GPIO Waver

GPIO Waver is a low-cost STM32F042 (48 MHz) board focused on expansion: it exposes two GPIO headers and little else. It’s ideal for prototyping new EMWaver add-on hardware, and it’s also the base board for modules like RFID Waver. It communicates over USB (no BLE) for Android (USB OTG) and the desktop EMWaver app. Bonus: the native USB stack also enables USB device emulation.

This is an open older design. Download its fabrication files — schematic, PCB, BOM, and gerbers — to build a board yourself.