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Thread: Sparkfun has a new Teensy 3.1 shield to Arduino form factor

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    Senior Member+ MichaelMeissner's Avatar
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    Sparkfun has a new Teensy 3.1 shield to Arduino form factor

    I was browsing the new products over at Sparkfun, and they have a new shield for Teensy 3.1 to fit it into an Arduino form factor: https://www.sparkfun.com/products/13288.

    I noticed they have an external power jack (4-12v). In order to use it, you have to cut the VIN<->VUSB solder jumper on the Teensy. However, they don't bring out VUSB to a pin, nor do they seem to provide a switch or other method of using the 5v power from USB.

    They give you access to the other inner through hole pins (A10, A11, AREF) as well as A8/A9 in a separate 6 pin header.

    The shield is clearly designed for the 3.1, having the battery for the real time clock. They don't bring out Vbat to the back, so you don't have access to the special A3 output pin of the LC.

    There is a solder jumper whether A6/A7 are routed to the A4/A5 Arduino pins instead of A4/A5. A4/A5 will still be routed to the 2 i2c pins on the shield. There is no mention of pull-up resistors on the 2 i2c pins on the shield, so I would assume you probably should add them in doing i2c if your devices don't already pull-up resistors.

    There is a comment in the setup guide about using the SPI header in case you have an AVR programmer that probably should be ignored.

    They don't ship 14 pin female headers, but instead ship a larger female header that you have to cut down to 14 pins.

    I tend to think the nRF24L01+ shield might be more generally useful (even without nRF24L01+) than the Sparkfun shield: https://www.tindie.com/products/pico...otyping-area-/

    Or the protoboard/shield that gives you access to the bottom pins: https://www.tindie.com/products/fret...rd-and-shield/

  2. #2
    Senior Member+ defragster's Avatar
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    Cool. Good find.

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    Senior Member Pensive's Avatar
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    No! I was about to design and build that. But isn't that useless because most of the shields will be running at 5v yesno? I was going to put in level converters for 100% compatibility. (or as close as)


    looks like that protoshield (last link) totally beat me to it by some time anyway but aren't all the shields going to use 5v with the analogue pins at least....?
    Last edited by Pensive; 06-19-2015 at 06:27 AM.

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    Don't let them stop you Pensive, especially if you were going to 'round it out' to be a better shield

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    Senior Member Pensive's Avatar
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    I may well do

    simple first pcb project

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    Senior Member Pensive's Avatar
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    Thinking about level shifting it all seems a little pointless, since the teensy will actually handle 5v OK (inadvisable, but it will be ok for the digital pins), and any decent board using analogue should be using aref which can be supplied with 3.3v. I think level shifting will just get in the way of other functions, so it would increase cost by requiring multiple jumpers to enable/disable the level shifting throughput.

    Nah. Market served there. I will focus on my other ideas

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by Pensive View Post
    No! I was about to design and build that. But isn't that useless because most of the shields will be running at 5v yesno? I was going to put in level converters for 100% compatibility. (or as close as)


    looks like that protoshield (last link) totally beat me to it by some time anyway but aren't all the shields going to use 5v with the analogue pins at least....?
    When the Arduino Due came out, they revised the spec to allow its use on both 3.3 and 5v systems (using the IOREF pin if memory serves). Whether a random shield supports 3.3v devices, depends on the board.

    I recall when Digistump came out with their Due (mostly) clone, they also provided a level shifting shield: http://digistump.com/products/51. I've seen some other level shifting shields, but since I've mostly given up on Arduino and their shields, I haven't kept track of them.

    However, the problem with level shifting in general is knowing how a pin is used. Is it only for digital input, is it only for digital output, is it for both digital input and output, is it for analog input, or is it for analog output. Then you get into the issue of speed. Would the level shifting react fast enough to drive ws2812b leds (neopixels) or pwm outputs? A lot of the level converters for i2c that are bi-directional, aren't fast enough for high speed devices.

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by stevech View Post
    Well I mentioned that board in my post. So it is old news in terms of providing an Arduino shield for Teensy. I just found it interesting that Sparcfun all of a sudden decided to do an official SF (i.e. red) shield for Teensy.

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    Senior Member+ MichaelMeissner's Avatar
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    Cool Now also a Teensy to Xbee shield

    Hmmm, this morning Sparcfun also added a Teensy to Xbee shield: https://www.sparkfun.com/products/13311.

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    It also has an ISP header. Sparkfun states in can be reprogrammed using an AVR programmer: "The ICSP header breaks out the SPI pins for Leonardo-compatible shields. You can also use this header to reprogram the Teensy if you have an AVR programmer."

    Would this be possible indeed? That leaves a great opportunity for OTA options I guess?!

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    Senior Member+ MichaelMeissner's Avatar
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    As I said, I believe the sentence about using an AVR programmer to be a mistake. The ICSP does bring out the SPI pins in an easy to use format, but you can't use it for programming the Teensy.

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    I thought so already indeed! Overlooked your comment on that indeed! I still think almost the only large disadvantage of the Teensy is that it is difficult to do over the air updates, which are more or less a must if one needs to integrate them in real world systems.

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    Unfortunately not. Apart from being bulky, the XBee shield is merely an adapter that connects the RX/TX to 0/1 or 6/7 (a bit clumsy, one would expect they would use Serial1 and then Serial2 or something).

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    Senior Member Pensive's Avatar
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    Shame.

    if an xbee adapter were to connect over SPI or i2c to an onboard avr chip w/ firmware could this afford programming facilities over the air? I'm a bit ignorant about under the hood matters.

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    The only option would be to interface programming chip I think: https://www.pjrc.com/store/ic_mini54_tqfp.html I should have thought of that when I read the line @Sparkfun about ISP.

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    Senior Member+ Frank B's Avatar
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    Quote Originally Posted by jakorten View Post
    I thought so already indeed! Overlooked your comment on that indeed! I still think almost the only large disadvantage of the Teensy is that it is difficult to do over the air updates, which are more or less a must if one needs to integrate them in real world systems.
    The only need is a bootloader.
    There are solutions.

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    Then I would appreciate some sharing Frank

  19. #19
    Senior Member+ Frank B's Avatar
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    Maybe you want to look at my github account...
    But be "warned": It's very basic and definatley needs customization and some experience. It does NOT "just work" (ok, there is an example for loading from SD and this should work ;-) ) It's NOT for beginners, and there is a risk that you brick your Teensy. Therefore i don't want to link it here.

    The good news: It's very flexible and easy to customize. It can load the flash from every thinkable source. You may want to and a CRC-Check.

    Edit:
    If you brick your Teensy, it's your problem ;-)
    I can't give support or any form of help.
    Last edited by Frank B; 06-20-2015 at 01:38 PM.

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    Thanks Frank, also for the disclaimer! Our main system has an SD card so that is not a problem.

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    Senior Member Pensive's Avatar
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    Just a note - Since the leonardo has now been discontinued, the adafruit untztrument would be best served by Teensy-LC and the sparkfun breakout (the only breakout in R3 form factor that will fit inthe space, if I am correct. About the same price too!

    I think i'll keep working on my Teenstrument code

    I'm sure that would be music to paul's ears. Ohhh I love a good pun.

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    As someone else mentioned, programability is not correct. About once or twice per month, my tech shows me a product description or a response to question from various mfr's sites. Am amazed how much misleading or incorrect information is provided by stafff members of Sparkfun and Adafruit.

    Do not really see that problem on this site. You people may not all be practicing engineers, but neither are you people stupid and/or full of doo-doo. Long live the Empire.

  23. #23
    Senior Member Pensive's Avatar
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    Well I don't need the AVR header function, so I've got a sparkfun breakout on order, i'll let you know how it goes.

    the main downside I see is they've (quite rightly) placed the teensy USB right on the edge. In Untztrument terms that exposes a weak USB socket.

    so I'll be mounting a type B female socket instead. I'll have to try soldering this in to the teensy pads rather than plugging it in the quick and easy way.

    its probably easier to conjure up a new part for the Untztrument which mounts the board further back or accommodates the other breakout board instead. We'll see, got to eye it all up first.

  24. #24
    Senior Member Pensive's Avatar
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    Ok, I'm on mobile so I can't post any pics, but I've been playing with the spark fun breakout shield and a teensy-LC, in an Untztrument.


    • The board is smaller than an uno or Leonardo, by around 7 or 8mm. So the matching mount points become a bit irrelevant. The USB and power sockets are never going to line up in uni/Leo products.
    • the mount points aren't quite right, but you can make it fit.
    • the USB socket ends up short of any openings designed for uno/Leo but annoyingly not short enough to plug in a panel mount socket - as predicted I'll have to hardsolder the USB socket.
    • The 3.1 Vbat runs to the battery holder. It's worth noting this before you mount the battery holder, when using a teensy-LC and neopixels /ws2811/12 this pin becomes the 5v pin on LC.


    That's all for now, many challenges but it's well documented and Creative Commons so I may have a crack at perfecting it as a Leonardo drop in replacement, reposition the teensy so the USB sockets etc. are in exactly the same place as a Leonardo.

  25. #25
    Senior Member Constantin's Avatar
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    Quote Originally Posted by Pensive View Post
    [LIST][*]The 3.1 Vbat runs to the battery holder. It's worth noting this before you mount the battery holder, when using a teensy-LC and neopixels /ws2811/12 this pin becomes the 5v pin on LC.
    On the plus side, you now have a rather large solder pad to solder to, once you remove the battery cage.

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