#define PIN_RED    2
#define PIN_GREEN  4
#define PIN_BLUE   0

void setup()
{
  pinMode(PIN_RED,   OUTPUT);
  pinMode(PIN_GREEN, OUTPUT);
  pinMode(PIN_BLUE,  OUTPUT);
}

void loop()
{
  analogWrite(PIN_RED, 255);
  analogWrite(PIN_GREEN, 0);
  analogWrite(PIN_BLUE, 0);
  delay(500);

  analogWrite(PIN_RED, 0);
  analogWrite(PIN_GREEN, 255);
  analogWrite(PIN_BLUE, 0);
  delay(500);

  analogWrite(PIN_RED, 0);
  analogWrite(PIN_GREEN, 0);
  analogWrite(PIN_BLUE, 255);
  delay(500);
}