void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(21, OUTPUT);
  pinMode(22, OUTPUT);
  pinMode(23, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);
  pinMode(14, OUTPUT);
}

void loop() {
 digitalWrite(21, HIGH);
 digitalWrite(14, HIGH);
 digitalWrite(22, LOW);
 digitalWrite(23, LOW);
 digitalWrite(13, LOW);
 digitalWrite(12, LOW);
  delay(1000); // this speeds up the simulation
 digitalWrite(22, HIGH);
 digitalWrite(13, HIGH);
 digitalWrite(21, LOW);
 digitalWrite(23, LOW);
 digitalWrite(12, LOW);
 digitalWrite(14, LOW);
 delay(1000);
 digitalWrite(23, HIGH);
 digitalWrite(12, HIGH);
 digitalWrite(21, LOW);
 digitalWrite(22, LOW);
 digitalWrite(14, LOW);
 digitalWrite(12, LOW);
 delay(1000);
}