Smart Watch with Teensy IC

[MichaelD33]

Hello,
I am working on building a custom smartwatch for fun, and I wanted to incorporate the MCU into the PCB, however, I do not want to buy the board and use that, I would rather use the IC itself, with a crystal and the rest of the components on a PCB. Can I pick one up? I can probably do the bootloading on my own, but I would need to bootloader and chip, or preferably the pre-bootloaded chip.

 

[vitormhenrique]

You can buy the MINI54 Chip for DIY Teensy with the bootloader https://www.pjrc.com/store/ic_mini54_tqfp.html

 

[MichaelD33]

You can buy the MINI54 Chip for DIY Teensy with the bootloader https://www.pjrc.com/store/ic_mini54_tqfp.html

Yeah, I saw that, but doesn't the teensy 3.1 use a ARM Cortex M4?

 

[Frank B]

Thats a fake question.. if he really wanted to build such a thing, he'd know more about the teensy, which chips are used, where to buy them and how the bootloader works...


edit: oh... ;-)

 

[vitormhenrique]

Teensy is a combination of the mini54 and a blank MK20DX256 (or MK20DX128 for Teensy 3.0).
The boaoloader is on the mini54 and it programs the MK20DX256 when you upload your sketch.

I think that is the way that it works.

Check Teensy schematics, I never made a DIY Teensy, but there are plenty topics on the forum about it.

 

[Constantin]

You need both chips if you want full Teensy functionality. The Mini54 is the bootloader while the MK20DX256 is the heart of the the Teensy 3.1. It's been deprecated and replaced by the MKL02Z. If you're interested, here is a eagle library or two of the parts in question.

You will want to follow Pauls schematics carefully to come up with a reference system that performs perhaps as well as the Teensy 3.x series.

You may be able to simplify the schematic somewhat, i.e. omit some ADC components if you don't need the ADC.

 

[pictographer]

Here you go: MK20DX256 and MINI54.

 

[PaulStoffregen]

If you don't need your product to be reprogrammable by USB, you can leave the MINI54 chip off the final PCB design. Code you develop with Teensyduino will generally work fine on a MK20DX256, but you may wish to edit usb_dev.c at some point, to remove the call to reboot. Without the MINI54, that will cause a fault that will stop your program.

Without the MINI54, you'll need to come up with some way to get your program loaded onto the MK20 chip. Some people have build special boards with just the MINI54. Others have purchased programmers from P&E Micro. You might also be able to get a distributor to pre-program your MK20 chips too.

Of course, if you want it to be upgradable by USB, using the Teensy Loader as if it were a Teensy board... well, that's why we sell the MINI54 chip, so you can make your own PCB that works the same as a real Teensy.