// PT is trig
// PE is echo

#define PT 8
#define PE 5
#define led1 LED_BUILTIN
int duration =0 ;
int d1= 10;
int d2= 1000;


void setup() 
{
  Serial.begin(9600 );
  pinMode(PT, OUTPUT );
  pinMode(PE, INPUT );
  pinMode(led1, OUTPUT );

}

void loop()
{
  digitalWrite(PT, HIGH );
  delay(10 );
  digitalWrite(PT, LOW );
  int dur = pulseIn(PE, HIGH );
  int dis = dur / 58.5 ;
  Serial.print("Distance in CM: ");
  Serial.println(dur / 58.5  ); // duration % 58 = distance in cm 
 
  if (dis < 3 )
     {
     digitalWrite(led1, HIGH );
     delay(d1);
     }
     else
     {
     digitalWrite(led1, LOW );
     delay(d1);
     }

  delay(d2);
}