#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);

#define ENCODER_CLK 2
#define ENCODER_DT 3
#define ENCODER_SW 4

int counter = 0;

void setup() {
  // Initial LCD:
  lcd.init();
  lcd.backlight();

  // Initial encoder
  pinMode(ENCODER_CLK, INPUT);
  pinMode(ENCODER_DT, INPUT);
  pinMode(ENCODER_SW, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(ENCODER_CLK), readEncoder, FALLING);
}

void readEncoder(){
  int dtValue = digitalRead(ENCODER_DT);
  if (dtValue == HIGH) {
    counter++;
  }
  if (dtValue == LOW){
    counter--;
  }
}

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

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

void loop()
{
  lcd.setCursor(3,0);
  lcd.print("Counter: ");
  lcd.setCursor(7,1);
  lcd.print(getCounter());
  lcd.print("          ");
  if(digitalRead(ENCODER_SW)==LOW){
    resetCounter();
  }
}