#define PULSANTE 2
bool bIS_LED_ON = false;

void setup() 
{
 pinMode( PULSANTE, INPUT_PULLUP );
 pinMode( LED_BUILTIN, OUTPUT );
}

void loop() 
{
  if ( digitalRead( PULSANTE ) == LOW );
  {
   digitalWrite( LED_BUILTIN, !bIS_LED_ON );
   bIS_LED_ON = !bIS_LED_ON;
  }
  while ( digitalRead( PULSANTE ) == LOW )
  {
    delay( 10 );
  }
}