#include <Servo.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd (0×27, 16,2);
Servo myservo;   
int pos = 0;
int cm = 0;

long readUltrasonicDistance(int triggerPin, int echoPin){
  pinMode(triggerPin, OUTPUT); 
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);
  return pulseIn(echoPin, HIGH);
}

void setup() {
 digitalWrite(12,LOW);
 myservo.attach(9); 
 Serial.begin(9600);
 
}

void loop() {
  cm = 0.01723 * readUltrasonicDistance(6, 7);
  if(cm<30){
  Serial.print(cm);
  Serial.println("cm");
  for (pos = 0; pos <= 90; pos += 4) { 
  myservo.write(pos);             
  delay(15);                       
 }
  delay(500);

   for (pos = 90; pos >= 0; pos -= 4) { 
   myservo.write(pos);
   delay(15);                                     
   }
   delay(5000); 
   }                          
}