I wanted to make some kind of visual feedback on the screen, as well as to debug my serial connection. So I made a bullseye that tracks mouse movement, maps the value between 0 – 179, and sends the mapped value to the Arduino as a serial message. Since this had to be updated in real time, and since p5 and Arduino both communicate in an asynchronous manner at a 9600 baudrate, I would send this updated value every loop.