The Rotary Encoder Module is an incremental electro-mechanical device that converts the angular position of a shaft to digital code. It features a rotational displacement encoder which outputs a series of pulses whenever the switch is rotated. This module provides an indication of how much the knob has been rotated and the direction of rotation. You could also use it to control devices like digital potentiometers. This Rotary Encoder Module is today's electronic alternative to the potentiometer. It is used in a wide range of applications.

Test Code

int redPin = 2;
int yellowPin = 3;
int greenPin = 4;
int aPin = 6;
int bPin = 7;
int buttonPin = 5;
int state = 0;
int longPeriod = 5000; // Time at green or red
int shortPeriod = 700; // Time period when changing
int targetCount = shortPeriod;
int count = 0;

void setup() {
pinMode(aPin, INPUT);
pinMode(bPin, INPUT);
pinMode(buttonPin, INPUT);
pinMode(redPin, OUTPUT);
pinMode(yellowPin, OUTPUT);
pinMode(greenPin, OUTPUT);
}

void loop() {
count++;
if (digitalRead(buttonPin)) {
setLights(HIGH, HIGH, HIGH);
}
else {
int change = getEncoderTurn();
int newPeriod = longPeriod + (change * 1000);
if (newPeriod >= 1000 && newPeriod <= 10000) {
longPeriod = newPeriod;
}
if (count > targetCount) {
setState();
count = 0;
}
}
delay(1);
}

int getEncoderTurn () {
// Return -1, 0, or +1
static int oldA = LOW;
static int oldB = LOW;
int result = 0;
int newA = digitalRead(aPin);
int newB = digitalRead(bPin);
if (newA != oldA || newB != oldB) {
//Something has changed
if (oldA == LOW && newA == HIGH) {
result = - (oldB * 2 - 1);
}
}
oldA = newA;
oldB = newB;
return result;
}

int setState() {
if (state == 0) {
setLights(HIGH, LOW, LOW);
targetCount = longPeriod;
state = 1;
}
else if (state == 1) {
setLights(HIGH, HIGH, LOW);
targetCount = shortPeriod;
state = 2;
}
else if (state == 2) {
setLights(LOW, LOW, HIGH);
targetCount = longPeriod;
state = 3;
}
else if (state == 3) {
setLights(LOW, HIGH, LOW);
targetCount = shortPeriod;
state = 0;
}
}

void setLights(int red, int yellow, int green) {
digitalWrite(redPin, red);
digitalWrite(yellowPin, yellow);
digitalWrite(greenPin, green);
}