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Thread: Multiple CS42448

  1. #1
    Junior Member
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    Multiple CS42448

    Hello,

    for my upcoming Audio project in need at least 12 Audio Inputs at the same time. Is it possible to use multiple CS42448 Chips in parallel?

    Cheers Marcus

  2. #2
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    I'm only familiar with the chip on the T3.2. Its Synchronous Audio Interface (SAI) has two sets of I2S inputs / outputs, but they must run synchronous with each other. You should probably start with the datasheet to check and see if they both can run TDM at the same time. If so, you might be able to create an Audio Library class to use them both -- kind of like the Quad I2S class.

  3. #3
    Senior Member PaulStoffregen's Avatar
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    I believe it should be possible, though I have not tried.

  4. #4
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    thanks for the quick feedback,

    unfortunatly I am not very familiar with writing an Audio-Lib for that.
    @Paul: Can you give me an hint?
    I am not focused on the CS42448, is the AD1974 from Analog Devices a possible solution?

  5. #5
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by Koerby View Post
    is the AD1974 from Analog Devices a possible solution?
    This depends on what you mean by "possible". If adapting the library which already fully supports CS42448 to support a pair of CS42448 chips is out of reach, how will you adapt it to support 3+ of the not-at-all-suported AD1974 chip?

    Looking briefly at the AD1974 datasheet, I can tell you I do not believe Teensy 3.6 will be able to support any of the "512 Fs" modes, like figure 8 on page 14. I do believe the "256 Fs" modes are likely to work with the existing TDM code. But you would still need to edit the TDM code to have two TDM inputs - the same challenge as needed for 2 CS42448 chips, on top of all the work to control the AD1974 by SPI.


    Can you give me an hint?
    This involves digging into the library code, and really learning how the SAI/I2S peripheral in the chip works. There's just no way around that. You also need to figure out how to configure the DMA TCDs (probably the most challenging part).

    I would start by comparing the normal I2S and the quad channel I2S. Then try to do the same with TDM, turning it into 2 TDM streams.

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