If for some reason you want to use one or more Arduino microcontrollers with a Raspberry Pi single board computer, the Instructables user JRV31 shows us how to combine the prototyping platforms using the WiringPi library and the Drogon Remote Control (DRC) sketch.
This method is simple and consists of an Arduino sketch that can handle the USB communication between one or more Arduinos and the Pi. The sketch is called Drogon Remote Control, and it has to be running on each Arduino connected to the Pi. Once the communication between the two platforms was established, the Pi and the Arduino become one system and let you use the features and power of both development boards.
In the Instructables tutorial, the user uses the Raspberry Pi to program both Arduinos. The first Arduino is used for digital and analog read/write functions while the second Arduino is programmed to blink the LED on pin thirteen.
The marriage between Pi and Arduino is very helpful for users who want to use the best things of Pi with the style of Arduino.