MicroPython - a lean and efficient Python implementation for microcontrollers and constrained systems

A Modbus library for Linux, Mac OS, FreeBSD and Windows

The Network UPS Tools repository. UPS management protocol Informational RFC 9271 published by IETF at https://www.rfc-editor.org/info/rfc9271 Please star NUT on GitHub, this helps with sponsorships!

Solo 1 firmware in C

libreswan

a collection of "Little Electronic & Arduino Projects", most involving electronics or an Arduino in one way or another!

The Neko Virtual Machine

BACnet Protocol Stack library provides a BACnet application layer, network layer and media access (MAC) layer communications services.

Cheap and simple I²C to USB interface

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

A really tiny Java Virtual Machine

ATtiny13 Software UART library.

This is tinyAVR (ATtiny13, ATtiny25, ATtiny45, ATtiny85, etc.) library to access devices using OneWire (1-Wire) protocol.

ATtiny13 - tiny library and several example projects (AVR-GCC)

Multiple power and data switch

Library to control a LED system via parallel port