Arduino shield for Arduino. No, really.

We’ve been accused on more than one occasion…okay, pretty much every single day…of harboring some kind of creepy Arduino love affair. The topic does come up an awful lot here, we’re not oblivious to that, and had been patiently waiting for April Fool’s Day to post an article lampooning the whole situation, both ourselves and critics alike, so that everybody could have a good laugh (or possibly annihilate the entire planet in the resulting flame war, we’re not sure). And what could possibly make for a more self-referential joke than an Arduino shield…for Arduino?

Truth, as it turns out, is stranger than fiction. “Core2duino” is — seriously now, no joke — an Arduino shield containing a second ATmega microcontroller and full complement of I/O pins. The two chips in this Young Frankenstein-esque assemblage coordinate over the I2C bus, providing, at least in theory, more processing power, more I/O, and perhaps a degree of fault tolerance. In reality, we’re pretty skeptical, but do have to give them props for a great Instructable, detailing the whole process start to finish with Eagle CAD files, board etching and drilling, and advice on where to score free Cosmopolitan magazines (it helps “if you know any women,” we’re told).

There’s no indication whether this works with stacking headers to allow for an Arduino shield for Arduino shield for Arduino, or perhaps some Möbius strip-like endless stack of Arduinos. Feel free to discuss in the comments. We’ll be waiting in our concrete bunker 37 miles away!


  1. tom says:

    You guys must have popped boners left right and center over this one.

  2. Dan says:

    Sweet! Now my dim-an-LED-with-a-potentiometer project can be twice as (over)powerful!

  3. tom says:

    @Caleb Kraft

    Oh my! I just got an extra life!!

  4. rd says:

    Hackaday editor troll status: Confirmed. :D

    Anyway, this could be useful in some situations. For instance, a 20MHz ATMega is just barely fast enough to output VGA video, but there are very few clock cycles left over for other calculations. With this configuration, one Arduino could do all the heavy calculations while the other shifts out the pixel data.

  5. tj says:

    If people did more with the Arduino than interface other prefab circuits, or do digital boy scout projects, people probably wouldn’t cringe at the mention of it. Nothing intriguing really comes from any of the projects it prototypes…

  6. medix says:

    Props if they actually implement a good bus communication setup (ie. OTHER than I2C) to actually take advantage of the ‘doubled’ processing power.

    (minus)props if they just flash more LEDs. We shall see. ;)

  7. Boudico says:

    Don’t let the door hit ya on the way out?

  8. IceBrain says:

    This seems to me as those people who buy two crappy graphics cards and SLI them together, when a single card for the same price would be much faster. It’s not like the ATmegas used are the high end in µC computing.

    But this could have an upside: If there is a “master” and a “slave”, the master could switch the slave on and off dynamically, allowing for greater energy conservation even when the whole circuit can’t be put to sleep.

  9. peter says:

    @bobob too far dude…

    somebody ban this n00b

  10. Ben Ryves says:

    @rd: AVGA gets around 3.3 MIPS at 25MHz
    generating VGA 112x112x4bpp, and I get around 2.7 MIPS at 20MHz generating PAL (composite) 192x128x1bpp, which is quite sufficient for simple games. :-)

  11. nave.notnilc says:

    not only multi-core but also green? :P

  12. StrangeRover says:

    How ’bout this?: Arduino Farm!

  13. Warren says:

    I don’t find myself posting comments often. But this article and all of the comments really made me laugh XD Thanks for making my day, hackaday :D

  14. djlspider says:

    to do what?

  15. Marco says:

    It’s about time that Wiring got some SMP support !

  16. octel says:


  17. octel says:

    why not just take another commercial arduino board, desolder the shield pins, and solder sockets in their place but on the opposite side?

  18. victor says:


    because there are no advantages of having extra pins if they all share common pins. Plus programming would be interesting…+

  19. Reggie says:

    an extra cpu is useful but extra pins are also very very desirable, this is a very cheap and easy way to add extra pins, hardware uart etc.

  20. Chris says:



  21. …that’s a lot of leds if you use this: :P

  22. TheDude says:

    Hey everybody!

    Let’s jump on the anti-Arduino-on-hackaday bandwagon! I hate it when I see things I don’t want to see on free websites! Hurrrrr!

  23. TheFish says:

    yo dawg i heard you like Arduinos so i put an Arduino on your Arduino so you can Process wile you Process.

  24. Gilliam says:

    @djlspider and @StrangeRover
    to make the first(?) folding@home arduino folding group. the one group with the most users active and fewest fold points.

  25. epicness says:

    Has someone banned bobob yet?!

  26. SIKDIDIT says:


  27. bobob says:

    maybe they’re all busy looking for a way to strap THREE arduinos together????

    (and dim an led with the whole mess)

  28. mutant says:


  29. bobob says:

    i like where you’re going with that mutant!!!!

  30. corvus says:

    Wow, I’m not sure if I am more amazed at some people’s hate for Arduino or at the fact that bobob spent more than 30 minutes posting this to hackaday, lol

  31. bobobob says:

    bobob.. i gotta say you are one of the crappiest trolls of all time. youve spent almost an hour trying to troll in the comments here with little to no response. i mean, come on. step it up.

  32. moo says:

    arduino 2 duo, is out i cant wait for quad cores!

  33. Drone says:

    VRRPduino! This is triple-lame because they posted it on the now highly-restricted Instructables site.

  34. Gnostus says:

    Arduinos are rad, if you people spent have the mental power putting together cool hacks and gizmos as you did bitching about arduino, hackaday probably would have some filler content to stick in between arduinos(Besides other arduino shields).

    For those of you who are so cool with the hackaday in-crowd that they have to live by the row row fight the arduino code of failatries/gayities, I bid you the award for being the biggest technosheep that was ever herded.

  35. Ryan says:

    OH MY GAWD!!! Some people enjoy things that I do *not* enjoy! I must post to the internet making fun of them for it!!!!

    You guys are fucking sad.

    People who program in anything other than ASM are luzers, amirite!?!?

  36. Lazlo says:

    Looking forward to this whole shebang being repeated with the mbed.
    then we can all flash leds in 32bit! with a RTOS!

  37. Rollyn01 says:

    Hmmm….. If this holds any merits, this could be the gateway to a multi-core arduino. If so, that can definitely be useful in large-scale profects that need a lot of processing resources in a cheap fashion. My question is, can it be expanded to allow for it to use a task managerment system that can support Linux?

  38. Rollyn01 says:


    Screw my previous post. A multi-shield mbed would kick all sorts of ass.

  39. digi says:

    The Arduino is awesome because before it came out, technologists (non-engineers) would use computers and VB to perform trivial tasks. I’d rather see an Arduino post than a dummy talking about a 555 timer and posting a Core2 Duo solution to simple CLI & parsing problem. What is the point of my rant? Arduino is a tool for simple things for people who “should” use simple tools. (Yes, you can quote me on that)

  40. Rollyn01 says:


    I’m confused. You support Arduino posts but only if they contain simple uses for it? Uhhh… please clarify your statements because you sound almost hypocritical.

  41. Rollyn01 says:

    Not hypocritical, illogical.

  42. duuuurp says:



  43. stunmonkey says:

    I can’t wait to see what the next generation Slothra powered by TWO Arduinos will do! ;)

  44. yobyfed says:

    Good stuff, This is great for extending I/O pins.

    Oh, and please ignore the people that whine about Arduino’s, Its a fucking brilliant, cheap, easy, accessible development platform. Get us some more Arduino projects please!

  45. ericwertz says:

    “Good stuff, This is great for extending I/O pins”.

    If everything looks like a nail to you, I suppose.

  46. Jay Vaughan says:

    For us ArduinoSYNTH hackers, this represents a great deal of extreme power. Where once there was one voice of FM synthesis, now there may be 3 .. or 4 .. or ..

  47. Ben Ryves says:

    For those claiming this is good for extending I/O pins, what’s wrong with regular I²C I/O expanders or even the old shift register solution?

  48. tj says:

    I actually gave a decent justification to the anti-arduino movement in my last comment. Show me something innovative that is prototyped with the arduino and I’ll give it more credit.

    People who can’t code assembler aren’t “luzers”..they just produce poor quality software because they don’t understand how compilers and hardware execution work.

  49. therian says:

    Dont worry about too much arduiono. Arduino users just about to get a middle finger, Atmel barely financially stay alive, soon it will eather shift off low cost uC or go out of business.

  50. Roly says:

    “Danny Hillis and Sheryl Handler founded Thinking Machines in Waltham, Massachusetts (it was later moved to Cambridge, Massachusetts) in 1983 and assembled a team to develop the CM-1 Connection Machine. This was a “massively parallel” hypercubic arrangement of thousands of microprocessors, each with its own 4 kbits of RAM, which together executed in a SIMD fashion. The CM-1, depending on the configuration, had as many as 65,536 processors. The individual processors were extremely simple, processing one bit at a time.”

    Um, apart from being a bit of overkill, can anybody enlighten me about what is *wrong* with using a PIC as a smart I/O port?

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