#include <LiquidCrystal_I2C.h>

#define clk 2
#define dt 3
#define sw 4

int counter=0;

LiquidCrystal_I2C lcd(0x27,16,2);

void setup() {
  // put your setup code here, to run once:
  lcd.init();
  lcd.backlight();

  pinMode(clk,INPUT);
  pinMode(dt, INPUT);
  pinMode(sw, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(clk),readEncoder,FALLING);
}

void readEncoder() {
  int dtValue = digitalRead(dt);
  if (dtValue == HIGH) {
    counter++; // Clockwise
  }
  if (dtValue == LOW) {
    counter--; // Counterclockwise
  }
}

int getCounter() {
  int result;
  noInterrupts();
  result = counter;
  interrupts();
  return result;
}

void resetCounter() {
  noInterrupts();
  counter = 0;
  interrupts();
}

void loop() {
  // put your main code here, to run repeatedly:
  lcd.setCursor(3, 0);
  lcd.print("Counter:");
  lcd.setCursor(7, 1);
  lcd.print(getCounter());
  lcd.print("        ");

  if (digitalRead(sw) == LOW) {
    resetCounter();
  }
}