//
// Throb is a class that brightens and dims an LED in a cycle, so it appears to throb.
// The constructor takes an initial brightness, and a pin number as arguments.
// Calling the method change() causes the brightness to change.
//
// By starting each LED off with a different brightness, they will change out of sync
// with one another. By calling the change() method a different number of times for each LED,
// they will throb at different rates.
//
// Only three LEDs can be controlled: those on pin 4 (P1.2), pin 9 (P2.1), and pin 12 (P2.4).
//

class Throb
{
  int brightness;
  int pin;
  int increment;
public:
  Throb( int b, int p ) { brightness = b; pin = p; increment = 1; pinMode( pin, OUTPUT ); }  
  void change( void )
  {
    if( brightness > 100 )
      increment = -1;
    else if( brightness < 0 )
      increment = 1;
    brightness += increment;
    analogWrite( pin, brightness );
  }
};

Throb *a, *b, *c;

void
setup()
{        
  a = new Throb( 5, P1_2 );
  b = new Throb( 16, P2_1 );
  c = new Throb( 64, P2_4 );
}

void
loop()
{
  a->change();
  
  b->change();
  b->change();
  
  c->change();
  c->change();
  c->change();
  
  delay( 20 );
}