threadx
                                Eclipse ThreadX is an advanced real-time operating system (RTOS) designed specifically for deeply embedded applications.
                            
                        How to download and setup threadx
Open terminal and run command
                                            git clone https://github.com/eclipse-threadx/threadx.git
                                        
                                        git clone is used to create a copy or clone of threadx repositories.
                                        You pass git clone a repository URL. it supports a few different network protocols and corresponding URL formats.
Also you may download zip file with threadx https://github.com/eclipse-threadx/threadx/archive/master.zip
Or simply clone threadx with SSH
                                            [email protected]:eclipse-threadx/threadx.git                                    
                                    If you have some problems with threadx
You may open issue on threadx support forum (system) here: https://github.com/eclipse-threadx/threadx/issuesSimilar to threadx repositories
Here you may see threadx alternatives and analogs
core netdata gun openpose EasyFlash darkflow firebase-js-sdk ws kong Rocket.Chat goaccess sc-crud-sample wekan ArduinoJson iot-433mhz Home-Monitoring-Raspberry-Pi-Node flogo awesome-iot-hacks refocus feathers AiLight xmpp.js johnny-five gobot cylon platformio-core blynk-library blynk-server Sming PJON