Powering Diavolino
The ATmega328P microcontroller requires 4.5 - 5.5 V dc when operating at 16 MHz.
Diavolino can be powered from a FTDI USB-TTL-5V cable, if you hook up the wire jumper that connects that power source to the board's "Vcc" line.
You can also power the board through a 3xAA or 3xAAA battery box, or through a plug-in power supply. For most situations that require wall-plug power, we recommend to use a 5 V power supply directly. If you have a specific reason to use a higher voltage wall wart (e.g., 9 V), then you'll also have to provide a voltage regulator to make the 5 V supply for the microcontroller.
Kit configurations
Diavolino kits are available with two configuration options: a optional bundled battery holder and an optional set of socket strips.
The battery holder is a 3xAA box with cover and switch. The battery holder has almost exactly the same footprint as the Diavolino board, and you can stick it on with double-sided foam tape if you're so inclined. It's a great setup for easy portable projects.
The socket strip set is a four-piece set of header sockets, two each 6-pin and 8-pin, that allow the board to interface with many existing Arduino accessories.
Additional resources
An extended introduction to Diavolino is available
here, including the release of the Diavolino design files under an open source license.