# Adafruit Feather M4 Express > High-performance Feather with ATSAMD51J19 Cortex M4F at 120MHz, 192KB RAM, 512KB flash, 2MB SPI flash, dual 12-bit DAC/ADC, AES-256 hardware crypto, LiPo charging, 21 GPIO, and native USB HID. Feather ecosystem compatible. ## Quick Facts - **Brand:** Adafruit - **Board Type:** dev-board - **Price:** ~$22.95 - **Product Readiness:** consumer - **CPU:** Microchip ATSAMD51J19 ARM Cortex M4F - **CPU Architecture:** ARM Cortex-M4F - **CPU Cores:** 1 - **RAM:** 192 KB - **Flash:** 512 KB - **Power:** 5V via Micro USB or 3.7V LiPo via JST connector - **Operating Voltage:** 3.3V - **Dimensions:** 50.8mm × 22.8mm × 7mm - **Weight:** 4.8g ## Open Source - **Firmware:** Yes - **Schematics:** Yes - **PCB Layout:** Yes ## Compatible Firmware circuitpython, arduino ## Use Cases - audio-synthesis - high-speed-dsp - education - prototyping - iot-sensor-platform ## Components - **ATSAMD51J19** (mcu): 32-bit ARM Cortex M4F at 120 MHz with 512 KB flash, 192 KB SRAM, AES-256, TRNG, native USB, I2S. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FSAM_D5xE5x_Family_Data_Sheet_DS60001507G.pdf&ref=openhardware.directory&product=adafruit-feather-m4-express&source=md-export) - **GD25Q16C** (flash): 2 MB SPI NOR flash for CircuitPython and data storage. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.gigadevice.com%2Fdatasheet%2Fgd25q16c%2F&ref=openhardware.directory&product=adafruit-feather-m4-express&source=md-export) ## Protocols - **I2C**: SDA: SDA, SCL: SCL - **SPI**: MOSI: D11, MISO: D12, SCK: D13 - **UART**: TX: D1, RX: D0 - **USB**: - **I2S**: ## GPIO Map | Pin | Name | Type | Functions | |-----|------|------|-----------| | D0 | RX | UART | digital-input, digital-output | | D1 | TX | UART | digital-input, digital-output | | D4 | GPIO | — | digital-input, digital-output | | D5 | GPIO | — | digital-input, digital-output, pwm | | D6 | GPIO | — | digital-input, digital-output, pwm | | D9 | GPIO | — | digital-input, digital-output, pwm | | D10 | GPIO | — | digital-input, digital-output, pwm | | D11 | MOSI | SPI | digital-input, digital-output, pwm | | D12 | MISO | SPI | digital-input, digital-output | | D13 | SCK | SPI | digital-input, digital-output | | SDA | SDA | I2C | digital-input, digital-output | | SCL | SCL | I2C | digital-input, digital-output | | A0 | ADC/DAC | — | digital-input, digital-output, analog-input, dac | | A1 | ADC/DAC | — | digital-input, digital-output, analog-input, dac | | 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 - **[CircuitPython]()** (open-source) - **[Arduino]()** (open-source) ## Description ## Overview The Adafruit Feather M4 Express is the high-performance member of the Feather family, powered by the Microchip ATSAMD51J19 ARM Cortex M4F processor at 120 MHz with hardware floating-point. It offers a significant performance uplift over M0-based Feathers while maintaining the standard Feather form factor and full compatibility with the extensive FeatherWing ecosystem. With 512 KB of internal flash, 192 KB of SRAM, and 2 MB of external SPI flash, the Feather M4 has ample storage for complex CircuitPython scripts, audio samples, and data buffers. The ATSAMD51J19 includes 6 hardware SERCOM units (configurable as SPI, I2C, or Serial), dual 1 MSPS 12-bit DAC outputs, dual 1 MSPS 12-bit ADC, I2S stereo audio, 8-bit parallel capture, and 16 PWM outputs. AES-256 hardware acceleration and a true RNG provide cryptographic capability for secure IoT applications. Native USB handles HID, MIDI, CDC serial, and mass storage modes simultaneously. The UF2 bootloader enables drag-and-drop firmware flashing: plugging in the board mounts it as a USB drive where .uf2 files or CircuitPython .py files can be copied directly. A built-in NeoPixel and a red LED provide visual feedback. The JST LiPo connector with built-in 100mA charger makes battery-powered deployments straightforward. The Feather M4 is ideal for audio synthesis, software-defined radio preprocessing, machine learning inference on small models, real-time data visualization, and any maker project that needs more processing power than an M0 can provide without sacrificing the convenient Feather form factor. ## Where to Buy - [Adafruit](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3857&ref=openhardware.directory&product=adafruit-feather-m4-express&source=md-export) — 22.95 ## Resources - [product page](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3857&ref=openhardware.directory&product=adafruit-feather-m4-express&source=md-export) - [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3857&ref=openhardware.directory&product=adafruit-feather-m4-express&source=md-export) - [documentation](https://openhardware.directory/r?to=https%3A%2F%2Flearn.adafruit.com%2Fadafruit-feather-m4-express-atsamd51&ref=openhardware.directory&product=adafruit-feather-m4-express&source=md-export) - [github](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fadafruit%2FAdafruit-Feather-M4-Express-PCB&ref=openhardware.directory&product=adafruit-feather-m4-express&source=md-export) ## Tags `circuitpython`, `arduino`, `atsamd51`, `cortex-m4`, `adafruit`, `feather`, `express`, `high-performance`, `lipo` ## Images ![Adafruit Feather M4 Express](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-feather-m4-express/639599783b54.jpg) ![Adafruit Feather M4 Express](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-feather-m4-express/743cf17967d1.jpg) --- [View full device page](https://openhardware.directory/devices/adafruit-feather-m4-express)