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Thread: Teensy Express

  1. #1
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    Teensy Express

    Just wanted to let you guys know about my next project dubbed Teensy Express.
    I have posted info on hackaday.io, though only one of the daughter cards is pictured atm https://hackaday.io/project/11717-teensy-express
    The goal of this board is to create a solderless expansion board with easily swappable project boards. I chose the PCIe mini connection due to high pin count, availability and no need the have a male connection on the daughter boards. This will allow users to simply design them using a prepared .brd file. The only constraint being 1mm board thickness.

    It'll make much more sense as soon as I render the motherboard image.
    Any thoughts and comments are welcome.



    The pictured board is just an exercise in what can be done with the daughter board size (this one being cca 6x4cm, maximum 6x5cm). There is 3mm space height on the bottom side, enough for many parts. This example includes 10DOF, ESP12, MicroSD slot, CAN-BUS transceiver, and an LTE/GPS module (with SIM). All able to work simultaneously with the Teensy.
    4.2V and 3.3V is supplied to this daughter board via the motherboard, from a battery or external VDC up to 14V.
    Last edited by Fyod; 05-31-2016 at 09:10 PM.

  2. #2
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    Here's a very basic look at the main board.



    The actual board has a different outline for routing wires and fitting the board into 3 different Hammond cases.
    This render lacks the PCIe mini connector, but its placement can be seen. Also, the headers for the Teensy will be much different. I have done lots and lots of research and come up with a way to break out all pins (including the bottom ones) and making the headers solderless press-fit. Thus the Teensy can be removed whenever needed.

    My goal here is to fill in what is in my opinion a very important gap. Many users breadboard, while others go all out and make dedicated Teensy-based boards. There's not much in between.
    The problem with breadboarding is that many would like to make a professional, permanent solution, but lack the skill or time to make a dedicated Teensy-based board, or the incentive to do so is low.
    An easily swappable peripherals board can save lots of time and money, while still looking professionally made and easy to troubleshoot.

    I have no idea if this is something interesting for the community, but I've already come up with about 6 projects that would otherwise end up with hotglue and wires everywhere (I don't breadboard much), so I'm excited to get atleast a couple working really soon.
    Last edited by Fyod; 05-31-2016 at 09:08 PM.

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Are you going to sell these? Maybe on Tindie?

  4. #4
    Quote Originally Posted by Fyod View Post
    Also, the headers for the Teensy will be much different. I have done lots and lots of research and come up with a way to break out all pins (including the bottom ones) and making the headers solderless press-fit. Thus the Teensy can be removed whenever needed.
    That sounds nice!!

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    Quote Originally Posted by PaulStoffregen View Post
    Are you going to sell these? Maybe on Tindie?
    Certainly hope to, yes.

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    Finally got the first boards in and I'm really excited about this.



    This is the main board and two sizes of express cards. The one on the right is an ESP board and the thin one will be GPS only board.
    The pictures don't show the solderless headers for the Teensy, still waiting for those to come in. The Teensy will be removable without any tools.



    Its alive! I chose a Wago connector for the 6-16V input since it is very easy to use. The battery connector is JST, but can be replaced with a similar Wago.
    The battery is charged by the input. There's also a tiny switch under the Teensy so that the Teensy and any peripherals can be turned off without unplugging anything.
    Board edge cutouts in front of the VIN/BAT inputs allow the wires to go under the board and to the opposite side if needed.
    A battery can also be placed and soldered directly onto the board. You can see two pads behind the Teensy that are masked if unused.



    This card is for prototyping and demonstrates the largest card size.
    All Teensy pins except 33 are broken out and there are rails for 3.3V, VBAT, GND. I accidentally had them omit the silkscreen.
    All express cards are firmly latched in place and easy to swap.
    Maximum layout space on the express card is about 30cm2 on each side, with 3mm component height on the bottom, which allows a large number of parts, pads, etc.



    This is a black mask 3/4 card with some awesome features that I'll be working on soon.
    All of the cards slightly stretch beyond the latching points and end flush with the motherboard. This will allow for mechanical parts (switches, pots, card slots) to be mounted at the very edge so that they can be manipulated from the outside when the project is mounted inside one of the cases.
    Last edited by Fyod; 07-19-2016 at 04:17 AM.

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    I designed the board so that it would fit into three Hammond enclosures for a very professional result.








  8. #8
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    Very useful indeed. When will they be available? Do you plan to distrubute them in Europe as well?

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    Senior Member Ben's Avatar
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    Very interesting! I'm curious to see the solderless solution for attaching the teensy and accessing the bottom pins!

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    Surely with a board this size you should increase the pin count right?
    Multiple PCI-e slots in parallel would be good with tristate buffers

    Actually I take that back, I see what you're going for here. I'd be very interested to know how you've done those solderless push connects

    As a crazy idea you should make the end of the PCB itself a PCI-e connector. That way you could have a master board that all these boards plug into
    You could even daisy chain them into one long length
    Last edited by Xenoamor; 07-19-2016 at 11:11 AM.

  11. #11
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    Quote Originally Posted by luni View Post
    Very useful indeed. When will they be available? Do you plan to distrubute them in Europe as well?
    I have a few I could send out if interested (once the headers arrive). I'm in Europe so no problemo.

    Quote Originally Posted by Ben View Post
    Very interesting! I'm curious to see the solderless solution for attaching the teensy and accessing the bottom pins!
    Thanks! I just hope I got my measurements correct. The Teensy should sit slightly closer to the main board than in the pictures. The height is important because the Teensy bottom pins are connected via pogo headers.

    Quote Originally Posted by Xenoamor View Post
    Surely with a board this size you should increase the pin count right?
    Multiple PCI-e slots in parallel would be good with tristate buffers

    Actually I take that back, I see what you're going for here. I'd be very interested to know how you've done those solderless push connects

    As a crazy idea you should make the end of the PCB itself a PCI-e connector. That way you could have a master board that all these boards plug into
    You could even daisy chain them into one long length
    I had a similar idea, but all PCIEm cards need to be 1mm thick and the main board here is 1.6mm for sturdiness and also aluminium cases most often have 1.6mm slots so this prevents the board from flopping around inside.

    The primary ideas are that
    1] It is very easy to design a board. I will provide blank eagle templates where the user only needs to connect to the mapped Teensy pins so to make a finished solution, you don't need to make a Teensy "clone", since this can be a bit more complicated and usually only has one certain use. Also the power input is taken care of, so you don't have to design any external circuits for it.



    2] You can design any number of boards, swap them, reuse them, depending on the intended use. Eg. you make and ESP8266 board an when the ESP32 comes out, all you need to do is fab and swap out the card, upgrade your program. No hassle.
    Last edited by Fyod; 07-19-2016 at 04:28 PM.

  12. #12
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    I have a few I could send out if interested (once the headers arrive). I'm in Europe so no problemo.
    Perfect, I'd be very interested in getting one or two. Any price ideas?

    I have to develop a control unit for a mechanical testing device. I want to do the low level motor control with a simple grbl board which would fit nicely on the extension board. If your Eagle template is available already I could start working on the layout next week.

    Best wishes
    Lutz

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    I'll post the uploaded files in a bit.

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    Maybe add a few Grove connectors too.

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    Those can easily be added to a custom daughter board.
    I would in fact recommend adding some kind of molex or atleast throughole pads that break out the pins that are not needed in the custom design. So say your custom daughterboard only uses 10 Teensy pins for the peripherals on that board - e.g. add a connector or make 10 SMD pads hidden on the bottom in case you need them later.

    Another idea is that you could use Molex board/board connectors (although some require advanced soldering) and this would allow you to stack more boards on top or add/remove peripherals depending on the design or customer requirements.
    Also, as one member PM'd me, you can design multiple daughter boards and your customer can choose price/specification tiers and it also allows them to upgrade later (and without any knowledge of electronics, since the board is easy to swap out, just like laptop RAM).
    E.g. I have designed daughter boards for GSM GPRS, HSPA, LTE without having to make a full design for each of them, eliminating the redundancy of parts that are always the same (CPU, bootloader, power, basic connections).

    One other thing I haven't mentioned is that these boards do not and will not have any commercial markings. I would like to allow Teensy users to take their project to a more professional level, and it doesn't look right when parts of a project have Seeed and Adafruit logos everywhere. Take credit for the project as a whole.
    Last edited by Fyod; 07-20-2016 at 02:36 PM.

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    Thanks for the files, looks good. Following quick observations / questions:
    1. The origin of the board is at bottom middle, this makes the free version complain about parts which are outside the allowed area for the free version (100x80mm / right / top of the origin). Moving it so that the origin is at bottom left would be great.
    2. What are the 4V2 pins? V_USB? Is the 3V3 derived from the Teensy or is it regulated from the power input?
    3. What are the "latch" connections meant for?
    Last edited by luni; 07-20-2016 at 02:34 PM.

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    1. Whoopsies, I'll fix that asap.
    2. 4V2 is the input from the 6.5V-16V DC/DC coverter and/or battery. When both are connected, the battery is charged by the main input. If the main input is removed and a battery is present 4V2 is VBAT = any voltage that the battery is supplying. 3V3 is in fact from the Teensy regulator so for higher current 3.3V components, I would definitely recommend T3.2. The voltage output of the converter can be changed to different values by replacing two resistors, but battery charging wouldn't be possible (say at 5V output).
    3. The latches are the ones that hold the daughterboard in place. They can be connected to Teensy Touch sensing pins so you could for example stop your program if someone touches the latches to remove the board.

    Edit: .brds updated
    Last edited by Fyod; 07-20-2016 at 03:01 PM.

  19. #19
    Senior Member Ben's Avatar
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    The more I think about it the more I like this whole concept. Do you have any pins left unused on the PCI connector? If yes, maybe make the motherboard compatible with the upcoming K66 Teensy? I think you can sign me up for preorder

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    Yep, I'm counting on making a K66 version. It should support all pins, since this board breaks ot a lot of Teensy pins twice.

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    4V2 is the input from the 6.5V-16V DC/DC coverter and/or battery. When both are connected, the battery is charged by the main input. If the main input is removed and a battery is present 4V2 is VBAT = any voltage that the battery is supplying. 3V3 is in fact from the Teensy regulator so for higher current 3.3V components, I would definitely recommend T3.2. The voltage output of the converter can be changed to different values by replacing two resistors, but battery charging wouldn't be possible (say at 5V output).
    I currently don't have use for the battery but use a 5V input and often need plenty of 3.3V power for external modules. Question is: can I adjust the dc/dc converter to 5V->3.3V and then use the V4.2 pins as 5V supply? (A schematic of the main board would be great!)

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    I'll try to think of something.
    What would the current requirements be for each voltage?

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    Reviewing the power requirements of my recent projects I think a more genreral approach could be quite useful:

    Click image for larger version. 

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    The DC/DC converter should be solderd in by the user depending on his/her Voltage requirements. Following scenarios would be possible:

    1. Everything powerd from USB:
      Place jumper 1, use V_USB (5V) and/or 3V3 on the extension board
    2. External 5V supply:
      Place jumper 2; apply 5V to the V_sup connector; use use V_sup and / or 3v3 on the extension board
    3. Large 3V3 load on extension board:
      Place jumper 2, apply 5V to the V_sup connector; solder 3v3 dc/dc converter to main board, use use V1(3V3) and/or V_sup(5V) on the extension board
    4. Special voltage (say 12V) required on extension board:
      Place jumper 3, apply 12V to the V_sup connector; solder 5V dc/dc converter to main board, use use V_sup (12V), and/or V1(5V) and/or 3V3 on the extension board


    ... just my thoughts.
    Last edited by luni; 07-21-2016 at 02:18 PM.

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    You can currently power everything from VUSB (uncut Teensy trace). There's a diode protecting the DC/DC conversion side, but not the battery (one must not be plugged in in this case).
    4V2 then becomes 5V (USB), 3.3V is still supplied from Teensy's regulator.

    The jumper idea is a good one, only problem is that I have pretty much run out of any available space on the input side in favor of the Teensy and as much space for the mPCIe as possible.
    I could put the jumpers on the bottom for easier manipulation, and voltage adjustment resistors too. I'll take this into consideration for future designs.
    The converter is QFN so I don't want to leave the burden of soldering those on the users

    For higher current stuff like LED strips, I would recommend adding an input from an external source on the daughterboard, and connecting the 5Vext input to "4V2", thus powering the Teensy.

    Here's a simplified schematic

    Last edited by Fyod; 07-22-2016 at 01:13 AM.

  25. #25
    Senior Member Ben's Avatar
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    My two cents: IMHO the ability to charge the Lipo over USB is a must-have, plus the motherboard should be able to supply 5V. This way the system always has 5V available. Pretty much like this product: https://www.adafruit.com/products/1944.

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