Adafruit
Adafruit Grand Central M4 Express featuring SAMD51 - Without Headers
The Adafruit Grand Central M4 Express is a powerful development board built around the Microchip ATSAMD51P20 — a 120 MHz Cortex M4 processor with hardware fl...
The Adafruit Grand Central M4 Express is a powerful development board built around the Microchip ATSAMD51P20 — a 120 MHz Cortex M4 processor with hardware floating point, 1 MB Flash, and 256 KB RAM. In the familiar Arduino Mega form factor, it brings 70 GPIO pins, dual DACs, 15 analog inputs, 8 MB QSPI Flash, an SD card slot, and a NeoPixel to your projects.
This headerless version ships without through-hole components soldered, making it ideal for direct soldering into custom builds or fitting into tight spaces. It supports both CircuitPython and Arduino IDE, with a UF2 bootloader for drag-and-drop firmware loading over USB.
Key Features
- ATSAMD51P20 Cortex M4 at 120 MHz – Hardware DSP and floating point support
- 1 MB Flash, 256 KB RAM – 32-bit, 3.3V logic and power
- 70 GPIO Pins Total – 62 accessible GPIO, 16 analog inputs, 2 true analog outputs (DAC)
- 8 Hardware SERCOM – Configurable as I²C, SPI, or UART
- 22 PWM Outputs – For servos, LEDs, and motor control
- Stereo I²S Input/Output – With MCK pin for audio projects
- 12-bit Parallel Capture Controller – For camera and video input
- Built-in Crypto Engines – AES-256, true RNG, and public key controller
- 8 MB QSPI Flash – Acts as storage for CircuitPython scripts and files, or as a datalogger in Arduino
- Micro SD Card Slot – Removable storage via SPI
- Native USB – Serial, HID keyboard/mouse, and UF2 bootloader for drag-and-drop programming
- Flexible Power – 7–9V DC via 2.1 mm jack (with on/off switch) or 5V via Micro-USB, with automatic switching
- Status LEDs and NeoPixel – Green power LED, RX/TX LEDs, red indicator LED, and one RGB NeoPixel
Ideal For
- Complex projects needing many I/O pins (Arduino Mega replacement)
- CircuitPython development with high performance and large storage
- Audio, sensor logging, and data-heavy applications
- Custom builds requiring a low-profile, headerless board
Package Contents
- 1× Adafruit Grand Central M4 Express (without headers) – Assembled and tested
- 1× 2.1 mm DC jack (loose, unsoldered)
- Bumper feet
Resources
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.
- Headers
- Rows of metal pins used to plug a module into a breadboard or connect it with jumper wires. Pre-soldered headers make the module easier to use straight away without needing to solder the pins yourself.
- 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.
- 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.
- 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.
- UART
- UART is a simple serial connection that sends data over separate transmit and receive wires, often labelled TX and RX. It matters because this module is designed to replace a wired UART cable with a wireless link while keeping the same serial data format.
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Brands
Microcontrollers
Related Tutorials
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