#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);
int voltage;
double output;

void setup() {
  // put your setup code here, to run once:
  lcd.init();
  lcd.backlight();
  lcd.setCursor(5, 0);
  voltage = analogRead(A0);
  output = (double) voltage * 5 /1023;
  lcd.print(output);
  lcd.setCursor(10, 0);
  lcd.print("V");
}

void loop() {
  // put your main code here, to run repeatedly:
  int val;
  val = analogRead(A0);
  if(val != voltage){
      voltage = val;
      lcd.clear();
      lcd.setCursor(5, 0);
      output = (double) voltage * 5 /1023;
      lcd.print(output);
      lcd.setCursor(10, 0);
      lcd.print("V");
  }
}