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Thread: Teensy4 with PCM5100 i2sslave, no sound

  1. #1
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    Teensy4 with PCM5100 i2sslave, no sound

    Hi people, just got the boards for a project with Teensy4, the DAC for the audio part is a PCM5100, which should work as i2sslave device but I get no sound,
    I've tested with a few examples from the audio library (replacing the output device with 'AudioOutputI2Sslave'
    the pins appears to be chosen correctly,
    Click image for larger version. 

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    the circuit of the DAC has the FMT pin to ground, so the audio format selected is i2s.
    Click image for larger version. 

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    My question is if there's something else I should add to the code to use that device, apart of the code generated by the audio design tool and the 'AudioMemory(xx);' in the setup.
    thanks in advance
    http://www.ti.com/lit/ds/symlink/pcm5100a.pdf

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    There is no reason to make the audio output a slave because then, the Teensy would expect getting the clocks from the external device but your DAC does not provide these. This DAC is already a slave which makes that the Teensy must be the master.

    If you had used a cheap 8$ logic analyzer, you would have seen that the Teensy does not output any I2S clocks when in slave mode.

  3. #3
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    ok I misunderstood the fact that the DAC does not need a clock with being a master i2s device,

    'The integrated PLL on the device removes the requirement for a system clock (commonly known as master clock), allowing a 3-wire I2S connection and reducing system EMI.'

    actually working as a regular i2s output,
    thanks!

  4. #4
    Senior Member+ Theremingenieur's Avatar
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    The PCM5100 series generates itself the master clock from the incoming bit clock. But that latter has to be provided, that's why the Teensy has to be the master.

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