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Thread: Quad audio output

  1. #1
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    Quad audio output

    Before I jump into that idea I had, I wanted to know something. I read from Teensy's website that the Audio Adaptor and the Teensy Audio Library have support for 4 audio outputs if you stack two Audio Adaptor boards together. What if you do not need the extra inputs and just needed the outputs? Can you put a PT8211 Audio Kit with the Audio Adaptor board?

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by Sonoblaise View Post
    What if you do not need the extra inputs and just needed the outputs? Can you put a PT8211 Audio Kit with the Audio Adaptor board?
    You have many options. Look at the Output section on the left side of the design tool.

    https://www.pjrc.com/teensy/gui/

    You can use any of those to get sound output.

  3. #3
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    Thanks a lot! I didnt think to look at it! Can I use any combination of those at the same time? For example using the quad outputs of two audio ahield and another device's output with I2S?

  4. #4
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by Sonoblaise View Post
    Can I use any combination of those at the same time?
    Some combinations do work together, if they don't try to use the same hardware resources. I2S and DAC work together, or example.

    Sadly, the design tool is not (yet) smart enough to know which objects use which hardware and prevent you from using combinations that conflict. Most of them do document their hardware usage pretty well in the documentation panel.

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    i2s_quad using two(2) PT8211 Codecs?

    I'm thinking that the format of the PT8211 is different than the SGTL5000,
    so that i2s_quad will only work with two SGTL5000, yes?

  6. #6
    Senior Member PaulStoffregen's Avatar
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    Correct, PT8211 is a different protocol. It is quite similar, but key details differ, so PT8211 does not work with I2S.

    The i2s_quad output has been tested with two SGTL5000. It should also work with pairs of other I2S chips, though PJRC only tests SGTL5000. But two PT8211 chips will not work with quad I2S.

    Some of the NXP/Freescale documentation calls the on-chip peripheral SAI (Synchronous Audio Interface) and sometimes they call it I2S. Really, SAI is technically a better name, since it is very flexible. It can be configured for TDM, the special format PT8211 uses, and lots of other ways. I2S is only the most commonly used protocol.

    I believe it should be technically possible, given enough time and programming skill, to create a quad PT8211 object. I have not tried this, and as far as I know nobody else has done it.
    Last edited by PaulStoffregen; 11-17-2017 at 10:45 PM.

  7. #7
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    Thanks Paul,
    Sounds like the SGTL5000 is a better choice for Quad outputs right now.
    Or just go for a native TDM part for more channels, like the Cirrus CS42448,
    since that is already supported.
    thanks again, Tom

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