Libopencm3Open source ARM Cortex-M microcontroller library
RiotRIOT - The friendly OS for IoT
3bc-langLow level language, tiny virtual machine that works on computers and microcontrollers. (Friendly Punched cards)
ArduinoQueueA lightweight linked list type queue implementation, meant for microcontrollers.
O7Oberon → ARMv{6,7E}-M compiler
px-fwlibopen source bare-metal C firmware and documentation for microcontrollers
Python-For-KidsA comprehensive and FREE Online Python Development tutorial FOR KIDS utilizing an official BBC micro:bit Development Board going step-by-step into the world of Python for microcontrollers.
NuttXOfficial micro-ROS RTOS
CMLFast, safe and easy to use Cortex-M HAL Library, written in C++ 17
cortexm-AEShigh performance AES implementations optimized for cortex-m microcontrollers
utestLightweight unit testing framework for C/C++ projects. Suitable for embedded devices.