Adafruit
Adafruit ItsyBitsy M0 Express - for CircuitPython Arduino IDE
The Adafruit ItsyBitsy M0 Express is a compact yet powerful microcontroller board built on the ATSAMD21 Cortex M0+ running at 48 MHz. At just 1.4" × 0.7", it...
The Adafruit ItsyBitsy M0 Express is a compact yet powerful microcontroller board built on the ATSAMD21 Cortex M0+ running at 48 MHz. At just 1.4" × 0.7", it delivers the same capability as the Metro M0 or Feather M0 Express in a fraction of the size — perfect for shrinking prototypes into final builds.
Ships with CircuitPython pre-loaded — plug it in, edit the Python code on the drive that appears, and your project runs immediately. No IDE or compiler installation required. It also works with the Arduino IDE for C/C++ development.
Key Features
- ATSAMD21G18 Cortex M0+ – 48 MHz, 32-bit processor with 256 KB Flash and 32 KB RAM
- 2 MB SPI Flash – Onboard storage for CircuitPython code, data logging, and files
- CircuitPython & Arduino – Ships with CircuitPython; also programmable via Arduino IDE
- Native USB – Serial console, HID keyboard/mouse, MIDI, or small disk drive
- 23 GPIO Pins – 11× 12-bit analogue inputs, 1× true analogue output, 13× PWM, 7× capacitive touch
- VHigh Output Pin – Outputs higher of VBAT or VUSB; Pin 5 is level-shifted to high voltage
- DMA NeoPixel Support – Drive NeoPixels on the VHigh pin without processor overhead
- Built-in RGB DotStar LED – Plus a red Pin 13 LED for status indication
- 3.3V Logic, 48 MHz – Hardware SPI, I2C, and serial
- Automatic Power Switching – Runs from USB or battery with seamless switchover
Ideal For
- Compact CircuitPython projects — no IDE installation needed
- Shrinking Metro M0 or Feather M0 prototypes into tiny builds
- USB HID devices, MIDI controllers, and data loggers
- NeoPixel and DotStar LED projects with DMA support
Package Contents
- 1× Adafruit ItsyBitsy M0 Express (with CircuitPython pre-loaded)
- 1× Header Strip (unsoldered)
Resources
Jargon buster
Plain-language definitions for the technical terms used above.
- CircuitPython
- A beginner-friendly version of Python designed to run directly on microcontroller boards. If a product supports CircuitPython, you can often program it by copying code files onto the board rather than setting up a more complex toolchain.
- GPIO
- General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
- HID
- Human Interface Device is a USB device class used for keyboards, mice, gamepads and similar controls. If a board supports HID over USB, it can act like an input device to a computer without needing a custom driver.
- I2C
- I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
- IDE
- Short for Integrated Development Environment, a program used to write, run and manage code. It matters because some learners prefer a traditional coding workspace instead of a guided notebook-style lesson.
- LED
- A light-emitting diode is a small electronic component that lights up when current flows through it in the correct direction. In this kit, LEDs create the flashing effect, so polarity and correct soldering matter for the project to work.
- microcontroller
- A microcontroller is a small computer on a chip that runs your program and controls connected inputs and outputs. For this product, it is the part that reads buttons and sensors, drives the display and speaker, and communicates over Bluetooth.
- MIDI
- MIDI is a standard way for electronic instruments, controllers, and software to send musical control messages such as notes, velocity, and timing. If a board supports MIDI, it can be triggered from keyboards, drum pads, sequencers, or other music gear rather than only from buttons or code.
- native USB
- Native USB means the microcontroller itself handles USB communication, rather than using a separate USB-to-serial chip. This matters for programming, debugging, and projects that need the board to act directly as a USB device.
- NeoPixel
- A type of addressable LED system where colour data is sent along a single digital data line from one LED or controller to the next. Compatibility matters because the timing and signal format must match for the lights or driver board to respond correctly.
- PWM
- Pulse Width Modulation is a way for a digital pin to simulate variable output power by switching on and off very quickly. It matters for controlling things like LED brightness, motor speed, or servo-style signals from a microcontroller pin.
- RAM
- RAM is temporary memory used while a device is running, and its contents are lost when power is removed. A “Run in RAM” mode is useful for testing settings without permanently programming the module, but it may not support every feature.
- RGB
- Short for red, green and blue, usually referring to an LED that can mix those three colours. It matters because controlling an RGB LED teaches how separate outputs combine to create different colours.
- SPI
- A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
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