const int trigPin = 13;
const int echoPin = 12;


const int ledGreen = 2;
const int ledBuzz = 4;

//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

long duration;
float distanceCm;
float distanceInch;

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");

  Serial.begin(115200); // Starts the serial communication
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input

  
  pinMode(ledGreen, OUTPUT);
  pinMode(ledBuzz, OUTPUT);

}

void loop() {
  // Clears the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(10);
  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate the distance
  distanceCm = duration * SOUND_SPEED/2;
  
  // Convert to inches
  distanceInch = distanceCm * CM_TO_INCH;
  
  // Prints the distance in the Serial Monitor
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
  Serial.print("Distance (inch): ");
  Serial.println(distanceInch);

  if(distanceCm < 10){
    
    digitalWrite(ledGreen, HIGH);
    digitalWrite(ledBuzz, HIGH);

  }else if(distanceCm < 40){
    
    digitalWrite(ledGreen, HIGH);
    digitalWrite(ledBuzz, LOW);

  }else if(distanceCm < 70){
    
    digitalWrite(ledGreen, LOW);
    digitalWrite(ledBuzz, HIGH);
  }
    else{
   
    digitalWrite(ledGreen, LOW);
    digitalWrite(ledBuzz, LOW);
  }
  
  delay(1000);
  
  }