Arduino Leonardo AVR Development Board is a microcontroller board based on the Atmel ATmega32u4. It offers 20 digital IOs (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16MHz crystal oscillator, a micro USB connection, a power jack, an ICSP header, and a reset button. 
The Arduino 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 an HID, such as a mouse or keyboard, in addition to a virtual (CDC) serial / COM port. The Leonardo board contains everything needed to support the microcontroller. Simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.
Specifications
- Microcontroller: ATmega32u4
- Operating voltage: 5V
- Input voltage (recommended): 7-12V
- Input voltage (limits): 6-20V
- Digital I/O pins: 20
- PWM channels: 7
- Analog input channels: 12
- DC current per I/O pin: 40mA
- DC current for 3.3V pin: 50mA
- Flash memory: 32Kb (ATmega32u4)
of which 4Kb is used by bootloader - SRAM: 2.5Kb (ATmega32u4)
- EEPROM: 1Kb (ATmega32u4)
- Clock speed: 16MHz
For more detail: Arduino Leonardo AVR Development Board
