STM32 core support for Arduino
Phobia Motor Controller
Arduino and PlatformIO IDE compatible TFT library
Serial Bootloader for Microchip, Atmel, NXP, TI, 8051 microcontrolers
An Open Source POWERLINK Stack
Native Apple HomeKit accessory implementation for the ESP8266 Arduino
A Java VM for ARDUINO and other micros using the leJOS runtime.
A framework for implementing real-time control systems
Open source observatory control software
Upload, save and run keystroke injection payloads with an ESP8266
Summary
Custom firmware and IDE for the VEX Cortex Microcontroller
Hardware and software for self-driving vehicles
Arduino lx200 based computerized telescope
A small microcontroller LED Pin-back button for just 1 $