int ledPin = 10;
void setup() {
 pinMode(ledPin, OUTPUT);
}


void loop() {
  S();
  delay(1000);
  O();
  delay(1000);
  S();
  delay(5000);
}


//sub rutin
void S (){
// 3 quick blinks to represent “S”
 digitalWrite(ledPin,HIGH);
 delay(150);
 digitalWrite(ledPin,LOW);
 delay(100);
 digitalWrite(ledPin,HIGH);
 delay(150);
 digitalWrite(ledPin,LOW);
 delay(100);
 digitalWrite(ledPin,HIGH);
 delay(150);
 digitalWrite(ledPin,LOW);
 delay(100);
}

void O (){
 //3 quick blinks to represent “0”
 digitalWrite(ledPin,HIGH);
 delay(400);
 digitalWrite(ledPin,LOW);
 delay(100);
 digitalWrite(ledPin,HIGH);
 delay(400);
 digitalWrite(ledPin,LOW);
 delay(100);
 digitalWrite(ledPin,HIGH);
 delay(400);
 digitalWrite(ledPin,LOW);
 delay(100);
}