#define echoPin 34 // attach pin ESP32 GPIO34 to pin Echo of HC-SR04
#define trigPin 25 // attach pin ESP32 GPIO25 to pin Trig of HC-SR04
#define relayIn 23

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an OUTPUT
  pinMode(echoPin, INPUT); // Sets the echoPin as an INPUT
  pinMode(relayIn, OUTPUT);
  Serial.println("Distance measurement using ESP32");
  delay(500);
  //Serial.println("Hello, ESP32!");
}

void loop() {
  // put your main code here, to run repeatedly:
  long d=distance();
  Serial.println("Distance:"+String(d));
  if(d>200) digitalWrite(relayIn, HIGH);
  else digitalWrite(relayIn, LOW);
  delay(1000); // this speeds up the simulation
}

long distance()
{
  long duration;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2); // wait for 2 ms to avoid
  // collision in the serial monitor
  digitalWrite(trigPin, HIGH); // turn on the Trigger to generate pulse
  delayMicroseconds(10); // keep the trigger "ON" for 10 ms to generate
  // pulse for 10 ms.
  digitalWrite(trigPin, LOW); // Turn off the pulse trigger to stop
  // pulse generation
  // If pulse reached the receiver echoPin
  // become high Then pulseIn() returns the
  // time taken by the pulse to reach the
  // receiver
  duration = pulseIn(echoPin, HIGH);
  return duration * 0.0344 / 2; // Expression to calculate
  // distance using time
}