#define trig 15
#define echo 2

void setup() {

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

void loop() {
  causeTrigger();
  float tof = readEcho();
  float distance = calculateDistance(tof);
  Serial.print("Distance: ");
  Serial.println(distance);
}

void causeTrigger()
{
  // digitalWrite(trig, LOW);
  // delayMicroseconds(10);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);
}

float readEcho()
{
  float data = pulseIn(echo, HIGH);
  return data;
}

float calculateDistance(float timeOfFlight)
{
  // time of flight is in micro-seconds
  float distance = timeOfFlight*0.5*343/1000000;
  return distance;
}