The Arduino Leonardo is a microcontroller board based on the ATmega32U4. Unlike previous Arduino boards, the ATmega32U4 has built-in USB communication, allowing the Leonardo to appear as a mouse and keyboard to a connected computer — in addition to a virtual serial/COM port.

With 20 digital I/O pins, 12 analog inputs, and 7 PWM channels, the Leonardo is well-suited for interactive projects. Simply connect it to a computer via micro USB cable, or power it with an external supply to get started.

Key Features

• Native USB – Built-in USB on the ATmega32U4 allows the board to emulate a keyboard, mouse, or serial device
• 20 Digital I/O Pins – 7 usable as PWM outputs, with 40mA per pin
• 12 Analog Inputs – 10-bit resolution (1024 values) on pins A0–A11
• Multiple Communication Protocols – UART, I2C (TWI), and SPI support
• USB Overcurrent Protection – Resettable polyfuse protects your computer's USB ports
• Open-Source Hardware – Schematics and Eagle files freely available

Specifications

• Microcontroller – ATmega32U4
• Operating Voltage – 5V
• Input Voltage – 7–12V recommended (6–20V limits)
• 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 (4KB used by bootloader)
• SRAM – 2.5KB
• EEPROM – 1KB
• Clock Speed – 16MHz
• Board Dimensions – 68.6 × 53.3 mm
• Weight – 20g

Power Options

• Micro USB – Connect directly to a computer for power and programming
• External Power Jack – 2.1mm centre-positive plug, 7–12V recommended
• VIN Pin Header – Supply voltage via the power connector pins

Ideal For

• USB HID projects (custom keyboards, mice, game controllers)
• Interactive installations and MIDI controllers
• General-purpose electronics prototyping
• Learning embedded programming with Arduino

Package Contents

• 1× Arduino Leonardo

Resources

• Getting Started with Arduino Leonardo
• Schematic (PDF)
• Eagle Design Files
• Pin Mapping (ATmega32U4)
• Arduino Language Reference
• Arduino IDE Download