# Adafruit ItsyBitsy 32u4 3V 8MHz

> Ultra-compact 3.3V Arduino-compatible board with ATmega32u4 at 8MHz, native USB HID, 23 GPIO pins, 2KB RAM, 28KB flash, and Micro USB. Measures 35mm × 17mm — smaller than a Feather with equivalent AVR 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:** 3.3V via Micro USB or up to 6V via VIN pin
- **Operating Voltage:** 3.3V
- **Dimensions:** 35mm × 17mm × 4.2mm
- **Weight:** 2.7g

## 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 8 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-32u4-3v&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 3V 8MHz is an ultra-compact Arduino-compatible development board measuring just 35mm × 17mm — smaller than any Feather board yet providing the same ATmega32u4 microcontroller found in the Arduino Leonardo and Adafruit Feather 32u4 family. The 3.3V variant runs at 8 MHz, making it compatible with 3.3V sensor ecosystems and SPI Flash add-ons.

Despite its tiny footprint, the board exposes 23 GPIO pins including 6 analog inputs, 4 PWM-capable pins, hardware Serial, I2C, and SPI peripherals. The ATmega32u4's native USB is fully exposed, allowing the ItsyBitsy to appear as a USB HID keyboard, mouse, MIDI device, or CDC serial adapter — all without any host-side driver installation. The AVR109-compatible bootloader is accessible via a double-press of the reset button.

A 3.3V regulator with 500mA output handles power from up to 6V input (reverse-polarity protected), and an onboard red LED on pin 13 provides basic visual feedback. The "VHigh" pin provides a 5V logic output even from 3.3V boards, useful for driving 5V-logic peripherals like NeoPixels and servos. The ItsyBitsy 32u4 3V is ideal for downsizing prototypes originally built on Arduino Leonardo or Feather 32u4 boards into tighter enclosures.

## Where to Buy

- [Adafruit](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3675&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-3v&source=md-export) — 9.95

## Resources

- [product page](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3675&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-3v&source=md-export)
- [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3675&ref=openhardware.directory&product=adafruit-itsybitsy-32u4-3v&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-32u4-3v&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-32u4-3v&source=md-export)

## Tags

`arduino`, `atmega32u4`, `usb-hid`, `3v3`, `compact`, `adafruit`, `itsybitsy`, `avr`

## Images

![Adafruit ItsyBitsy 32u4 3V 8MHz](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-itsybitsy-32u4-3v/874dfffc413b.jpg)
![Adafruit ItsyBitsy 32u4 3V 8MHz](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-itsybitsy-32u4-3v/0676ecef67e1.jpg)

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