Uduino is another Open Source plugin for Unity, which allow to communicate between a Arduino board with Unity.
This project was created after too much frustration on how to properly connected Unity & Arduino. During past past experiences I was facing some problems: difficulties to detect a specific Arduino board when several are connected, freeze and crash when communicating with serial ports, and many more...
Uduino aims to be a comprehensive and easy to setup solution for your Arduino/Unity projects. It features simple declaration both on Unity and Arduino side.
While waiting for a sustainable open-source alternative, I removed Uduino source code from Github. You can now get Uduino on Unity Asset Store and get more informations on the official website.