long previousMicros;
long currentMicros;
uint8_t state = 1;

void setup() {
  pinMode(1, OUTPUT);    // sets the digital pin 2 as output
  digitalWrite(1, LOW);
  previousMicros=millis(); 
}

void loop() {
  currentMicros = millis(); 
  if ((currentMicros - previousMicros) > 100)
  {
    previousMicros = currentMicros;
    state=!state;
    if(state)
    {
      digitalWrite(1, 1);
    } 
    else 
    {
      digitalWrite(1, 0);
    }
  }
}