#define PIN_RED 2
#define PIN_YELLOW 3
#define PIN_GREEN 4
#define TIME 2500

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

void loop() {
  digitalWrite(PIN_RED, LOW);
  digitalWrite(PIN_YELLOW, HIGH);
  digitalWrite(PIN_GREEN, HIGH);
  delay(TIME);
  digitalWrite(PIN_RED, LOW);
  digitalWrite(PIN_YELLOW, LOW);
  digitalWrite(PIN_GREEN, HIGH);
  delay(TIME);
  digitalWrite(PIN_RED, HIGH);
  digitalWrite(PIN_YELLOW, HIGH);
  digitalWrite(PIN_GREEN, LOW);
  delay(TIME);

  digitalWrite(PIN_RED, HIGH);
  digitalWrite(PIN_YELLOW, LOW);
  digitalWrite(PIN_GREEN, HIGH);
  delay(TIME);

}