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Thread: Stacking audio board and Teensy

  1. #1
    Join Date
    Jun 2015
    Cambridge, UK

    Stacking audio board and Teensy

    I have a Teensy4.1 and audio board. My intention is to try the impressive SDR project which is described in a thread on this forum.

    My problem, is how best to stack or connect the Teensy and audio board, while still allowing easy connection to all other (unused) pins.

    Now I have a previous project in which I used a Teensy3.1 and audio board. I plugged them both into a breadboard and had jumper wires for all necessary audio connections. When I tried playing back a MP3/WAV there was bad distortion. The only way to get the pair to work without distortion was to stack them vertically. Also to get access to the pins not used by the audio board, I resorted to soldering wires directly to the top pins of the Teensy, but it looks horrible.

    Now I normally use the double pins in my Teensy so that the board can be plugged into a solderless breadboard. I would like to be able to plug the Teensy4.1 into a breadboard (without the audio board), but I would also like to be able to connect or stack the Teensy4.1 and audio board, while still allowing access for jumper wires to the unused pins on the audio board and the extra pins (not connected to the audio board) of the Teensy4.1.

    One idea is to use the Arduino connectors, as they have long pins on the bottom to plug into the breadboard, but allow other pins to be plugged into the top part of the connector.

    Click image for larger version. 

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    I considered using the above type connectors for both the Teensy4.1 (which would be on the bottom) and the audio board (on the top).

    Any other ideas?

  2. #2
    Senior Member
    Join Date
    Apr 2020
    DFW area in Texas
    In my recently completed TeensyMIDIPolySynth project (, I stacked the Teensy 4.x on top of the Rev D Audio Shield (to allow easy access to the programming button, a painful lesson learned from having the opposite stacking order on an earlier prototype !!). Your suggestion to solder the same Arduino connector into each of the Teensy & Audio Shield is a very good one. That way, you could stack them either way, or place each of them individually on a breadboard...maximum flexibility.

    Good luck & have fun !!

    Mark J Culross

  3. #3
    Senior Member+ MichaelMeissner's Avatar
    Join Date
    Nov 2012
    Ayer Massachussetts
    I do that all of the time. I generally put stacking headers on both the Teensy and the Audio Shield.

    Though there are things to consider:

    If you stack the audio board on top of the Teensy 4.0, you might not be able to access the 5 pins on the back row. You can either put a stacking header in, and just use solid wires to bring out the pins you want. Or you can use a right angle header so that you can access the pins behind the Teensy.

    Similarly for the VUSB pin on both the Teensy 4.0 and 4.1. That could be done with a stranded wire soldered to the board with a dupont male/female header if needed. Or you can use a header that is 1 pin longer than the 14 or 28 pins needed, and connect the wire to that.

    If you use any of the breakout boards to bring out the pins on the bottom of the Teensy 4.0, I find it difficult to solder in stacking headers on top, while having to solder in the connections of the breakout board.

    I generally prefer to put the audio shield on top. You could put it under the Teensy, though I tend to prefer not mounting a longer board like the Teensy 4.1 or the Teensy 4.0 with breakout boards on a shorter board.

    If you are doing a Teensy 4.0, Adafruit makes a stacking kit for their ItsyBitsy microprocessor, which has the same 2x14 + 1x5 layout as the Teensy:

    However, do NOT get the Sparkfun Teensy stacking headers if you aren't going to use a stacking header for the back pins. Unlike the Adafruit ItsyBitsy header kit, the Sparkfun kit has 2 13-pin headers and 1 7-pin header.

    If you are doing a Teensy 4.1, I don't generally see stacking headers that are exactly 24 pins long. You can get a larger stacking header, and cut it down. I pull out the next pin, and use a diagonal cutter to trim it down, possibly finishing it with a rotary tool like a Dremel (tm).

    The other way to do it is to have a parallel prototype board, and just connect the 28 wires in parallel. However, Paul always stresses that the wires between the Teensy and the Audio board should be as short as possible. Several boards that I've seen include (I use the DrAzzy board quite a bit):
    Last edited by MichaelMeissner; 06-06-2020 at 06:19 PM.

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