ATTiny usb bootloader with a strong emphasis on bootloader compactness.

Arduino core for ATtiny 1634, 828, x313, x4, x41, x5, x61, x7 and x8

A FreeRTOS Library for all Arduino ATmega Devices (Uno R3, Leonardo, Mega, etc).

Arduino GFX developing for various color displays and various data bus interfaces

AVRDUDE is a utility to program AVR microcontrollers

A lightweight, secure, easy-to-use crypto library suitable for constrained environments.

Easy AVR USB Keyboard Firmware and Keymapper

Arduino core for the tinyAVR 0/1/2-series - Ones's digit 2,4,5,7 (pincount, 8,14,20,24), tens digit 0, 1, or 2 (featureset), preceded by flash in kb. Library maintainers: porting help available!

Arduino hardware package for ATmega64, ATmega128, ATmega165, ATmega169, ATmega325, ATmega329, ATmega640, ATmega645, ATmega649, ATmega1280, ATmega1281, ATmega2560, ATmega2561, ATmega3250, ATmega3290, ATmega6450, ATmega6490, AT90CAN32, AT90CAN64 and AT90CAN128

SAE J1939 protocol free to use for embedded systems or PC with CAN-bus

A community delivered, open source embedded operating system project.

A set of various projects based on ESP8266, ESP32, ATtiny13, ATtiny85, ATtiny2313, ATmega8, ATmega328, ATmega32, STM32 and more.

open source bare-metal C firmware and documentation for microcontrollers

Board definitions for SparkFun-manufactured AVR, ARM, and ESP-based Arduino boards.

A lightweight, header-only, hardware-agnostic Modbus RTU/TCP library

I2C based soil moisture sensor

µCNC - Universal CNC firmware for microcontrollers

ERIKA Enterprise v3 RTOS

RTOS for microcontrollers

An open-source OS for embedded applications that supports prioritized cooperative scheduling, time control, inter-task communications primitives, hierarchical state machines and CoRoutines.