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Thread: Feedback Wanted: Teensy 3.2 "Stamp"

  1. #1

    Feedback Wanted: Teensy 3.2 "Stamp"

    Hello,

    I recently put together this little board, and I'd love to get feedback!

    • It should have 100% software & functionality compatibility with the Teensy 3.2
    • It's programmable via Teensy Loader or Teensyduino via Arduino (via official PJRC bootloader)
    • Programmed via USB with a custom/simple/tiny/cheap micro USB cable to 5x pogo pin adapter
    • Overall size is exactly 30 x 30 mm, 56-pins (4 sides x 14), 2.0 mm pitch, 1.0 mm thick PCB
    • Exposes all equivalent Teensy 3.2 pins, including all of its underside pins
    • Designed for a surface-mount landing pattern, no through holes necessary
    • Can be reflowed in place, also large enough to be soldered by hand
    • Design has been assembled, verified working well enough to program the chip and run blink code
    • Has an integrated 32.768 kHz RTC crystal

    Some specific questions:

    • Do you see utility in this?
    • How much would you want to pay for something like this?
    • Should it be even smaller? There's room, since the passives are 0603 and still have plenty of space between them. I'd have to reduce the pitch to 1.5, 1.27, or 1.0 mm, which could make hand-soldering the board in place much more difficult.
    • Do you think there will be any problems regarding re-reflowing this onto another PCB? If so, any ideas about how this could be potentially mitigated?
    • Is there any interest in a 3.5 or 3.6 version of this sort of thing?
    • Is there anything else you'd like to see included onboard?
    • Is around $10 a reasonable cost for the USB to pogo programming adapter?

    Any other thoughts?

    Thanks!

    Dan






  2. #2
    I really like what you have done - I have struggled to package T3.6 and to a lesser extent T3.2 and your alternative potentially gives options that are not available any other way.

    For me though, I value mm˛ and while you have acheived a ~20% reduction in length, your board is ~40% increase in real estate. I don't use the underside pads, and this is maybe where your board comes in very beneficial.

    I love the castellations that should allow a flush-mount to a daughter/parent board, but I'm not sure I would want to reflow though - I would want to test my other board then hand-solder to minimise scrap risk and cost.

    $10 for the Pogo board seems good to me.

    I would love to see a T3.6 with alternative footprints, a 30x30 with deleted SD slot, and/or the USB connector and/or the USB Host. I guess I will end up one day having to roll my own.

    Keep up the good work and best of luck with your project.

  3. #3
    Member dauntless89's Avatar
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    Quote Originally Posted by loglow View Post
    Some specific questions:

    • Do you see utility in this? Yes.
    • How much would you want to pay for something like this? Comparable to a Vanilla 3.2. Not much/any extra, at least (as far as my concern goes).
    • Should it be even smaller? There's room, since the passives are 0603 and still have plenty of space between them. I'd have to reduce the pitch to 1.5, 1.27, or 1.0 mm, which could make hand-soldering the board in place much more difficult. The main drawback as I see it is the non-standard pitch. It would be nice to not have to sacrifice breadboarding ability, but you're not going to make it smaller or even keep it the same size with a .1" pitch. I suppose everything's a tradeoff.
    • Do you think there will be any problems regarding re-reflowing this onto another PCB? If so, any ideas about how this could be potentially mitigated? Nothing to add...
    • Is there any interest in a 3.5 or 3.6 version of this sort of thing? Yes.
    • Is there anything else you'd like to see included onboard? Not off hand.
    • Is around $10 a reasonable cost for the USB to pogo programming adapter? Sure.

    Any other thoughts?
    Replies in red.

  4. #4
    The T36 is approximately 10mm too long for my next project that needs dual Can Bus but where the SD is not essential.
    I would love to see something like this that was open source (assuming PJRC can still be as profitable selling bootloader chips instead of full boards). I realize that might be dreaming, but I would love to get my hands on a KiCAD model of T36 reference board in a reasonably small form factor that prefferably I could buy off-the-shelf in a known-good working design, then edit/move/remove unwanted function and features when I want to build 100.

  5. #5
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    This would be awesome, especially if it was reflow compatible.

    Have you built one, or is that a render? Did you cannibalize an official Teensy for parts or are you working with PJRC to deal with the bootloader?

    I'm currently working on a project in which I want to embed a Teensy, and was going to try to engage PJRC to see if I could license and embed a 3.2 on my I/O board (main CPU is an RPi, Teensy drives the control panel)

    A feature I'd love to see is a pogo compatible debug header (that does the "right thing" with the boot loader and it's reset pin to get it out of the way of a JTAG debugger)

    -- pryankster

  6. #6
    I absolutely love love love love love this concept. I'd very much appreciate a JTAG header.

  7. #7
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    If he puts the PJRC bootloader on the USB separate unit (if not already done), you wouldn't need bootloader chips on those 30x30 mm boards, this would reduce the cost factor if using 1 programmer for many teensy 3.2 boards, as well as allow JTAG ability since the bootloader is not interefering with the chip

  8. #8
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    I would definitely use it. I have done dozen's of teensy projects and specified many 100s of boards but I never use breadboards with them. Custom base boards and daughterboards end up with extra volume and it is expensive soldering headers and sockets. If you could get the volume up I would like to see similar prices to Teensy LC and 3.2 (and both options). The form factor reminds me of PLCCs. It might be interesting to consider that as I have seen people doing PCBs that fit in PLCC sockets.

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