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Thread: Teensyduino on bare chip

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  1. #1
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    Teensyduino on bare chip

    Hi all, I'm new
    Not only new to Teensy, but also Arduino.

    Ordered a Teensy 3.1 and codec board. It looks like a fantastic tool! However, I'm the kind of person who will eventually want to stick the bare ARM chip onto a custom PCB when I'm wrapping up a project. I like things to be streamlined and minimalist when I screw the lid on and put the finishing touches of paint.

    Is it possible to keep using Teensyduino (and libraries) but program the MK20DX256VLH7 on a custom board with an appropriate JTAG programmer? Assume that I'm completely comfortable with making my own boards (which I am, even with 0.4mm pitch QFP). My query is more about the software side. Would Teensyduino prevent me from flashing the final HEX onto a bare chip and having it work?

    I had a bit of a search, found references to bare metal, but by people looking to do the opposite from me. To use a different IDE with the Teensy. Though I can read write C-style programming fine, pages and pages of chip/peripheral configurations just do do a simple timer interrupt makes my brain shrivel up. It's just too much for me. I want to focus on my actual program, and the hardware, which is why I want to give Teensyduino a shot.

    Thanks!

  2. #2
    Senior Member PaulStoffregen's Avatar
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    We sell this chip, which is intended to help you make your own PCB.

    http://www.pjrc.com/store/ic_mini54_tqfp.html

    It's also possible, in theory, to program MK20 chips with tools from companies like P&E Micro. But you'll have to resolve a lot more small issues, and I can't help you. I highly recommend going the Mini54 route first.

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    Quote Originally Posted by PaulStoffregen View Post
    We sell this chip, which is intended to help you make your own PCB.

    http://www.pjrc.com/store/ic_mini54_tqfp.html

    It's also possible, in theory, to program MK20 chips with tools from companies like P&E Micro. But you'll have to resolve a lot more small issues, and I can't help you. I highly recommend going the Mini54 route first.
    Sounds like a reasonable solution. I understand the mini54 comes pre-programmed with what the MK20 chip needs then?

    I've used/programmed plenty of bare AVRs and PIC32s on my own boards using a variety of programmers. This whole world of bootloaders and "needing" a secondary microcontroller just so that your main one can work is new to me, and admittedly a bit odd. I suppose I'll get used to it.

    Thanks!

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    Is the Mini54 chip only used during programming? Or is it necessary to help boot up the MK20 on power-on?

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    the MIN54 chip holds the bootloader, which saves ram on the MK20 chip. It also makes uploadig new hex files a breeze.
    the strength if Teensyduino is all the libraries that are often more performant then the Arduino equivalents. There are several libraries that have no equivalent on for notmal Arduino (or Clone) boards. E.g. the Audio library or OCTOWS2811. I am susumignyou are referring to the Audio adapter as " the codec"

    As for IDE's, there are several alternatives that will allow you use a full fleged IDE while retining al l the goodness of Teesnyduino.

    Visual Studio with the Visuial Moicro plugin (Win only)
    Eclipse Arduino IDE/plugin (Mac, Win, Linux)
    embedXcode (Mac only)
    etc.

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    Don't forget even a teensy 3.1 is pretty streamlined :P. It's relatively tiny, and you can fit some components between the edges.


    I'd look at this:


    (Hours to add the board and MINI54 to custom PCB) * wage$ - (small part cost savings [$3-10?])* units sold + $extra parts to populate & tooling
    =
    Value of Slightly smaller Board??



    It's a hard proposition, unless you're making a lot of units or have an extreme board size situation.

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    I've been curious about this too, however at the smaller quantities I am looking at I don't see it saving any money... Paul's MINI is $8 plus the 3.1 chip ~$7 is only $2 shy of OSH Park's Teensy 3.1. And after reading other threads about traces running near the crystal, I decided it wasn't worth the additional development time!

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    I've been thinking about this too and have opted to make a "backpack" for the teensy, that will probably render the bottom pins unusuable (trying to keep the mating thin as possible), but will have many features. If I ever make this into a new board than it could be thinner (two teensies side by side), but also a lot more work and "rethinking the wheel".

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    Quote Originally Posted by Fyod View Post
    I've been thinking about this too and have opted to make a "backpack" for the teensy, that will probably render the bottom pins unusuable (trying to keep the mating thin as possible), but will have many features. If I ever make this into a new board than it could be thinner (two teensies side by side), but also a lot more work and "rethinking the wheel".


    Best option I've seen for the bottom pins is to use SMD male header pins on the teensy side, and solder them into holes on your PCB. It means your part is not removable, but this is normal for a final backpack board [not necc intended to be removable.] The SMD pads are not very strong so you probably don't want to have them go into a female header in order to be removable, plus it would be hard to get the right size pins for everything.

    The downside is that 0.04" holes on a 2-layer board, even more on a 4-layer board, waste a lot of space since they're through-plated [is that the right term for meaning they exist on top and bottom through all layers?]

  10. #10
    Senior Member jimmayhugh's Avatar
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    Quote Originally Posted by Tomek View Post
    Best option I've seen for the bottom pins is to use SMD male header pins on the teensy side, and solder them into holes on your PCB. It means your part is not removable, but this is normal for a final backpack board [not necc intended to be removable.] The SMD pads are not very strong so you probably don't want to have them go into a female header in order to be removable, plus it would be hard to get the right size pins for everything.

    The downside is that 0.04" holes on a 2-layer board, even more on a 4-layer board, waste a lot of space since they're through-plated [is that the right term for meaning they exist on top and bottom through all layers?]
    Here's my method for using all available signals with a socket.

  11. #11
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    Quote Originally Posted by jimmayhugh View Post
    Here's my method for using all available signals with a socket.

    That is a superb option for prototyping, I forgot about it. It seems a little annoying to remove the pins from their plastic casing if it's for like 5+ units though.

    Since the spacing is different for the socket of the SMD connection option, it's a decision that has to be made whether you'd want to prototype with the SMD header version or the clever SMD/through-hole combo.

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