• Microcontroller: ATmega32u4
  
• Operating Voltage: 5V 
  
• Input Voltage: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: 40 mA 
  
• DC Current for 3.3V Pin: 50 mA 
  
• Flash Memory: 32 KB 
  
• SRAM: 2.5 KB (ATmega32u4) 
  
• EEPROM: 1 KB (ATmega32u4) 
  
• Clock Speed: 16 MHz

The Arduino 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 Arduino 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.