int LED_GREEN   = 3;
int LED_RED     = 4;
int LED_BLUE    = 2;

void setup() 
{
  pinMode(LED_RED, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_BLUE, OUTPUT);
}

void loop() 
{
  // All off
  digitalWrite(LED_RED, LOW);
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_BLUE, LOW);

  delay(1000);

  // red on
  digitalWrite(LED_RED, HIGH);
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_BLUE, LOW);

  delay(1000);

  // green on
  digitalWrite(LED_RED, LOW);
  digitalWrite(LED_GREEN, HIGH);
  digitalWrite(LED_BLUE, LOW);

  delay(1000);

  // blue on
  digitalWrite(LED_RED, LOW);
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_BLUE, HIGH);

  delay(1000);

  // red & green on
  digitalWrite(LED_RED, HIGH);
  digitalWrite(LED_GREEN, HIGH);
  digitalWrite(LED_BLUE, LOW);

  delay(1000);

  // red & blue on
  digitalWrite(LED_RED, HIGH);
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_BLUE, HIGH);

  delay(1000);  

  // green & blue on 
  digitalWrite(LED_RED, LOW);
  digitalWrite(LED_GREEN, HIGH);
  digitalWrite(LED_BLUE, HIGH);

  delay(1000);  

  // all on
  digitalWrite(LED_RED, HIGH);
  digitalWrite(LED_GREEN, HIGH);
  digitalWrite(LED_BLUE, HIGH);

  delay(1000);
}