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Thread: Advice on low-profile headers to stack Teensy 3.2 + Prop Shield + TeensyView OLED

  1. #1

    Advice on low-profile headers to stack Teensy 3.2 + Prop Shield + TeensyView OLED

    Hey all,
    I'm trying to build the smallest package (height-wise) that I possibly can for a Teensy 3.2 + Prop Shield + TeensyView. Ideally, I would like to be able to separate all of the components if needed, and plug into a breadboard or protoboard. I'm sure I'm not the only one who's tried to do this, so if anyone has recommendations for headers, I would greatly appreciate it. My stack will be organized: TeensyView (top), Teensy 3.2 (middle), Prop Shield (bottom), then breadboard or protoboard. Using standard stackable headers makes my stack HUGE (see pic just for Teensy + TeensyView for illustration...with the Prop shield it would be close to 3" tall).

    I was looking at these Swiss Machine Pin headers as an option: https://www.sparkfun.com/products/743 and https://www.sparkfun.com/products/117

    Any thoughts/advice would be greatly appreciated. Thanks!

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  2. #2
    Senior Member+ defragster's Avatar
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    I tried machine pin headers - found them lacking insertion integrity. They just don't connect hard enough and get looser quickly. And they wouldn't do 3 layers with their short thin pins.

    Adafruit makes a short female header - about half the height? They are 5mm tall instead of 8mm and use normal pins on 0.1" spacing.

    Perhaps long pins on the T_3.2 where half above and half below then the adafruit low profile headers above and below facing the right way would be minimal height - but removable. But that wouldn't leave exposed bottom pins for a fourth layer PCB/PROTO.

    Those adafruit headers do feed through - unless solder fills it in.

  3. #3
    Senior Member+ MichaelMeissner's Avatar
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    I've done this, but if you want the minimum height, you are going to have solder the main components together. One thing is to make sure of is provide a way to press the program button. Fortunately, if you mount the prop shield on the bottom, the Teensy in the middle, and the TeensyView on top, the TeensyView has an opening to get at the button. Alternatively, you could have a wire to bring out the Program and Ground pins to somewhere else, and attach them to a momentary switch.

    I would suggest:
    • Get some long male pins, such as https://www.adafruit.com/product/400;
    • Cut the long pins to 2 sets of 14 pins each;
    • Cut a set of standard male pins to 1 set of 5 pins;
    • Use sandpaper or a rotary tool (dremel) to make sure the 5 pins will fit between the 2 sets of 14 long pins;
    • Mount the long pins with the plastic part on top of the prop shield, and measure the pin as it sticks through the prop sheild so it fits in your breadboard and/or female headers (initially keep it long enough for the full size female headers or breadboard -- you can always cut down the pins later if you use the low profile female header0;
    • Flip the prop shield over and solder the pins to the prop shield. Make sure you mount the pins in a breadboard, so that the two rows are parallel;
    • Also mount the 5 pins at the back of the Teensy, pushing the pin through so it just clears the prop shield, and solder those (you really only need the DAC pin);
    • Either solder wires to the front/back of the prop shield to bring out the audio and LED pins, or solder in a right angle header (female or male, depending on how you want to connect things);
    • Flip the prop shield over and put it in a breadboard. Use jumper wires to test the prop shield to make sure all of the connections are stable;
    • You should have the plastic spacer parts on top of the prop shield; Make sure there is enough clearance for the Teensy;
    • Now mount the Teensy, and solder each of 2 rows of 14 pins and the back row of 5 pins to the pins;
    • Using female jumper cables, make sure each pin is connected. I have a simple sketch that reads a pin number from USB, and then turns off the previous pin and lights up the indicated pin to verify that all connections are soldered;
    • Using diagonal cutters, snip each of the back row of 5 pins just above the solder joint. If you are bringing out the program and ground pins, solder wires to them first (ditto if you are bringing out the real time clock connection);
    • Take some normal male headers, and cut them to 2 sets of 14 pins. Push all of the pins out, and use the spacer as the spacer for mounting the TeensyView. Make sure the board isn't touching;
    • Solder the TeensyView in place and make sure all of the connections are solid.


    That being said, I am not that good at soldering, and if I rush, I find I either have solder bridges or things aren't connected. So take your time.

  4. #4
    This is exactly what I did and it worked great, thank you!

  5. #5
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    Short of directly soldering the boards together as MichaelMeissner recomends, you can look at the offerings from Advanced Interconnections or Mill-Max . Certainly not cheap, but, can be very low profile and reliable connections. They are available at Digi-Key or Mouser.

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    I've been evolving a pc board for an Artnet lighting controller (haven't we all ). When it came time to start thinking about how to package it, it became clear that I didn't wan't something tall-and-thin like what results from stacking Teensy + adapter + WIZ8x0io. Instead, I wanted something short-and-flat. I also wanted mounting holes and extra pins broken out to aid in debugging.

    My solution was to layout the Teensy and WIZ8x0io side-by-side and incorporate the needed parts of the Adapter Board into my pc board.

    So, just wanted to show another alternative. You are asking about "shortest package possible". Consider the possibility of laying out your components horizontally on a pc board (or proto board) rather than stacking vertically.

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  7. #7
    That's awesome, thank you both grease_lightning and markonian. The issue is that this is a controller for a wearable, so more than just flat I want the smallest package I can get by volume. But I have no doubt I'll get into crazier stuff markonian, and when I do, I'll try that .

  8. #8
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    Markonian is on the right track to keep the whole assembly as compact as possible. An additional twist I have done is to notch out the PCB to accommodate the height of larger modules like the wiznet 820/850. (apologies for the poor image)

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  9. #9
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    Quote Originally Posted by grease_lighting View Post
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    <drool>

    We're getting off topic. But that picture really made my day. I'd considered the notch but was thinking it would require one more daughter board. I didn't think of the simple pins inversion. That's really good!

  10. #10
    Senior Member+ MichaelMeissner's Avatar
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    Cool

    I tend to like various prototype boards. One of the boards that was nice for laying out a Teensy 3.2 and other components was the robot50.net board. It allowed you to lay out two parts in parallel. The maker is no longer selling them, but she has put the gerber files up so you can have your own made, and describes how she designed the pcb. She asks that you keep the roboto50.net on the silkscren:


    Alternatively, there is the Mint-tin size prototype board that fits in an Altoids (tm) mint tin:


    This is nice since it has 24 rows, you can use a Teensy 3.5/3.6 instead of the 3.2, and you can lay out a piece that is 0.4" wide with two parallel tracks on one side, and have a bunch of interconnects on the other.

    The same maker also makes some larger boards, as well as various sized smaller boards (the 1x2" board is just right for putting a Teensy 3.2 in it, with a row of pins on the outside and another on the inside for connections):


    Adafruit has its perma-proto series:


    I'm not a fan of busboard systems, since they tend to be singled sided boards, and the above boards are double sided, and look to be better made. That being said, busboard does have some interesting features (including 3 power rails on each side, which would allow for ground, VIN, 3.3v on on side, and ground, analog ground, 3.3v on the other).

  11. #11
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    My wish is that I could buy something similar to Adafruit's FeatherWing Prototyping Add-on boards, except these would have native Teensy 3.2 pinout. Imagine both vertical and horizontal expansion.

  12. #12
    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by markonian View Post
    My wish is that I could buy something similar to Adafruit's FeatherWing Prototyping Add-on boards, except these would have native Teensy 3.2 pinout. Imagine both vertical and horizontal expansion.
    You can use female stacking headers with large pins to create this for the 28 standard pins (the 5 pins in the back, the 4 pins inside, and the 10 pads underneath are problematical). Sparkfun has a kit made for Teensy 3.0/3.1/3.2/LC:


    You would use a prototype board with the stacking pins soldered in, and you can then attach things to each board. You can also order 18/20/40 pin versions of the female stacking pins, and cut them down to size (pull out the 15th pin, and use diagonal cutters, and sand down the cut -- be sure to cut in the middle where the pin was removed -- if you cut it too close, the last pin may come out):


    I've thought of using 20 pin headers to bring out the extra pins (DAC, Vbattery, Vusb, Aref, A10, A11) and/or the pins from the prop. shield.

    Alternatively if you want prototype access to all of the pins, including the underneath pads, you could get this:


    But frankly if you need more pins, it is easier to use a Teensy 3.5 or 3.6. Of course if you need even more pins, the same seller also has breakout boards for the 3.5/3.6:

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