Interfacing of Ultrasonic Sensor with ESP32 | Values in Smartphone via Classic Bluetooth

#include "BluetoothSerial.h"


#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled!
#endif


#define trigPin 2
#define echoPin 4




// Define variables:
float duration=0.00;
float distance=0.00;
String fullString = "";
BluetoothSerial SerialBT;


void setup() {
  // Define inputs and outputs:
  pinMode(trigPin, OUTPUT);


  pinMode(echoPin, INPUT);


  //Begin Serial communication setting the  baud rate  at 115200:
  Serial.begin(115200);
  SerialBT.begin("MyESP32"); //Bluetooth device name
  Serial.println("My ESP32 started, now you can pair it with a Bluetooth device!");
}


void loop() {
  // Clear the trigPin by setting it LOW:
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);


  // Trigger the sensor by setting the trigPin high for 10 microseconds:
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);


  // Read the echoPin, pulseIn() returns the duration (length of the pulse) in microseconds:
  duration = pulseIn(echoPin, HIGH);
  // Calculate the distance:
  distance = duration /58.82 ;


  // Print the distance on the Serial Monitor (Ctrl+Shift+M):
//  Serial.print("Distance = ");
//  Serial.print(distance);
//  Serial.println(" cm");
  //SerialBT.write ("Distance = ");
 fullString = "Distance = " + String(distance,3) + " cm " + "\r\n";
 for(int i = 0; i < fullString.length(); i++)
  {
    SerialBT.write(fullString.c_str()[i]);
    Serial.write(fullString.c_str()[i]);
  }


  delay(1000);
 
}