Updates and Design Files

I hope you all had a great holiday season. It was great to be able to have everything sent out before so we could enjoy some time off.
We are now back at it again and working on documentation and are also hopping to have the ability to buy additional minions set up here in the next week or so.

A google group has been started over at https://groups.google.com/d/forum/minioncity by Baruch. I’ll be watching there as questions come up as well as comments to the blog.

So first off here is the schematic of the minions.
There are a few key differences from the normal arduino.
First off is the lack of an led on pin 13. Routing was getting a little tight so removed it. The two LEDS on the board are tied to TX and RX. Which is why you see them blink when downloading your code.

The second is the radio. It uses 5 lines to talk to the processor.

  • MOSI
  • MISO
  • SCK
  • D3
  • D10

MOSI,MISO and SCK are part of the spi bus and are not part of the numbered ports in arduino. As a side note if you want to reprogram the processors bootloader you need a pullup resister on D10. D10 is the select line on the radio. The RF12 library uses an internal pullup resister to do the job but when you are resetting the processor to burn in a bootloader it is released and causes problems with the programmer. The battery shield added a 10k resister for programming.

D3 and D10 are part of the normal pins and shouldn’t be used when you are using the radio.

The eagle files for the main board and the battery shield are available at


(Schematics and board layout)

13 Responses to Updates and Design Files

  1. Baruch Even says:

    Great! Thanks.

    I’m now feeling bad that I said to friends that the minion is great but seriously lacks documentation. This fills the gap nicely.

    I’m wondering also what is then the relation between pin 16 and the amber led. It looked like the output on pin 16 lighted it up.

    • Nate says:

      Pin 16 on the processor or the header breakout?
      (16 on the processor is tied to the crystal and shouldn’t affect the LED)

      • Baruch Even says:

        pin 16 as referred from Arduino when I tried to probe all pins as leds. Well, I actually was wrong and it is pin 17. A simple blink sketch on pin 17 turns the led on and off with no serial traffic.

  2. Nate says:

    The extra pins have been mapped to the ICSP header. Their mappings are:
    D14 – MISO – PB3
    D15 – SCK – PB1
    D16 – MOSI – PB2
    D17 – SS – PB0

    D17 or SS is also the RXLED see
    for more.

  3. Baruch Even says:

    I’m a novice in this microcontroller world and I am completely baffled as to the different numbering and naming schemes. How do I find what Arduino pin number is assigned to on the Atmel chip and on the board?

    • Nate says:

      The arduino world takes care of that for you. You just need to go by the labled number on the board. That will match up with the ones in the arduino enviroment.
      D0-D13 are the normal digital inputs.
      D14-D17 are special inputs that have more than one function. Such as the D17 it is used as both the RXLED and also the SlaveSelect on the spi bus. Since we are using the SPI bus with the radio you don’t want to touch D13-D16
      D17 is fine to use because the RF12 library uses D10 instead of D17 as the select line.

  4. Bryan Schmidt says:

    Looking forward to be able to order a couple of these! Great work!

  5. Ray says:

    I would buy these if they were available somewhere for purchase.

    Will these be available somewhere in the future?



  6. Mike D says:

    I missed out on Kickstarter… when can I order a few? Could you email me when you have more? Thanks!

  7. Ben Hockley says:

    Are you accepting any more orders for minions? I got a couple through the kickstarter, but some more could be useful.

  8. Nick says:

    Thanks for posting these! I had an ATMega32u4 I had soldered to a TQFP breakout board a while back, and was just wondering how I should go about attaching all the support circuitry to it yesterday when I remembered the Minion “Skeleton” (bare PCB Minion) I’d gotten as a reward from your kickstarter!

    With the eagle files to guide me, it was a snap to figure out what went where and solder it all up. I even had most of the parts already, just had to substitute in a T/H HC-49 instead of SMD, and a lower max-VIN vreg and FDN340P mosfets. My new Franken-Minion doesn’t have a radio, but it works great as a tiny Leo clone. Just out of curiosity, is the standard Arduino Leonardo bootloader, Caterina-Leonardo.hex, the same one you’re burning onto Minions?

    Thanks for making it, and especially thanks for sticking up the design files! You saved me from creating some sort of ugly protoboard sandwich, and now I can use a breadboard and even have labelled pins! It’s great!

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