RTC shield, I²C, Arduino compatible, DIY

Hi! I'm back, again with arduino and a new shield, once more a DIY shield. 

So, let's start! The picture on the right is the circuit used to build the shield (I want to thank my friend Nuno Portela, who grabed this, and converted to eagle schematic, printing and driling the circuit afterwards).

The schematic on the left is the proposed circuit, which was then printed. All the components are easy to find, so the final result is almost inexpensive.

I've attached also a picture of the final result, 2 boards with cr2032 button cells. 

Concerning the code, I couldn't find where I got mine, so I'm posting it here.

Enjoy!