Reading one Rotary Encoder from a Raspberry Pi with Processing 3

rotary_encoder.pde

/*
Reading one Rotary Encoder from a Raspberry Pi

Translated from C to Processing by Heracles Papatheodorou
via http://theatticlight.net/posts/Reading-a-Rotary-Encoder-from-a-Raspberry-Pi/


		GND 	MIDDLE encoder leg
GPIO22	GPIO23	LEFT and RIGHT legs
3.3V			LEFT and RIGHT, splits to two 10k resistors for pull-up

Processing doesn't support pull-ups, hardware pull-up required:
	https://learn.adafruit.com/processing-on-the-raspberry-pi-and-pitft/hardware-io
	https://learn.sparkfun.com/tutorials/pull-up-resistors/what-is-a-pull-up-resistor

Processing reference:
	https://github.com/processing/processing/wiki/Raspberry-Pi
	https://processing.org/reference/libraries/io/index.html

Reading rotary encoders on the RaspPi:
	http://theatticlight.net/posts/Reading-a-Rotary-Encoder-from-a-Raspberry-Pi/
	https://projects.drogon.net/raspberry-pi/wiringpi/functions/
*/

import processing.io.*; // import the hardware IO library

int pin_a = 19;
int pin_b = 13;
long value = 0;
int lastEncoded = 0;

void setup() {
	noCursor();

	GPIO.pinMode(pin_a, GPIO.INPUT_PULLUP);
	GPIO.pinMode(pin_b, GPIO.INPUT_PULLUP);
	
	GPIO.attachInterrupt(pin_a, this, "updateEncoder", GPIO.CHANGE);
	GPIO.attachInterrupt(pin_b, this, "updateEncoder", GPIO.CHANGE);
}

void draw() {
	
}

void updateEncoder(int pin) {
	int MSB = GPIO.digitalRead(pin_a);
	int LSB = GPIO.digitalRead(pin_b);

	int encoded = (MSB << 1) | LSB;
	int sum = (lastEncoded << 2) | encoded;

	if (sum == unbinary("1101") || sum == unbinary("0100") || sum == unbinary("0010") || sum == unbinary("1011")) {
		value++;
	}
	if (sum == unbinary("1110") || sum == unbinary("0111") || sum == unbinary("0001") || sum == unbinary("1000")) { 
		value--;
	}

	lastEncoded = encoded;

	println(value); //DEBUG
}