  Cheap micro-controllers, such as the Arduino or other controllers based on
the Atmel AVR CPUs are being deployed in a wide variety of projects, ranging
from sensors networks to robotic submarines. In this paper, we investigate the
feasibility of using the Arduino as a true random number generator (TRNG). The
Arduino Reference Manual recommends using it to seed a pseudo random number
generator (PRNG) due to its ability to read random atmospheric noise from its
analog pins. This is an enticing application since true bits of entropy are
hard to come by. Unfortunately, we show by statistical methods that the
atmospheric noise of an Arduino is largely predictable in a variety of
settings, and is thus a weak source of entropy. We explore various methods to
extract true randomness from the micro-controller and conclude that it should
not be used to produce randomness from its analog pins.
