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PCM1864 with 2 I2S/ TDM input and mixed as single TDM output

Rocson He
Intellectual 1830 points
Other Parts Discussed in Thread: PCM1864, TLV320AIC3268, TLV320AIC3262

Hi Team,

I have customer that has one new application requirement for before-market automotive infotainment, as below block, some summary as below items.

Could you help double check if PCM1864 is suitable ?

1)  2 or more I2S or TDM format, digital input interface

2)  at lease one Analog input for Mic

3) Mic input gain adjustable, up to 30dB

4) The output is TDM format, connecting to SOC. And it should be able to combine and mix the several input channel into one output.

Some questions that need your help about PCM1864 :

1. Could the DMIN and DMIN2 be used as the I2S or TDM input ?

2. Could the input format set to I2S, while output setting as TDM, or the input also has to be TDM format ? And how to configure ?

3. If it's suitable, PCM1864 should be set in slave mode ? with BCK and LRCLK from SOC, and SCKI could be omitted, or connect from crystal ?

4. Any other more suitable solution for this application requirement ? Like TLC320AIC3268 ?

Thanks for your help in advance.

  • 0
    TI__Intellectual 1830 points
    sorry for typo, in above, it should be TLV320AIC3268, not "TLC320AIC3268".
  • 0 in reply to Rocson He
    TI__Guru 57800 points

    Hi, Rocson,

    Thanks for the clarification, my colleague was notified about your question and will provide his feedback after the Holiday.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    TI__Mastermind 27920 points
    Hi Rocson,

    1. The PCM1864 can take in 2 channels of audio either in I2S or TDM format, that can then be directly output or mixed into another output over I2S or TDM.

    2. Yes this is possible while also inputting 2 audio channels over TDM or I2S.

    3. Yes, the PGA for an analog input can go up to 32 dB of gain. There is also digital gain available and the mixer can gain up the signal.

    4. If you are talking about one TDM data stream, this is possible, but only with 2 input channels. However, if the sources can do TDM then they can send their data on the TDM bus for the PCM1864 to ignore and the SoC can look on the bus for the data. If you actually want to mix the audio together the PCM1864 is capable of doing this.

    Second set of questions:

    1. DMIN1 and DMIN2 are for digital mics (PDM) and do not support I2S data.

    2. Both input and output will be the same, so if using TDM for output, input must also be over TDM.

    3. The PCM1864 is quite flexible clocking wise, and can operate as a slave, as well as without the SCKI input, but BCK will have to be at 256*Fs for TDM mode. In this case it would use its PLL to generate an internal master clock. You could also use an external crystal with the PCM1864, and have it as the master.

    4. Depending on some clarifications above, I think the PCM1864 could work. Performance wise and integration of PGA is beneficial for the PCM1864, but more flexibility in processing and inputs to outputs could be beneficial from the AIC parts such as AIC3268.

    Justin
  • 0 in reply to Justin Bohr
    Expert 1680 points

    Hello Sirs,

    Encounter to see this similar function inquiry .My inquiry is

    Two I2S need to be mixed and output an single I2S or TDM. Is PCM1864 a right choice ?

    May I know which pins for two I2S input pin ?  TKS !

  • 0 in reply to Terry Wu
    TI__Guru 57800 points

    Hi, Terry,

    The PCM1864 is an audio ADC that is able to stream up to four channels of audio in either I²S or TDM format. This device features also a digital mixer that is able to take an stereo input from an external I²S source. Unfortunately, this device supports only a single stereo I²S input, so if you need to take two or more stereo I²S inputs and mix them, you will need a different device. Can you please provide more information about your end-system requirements so we can provide the most suitable solution?

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Expert 1680 points

    Hello Diego,

    Many thanks your reply~

    Due to SoC only single port I2S and need to receive two I2S input ( Wifi module and audio codec )

    One option is Wifi I2S add a audio DAC mix into Audio codec and output I2S to SoC . Afraid audio quality from D to A  & A to D .

    So we want to find a I2S mixer IC ( Two I2S input and one I2S output ).

    Many thanks ~

  • 0 in reply to Terry Wu
    TI__Guru 57800 points

    Hi, Terry,

    Thanks for the additional feedback. Unfortunately we don't have a simple device capable to only mix two I²S signals. We have a couple audio codecs (like TLV320AIC3262) that have up to three audio serial interfaces that can be mixed internally by using the integrated miniDSP of the codec, but probably this would be an overkill for just the I²S mixing function.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer