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TLV320AIC34 - AGC Configuration

hi

I'm trying to use the AGC Noise Gate Threshold function ,

as far as I understand it should suppress all audio input under a certain level,

but when I tried it , it also suppressed my recording.

do I need to train this threshold before activating it? how can I control the cutoff value?

thanks

 

  • Hi, Guy,

    Welcome to E2E and thank you for your interest in our products.

    You're right, the AGC Noise Gate Threshold function suppresses all audio input under a certain level. A wrong configuration could cause the suppression of the entire signal. Could you provide your register configuration? Additionally, could you provide the input signal characteristics?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.

  • im trying to record a simple speech signal at the moment,
    regarding register configuration i tried min/max value of this register just to check the edges,
    is the configuration is absolute or is it relative to the PGA configuration?

    thanks
  • Hi, Guy,

    When the AGC is enabled, the PGA value is ignored. I mean, the AGC controls the PGA value by the defined values. Could you provide your register configuration to have a better approach of this issue?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.
  • the configuration is as followed:

    i i2cfast

    # - Set to 44.1[kHz]
    w 30 07 80

    # - MIC3R_x is not connected to the left and right ADC PGA
    w 30 11 FF

    # - MIC3L_x is not connected to the right- and left ADC PGA
    w 30 12 FF

    #  -LINE2LP_x and LINE2LM_x to Left-ADC
    #Fully differential, 0db
    w 30 14 87

    #LINE1RP_x and LINE1RM_x to Left-ADC Control Register -
    #Fully differential, 0db
    w 30 15 87

    #  -LINE2RP_x and LINE2RM_x to Right-ADC
    #Fully differential, 0db
    w 30 17 87

    #LINE1LP_x and LINE1LP_x and LINE1LM_xM_x to Right-ADC Control Register -
    #Fully differential, 0db
    w 30 18 87

    # - The left-ADC PGA is not muted && Gain = 59 dB
    w 30 0F 59

    # - The right-ADC PGA is not muted && Gain = 59 dB
    w 30 10 59

    # - MICBIAS_x output is powered to 2.5 V & If digital MIC is enabled, both left and right digital MICs are available
    w 30 19 80

    #Enable left AGC
    #w 30 1a 80

    #Enable right AGC
    #w 30  1d 80

    #Left-AGC Control Register C
    w 30 1c 02

    #Right-AGC Control Register C
    w 30 1c 02

    #WCLK and BCLK
    w 30 08 40
    w 30 08 C0

    in general this configuration does suppress some noise , but it is not so good when the frequency is changed

    is there a df/dt limit for the AGC?

    thanks

  • Hi, Guy,

    There isn't a df/dt limit for the AGC, but the AGC has a attack and decay time that can be configured by the user. Have you tried changing these values?

    Best regards,
    Luis Fernando Rodríguez S.