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; these are detailed on the "Getting started with the Arduino Leonardo" guide on the Arduino website.
|INPUT VOLTAGE (RECOMMENDED)||7-12V|
|INPUT VOLTAGE (LIMITS)||6-20V|
|DIGITAL I/O PINS||20|
|ANALOG INPUT CHANNELS||12|
|DC CURRENT PER I/O PIN||40 mA|
|DC CURRENT FOR 3.3V PIN||50 mA|
|FLASH MEMORY||32 KB (ATmega32u4) of which 4 KB used by bootloader|
|SRAM||2.5 KB (ATmega32u4)|
|EEPROM||1 KB (ATmega32u4)|
|CLOCK SPEED||16 MHz|