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Use the Low Pass Filter in the AIC3106 on the LCDK 6748 while running the mcasp example

Eric Rajchel
Prodigy 40 points

Hello,

I read online that while using the mcasp example on the LCDK6748 board it is possible to enable a low pass filteron the AIC3106 chip. The post referenced the datasheet which we have but cannot find the registers that need to be set. Anybody know how to do this?

Here is the forum where I found this referenced.

e2e.ti.com/.../1219953

Eric

  • 0
    TI__Mastermind 35645 points

    Hi Eric,

    Thanks for your post.

    To my knowledge, the AIC3106 codec performs with 20-kHz low-pass filter which removes out-of-band noise and it is obvious that the low pass filter is enabled by default with specified passband & stop band. So, it is not required explicitly to enable low pass filter on the AIC3106 codec chip and if failed to use the LPF on the AIC3106, it will result in higher total hormonic distortion and lower SNR.

    From  the above, it is very clear that, a weighted LPF is used on the AIC3106 which does performs well and without which, the audio output would result very noisy.

    Alernatively, you could try using kernel functions that exist in DSP libraries supplied by TI. Your project must include these libraries to be able to use these functions. So, please download the TI C67x DSPLIB from the below link in which you could see filtering library functions:

    http://www.ti.com/tool/sprc121

    Also, please refer the c67x DSP FIR/IIR signal processing examples from the application report as given below:

    http://www.ti.com/lit/an/spra947a/spra947a.pdf

    Kindly check the c67x DSP library programmer's guide for filtering functions as below:

    http://www.ti.com/lit/ug/spru657c/spru657c.pdf

    Thanks & regards,

    Sivaraj K

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