Description of the lecture: The use of open platforms for programming microcontrollers has leveraged the Internet of Things in Brazil and in the World. One of the most widely used and recognized today is the Arduino. This open-source and open-hardware electronic prototyping tool has gained fans at a fast pace. However, initially only C ++ programming limited the mass adoption of the technology. With the advent of the Firmata protocol, which exposes the ports in a common interface, several programming languages have gained an API that optimizes and clarifies the use of sensors and actuators. Nowadays, it is possible to program microcontrollers with different languages and, Ruby, could not be left out. The objective of this lecture is precisely to show the forms of Arduino-Ruby communication with and without protocol Firmata..