#include <Servo.h>

int ser_pin = 11;
int pos = 0;
Servo servo1;

void setup()
{
  pinMode(12, INPUT);
  servo1.attach(ser_pin);
}

void loop(){
  int motion = digitalRead(12);
  if (motion == HIGH){
    for(pos = 0; pos <= 180; pos++){
      servo1.write(pos);
      delay(30);
    }
    delay(3000);

    for(pos = 180; pos >= 0; pos--){
      servo1.write(pos);
      delay(30);
    }
  }
  delay(30);
}