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TLV320AIC3105: Mixing analog inputs with digital I2S input plus effects

jerome d.
Expert 1325 points
Part Number: TLV320AIC3105


Hi All
In my app, I have 2 stereo analog inputs connected to LINE 1 and 2 L/R.
In addition to those 2 analog inputs, I have a I2S input.
I want to mix all those 3 inputs and forward them to LINE OUT L/R.

Inside the codec, I can do this mix, but I'd like to be able to apply the 2 bands equalizer on the mixed signals, before going to the line outputs.

From my understanding, it seems the block before the effects is a multiplexor, not a mixer. So basically the input of the effects is the output of the ADC OR the digital input.
Is this correct ?
If I close the switch SW-D1 shown in block diagram page 18, continue using the I2S inputs, and keep the DAC ON, will the effects block receive the mix of ADC OUT + I2S IN ?

I'd like to avoid using an additional DAC for I2S input, just to be able to mix 3 analog inputs before going to the effects, that would result in DIGITAL -> ANALOG -> DIGITAL -> EFFECTS -> ANALOG, which makes no sense.

Thanks for clarifying 

Jerome


  • 0
    TI__Mastermind 27710 points

    Hi Jerome,

    jerome d. said:
    From my understanding, it seems the block before the effects is a multiplexor, not a mixer. So basically the input of the effects is the output of the ADC OR the digital input.

    The block you're referring to is page 0, register 8: Audio Serial Data Interface Control Register. This block governs the type of data being received and whether 3D audio processing will occur. In this register it is unclear based on the d/s whether it can receive multiple digital data inputs before effects processing, I will confirm details with CODEC expert tomorrow.

    jerome d. said:
    If I close the switch SW-D1 shown in block diagram page 18, continue using the I2S inputs, and keep the DAC ON, will the effects block receive the mix of ADC OUT + I2S IN ?

    SW-D1 through SW-D4 must all be closed or on together through register 107. Meaning with SW-D2 & SW-D4 closed it may force this path to be record only. I again will confirm if effects block can receive ADC OUT + I2S IN.

    Here is another more in-depth BD of the AIC3104 codec which is practically the same as 3105 but with Diff inputs

  • 0 in reply to Daveon Douglas
    Expert 1325 points

    Thanks for your reply.

    If SW-D1 to D4 must be closed all together, what I want to achieve is therefore not possible.
    (I need the DAC ON, while ADC outputs go the the effects block).
    Thanks.

  • 0 in reply to jerome d.
    TI__Mastermind 27710 points

    Hi Jerome, 

    Codec expert if OoO today, please wait until monday next week to see if there is a solution for your application.

    Kind regards,

  • 0 in reply to Daveon Douglas
    TI__Mastermind 27710 points

    Hi Jerome,

    I confirmed that the features in effects block can only be used on digital input from processor/I2S. There is no way to do this for an analog input that is why the closed switches will become record only. An analog input will either become DOUT or gained up/down or mixed with other analog signals.

    To do effects, the signal must be in the digital domain. You can mix both L & R single-ended analog inputs, close the switches which puts device in record mode, configure signal in effects block, result is DOUT. From here you have to have the host processor mix DOUT + your I2S in as there is only one DIN. 

    Regards,