#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

#define Start 7
#define Stop 8
#define Reset 9
int cont = 0;
boolean memoria=0;

LiquidCrystal_I2C lcd(0x27,16,2);

void setup()
{
  lcd.init();
  lcd.backlight();

  lcd.setCursor(2,0);
  lcd.print("cronometro");

  pinMode(Start, INPUT_PULLUP);
  pinMode(Stop, INPUT_PULLUP);
  pinMode(Reset, INPUT_PULLUP);
} 


void loop()
{
  lcd.setCursor(2,1);
  lcd.print(cont);
  lcd.print("                        ");
  
  delay(100);
  if(digitalRead(Start)==0) memoria=1;
  if(digitalRead(Stop)==0) memoria=0;
  if(digitalRead(Reset)==0) memoria=0, cont=0;
  if(memoria==1) cont++;

}