Documentation

// KY-040 Rotary Encoder - Arduino Example
// CLK = D2 (interrupt), DT = D3, SW = D4

const int CLK = 2;
const int DT  = 3;
const int SW  = 4;

volatile long counter = 0;
volatile int lastCLK = HIGH;

void readEncoder() {
  int cur = digitalRead(CLK);
  if (cur != lastCLK && cur == LOW) {
    if (digitalRead(DT) != cur) counter++;
    else                         counter--;
  }
  lastCLK = cur;
}

void setup() {
  Serial.begin(9600);
  pinMode(CLK, INPUT);
  pinMode(DT,  INPUT);
  pinMode(SW,  INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(CLK), readEncoder, CHANGE);
}

void loop() {
  static long last = 0;
  if (counter != last) {
    Serial.print("Count: ");
    Serial.println(counter);
    last = counter;
  }
  if (digitalRead(SW) == LOW) {
    Serial.println("Button pressed!");
    delay(200);  // debounce
  }
}

// KY-040 Rotary Encoder - ESP32 Example
// CLK = GPIO 18, DT = GPIO 19, SW = GPIO 21

const int CLK = 18;
const int DT  = 19;
const int SW  = 21;

volatile long counter = 0;
volatile int lastCLK = HIGH;

void IRAM_ATTR readEncoder() {
  int cur = digitalRead(CLK);
  if (cur != lastCLK && cur == LOW) {
    if (digitalRead(DT) != cur) counter++;
    else                         counter--;
  }
  lastCLK = cur;
}

void setup() {
  Serial.begin(115200);
  pinMode(CLK, INPUT);
  pinMode(DT,  INPUT);
  pinMode(SW,  INPUT_PULLUP);
  attachInterrupt(CLK, readEncoder, CHANGE);
}

void loop() {
  static long last = 0;
  if (counter != last) {
    Serial.printf("Count: %ld\n", counter);
    last = counter;
  }
  if (digitalRead(SW) == LOW) {
    Serial.println("Button pressed!");
    delay(200);
  }
}

#!/usr/bin/env python3
# KY-040 Rotary Encoder - Raspberry Pi Example
# CLK=GPIO17, DT=GPIO27, SW=GPIO22

from gpiozero import RotaryEncoder, Button
from signal import pause

rotor = RotaryEncoder(17, 27, max_steps=0)
button = Button(22, pull_up=True)

def turned():
    print("Count: {}".format(rotor.steps))

def pressed():
    print("Button pressed!")

rotor.when_rotated = turned
button.when_pressed = pressed

print("Turn the knob or press the button. Ctrl+C to quit.")
pause()

# KY-040 Rotary Encoder - Pico MicroPython Example
# CLK=GP15, DT=GP14, SW=GP13

from machine import Pin
import time

clk = Pin(15, Pin.IN, Pin.PULL_UP)
dt  = Pin(14, Pin.IN, Pin.PULL_UP)
sw  = Pin(13, Pin.IN, Pin.PULL_UP)

counter = 0
last_clk = clk.value()

def on_rotate(pin):
    global counter, last_clk
    cur = clk.value()
    if cur != last_clk and cur == 0:
        if dt.value() != cur:
            counter += 1
        else:
            counter -= 1
    last_clk = cur

clk.irq(trigger=Pin.IRQ_FALLING | Pin.IRQ_RISING, handler=on_rotate)

last_print = counter
while True:
    if counter != last_print:
        print("Count:", counter)
        last_print = counter
    if sw.value() == 0:
        print("Button pressed!")
        time.sleep_ms(200)
    time.sleep_ms(10)