# Adafruit HalloWing M0 Express > Skull-shaped wearable microcontroller with ATSAMD21G18 at 48MHz, 1.44" 128x128 TFT display, 3-axis accelerometer, light sensor, 4 capacitive touch pads, 2W speaker driver, 8MB SPI flash, and LiPo charging. ## Quick Facts - **Brand:** Adafruit - **Board Type:** dev-board - **Price:** ~$34.95 - **Product Readiness:** consumer - **CPU:** ATSAMD21G18 ARM Cortex M0+ - **CPU Architecture:** ARM Cortex-M0+ - **CPU Cores:** 1 - **RAM:** 32 KB - **Flash:** 256 KB - **Power:** 5V via USB or LiPo battery via JST connector - **Operating Voltage:** 3.3V - **Dimensions:** 60mm × 51mm × 11mm - **Weight:** 17.5g - **Display:** 1.44" TFT LCD 128×128 ## Open Source - **Firmware:** Yes - **Schematics:** Yes - **PCB Layout:** Yes ## Compatible Firmware circuitpython, arduino ## Use Cases - wearable - cosplay - halloween - badge - animated-display - education ## Components - **ATSAMD21G18** (mcu): 32-bit ARM Cortex M0+ at 48 MHz with 256 KB flash, 32 KB SRAM, native USB. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fww1.microchip.com%2Fdownloads%2Fen%2FDeviceDoc%2FSAM-D21DA1-Family-Data-Sheet-DS40001882G.pdf&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) - **ST7735R** (display-driver): 128x128 color TFT LCD controller for full-color graphical display output. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.crystalfontz.com%2Fcontrollers%2FSitronix%2FST7735R%2F&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) - **LIS3DH** (imu): 3-axis digital accelerometer for motion detection and tilt sensing. — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.st.com%2Fresource%2Fen%2Fdatasheet%2Flis3dh.pdf&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) ## Protocols - **I2C**: SDA: D4, SCL: D5 - **SPI**: MOSI: D11, MISO: D12, SCK: D13, SS: D10 - **UART**: TX: D1, RX: D0 - **USB**: ## GPIO Map | Pin | Name | Type | Functions | |-----|------|------|-----------| | D4 | SDA | I2C | digital-input, digital-output | | D5 | SCL | I2C | digital-input, digital-output | | D6 | GPIO | — | digital-input, digital-output, pwm | | D9 | GPIO | — | digital-input, digital-output, pwm | | D10 | SS | SPI | 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 | | A0 | ADC/DAC | — | digital-input, digital-output, analog-input, dac | | A1 | ADC | — | digital-input, digital-output, analog-input | | A2 | ADC | — | digital-input, digital-output, analog-input | | A3 | ADC | — | digital-input, digital-output, analog-input | ## Available Software - **[CircuitPython]()** (open-source) - **[Arduino]()** (open-source) ## Description ## Overview The Adafruit HalloWing M0 Express is a skull-shaped development board combining the ATSAMD21G18 microcontroller with a built-in 1.44" 128×128 TFT color LCD, making it an all-in-one platform for animated eyes, badges, and interactive cosplay projects. The skull PCB shape is both a functional board and a visual design element. The ATSAMD21G18 runs at 48 MHz with 256 KB flash and 32 KB SRAM, supplemented by 8 MB of SPI flash for storing images, animations, audio samples, and CircuitPython code. The 1.44" TFT displays full-color graphics at 128×128 resolution, and the Feather-compatible header strips expose GPIO for connecting additional components. Four capacitive touch pads on the outer edge of the skull provide touch-sensitive input without physical buttons. Onboard sensors include a 3-axis accelerometer for motion/tilt detection and a light sensor for ambient brightness measurement — both useful for creating reactive animated displays. A Class-D mono speaker driver capable of 2W into 4-8Ω speakers enables audio playback and sound effects. JST-PH connectors provide access to NeoPixel chains, additional sensors, and I2C peripherals. A LiPo connector with built-in charging enables battery-powered operation. The HalloWing ships with CircuitPython pre-installed and is compatible with the Arduino IDE. It is most commonly used for animatronic eye projects (including servo-controlled realistic eyes), wearable cosplay props, interactive Halloween decorations, and novelty badges — any project benefiting from a built-in TFT screen in an unusual form factor. ## Where to Buy - [Adafruit](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3900&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) — 34.95 ## Resources - [product page](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3900&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) - [product](https://openhardware.directory/r?to=https%3A%2F%2Fwww.adafruit.com%2Fproduct%2F3900&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) - [documentation](https://openhardware.directory/r?to=https%3A%2F%2Flearn.adafruit.com%2Fadafruit-hallowing&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) - [github](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fadafruit%2FAdafruit-HalloWing-M0-Express-PCB&ref=openhardware.directory&product=adafruit-hallowing-m0-express&source=md-export) ## Tags `wearable`, `halloween`, `tft-display`, `circuitpython`, `arduino`, `atsamd21`, `skull-board`, `cosplay`, `badge`, `capacitive-touch` ## Images ![Adafruit HalloWing M0 Express](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-hallowing-m0-express/2b41878c902b.jpg) ![Adafruit HalloWing M0 Express](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-hallowing-m0-express/dc4cd52fd4c6.jpg) ![Adafruit HalloWing M0 Express](https://nbg1.your-objectstorage.com/openhardware-directory/entities/adafruit-hallowing-m0-express/c7206736bd02.jpg) --- [View full device page](https://openhardware.directory/devices/adafruit-hallowing-m0-express)