int trigger_pin=14;
int echo_pin=13;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(echo_pin, INPUT);
  pinMode(trigger_pin, OUTPUT);
  pinMode(4, OUTPUT);
}
long wdistance (){
 digitalWrite(trigger_pin,LOW);
 delay(10);
 digitalWrite(trigger_pin,HIGH);
 delay(100);
 digitalWrite(trigger_pin,LOW);
 float d=pulseIn(echo_pin,HIGH);
 return(d*0.034/2)+1;
 delay(1000);
}
void loop() {
  int c=wdistance ();
  Serial.println(String(c));
  if(c>=200){
    digitalWrite(4, HIGH);
    Serial.println("detected");
    }
    else{
      digitalWrite(4, LOW);
    Serial.println("not detected");// put your main code here, to run repeatedly:
  }
delay(1000); // this speeds up the simulation
}