#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C LCD = LiquidCrystal_I2C(0x27, 16, 2);

void setup() 
{
  LCD.begin(16, 2);
  pinMode(8, INPUT);
  pinMode(7, OUTPUT);
  pinMode(A0, INPUT);
}

void loop() 
{
  while(digitalRead(8) == HIGH);
  int ido = map(analogRead(A0), 0, 1023, 0, 600);

  while (ido > 0)
  {
    LCD.backlight();
    LCD.setCursor(0,0);
    LCD.print("   ");
    LCD.setCursor(0,0);
    LCD.print(ido);
    delay(500);

    ido--;
    if (ido == 0)
    {
      digitalWrite(7, HIGH);
      LCD.clear();
      LCD.print("time out");
      delay(100);
      digitalWrite(7, LOW);  
    }

    if(digitalRead(8) == LOW)
    {
      break;
    }

    LCD.clear();
  }

}