#include <Servo.h>

//Declare and initialize the ser_pin
int ser_pin = 11;
//
int pos = 0;
//Create a servo obj
Servo servo1;

void setup() 
{
  pinMode (12, INPUT);
  servo1.attach(11);
}

void loop() 
{
  int motion = digitalRead (12);

  if ( motion == HIGH) 
  { 
    
    //Move servo from 0 to 180 degrees
  for (pos = 0; pos <= 180; pos +=1) 
  {
    servo1.write (pos);
    delay (30);
  }

  //wait for 3 seconds 
  delay (3000);

  for ( pos =180; pos >= 0; pos -=1) 
  {
    //Move servo back from 180 degrees to 0 degrees
    servo1.write (pos);
    delay(30);
  }
      //Small delay before restarting the loopy loop
      delay(30);
  }

}