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 | 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 Length | 68.6 mm Width | 53.3 mm Weight | 20g 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. You also get the USB cable for FREE with this pack ! 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.