Teensy (ATmega32u4 USB dev board) in stock!

Teensy Lrg
The Teensy is a complete USB-based microcontoller development system, in a very small footprint! All programming is done via the USB port. No special programmer is needed, only a standard “Mini-B” USB cable and a PC or Macintosh with a USB port.

Key Features:

  • USB can be any type of device
  • AVR processor, 16 MHz
  • Single pushbutton programming
  • Easy to use Teensy Loader application
  • Free software development tools
  • Works with Mac OS X, Linux & Windows
  • Tiny size, perfect for many projects
  • Available with pins for solderless breadboard

Comes with assembled Teensy board (ATmega32u4 with bootloader preinstalled) and header to allow easy breadboarding. We suggest using AVR-gcc (like WinAVR) with the LUFA library or ‘Teensyduino’ Be sure to check out the multiple resources available at PJRC!

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  1. Hello,
    what license is it distributed under?

  2. paul, good question…we’ll ask!

  3. I got instant cavities from the sheer cuteness!

    But in all seriousness, their site mentions a footprint on the bottom for an optional 3.3V regulator, but they don’t say if it’s the 3-pin or 5-pin version. Could you flip it over and tell us what you see? Thanks.

  4. @Phil: Regarding http://pjrc.com/teensy/schematic.html

    From the schematic, it looks like the 3-pin version of the MCP1825. But even still, is the footprint for the DDPAK-3, the TO-220-3, or the SOT-223-3? It’d be nice to know.

  5. its SOT-223

  6. Thanks for the info about the regulator. Were you able to find out about the license?

  7. no response to my email, you may want to try asking them as well?

  8. There was a big curfuffle about the licensing on the arduino forums when the project was announced there.

    From what I can remember the bootloader is closed source and getting the bloke behind it to admit that was like pulling teeth.

    Might be worth searching out the thread.

  9. Hi, Paul here, the guy behind the Teensy design.

    First, let me apologize for the delayed response. I had a major deadline on Monday (the day this question was asked) that put pretty much everything on hold last week. Only now, Thursday morning, I’m finally getting caught back up.

    Regarding licensing, the Teensy is not open hardware.

    However, all of the example code is open source under very permissive licensing and the design is well documented. The goal is that any projects you create are not encumbered. Projects created using the Teensy can be distributed under almost any open source license or can be turned into proprietary products**.

    I know there are some people who feel very strongly regarding open hardware philosophy. The development of Teensy has been funded by a business model which doesn’t enable open hardware. I really do want to facilitate and help you with your project and if you have a concern about licensing or I have missed some detail that will encumber you, please do email me at paul at pjrc dot com. However, the Teensy is not intended as an open hardware project which can be cloned like the Arduino (eg, Seeed Studio’s Seeeduino).

    Regarding the 3.3 volt option, the board has a place for a MPC1825 voltage regulator. The full part number is MCP1825S-3302E/DB. Here is a link to the Digikey page for this part:


    To convert to 3.3 volts, you need to solder the regulator to the bottom side. There are 3 solder pads. You need to cut apart the 2 pads labeled “5V” and solder together the 2 pads labeled “3V”.

    Atmel does not specify the chip to run beyond 8 MHz with 3.3 volts, even though it usually will run at 16 MHz, at least at room temperature. Still, if you are concerned about reliability, you should set the clock prescaler to 8 MHz. If you are using C, this is easy, just do it at the beginning of your code (as all the example do). The default at boot is only 2 MHz, so unless you want only 2 MHz, you have to set it to your desired speed anyway. Also make sure you change F_OSC in your Makefile.

    If you are using the Arudino software (with Teensyduino), you will need to edit boards.txt, and also edit line 38 in wiring.c. There are 2 copies of that file depending on which USB option you’ve selected, so make sure you get the right directory. On my to-do list for the next version is making that automatically adjust itself based on boards.txt.

    Also on my to-do list is a page with detailed instructions and photos for the 3.3 volt conversion. Really, it’s coming soon, honest. As a temporary fix, I added the full part number onto the schematic page.

    Please do email me if you have any questions. I do try to answer every message, though admittedly I do get behind from time to time too. I am only human and I’m sure there’s details I’ve missed. I also have a VERY long to-do list of additional documentation and features to add to the Teensy, which will be slowly appearing over the next few months.



    ** When using Arduino, some LGPL code from the Arudino Team is built into your project. This can have implications for proprietary projects. I have been slowly replacing this code, in most cases with optimized MIT licensed versions (eg, digitalWrite is more than 2X faster than the original LGPL version).

  10. The page with instructions and photos for 3.3 volts is now online.


  11. Paul–looks great, I’ll go order a couple. I’ve been hoping someone would do a small breakout board for this device. I don’t care about Arduino licensing blah, but is it using Atmel’s USB bootloader for this part, or a custom one? And are all of the pins brought out to allow it to be programmed directly using the SPI pins?

  12. Anyone knows of a similar board which is open hardware?

    Specially interested in the direct USB feature.

  13. Looks like the closest open hardware equivalent is the Micropendous2. However, I haven’t found any source for actual hardware, so I went for the Teensy. So far, it works nicely.

  14. Amanda, you can program it using SPI BUT!! the super duper RESET gets in the way, you have to cut tracks etc. I purchased one of the TEENSY++ baords from Paul and used ISP to program it which erases the boot loader, then I discovered later that Paul would not give me a copy of his precious bootloader so I could restore normal functionality, like someone else already menttioned it was like extracting hen’s teeth getting a simple NO YOU CAN’T have it answer from Paul. A nice idea however PCB board quality leaves a lot to be desired tracks lift easily etc, I was excited about this board UNTIL I started exchanging emails with Paul and for the life of me I cannot work out what is so valuable about his boot loader

  15. Joe: size. Paul’s bootloader takes up much less space than the standard Atmel one. I’ve been having fun with the two Teensys that I ordered from ladyada (and I really like the part!), but I agree, build quality is serviceable but not great. That said, for the price I’m not complaining.

  16. joe/amanda, thanks for the feedback. I am planning a different (not as teensy, different layout/bootloader, etc) atmega32u4 breakout to offer in parallel, and will incorporate your suggestions.

  17. I got a Teensy straight from PJRC, and have been mostly impressed. What I’m less impressed by, however, is the closed-source bootloader.

    Like many a hobbyist, I use development boards like the Arduino, Seeeduino, Teensy, etc.. for prototyping designs whose chips won’t be on dev boards, but rather soldered directly into the final board.

    Even though I can put the LUFA loader on the Atmega32U4, prototyping on the Teensy is diminished, because I *know* I’ll have to splat a different bootloader on the chip in the final design.

    Either that, or I have to splat a different bootloader on the Teensy itself, which sounds to be a PITA.

    Limor, I look forward to seeing your Atmega32U4 breakout.

    Paul, if you’re listening, please reconsider the closed-source status of your excellent bootloader.


  18. Hi, Paul here, creator of the Teensy.

    First, if you received a Teensy with a manufacturing defect of any sort, please contact me directly, by email ([email protected]) or by phone at 503-625-9328 (USA, pacific time zone). Even if you purchased it from Lady Ada, if it was a manufacturing defect, I will give you a warranty replacement. So far, I have heard only one report of a USB connector coming off the board, and I have been unable to convince that person to return the board for a replacement. Lady Ada has not reported any defective returns.

    Regarding the bootloader code, I have and still am considering some sort of licensing. Again, if you need this, please contact me directly. (this page’s comments are not the place to contact me) I need to hear about your actual needs.

    Much as I’d love to make everything open source, the reality is the Teensy business model doesn’t permit cloning. By cloning, take a look at the Seeeduino ($24) and Duemilanove ($30) side by side. As clones have proliferated, Arduino has relied on trademark protection, which can work for a large, well established project. Teensy can not work that way, at least not at this point.

    Certainly a number of people have made breakout boards consisting of a similar chip and Atmel’s stock bootloader and flip utility and a collection of 3rd party libraries. Teensy aims to be much more than this, including easier software, tutorials and examples, arduino compatibility (the special bootloader is needed), and much more. I have an extremely long and ambitious to-do list for Teensy!!

    Throughout 2010, you’ll see quite a number of additions for Teensy… assuming the Teensy business model continues its slow but steady success. For example, Teensyduino 0.7 featured digitalWrite and digitalRead about twice as fast as standard Arduino, and 0.8 has dramatically faster I/O. (yes, code has been contributed back to arduino, see issue tracker #140 and #59 for starters)

    This all takes funding, admittedly very meager funding (it is only a $20 board), but funding nonetheless, and that requires a business model. Absent even a modestly successful business model, Teensy would be little more than a web page and some downloadable open source files, and true USB support via the Arduino environment would be nothing more than a pipe dream**

    Please do contact me if you have any concerns. I do try to answer every email, though often I do get behind and tech support emails from customers always take priority. Please understand that I don’t visit this page regularly, so this isn’t the place to ask me anything and expect I will see it and reply.


    ps: Very few people, to the best of my knowledge, have actually erased the bootloader. To erase the bootloader, you need to connect a SPI-based programmer. There is no 6 or 10 pin ISP header on any Teensy. You have to solder up wires between the Teensy and your programmer. It’s not something done easily or by mistake. In most of the cases, I have offered to swap their erased board for a fresh one (for free, except their cost to ship back). So far, nobody has taken me up on that offer.

    ** When I began Teensyduino, about 1 year ago, there had been numerous requests to make an Arduino board based on one of these USB chips. The Arduino team responded that it would be far too difficult to support such a chip from the Arduino IDE.

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