const int trig = 17;
const int echo = 16;
const int ledpin = 13;
float distance;
float duration;

void setup()
{

  Serial.begin(115200);
  pinMode(echo, INPUT);
  pinMode(trig, OUTPUT);
}

void loop()
{
  Serial.println("distance=" + String(getdistance()));
  delay(10);
}
float getdistance()
{
  digitalWrite(trig, LOW);
  delayMicroseconds(2);
  digitalWrite(trig, HIGH);
  delay(10);
  digitalWrite(trig, LOW);
  duration = pulseIn(echo, HIGH);
  return (duration * 034 / 2);

}