const int SERVOPIN = A4;

void setup() {
  pinMode(SERVOPIN, OUTPUT);
  digitalWrite(SERVOPIN, LOW);
}

void loop() {
  for(uint8_t i=0; i<100; i++){
    digitalWrite(SERVOPIN, HIGH);
    delayMicroseconds(1000);
    digitalWrite(SERVOPIN, LOW);
    delay(19);
  }

  for (uint8_t i = 0; i < 100; i++) {
    digitalWrite(SERVOPIN, HIGH);
    delayMicroseconds(2000);
    digitalWrite(SERVOPIN, LOW);
    delay(18);
  }

  for (uint8_t i = 0; i < 250; i++) {
    digitalWrite(SERVOPIN, HIGH);
    delayMicroseconds(1000);
    digitalWrite(SERVOPIN, LOW);
    delay(19);
  }

  uint16_t microsecs = 1000;
  bool upcount = true;
  while (true) {
    if(upcount){
      if(microsecs < 2000){
        microsecs++;
      }else{
        upcount = false;
      }
    }else{
      if(microsecs > 1000){
        microsecs--;
      }else{
        upcount = true;
      }
    }
      digitalWrite(SERVOPIN, HIGH);
      delayMicroseconds(microsecs);
      digitalWrite(SERVOPIN, LOW);
      delayMicroseconds(2000 -  microsecs);
      delay(18);

  }
}