#define BLYNK_TEMPLATE_ID "TMPL3nXhF3sst"
#define BLYNK_TEMPLATE_NAME "Ultrasonic Sensor"
#define BLYNK_AUTH_TOKEN  "oWAdJ_z4YGe_oaO20oRS9qVNwkEJwDPO"
 
#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>

// Blynk credentials
char auth[] = BLYNK_AUTH_TOKEN;
char ssid[] = "Wokwi-GUEST"; // Change if using different WiFi
char pass[] = "";

// Ultrasonic pins
const int trigPin = 5;
const int echoPin = 18;

// Sound speed in cm/us
#define SOUND_SPEED 0.034

long duration;
float distanceCm;

void setup() {
  Serial.begin(115200);
  Blynk.begin(auth, ssid, pass);

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  Blynk.run();

  // Send ultrasonic trigger pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read echo response
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate distance in cm
  distanceCm = duration * SOUND_SPEED / 2;

  // Display in Serial Monitor
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);

  // Send to Blynk (V0)
  Blynk.virtualWrite(V0, distanceCm);

  delay(1000); // 1-second interval
}