const int redLED=17;
const int yellowLED=16;
const int greenLED=4;
void setup(){
  Serial.begin(115200);
  if(!Serial) Serial.println("serial is not ok");
  pinMode(redLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  delay(1000);
}
void loop(){
  
  digitalWrite(greenLED, HIGH);
  Serial.println("green is on");
  delay(2000);
  digitalWrite(greenLED, LOW);
  Serial.println("green is off");
  digitalWrite(yellowLED, HIGH);
  Serial.println("yellow is on");
  delay(600);
  digitalWrite(yellowLED, LOW);
  Serial.println("yellow is off");
  digitalWrite(redLED, HIGH);
  Serial.println("red is on");
  delay(1800);
  digitalWrite(yellowLED, HIGH);
  Serial.println("yellow is on");
  delay(400);
  digitalWrite(redLED, LOW);
  Serial.println("red is off");
  digitalWrite(yellowLED, LOW);
  Serial.println("yellow is off");
}