Arduino, Arduino Development Board'sLeonardo R3 Board – Compatible Model High Quality
The Leonardo is an open source precise microcontroller board based on the ATmega32U4 SMD chip. It has 23 digital input/output pins (of which 7 can be used as PWM outputs and 12 can be used as analog inputs), a 16 MHz crystal, a USB connection, a power jack, an in-circuit system programming (ICSP) header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer (or appropriate wall power adapter) with a Micro USB cable or power it with a AC-to-DC adapter or battery to get started.
The Leonardo differs from all preceding boards in that the user-programmable ATmega32U4 AVR microcontroller has built-in USB functionality, eliminating the need for a secondary processor. This makes the Leonardo more versatile: in addition to supporting a virtual (CDC) serial/COM port interface, it can appear to a connected computer as a mouse and keyboard.