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Thread: Any Plans for a Teensy Board with Bottom Pads on Top?

  1. #101
    Quote Originally Posted by PaulStoffregen View Post
    I'm pretty sure Adafruit could make a Teensy clone or work-alike product if they really wanted. Limor has the hardware skill and Kevin & Phil B have the software talent needed. Tony & Scott (in Seattle) are also very capable programmers, as anyone can see by the results with their fork of Python.

    Ethics and good business sense, rather than technical chops, are mainly what's stopping them from doing anything like this. First and foremost, Limor and Phil T are good people. They also have a very successful business model, which involves higher profit margin than Teensy, and a very different sales focus on novices and casual users, rather than the more advanced but relatively small ground of people best described as having "outgrown Arduino" and needing more powerful hardware & libraries.
    Oh they certainly have the skill, but I specifically mentioned "polish". I never found any of their software polished and optimized. Especially not in the way Teensy stuff is. Likely they are always too busy on the next big thing. I didn't want to insult anyone. Sorry for any offence.

  2. #102
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    I'll add my 2 cents, because I love Teensy so much (Great Work, Paul!!!! Thanks!!!) I can't resist.

    I've successfully used 3.2 on some projects, with excellent results. At the moment it's my OS-less platform of choice. Killer feature is all those interrupts available!!

    I'm now exploring 3.6 because I need USB host and uSD support; great to have both onboard!
    3.2 and moreso 3.6 have even too much power, RAM and Flash space for my needs (not that I'm complaining).
    Price is very nice for both 3.2 and 3.6. Personally I don't need to save a few bucks going with LC or so.

    What I'd love:
    Low-power versions. Really optimized from the ground up for low power (both while sleeping and while working). Most of my projects are battery-powered or solar-powered
    Mounting holes somewhere in the PCB.

  3. #103
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    Quote Originally Posted by Cosford View Post
    Without wishing to make too strong a case, I thought I might just describe my usage of the Teensy 3.2 in a product.

    We required access to more GPIO than what was accessible via the through hole pins headers, and didn't have the space on the PCB to cater for the 'long' form factor used on the larger Teensy boards.
    Instead, we chose to design an adapter board which would add a second row of 2.54mm pins on each side of the 3.2 - with connections made to the bottom pads via 'half-vias'. This provided the advantage of access to these GPIO whilst making the overall size of the Teensy itself only ~5mm wider, in a robust form.

    Of course, this only helps on custom PCBs or stripboard designs - as if placed in a breadboard, the pins would be shorted together. However, I do wonder if there might be a business advantage in providing a particular version of a Teensy board in this type of form factor, specifically aimed at product development or small production runs. I'm conscious though, that PJRC aims to limit the amount of support it can offer to designers implementing the board in commercial designs.

    Just a few cents of my experience working with the boards in a commercial environment.
    Thought I would address the breadboard issue a bit more, in regards making a T3.x with additional parallel rows of pins on the top and/or bottom edges. Cosford mentions here a viable solution.

    Also, for people adamant about breadboards, they are probably not using the underside pins in an case ... and in regards the breadboard shorting the side-row pins out, all you need do is not install the parallel side-row headers when using a breadboard. Also, unless I am mistaken, I/O pins on T3.x modules are "floating" and not even connected to the pads, until this is specifically done in software.

  4. #104
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    theyre not floating as in INPUT. the pin is actually DISABLED by default.

  5. #105
    Quote Originally Posted by PaulStoffregen View Post
    @tonton81 - There's no need to get upset. I see this mainly as a brainstorming session. We have this conversation in the lead-up to every new Teensy model.



    Please let me explain how the Teensy panels are designed for manufacturing. Hopefully a picture will help.

    Attachment 12379

    Now the panels don't necessarily *have* to be made this way, but this shape is the result of years of gradually refining things with the contract manufacturers we use (PJRC doesn't have its own pick & place or reflow machines).

    The left and right side of each Teensy are made by routed slots in the panel. The top and bottom are V-score in the panel, which a machine uses to cut the panel apart after it's fully built. V-score can't be used along the edge with the USB connector, because it overhangs the edge of the PCB.

    The rigidity of the panel is a big issue for manufacturability. The pick & place machine moves very fast. If the panel flexes or vibrates, they have to run slower or risk parts shaking loose or off-center. Years ago this was an issue when we had longer slots. As you can see in the photo, we redesigned the panels to use short slots. A big unused strip in the center of the panel acts as a stiffening bar. When we added that, it dramatically reduced the vibration during assembly. It's one of many little refinements we've made over the years.

    Another little feature you might notice in the picture are the 6 tooling holes in the edge of the panel. Currently we used only 2 of these. The contract manufacturer has a jig that was specially made for Teensy which pins that fit those 2 holes, and a spring loaded horizontal clamp on the other side. Without such a jig, they need to carefully align each panel to the solder paste screen. The jig lets them do this alignment once per run, and they can put extra time & effort into getting it really accurate if it's done only once. Then each panel gets placed quickly and easily with excellent repeatability thanks to the jig.

    Just because we have a very well refined process doesn't necessarily mean we're forever locked into doing things just one way. But I think anyone can see how requiring one or both of the long sides to have routed slots rather than V-score is a huge change to the way we do the manufacturing!

    A few years ago when Particle Photon (then "Spark") made their board with castellated edges, everyone was asking for this feature. But it requires using slots the define nearly all edges of the board, with "mouse bite" tabs. I saw those guys at a Hackaday event and asked if they'd had issues with the panel rigidity. They didn't answer with any specifics, but it was pretty clear that had been a big pain point. They wouldn't say what they'd done to deal with the issue. Maybe they've made some sort of carrier to secure it during pick & place? Maybe their panels are much smaller? Or maybe they've just tuned their placement process (likely running slowly) and just accept a higher failure rate or more rework?

    On a personal level, I like to spend my time focusing on developing the software side and helping people get their projects working. Documentation is also a big goal, though you might not always know that from the sorry state of many of the web pages. Still, I *want* to work much more on that side.

    Experience has shown that manufacturing problems absolutely kill any hope for software development & documentation, and even support suffers pretty badly. It's also incredibly stressful. Maybe this would be difference it PJRC was a huge company, but the reality is we're just 4 people and a couple contract manufacturers. Even with things as well refined as we have them now, problems happen all the time. It's just a fact of life in manufacturing anything. For example, just a few days ago we had a high failure rate in part of a batch. The bed-of-nails test just gives a pass vs fail. To actually diagnose *why* they failed requires quite a lot of my attention. Let me tell you, this has a way of suddenly becoming the very most urgent thing when we have customers waiting! In the case last week, it turned out a few of the PCB panels with marked defects (every panel gets electrical test at the PCB manufacturer) got built by mistake. Nobody noticed the remnants of the Sharpie X marks. I didn't even see them while handling the boards, until after I'd gotten info from the tester and was looking around the boards under the microscope! But ultra-urgent problems aren't always a quality issues. Pins starting to wear out and sticking on the bed-of-nails testers are another one that comes up occasionally. But just as often, something comes up that's entirely new and requires "drop everything" immediate attention to solve, if we're going to get everyone's orders shipped.

    So while I'm not saying absolutely no to ideas like castellated edges, I do have a very strong desire to stay with this well tested panel design. Getting another jig made isn't too bad, under $1000 as I recall. But a panel using almost all routed slots with only small mouse bit tabs to hold the boards is a direction PJRC almost certain will not go.

    Apologies for commenting on the rather old post, but this gave me an idea:

    How about making a board with castellated edges specifically for bridging the bottom pads to another board?
    The board would be long and thin, but have no actual components on it, so pick-an-place problems wouldn't be an issue.

    It would look something like this:



    The bridge would offer a simple way to get to all the bottom pads. For breadboarding, the extension board would just break out all the pads as pins, but there is no reason why something like an audio board or eMMC adapter couldn't be made to fit the same bridge. The only drawback that I can think of is that the users will need to do some extra soldering.

  6. #106
    Senior Member+ defragster's Avatar
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    hubbe - there are some published OSH designs for similar boards for Teensy - Frank B made one for T_3.2 that I mounted and used. And a BreakoutBoard that brought the bottom pads out to rows that I used to mirror the T_3.2 to the T_3.6 during that Beta. It works well and OSH can make the boards. The one by Frank brought them to a compact square grid on the end. Links are around somewhere ...

  7. #107
    Senior Member+ MichaelMeissner's Avatar
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    Here are the FrankB boards for Teensy 3.2:


  8. #108
    Senior Member+ KurtE's Avatar
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    During the 3.5/6 beta I did my own one as well for those boards... I assembled one.
    Click image for larger version. 

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    I did it as a double row, which worked, but then was not good for breadboard or the like. Could have done another one, but for simple breadboard like applications...

    I used a few from Talldog, like: https://www.tindie.com/products/logl...on-a-standard/

  9. #109
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    I do the same with my 3.5/3.6's, I just put breadboard header extensions between the teensy and breadboard on the outer edges so it's sits high above the breadboard, allowed me to add jumper wiring female connectors when needed during testing on the other pins

    Click image for larger version. 

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