The classic Arduino Nano is the smallest board to build your projects with.
The Arduino Nano is a small, complete, and breadboard-friendly board
based on the ATmega328 (Arduino Nano 3.x). It has more or less the same
functionality of the Arduino Duemilanove, but in a different package. It
lacks only a DC power jack, and works with a Mini-B USB cable instead
of a standard one.
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