All of the Processing API can be used on the Raspberry Pi. There is some additional functions that are particularly relevant to the Raspberry Pi, as they allow Processing to make use of the Pi’s extension header pins. This functionality is available through the Hardware I/O library, and is documented below.
The GPIO class reads and writes from General Purpose I/O pins.
The I2C class communicates with peripherals over I2C interfaces.
The SoftwareServo class controls RC servo motors attached to General Purpose I/O pins.