But it's possible to go even smaller, as the makers of a new Arduino-compatible product called "Microduino" show. At 1" × 1.1", it's nearly as small as a quarter.

Except, on the Micro, there is no actual serial bus involved in programming the Arduino, as everything is done over USB. So the TX and RX leds are driven by a couple of pins on the ATmega32U4 (see a ...

Featuring support for two Arduino Micro boards, the XPlorerBoard makes life easy by eliminating loose parts, and adding in very handy features such as a 3V and 5V logic level converter, on-board ...