trying to delay between sequences I am trying to build a set of four stars using an Arduino, potentiometer and a four channel relay to control how fast it speeds across the stars. My question is how can I delay the process, say for 20 or 30 seconds before it starts again?
Use Delay(  ).
Or this code

long previousMillis;

void setup(){
  previousMillis = millis();//in void setup
  bool lS=LOW;//in void setup
}

void loop(){
  long currentMillis= millis();//in void loop

  if(currentMillis-previousMillis&gt;=20000){
     if (lS==LOW){
       digitalWrite(pinNo,HIGH);
       lS=HIGH;
     }
     else
     {
       digitalWrite(pinNo,LOW);
       lS=LOW;
     }
     previousMillis= millis();
  }
  delay(1);
}


While this does not serve your purpose, it shows you an how to switch on and off and LED after every 20 sec without keeping the Arduino idle for 20 sec.You could improve on it and make your own code.