int RED = 5;
int YELLOW = 18;
int GREEN = 19;
void setup() {
pinMode(5, OUTPUT); // RED
pinMode(18, OUTPUT); // YELLOW
pinMode(19, OUTPUT); // GREEN
}
void loop() {
digitalWrite(5, HIGH);
digitalWrite(18, LOW);
digitalWrite(19, LOW);
delay(3000);
digitalWrite(5, LOW);
digitalWrite(18, HIGH);
digitalWrite(19, LOW);
delay(1000);
digitalWrite(5, LOW);
digitalWrite(18, LOW);
digitalWrite(19, HIGH);
delay(3000);
}