#define pinServo  1
void servoAttach(byte pin){
  pinMode(pin, OUTPUT);
}
void servoWrite(byte pin, byte angle){
  int pulseHigh = map(angle,0,180,430,2100);
  int pulseLow  = 20000-pulseHigh;
  for (int i=0;i<50;i++){
    digitalWrite(pin, HIGH);        
    delayMicroseconds(pulseHigh);    
    digitalWrite(pin, LOW);         
    delayMicroseconds(pulseLow);   
  }
}
void setup() {
  servoAttach(pinServo);    
}
int pos = 0;
void loop() {
  for (pos = 0; pos <= 180; pos += 1) {
    servoWrite(pinServo, pos);
  }
  for (pos = 180; pos >= 0; pos -= 1) {
    servoWrite(pinServo, pos);
  }
}