This is an addon shield to an addon shield. That's right, you have to have the Core2duino on your Arduino to be able to understand why you would want this in the first place. So once you have your Core2duino saddled up, give this one a shot (you don't technically have to have the core2duino to use this with your arduino or standalone, but only pins that are plugged in will work).

It will fit on any Arduino (including Mega) and allows for an additional shield to be added on top (shield will be connected to the base Arduino) other pins will be free.

It can be powered via the Base Arduino or the VIN pins - power will be routed through the VIN pin from base Arduino and back out as +5v to Core2/3duino.

Why do this? well, the short answer is - why not? You end up with:

3 separate processors
60 input/output of which:
24 digital I/O pins
18 pwm pins
18 analog inputs
including 6 external interrupts

...all for about $25 more than your Arduino. (about $10-12 each) 

Anyways, it only took about an hour to modify the Core2duino Eagle file into this.

This is a fun project to try and the .brd file has adequate spacing for ease with etching.

Most of these instructions are very similar to the Core2duino... differences are noted.

I will be happy to help if anyone has questions.

The next version is likely to have an FTDI programming cable connection for easy in system programming.

Step 1: What You Need to Get Started


1. (1)pc copper clad (3"x4") or assortment
2. (1) 28-pin dip socket
3. 16 mHz crystal resonator w/ built-in capacitor
4. An Atmega168 with Arduino bootloader
5. (2) stackable header set
6. (2) 6-pos female headers (2) 8-pos female headers .1"
7. (4) male pin headers (optional) .1"

Other things needed:

power LED, any size/color
330 ohm-1k ohm resistor for power led
10k resistor for reset button
reset button
.1uf capacitor optional
16v 22uf-220uf capacitor optional

etchant solution (muriatic acid + hydrogen peroxide)
paper towels
scotch brite pads
Laser Printer
magazine paper
rubber gloves
aquarium bubbler
<p>Hello, Thank you for presenting this work.</p><p>I wonder to know if possible using Core2duino as a dual core microcontroller or not?</p><p>I need to use MC1 (master) for recieving data from Bluetooth and save it in a buffer then reading that data from the buffer using MC2 (slave) for operating 2D matrix LED.</p><p>what do you think? can we use it?</p><p>In this case I can have two buffers, while I am writting in buff1 by using MC1. Reading from buff2 by using MC2 and so on.</p>
perhaps a bit dumb, but what is 'magazine paper'?<br>I presume this needs to be printed by a laser, not an inkjet?
this is tight
have you ever considered having the board made by a company such batchpcb and selling them? for those of us who do not want to etch them ourselfs?
&nbsp;it's amazing, the text on this page is exactly like that on the last page of the core2duino instructable. &nbsp;BTW, this is overkill. &nbsp;For the cost of a duemilanove, core2duino and core3duino i could just get an arduino mega, probably easier to use. &nbsp;I wonder if hackaday will feature this?<br />
&nbsp;Yo dawg, we heard you like arduinos, so we put an arduino, on yo arduino, on yo arduino so you can prototype while you prototype while you prototype!
Yes, I&nbsp;said that in the instructable, It is essentially the same as the Core2duino.&nbsp; And yes, this is overkill, you might even say &quot;this is stupid&quot; as is etched on the pcb. Hackaday making fun of the Core2duino was actually what prompted the idea in the 1st place. <br /> <br /> I won't defend needing the core3duino, but there are times when having 2 separate cpu's is a must.&nbsp;While testing my larger bots, I always use 2 Arduinos to decode the drive and failsafe r/c channels separately. That way if something goes way wrong or the code doesn't work as it should, you have a way to shut the thing off before it busts a hole in the wall and your wife tells you no more inside testing ;)<br />
Pretty excellent!&nbsp;&nbsp;Super-de-duper overkill, unless you happen to need more IO and only want to expand rather than upgrade (i.e. mega).<br /> <br /> Very well done!<br />
Is there no communication between the microcontrollers?<br />
Using I2C, you can connect 1 Arduino (master)&nbsp;to a host of slave Arduino's through Analog ports 4 and 5. <br />

About This Instructable




Bio: I have always been one to take things apart to figure out how they work, so most of what I own has been dismantled. If ... More »
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