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Thread: Using more than 2 pt8211 boards

  1. #1
    Junior Member
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    Using more than 2 pt8211 boards

    Hi All,

    Does anyone know if it is possible to output audio to more than 2 pt8211 boards from a teensy4.0?
    I noticed that with the audio design tool, the objects 'pt8211' and 'pt8211_2' use different I2S ports of the teensy.
    Is it possible to output audio to multiple pt8211 boards from the various pins of the same I2s port, basically the same as is done with the 'I2S_quad' and i2s_hex' objects for multible STGL5000 audio shields?

    Thanks.

  2. #2
    Senior Member PaulStoffregen's Avatar
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    If "possible" means can be done with the existing audio library, then no, using more than 2 of these chips isn't supported.

    But if we're talking about what ought to be theoretically possible with a tremendous amount of work in the software, then yes, I believe it should be possible to connect up to 4 of these chips to the first port, similar to how the 8 channel I2S can output 2 strereo streams on the 4 data pins. Of course, using a 5th chip on the other port would still work, since the 2 ports are independent. But no software exists to support this, so it would involve quite a lot of low-level programming inside the audio library.

  3. #3
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    Sorry for hijacking the topic, but is there any documentation on how to wire 2 pt8211 with the library?

  4. #4
    Senior Member PaulStoffregen's Avatar
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    Two separate pieces of documentation do exist, one for each port.

    https://www.pjrc.com/teensy/gui/?info=AudioOutputPT8211

    https://www.pjrc.com/teensy/gui/?inf...OutputPT8211_2

    On each, look for "Hardware" on the right side documentation panel for the specific info about how to wire each. All the other audio library features are also documented this way.

    So far there isn't a single document showing use of both together. Likewise for nearly all possible combinations of audio inputs and outputs, the documentation is for each individual feature. However, the design tool does have code which "knows" about the hardware resources and logical configuration each input and output requires, so even though there isn't documentation about use of specific combinations, if you drag a combination that can't work onto the canvas, little yellow error icons appear to tell you that combination can't work together. If you give this a try, you'll see no errors appear with those 2 PT2811 outputs on the same canvas. But if you try to create a 3rd instance of either, or if you drag any of the I2S ones onto the same canvas, you'll see those little yellow errors appear.

  5. #5
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    Hi Paul and all,
    If it's any help, I have some docs & info on my Google drive, regarding my T4 Laser Synth project, which has 2 SGTL5000 audio boards + one PT8211_2 for 6 audio output channels. There's a 6 month old assembly doc covering the initial prototype, T4 Laser Synth I.
    I've been using the T4 Laser Synth II variation on the same theme for the past few months to develop the MIDI controller to record imagery live from an Akai APC40 onto a Reaper 6 DAW. The only hardware difference is that the PT8211 is mounted upside down on the same level as the SGTL5000, just for aesthetics to fit inside the aluminum case.
    This week, I'll begin building a second laser projector and the T4 Laser Synth III, using the CS42448 audio board from OSHA, assuming that I can populate the SMD bits.
    I'm no guru, but very happy to share any info if it helps others.
    BR

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