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Thread: Teensy 4 and Prop Shield audio compatibility?

  1. #1
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    Teensy 4 and Prop Shield audio compatibility?

    Just got a Teensy 4 and a Prop Shield LC, and I'm seeing references to the 4 not having a DAC pin. Since the Prop Shield wants DAC (I think) does that mean it can't work with the Teensy 4? Or am I in my newbosity missing something?

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    Never mind, https://forum.pjrc.com/threads/57208...l=1#post212602 pretty much answers my question.

    Audio shield or downgrade to 3.x it is then!

  3. #3
    Senior Member+ defragster's Avatar
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    Indeed no DAC on T4 - good find on Paul's note … the current Audio Shield can be made to work - though Paul has noted there will be a T4 specific updated version available soon that will direct mount.

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by holtt View Post
    Just got a Teensy 4 and a Prop Shield LC, and I'm seeing references to the 4 not having a DAC pin. Since the Prop Shield wants DAC (I think) does that mean it can't work with the Teensy 4? Or am I in my newbosity missing something?
    You aren't missing anything, but.......

    If you aren't using SPI (including the flash memory on the prop shield), pins 10 and 12 are MQSR and MQSL output pins, and these do low grade sound output (like the DAC). You could plug either 10 or 12 into the DAC pin with a jumper wire to use that. Here is a simple sketch I wrote when I was looking into sound options on the Teensy 4.0:


    The other way to create sound is to use i2s and get an i2s amplifier and hook it up to a speaker. Here is the i2s program I wrote using a MakerHawk MAX98347A I bought on Amazon:


    If you wanted to use the prop shield for other purposes, you would need to not connect pin 7 of the prop shield (led enable) to the Teensy, since it is the I2S #1 output.

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    There is a 3.x something kicking around at work in our maker space - I may borrow/swap it to work on my prototype for now. Probably will just get a full Audio Shield, since I want the processing ability of the 4 in the longer run.

  6. #6
    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by holtt View Post
    There is a 3.x something kicking around at work in our maker space - I may borrow/swap it to work on my prototype for now. Probably will just get a full Audio Shield, since I want the processing ability of the 4 in the longer run.
    Note, if it is the 3.5 or 3.6, the DAC pins are in a different location, and you would need to run a wire from A21 to the DAC if you want to use the prop shield's mono amplifier.

    Also note, due to the T3.5/T3.6 being longer, you may have problems accessing the 4 pins at the back that are used to drive WS2812B (neopixel) or APA102 (dotstar) LED strings.

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