RotaryEncoder

main.cpp

#include <Arduino.h>
#include "RotaryEncoder.h"

RotaryEncoder encoder(34, 35);

void setup() {
  Serial.begin(115200);
}

void loop() {
  if (encoder.available()) {
      Serial.print(encoder.getPosition());
  }
}

RotaryEncoder.cpp

#include "RotaryEncoder.h"

#include <Arduino.h>
#include <FunctionalInterrupt.h>

RotaryEncoder::RotaryEncoder(int gpio_clk, int gpio_dt)
    : gpio_clk(gpio_clk)
    , gpio_dt(gpio_dt) {
    pinMode(gpio_clk, INPUT);
    pinMode(gpio_dt, INPUT);
}

RotaryEncoder::~RotaryEncoder() {
    detachInterrupt(gpio_clk);
    detachInterrupt(gpio_dt);
}

void RotaryEncoder::begin() {
    attachInterrupt(gpio_clk, std::bind(&RotaryEncoder::ISR, this), CHANGE);
    attachInterrupt(gpio_dt, std::bind(&RotaryEncoder::ISR, this), CHANGE);
}

bool RotaryEncoder::available() {
    return changed;
}

int RotaryEncoder::getPosition() {
    changed = false;
    return position;
}

void RotaryEncoder::setPosition(int newPosition) {
    position = newPosition;
}

void RotaryEncoder::ISR() {
    int clk = digitalRead(gpio_clk);
    int dt  = digitalRead(gpio_dt);

    switch (state) {
        case 0:
            if (!clk) state = 1;
            else if (!dt) state = 4;
            break;
        case 1:
            if (!dt) state++;
            break;
        case 2:
            if (clk) state++;
            break;
        case 3:
            if (clk && dt) {
                position++;
                changed = true;
                state = 0;
            }
            break;
        case 4:
            if (!clk) state++;
            break;
        case 5:
            if (dt) state++;
            break;
        case 6:
            if (clk && dt) {
                position--;
                changed = true;
                state = 0;
            }
            break;
        default:
            break;
    }
}

RotaryEncoder.h

#pragma once

class RotaryEncoder {
  public:
    RotaryEncoder(int gpio_clk, int gpio_dt);
    ~RotaryEncoder();
    void begin();
    bool available();
    int  getPosition();
    void setPosition(int newPosition);

  protected:
    void ISR();

  protected:
    int  gpio_clk, gpio_dt;
    int  position = 0;
    int  state    = 0;
    bool changed  = false;
};