#define PIN_ECHO 2
#define PIN_TRIG 3
#define RED_LED 4
#define GREEN_LED 5
#define BUTTON_PIN 6
#define BUZZER_PIN 7

void setup() {
  Serial.begin(115200);
  pinMode(3, OUTPUT);
  pinMode(2, INPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
}

void loop() {
  readDistanceCM();
  
  // Example 1: Switch on a LED with a button press
  if (digitalRead(BUTTON_PIN) == LOW) {
    digitalWrite(4, HIGH); //RED_LED
  } else {
    digitalWrite(4, LOW);
  }

  // Example 2: Switch on a LED and a Buzzer with a button press, off otherwise
  if (digitalRead(BUTTON_PIN) == LOW) {
    digitalWrite(5, HIGH);
    tone(BUZZER_PIN, 1000);  // 1000 Hz tone
  } else {
    digitalWrite(5, LOW); //GREEN_LED
    noTone(BUZZER_PIN);
  }

  // Example 3: Switch on a LED and make the Buzzer sound continuously with a button press, off otherwise
  if (digitalRead(BUTTON_PIN) == LOW) {
    digitalWrite(5, HIGH);
    tone(BUZZER_PIN, 1000);  // 1000 Hz tone
  } else {
    digitalWrite(5, LOW);
    noTone(BUZZER_PIN);
  }
}

void readDistanceCM() {
  // Start a new measurement
  digitalWrite(3, HIGH);
  delayMicroseconds(10);
  digitalWrite(3, LOW);

  // Read the result
  int duration = pulseIn(PIN_ECHO, HIGH);
  int distanceCM = duration / 58;

  // Output the distance
  Serial.print("Distance in CM: ");
  Serial.println(distanceCM);

  // Example 4: Indicate through LED ON if the distance is less than 150 cm else LED OFF
  if (distanceCM < 150) {
    digitalWrite(4, HIGH); //RED_LED
  } else {
    digitalWrite(4, LOW);
  }

  // Example 5: Indicate through two LEDs
  if (distanceCM < 150) {
    digitalWrite(4, HIGH); //RED_LED
    digitalWrite(5, LOW);
  } else {
    digitalWrite(4, LOW);
    digitalWrite(5, HIGH); //GREEN_LED
  }
}