//
// A more sensitive LED light detector.
// The LED connected to P2.0 and P2.1 is the sensor.
// It should not light up (if it does, you have it in backwards).
// The LED connected to P2.2 and P2.3 should light up -- it is
// the LED that illuminates anything in front of us.
//
enum
{
  CHARGE_THE_LED=0b01, READ_THE_LED=~0b01, NO_PULLUP=~0b01, LED_HAS_CHARGE=0b01, LED_PINS=0b11
};

void
setup( void )
{
  delay( 5000 );
  Serial.begin( 9600 );
  Serial.println( "Light sensor demo" );
  P2DIR = 0b1100;
  P2OUT = 0b1000;
}

void
loop( void )
{
  P2DIR |= LED_PINS;
  P2OUT |= CHARGE_THE_LED;
  P2DIR &= READ_THE_LED;
  P2OUT &= NO_PULLUP;

  unsigned long count = 0;
  while( P2IN & LED_HAS_CHARGE )
    count++;
  for( unsigned x = 0; x < count/10000; x++ )
    Serial.print( "#" );
  Serial.println( "" );
}