// Ultrasonic sensor pin definitions
#define TRIG_PIN 27
#define ECHO_PIN 26

// Timing variables to control the reading interval
unsigned long lastReadTime = 0;
const unsigned long readInterval = 1000; // Interval set to 1 seconds

void setup() {
  Serial.begin(115200);

  // Set TRIG as output (to send the pulse)
  // and ECHO as input (to receive the reflected signal)
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

void loop() {
  unsigned long currentTime = millis();

  // Check if enough time has passed before taking a new reading
  if (currentTime - lastReadTime >= readInterval) {
    lastReadTime = currentTime;

    // Send a 10 µs HIGH pulse to TRIG to start measurement
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);

    // Measure the duration of the HIGH pulse received at ECHO
    long duration = pulseIn(ECHO_PIN, HIGH);

    // Convert duration to distance (in cm)
    // 0.0343 cm/µs is the speed of sound divided by 2 (go and return)
    float distanceCm = duration * 0.0343 / 2;

    // Print the measured distance to the Serial Monitor
    Serial.println("=== Ultrasonic Sensor ===");
    Serial.print("Distance: ");
    Serial.print(distanceCm);
    Serial.println(" cm");
    Serial.println("=========================\n");
  }
}