byte red = 19;
byte green = 18;
byte yellow = 5;
int rMillis = 0, gMillis = 0, yMillis = 0;
int rPrev = 0, gPrev = 0, yPrev = 0;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(red, OUTPUT);
  pinMode(green, OUTPUT);
  pinMode(yellow, OUTPUT);
}


void loop() {
  // this speeds up the simulation
  gMillis = millis();

  digitalWrite(green, HIGH);
  for (int i = 30; i >= 1;)
  {
    gMillis = millis();

    if (gMillis - gPrev > 1000)
    {
      gPrev = gMillis;
      Serial.println("Go for " + String(i) + " seconds");
      i--;
    }
  }
  digitalWrite(green, LOW);
  digitalWrite(yellow, HIGH);
  for (int i = 5; i >= 1;)
  {
    yMillis = millis();


    if (yMillis - yPrev > 1000)
    {
      yPrev = yMillis;
      Serial.println("Observe " + String(i) + " seconds");
      i--;
    }
  }

  digitalWrite(yellow, LOW);
  digitalWrite(red, HIGH);
  for (int i = 30; i >= 1;)
  {

    rMillis = millis();

    if (rMillis - rPrev > 1000 )
    {
      rPrev = rMillis;
      Serial.println("Stop " + String(i) + " seconds");
      i--;
    }
  }
  digitalWrite(red, LOW);



}