int a = 2, b = 4, c = 16, d = 17, e = 5, f = 18, g = 21;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(a, OUTPUT);
  pinMode(b, OUTPUT);
  pinMode(c, OUTPUT);
  pinMode(d, OUTPUT);
  pinMode(e, OUTPUT);
  pinMode(f, OUTPUT);
  pinMode(g, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  fn();
  delay(10); // this speeds up the simulation
}

void fn(){
  //nine
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
  delay(1000);

  //eight
  digitalWrite(e, HIGH);
  delay(1000);

  //seven
  digitalWrite(d, LOW);
  digitalWrite(e, LOW);
  digitalWrite(f, LOW);
  digitalWrite(g, LOW);
  delay(1000);

  //six
  digitalWrite(b, LOW);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(d, HIGH);
  delay(1000);

  //five
  digitalWrite(e, LOW);
  delay(1000);

  //four
  digitalWrite(a, LOW);
  digitalWrite(d, LOW);
  digitalWrite(b, HIGH);
  delay(1000);

  //three
  digitalWrite(f, LOW);
  digitalWrite(a, HIGH);
  digitalWrite(d , HIGH);
  delay(1000);

  //two 
  digitalWrite(c, LOW);
  digitalWrite(e, HIGH);
  delay(1000);

  //one 
  digitalWrite(a, LOW);
  digitalWrite(g, LOW);
  digitalWrite(d, LOW);
  digitalWrite(e, LOW);
  digitalWrite(c, HIGH);
  digitalWrite(b, HIGH);
  delay(1000);

  //zero 
  digitalWrite(a, HIGH);
  digitalWrite(f, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(d, HIGH);
  delay(1000);

  //turnoff
  digitalWrite(e, LOW);

}