Power optimization base on Atmel PicoPower demo on their website

You will need some way to load the code into the ATmega328P.
Loading using Arduino might work.

NOTE:
ADC is not setup properly and may or may not work

This release is GNU license located at www.gnu.org/licenses/gpl.html
Basically it states if my code kills you I am not liable and
I offer no warranty it will work as stated.

Also if you modify it, you need to release it and etc.