports the input value to a register that then has to be polled or its being handled by the processor directly.  

    best regards,

    -Steve Wilson 

  • 0 in reply to Steve-Wilson
    Intellectual 620 points
    Hello Steve ,

    can you tell me how to implement echo cancellation and noise reduction in tlv320aic3106 codec .Actually the noise i am getting is a positive feedback because mic and speaker are a bit near .So could you please tell me how can i eliminate it to maximum extend in software.


    With Regards ,
    Pranav
  • 0 in reply to pranav prakash55
    TI__Mastermind 30220 points
    Pranav,

    The AIC3106 is a very simple codec, the ADC has simple HPF for processing and thats about it. The DAC has some Filters, but thats it.

    If you are looking for AEC/ Noise cancellation an external processor paired with the AIC3106 would be a good choice.

    best regards,
    -Steve Wilson