//  Created by Rahul Ashokayan on 2026.10.22.
//  Copyright © 2026 Riant Studio. All rights reserved.

// Sample: Uno R3 + HC-SR04: VCC -> 5V, GND -> GND, TRIG -> D7, ECHO -> D6.
// The 5V echo signal must not be connected directly to a 3.3V-only board.
const byte triggerPin = 7;
const byte echoPin = 6;

void setup() {
  digitalWrite(triggerPin, LOW);
  pinMode(triggerPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);

  const unsigned long duration = pulseIn(echoPin, HIGH, 30000UL);
  if (duration == 0) {
    Serial.println("No echo within timeout");
  } else {
    const float distanceCm = duration * 0.0343f / 2.0f;
    Serial.print(distanceCm, 1);
    Serial.println(" cm");
  }
  delay(100);
}