# Adafruit ItsyBitsy 32u4 5V 16MHz

> Ultra-compact 5V Arduino-compatible board with ATmega32u4 at 16MHz, native USB HID, 23 GPIO pins, 2KB RAM, 28KB flash, and Micro USB. Measures 35mm × 18mm — small form factor with full Arduino Leonardo capability.

## Quick Facts

- **Brand:** Adafruit
- **Board Type:** dev-board
- **Price:** ~$9.95
- **Product Readiness:** consumer
- **CPU:** Atmel ATmega32u4 AVR
- **CPU Architecture:** AVR
- **CPU Cores:** 1
- **RAM:** 2 KB
- **Flash:** 28 KB
- **Power:** 5V via Micro USB or up to 16V via VIN pin
- **Operating Voltage:** 5V
- **Dimensions:** 35mm × 18mm × 4.1mm
- **Weight:** 2.6g

## Open Source

- **Firmware:** Yes
- **Schematics:** Yes
- **PCB Layout:** Yes

## Compatible Firmware

arduino

## Use Cases

- usb-hid
- wearable
- prototyping
- education
- compact-controller

## Components

- **ATmega32u4** (mcu): 8-bit AVR microcontroller at 16 MHz with 32KB flash, 2.5KB SRAM, native USB HID/CDC/MIDI. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FAtmel-7766-8-bit-AVR-ATmega16U4-32U4_Datasheet.pdf&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-5v&source=md-export)

## Protocols

- **I2C**: SDA: D2, SCL: D3
- **SPI**: MOSI: D16, MISO: D14, SCK: D15, SS: D10
- **UART**: TX: D1, RX: D0
- **USB-HID**: 

## GPIO Map

| Pin | Name | Type | Functions |
|-----|------|------|-----------|
| D0 | RX | UART | digital-input, digital-output |
| D1 | TX | UART | digital-input, digital-output |
| D2 | SDA | I2C | digital-input, digital-output |
| D3 | SCL | I2C | digital-input, digital-output, pwm |
| D4 | GPIO | — | digital-input, digital-output |
| D5 | GPIO | — | digital-input, digital-output, pwm |
| D6 | GPIO | — | digital-input, digital-output, pwm |
| D7 | GPIO | — | digital-input, digital-output |
| D9 | GPIO | — | digital-input, digital-output, pwm |
| D10 | SS | SPI | digital-input, digital-output, pwm |
| D11 | GPIO | — | digital-input, digital-output, pwm |
| D12 | GPIO | — | digital-input, digital-output |
| D13 | LED | — | digital-input, digital-output |
| D14 | MISO | SPI | digital-input, digital-output |
| D15 | SCK | SPI | digital-input, digital-output |
| D16 | MOSI | SPI | digital-input, digital-output |
| A0 | ADC | — | digital-input, digital-output, analog-input |
| A1 | ADC | — | digital-input, digital-output, analog-input |
| A2 | ADC | — | digital-input, digital-output, analog-input |
| A3 | ADC | — | digital-input, digital-output, analog-input |
| A4 | ADC | — | digital-input, digital-output, analog-input |
| A5 | ADC | — | digital-input, digital-output, analog-input |

## Available Software

- **[Arduino]()** (open-source)

## Description

## 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.

## Where to Buy

- [Adafruit](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3677&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-5v&source=md-export) — 9.95

## Resources

- [product page](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3677&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-5v&source=md-export)
- [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3677&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-5v&source=md-export)
- [documentation](https://openhardware.directory/r?to=https%3A%2F%2Flearn.adafruit.com%2Fintroducting-itsy-bitsy-32u4&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-5v&source=md-export)
- [github](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fadafruit%2FAdafruit-ItsyBitsy-32u4-PCB&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-5v&source=md-export)

## Tags

`arduino`, `atmega32u4`, `usb-hid`, `5v`, `compact`, `adafruit`, `itsybitsy`, `avr`

## Images

![Adafruit ItsyBitsy 32u4 5V 16MHz](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-itsybitsy-32u4-5v/7c108731201e.jpg)
![Adafruit ItsyBitsy 32u4 5V 16MHz](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-itsybitsy-32u4-5v/896c572125a3.jpg)

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