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AIC3254 using I2S Mic as input, I2S output and DSP

Other Parts Discussed in Thread: TLV320AIC3254, TLV320AIC3254EVM-K

Hi,

I'm using the TLV320AIC3254 EVM and have been able to use analog mics through the IN1 and IN2 inputs with good results using the PGA, AGC and DSP filters.  My signal is routed out the Primary I2S Interface.

Question 1:  Is it possible to use an I2S mic as input (possibly with the secondary I2S input) and have output on an I2S output?  If so, would I still have access to AGC and filters for shaping, etc?  What registers would I need to configure?  Is there a sample script using an I2S input and I2S output?

Thanks,

Steve

  • Hi Steve,

    To send I2S In data to I2S Out data you need to use PurePath Studio to program the miniDSP. Refer to this wiki page: https://e2e.ti.com/support/data_converters/audio_converters/w/design_notes/2844.what-you-need-to-develop-minidsp-code

    The default configuration should work. You just need to route the I2S_In component to the I2S_Out component using an interprocessor component in between.

    Note that in such case I2S_In could not be used for any other function (such as music input) because the primary and secondary I2S interfaces are mutually exclusive. But if you plan to use one I2S input at a time, you could use the secondary audio interface for the microphone and toggle the interfaces as needed. Refer to the TLV320AIC3254 Application Reference Guide for details on how the sec. audio interface works. You can also use the AIC3254 CS software to control registers (you can download it on the TLV320AIC3254EVM-K web site).

    The hardware AGC function relies on the MicPGA so an I2S digital mic will not work with the h/w AGC. However, you could use a software AGC component in PurePath Studio that performs a similar function completely in digital. However, you will not get the benefit of increased dynamic range of the MicPGA.

    You can change the configuration of the PurePath Studio process flow as described in this wiki page: https://e2e.ti.com/support/data_converters/audio_converters/w/design_notes/2777.modifying-the-device-configuration-of-a-pps-process-flow

    Regards,

    J-

  • Hi J,

    Thanks for your reply.  We have been using PurePath Studio and AIC3254 CS.  Nice tools!

    Just so I'm clear...  I am using the I2S Primary output continuously as our audio path output.  From your reply it appears that I cannot use the secondary I2S interface as an input while simultaneously using the Primary I2S as my output.  Do I understand this correctly?

    Is there a way to configure the 3254 to use an I2S microphone as input, while simultaneously using I2S as my audio output?

    Steve

  • Hi Steve,

    Yes, you understood correctly. Have you considered using a digital PDM microphone (instead of I2S)? That we can support.

    In terms of flexibility, an analog microphone gives you the ability to control the MicPGA gain, which is useful if you plan to use the AGC.

    Regards,
    J-