const int trigPinA = 2; // Transmitter trigger pin
const int echoPinB = 3; // Receiver echo pin
const int LED_PIN_TRANSMITTER = 8; // Transmitter LED pin
const int LED_PIN_RECEIVER = 9; // Receiver LED pin

void setup() {
  Serial.begin(9600);
  pinMode(trigPinA, OUTPUT);
  pinMode(echoPinB, INPUT);
  pinMode(LED_PIN_TRANSMITTER, OUTPUT);
  pinMode(LED_PIN_RECEIVER, OUTPUT);

  Serial.println("Setup complete. Starting measurements...");
}

void loop() {
  // Check if the receiver is set up properly
  Serial.println("Checking receiver setup...");
  digitalWrite(LED_PIN_RECEIVER, HIGH); // Turn on receiver LED to indicate it's ready
  delay(100); // Short delay for indication
  digitalWrite(LED_PIN_RECEIVER, LOW);

  // Send ultrasonic pulse from Transmitter
  Serial.println("Transmitter sends signal...");
  digitalWrite(trigPinA, HIGH);
  digitalWrite(LED_PIN_TRANSMITTER, HIGH); // Turn on transmitter LED
  delayMicroseconds(10); // Ensure trigger pulse duration
  digitalWrite(trigPinA, LOW);
  digitalWrite(LED_PIN_TRANSMITTER, LOW); // Turn off transmitter LED

  // Delay for receiver readiness
  delayMicroseconds(200); // Adjust as needed for receiver readiness

  // Measure the time for the pulse to be received by Receiver
  Serial.println("Waiting for echo...");
  long duration = pulseIn(echoPinB, HIGH, 100000); // Set appropriate timeout

  // Check if a valid signal was received
  if (duration > 0) {
    Serial.println("Receiver receives signal...");
    // Calculate distance based on speed of sound in air: 343 m/s (34300 cm/s)
    float distance = (duration * 0.0343) / 2.0;

    // Print distance
    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.println(" cm");

    // Blink receiver LED to indicate signal reception
    digitalWrite(LED_PIN_RECEIVER, HIGH);
    delay(100); // Blink duration
    digitalWrite(LED_PIN_RECEIVER, LOW);
  } else {
    Serial.println("No valid signal received from receiver. Check alignment and ensure a reflective surface is present.");
  }

  // Small delay before next measurement
  delay(1000); // Adjust as needed for measurement frequency
}