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The Feather M0 Express is Adafruit's CircuitPython-optimised Feather, built around the ATSAMD21G18 ARM Cortex M0+ processor. It combines the standard Feather...

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The Feather M0 Express is Adafruit's CircuitPython-optimised Feather, built around the ATSAMD21G18 ARM Cortex M0+ processor. It combines the standard Feather M0 platform with 2 MB of SPI flash storage, a Mini NeoPixel, and a UF2 bootloader for drag-and-drop programming — no special tools or drivers required.

The 2 MB SPI flash acts as a tiny built-in drive. In CircuitPython, it stores your scripts, libraries, and files directly. In Arduino, you can read and write files to it like a small datalogger or SD card. The board also includes a prototyping area for adding custom circuitry.

Key Features

  • ATSAMD21G18 Processor – ARM Cortex M0+ running at 48 MHz, 3.3V logic
  • 256 KB Flash + 32 KB RAM – 8× more flash and 16× more RAM than ATmega328/32u4
  • 2 MB SPI Flash Storage – On-board file storage for CircuitPython scripts or Arduino data logging
  • UF2 Bootloader – Drag-and-drop firmware loading via USB; compatible with CircuitPython, MakeCode, and Arduino IDE
  • Mini NeoPixel – On-board addressable RGB LED for status indication
  • Native USB – Built-in USB-to-Serial for programming and debugging, no FTDI chip needed
  • 20 GPIO Pins – Hardware Serial, I2C, and SPI support with PWM on all pins
  • Analogue I/O – 6× 12-bit analogue inputs and 1× 10-bit DAC output
  • LiPo Battery Support – JST connector with built-in 100 mA charger and charging status LED
  • 32.768 kHz Crystal – For accurate clock generation and RTC
  • Compact Design – 51 mm × 23 mm × 8 mm, weighing just 5 g
Note: CircuitPython is not pre-loaded. The UF2 bootloader is pre-installed — simply drag the CircuitPython firmware file onto the USB drive to install it.

Also Available

Ideal For

  • CircuitPython development and learning
  • Portable battery-powered projects
  • Data logging with on-board flash storage
  • Rapid prototyping with drag-and-drop programming

Package Contents

  • 1× Feather M0 Express (ATSAMD21G18)
  • 1× Header pin set
Note: LiPo battery and USB cable sold separately.

Jargon buster

Plain-language definitions for the technical terms used above.

Bootloader
Small starter software on a microcontroller that lets new code be uploaded before the main program runs. Knowing how to enter bootloader mode matters when you need to program the board or recover it after a faulty sketch.
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.
DAC
A digital-to-analogue converter turns numbers from the microcontroller into a real analogue voltage. It matters if you want to generate simple waveforms, audio-style signals, or variable control voltages rather than just on/off outputs.
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.
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.
LiPo
A lithium polymer rechargeable battery commonly used in portable electronics projects. It matters because LiPo batteries need correct charging circuitry and care, and this board includes hardware intended for that battery type.
LoRa
LoRa is a long-range, low-power radio technology often used for telemetry and remote sensors. It matters here because the connector and pinout are compatible with some LoRa telemetry products, even though this module uses Bluetooth instead.
microSD card
A microSD card is a small removable memory card used to store files such as audio tracks. For this product, the card is where the sound files live, so its capacity and formatting can affect how many sounds you can use.
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.
RTC
A Real-Time Clock keeps track of time even when the main processor is asleep or powered down, usually with a small backup battery. It matters for data logging and tracking projects that need accurate timestamps.
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.

Related Tutorials

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