#include <HCSR04.h>

HCSR04 hc(22,21);//initialisation class HCSR04 (trig pin , echo pin)
const int LED = 23;
int distance;

void setup(){
  Serial.begin(115200); 
  pinMode(LED, OUTPUT);
  digitalWrite(LED, LOW); 
}

void loop(){
  distance = hc.dist();   //return curent distance in serial
  Serial.println( distance );
  if ( distance < 10){
    digitalWrite(LED, HIGH);
  }else{
    digitalWrite(LED, LOW); 
  }
  delay(500);
}