Adafruit HalloWing M4 Express

Overview

The Adafruit HalloWing M4 Express is a Halloween-themed microcontroller board shaped like a skull, designed for spooky props, wearable costumes, and interactive displays. At its core sits the ATSAMD51J19 ARM Cortex-M4F running at 120MHz — the same powerful chip found in Adafruit's Feather M4 and PyGamer — paired with 512KB of internal Flash, 192KB of RAM, and 8MB of SPI Flash for storing images, sounds, and animations.

The front of the skull features a 1.54-inch IPS TFT LCD at 240×240 pixels, offering roughly four times the pixel density of the original M0 version. Below the screen sit four capacitive touch inputs shaped like fanged teeth, each with alligator-clip-friendly pads, enabling interactive animations triggered by touch or proximity. Four side-mounted NeoPixel LEDs add colorful effects, while a mono Class-D speaker driver (up to 1W into 4–8Ω) provides audio output for sound effects and music.

The board ships with a 3-axis accelerometer (MSA311 in current production) for motion-reactive effects and a light sensor for ambient detection. A LiPoly battery port with recharging circuitry makes wireless, untethered deployment straightforward. The female header strips expose a Feather-compatible pinout, so any FeatherWing can be stacked on the back.

Programming is fully supported through both CircuitPython (with drag-and-drop firmware via UF2 bootloader) and the Arduino IDE. The PCB was redesigned in black in March 2023, giving the board its distinctive "Goth Black" aesthetic. Note that the LiPoly battery is sold separately; Adafruit recommends 350mAh or 500mAh 3.7V cells.