Similar to an Arduino UNO,
can be recognized by computer as a mouse or keyboard.
The Arduino Leonardo is a microcontroller board based on the ATmega32u4 (datasheet).
It has 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs),
a 16 MHz crystal oscillator, a micro USB connection, a power jack, an ICSP header, and a reset button.
It contains everything needed to support the microcontroller; simply connect it to a computer
with a 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 ATmega32u4 has built-in USB communication,
eliminating the need for a secondary processor. This allows the Leonardo to appear
to a connected computer as a mouse and keyboard,
in addition to a virtual (CDC) serial / COM port.
It also has other implications for the behavior of the board;