int t_p=5;
int e_p=18;
float ss=0.034;
long durn;
float dist_cm;

void setup() {
  
  Serial.begin(115200);
  pinMode(t_p, OUTPUT);
  pinMode(e_p, INPUT);
}

void loop()
 {
  digitalWrite(t_p, LOW);
  delayMicroseconds(2);
  digitalWrite(t_p, HIGH);
  delayMicroseconds(10);
  digitalWrite(t_p, LOW);
  durn=pulseIn(e_p, HIGH);
  dist_cm= durn*ss/2;
  Serial.println("distance= ");
  Serial.println(dist_cm);
    delay(1000); 
}