SMT Teensy 3.1?
- Thread starter dougm
- Start date
pictographer
Well-known member
I don't speak for PJRC, but my bet is a slightly smaller module without the USB connector or reset button would not have a positive return on investment. Without a smaller MCU, there really isn't much smaller you could make it and by doing these things, the result would be much harder for hobbyists and small businesses.
If your need includes something of value in addition to the Teensy, maybe you would do well designing and building this board yourself. The schematics and preprogrammed bootloader chip are available from PJRC. Several others have successfully designed their own Teensy boards.
Before you go do that, a good idea is a far cry from success in the market. If it's at all possible to test the market with some prototypes that are slightly too big and slightly too expensive, you're much better finding out whether anyone else is inspired by your dream before you exhaust your time and money.
If your need includes something of value in addition to the Teensy, maybe you would do well designing and building this board yourself. The schematics and preprogrammed bootloader chip are available from PJRC. Several others have successfully designed their own Teensy boards.
Before you go do that, a good idea is a far cry from success in the market. If it's at all possible to test the market with some prototypes that are slightly too big and slightly too expensive, you're much better finding out whether anyone else is inspired by your dream before you exhaust your time and money.
Height is my concern, not overall size, so it would be exactly the same module (including USB and reset button), just remove the TH .100 holes and replace them with the board edge connectors like the Xbee module has and maybe bring the connectors that are currently on the bottom of the current module out to the edge.
But it's good to know the boot loader chip is available, failing a module I can just integrate the Teensy circuit straight into my board.
Thanks,
DougM
But it's good to know the boot loader chip is available, failing a module I can just integrate the Teensy circuit straight into my board.
Thanks,
DougM
PaulStoffregen
Well-known member
Definitely making a custom board with the Mini54 is the way to go.
It's simply not economically feasible for PJRC to make different versions with more form factors.
It's simply not economically feasible for PJRC to make different versions with more form factors.
pictographer
Well-known member
Hmm... Still trying to make sense of this. The Teensy 3.1 is roughly 0.7" x 1.4" x 0.18". Since you're not removing the connector, the dimension I'd call height will remain 0.18". The edges of the board could be reduced by half the 0.1 for each through-hole for an overall reduction to 0.6" x 1.35". That's a very slight reduction.
Are you assuming the Teensy needs to be mounted to very tall headers and stacked on top of another board? Maybe there's another mounting approach?
The thinest approach I can think of would be to use flexible flat cable. I'd prep each TH with a blob of solder. Tin the pads on the cable. And reheat each pad from the side opposite the Teensy PCB or maybe just reheat the blob of solder in the hole.
If it needed to be automated, maybe this could be made to work with solder paste and reflow?
Are you assuming the Teensy needs to be mounted to very tall headers and stacked on top of another board? Maybe there's another mounting approach?
The thinest approach I can think of would be to use flexible flat cable. I'd prep each TH with a blob of solder. Tin the pads on the cable. And reheat each pad from the side opposite the Teensy PCB or maybe just reheat the blob of solder in the hole.
If it needed to be automated, maybe this could be made to work with solder paste and reflow?
I want to do a production run of these and didn't really want to reinvent the Teensy board, so having to reflow into the current header holes would be too weird to try to explain to a production house. So basically a production-ready version of the Teensy rather than a breadboard friendly version.
The overall height of the board, excluding headers, is fine.
Thanks, (and thanks Paul)
DougM
The overall height of the board, excluding headers, is fine.
Thanks, (and thanks Paul)
DougM
In general these modules use a solder mixture with a higher temperature than normal, so that when reflowing the module on another PCB, it does not reflow the components on the module itself again. I think the teensy is produced with a normal solder. Castellations are pretty standard. But if my memory does not fail me, I even remember having seen IPC specification for reflowing using through holes.
If anybody ever wants to try to make modules using castellations, be sure to specify the location for the mouse-bites, as not to damage the castelations. I have actually experienced a production company that used the castelations as mouse bites.
If anybody ever wants to try to make modules using castellations, be sure to specify the location for the mouse-bites, as not to damage the castelations. I have actually experienced a production company that used the castelations as mouse bites.
GremlinWrangler
Well-known member
Bootloading a Teensy is both complex and simple.
The main mK20 can be empty at build and as such can be got anywhere. The magic is in the mini54 which if triggered will wipe the Mk20 and then load a USB bootloader to the Mk20 ready for it to get the actual system code (and also means that almost anything that bricks the Mk20 can be fixed by pressing the button to bring the mini54 into action. The mini54 the code is propriety but you can buy bulk ICs pre programmed:
https://www.pjrc.com/store/ic_mini54_tqfp.html
Note further down the page links to adventures from various projects making custom Teensys.
It is also possible to make a custom 'loader' mini54 board which can be used to factory program any number of MK20s if that's what your project requires, but again the actual implementation is non trivial and you lose the ability for the end user to reprogram (which may not be a bad thing of course!).
The main mK20 can be empty at build and as such can be got anywhere. The magic is in the mini54 which if triggered will wipe the Mk20 and then load a USB bootloader to the Mk20 ready for it to get the actual system code (and also means that almost anything that bricks the Mk20 can be fixed by pressing the button to bring the mini54 into action. The mini54 the code is propriety but you can buy bulk ICs pre programmed:
https://www.pjrc.com/store/ic_mini54_tqfp.html
Note further down the page links to adventures from various projects making custom Teensys.
It is also possible to make a custom 'loader' mini54 board which can be used to factory program any number of MK20s if that's what your project requires, but again the actual implementation is non trivial and you lose the ability for the end user to reprogram (which may not be a bad thing of course!).