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AIC32x4: Different beep sound quality between 44.1kHz and 11.025kHz in case of using PRB_P25

Kaka
Guru 24520 points

Hi community member,

Would you please provide the advices for me in order to improve the following phenomenon?

[Phenomenon]

When changed the sampling frequency from 44.1kHz to 11.025kHz, the sound quality was different .

I heard the beep sound higher than the sound which I expected.

I used the following register values.

------------------------------------------------ 

 Beep: 2kHz  FS: 44.1kHz

    Page0 Reg 76 : 0x23

    Page0 Reg 77 : 0xFB

    Page0 Reg 78 : 0x7A

    Page0 Reg 79 : 0xD6

------------------------------------

 Beep: 2kHz   FS: 11.025kH

    Page0 Reg 76 : 0x74

    Page0 Reg 77 : 0x4B

    Page0 Reg 78 : 0x35

    Page0 Reg 79 : 0x79

------------------------------------------------ 

In order to calculate those above values, I referred to the document of "slaa446"  on page 9.

If you have any question, please let me know.

Best regards.

Kaka

  • 0
    Guru 24520 points

    Hi community member,

    I captured the waveforms of audio signal with each sampling frequency.

     - 44100Hz

     

     - 11025Hz 

     

    For the sampling frequency of 11025Hz, the audio signal was approximately 1kHz audio signal even though I was set the 2kHz beep audio.

    Note:

    Of cause, I was changed the PLL settings in order to correspond the RC class of 12.  Just in case, I summarized those setting as below.

     For 44100Hz :

        Beep: Reg76 =0x23, Reg77 = 0xFB, Reg78 = 0x7A, Reg 79= 0xD6, AOSR/DOSR=128

        PLL  : R=1, P=2, J=15,D=0, MDAC/MADC=3, NDAC/NADC=5

    For 11025Hz :

        Beep : Reg76 =0x74, Reg77 = 0x4B, Reg78 = 0x35, Reg 79= 0x79, AOSR/DOSR = 128

        PLL : R=1, P=2, J=15,D=0, MDAC/MADC=3, NDAC/NADC=20

    If you have any questions, please let me know.

    Best regards,

    Kaka

  • 0 in reply to Kaka
    TI__Guru**** 189401 points

    Hi, Kaka,

    Sorry for the delay. We are a little short-staffed right now due to vacations in the US.

    I have asked my colleague to look into this for you.

    -d2

  • 0 in reply to Kaka
    TI__Mastermind 46195 points

    Hi Kaka-san,

    Your beep settings are correct.

    Looks like you are using a 5.6448 MHz MCLK, correct?

    Please try the following divider settings.

    For 11025Hz :

        Beep : Reg76 =0x74, Reg77 = 0x4B, Reg78 = 0x35, Reg 79= 0x79, AOSR = 128, DOSR = 512

        PLL : R=1, P=2, J=15,D=0, MDAC/MADC=3, NDAC = 5, NADC=20.

    Regards,

    J-

  • 0 in reply to J-
    Guru 24520 points

    Hi J,

    Thank you for your response.

    I had a mistake in the MCLK value.  When I calculated the PLL settings, I had supposed the frequency of MCLK is 11.2896MHz.

    Actually, the MCLK was 5.6448MHz.  This is why the BEEP frequency was half value. 

    Just in case, I attached the waveform as below.

    7024.TEK00009.TIF

    Please let me confirm the following question.

    Is this waveform correct as AIC32x4 operation?

    It seems that there are difference waveforms between 44.1kHz and 11.025kHz.

    Best regards,

    Kaka

  • 0 in reply to Kaka
    TI__Mastermind 46195 points

    Kaka-san,

    Please set the DOSR value for 11.025kHz case such that DOSR = 128*(44.1/11.025) = 512.

    Regards,

    J-

  • 0 in reply to J-
    Guru 24520 points

    Hi J,

    Thank you for your response.

    I confirmed the beep sound with your case. I attached it as below.

    Please check it again.

    2451.TEK00011.TIF

    It seems that it did not improve the beep sound with your case.

    Do you have any other ideas?

    Best regards,

    Kaka

    http://e2e.ti.com/support/data_converters/audio_converters/f/64/t/183494.aspx