Adafruit ItsyBitsy 32u4 5V 16MHz

Overview

The Adafruit ItsyBitsy 32u4 5V 16MHz is an ultra-compact Arduino-compatible development board that runs at the full 5V 16MHz speed of the ATmega32u4 — identical to the Arduino Leonardo — in a package measuring just 35mm × 18mm. This makes it the ideal choice for downsizing 5V Arduino projects into smaller enclosures without changing any code.

The board exposes 23 GPIO pins including 6 analog inputs, 4 PWM-capable pins, hardware Serial, I2C, and SPI. The native USB capability of the ATmega32u4 is fully accessible, enabling the ItsyBitsy to emulate USB HID devices such as keyboards, mice, joysticks, and MIDI controllers, or to act as a USB serial CDC device. The AVR109-compatible bootloader can be accessed with a double-press of the tiny onboard reset button.

A 5V ultra-low-dropout regulator provides up to 150mA output, and a secondary 3.3V regulator provides power for 3.3V peripherals. The board accepts input up to 16V (reverse-polarity protected). A 3.3V output pin is available for powering external 3.3V sensors and modules, and an automatic power switching circuit ensures safe operation whether powered from USB or battery.

The ItsyBitsy 32u4 5V is the go-to compact Arduino for 5V-logic systems, NeoPixel driving from USB power, and projects that must maintain Arduino Leonardo/Uno compatibility while shrinking the physical footprint significantly.