const int LEDpin = 3;
const long onDuration = 100;// OFF time for LED
const long offDuration = 500;// ON time for LED
int LEDState = HIGH; // initial state of LED

long rememberTime = 0; // this is used by the code

void setup() {
  pinMode(LEDpin, OUTPUT); // define LEDpin as output
  digitalWrite(LEDpin, LEDState); // set initial state
}

void loop() {
  // LED blink with millis

  if ( LEDState == HIGH )
  {
    if ( (millis() - rememberTime) >= onDuration) {
      LEDState = LOW;// change the state of LED
      rememberTime = millis(); // remember Current millis() time
    }
  }
  else
  {
    if ( (millis() - rememberTime) >= offDuration) {
      LEDState = HIGH; // change the state of LED
      rememberTime = millis(); // remember Current millis() time
    }
  }

  digitalWrite(LEDpin, LEDState); // turn the LED ON or OFF

}// loop ends