#define TRIG_PIN PA10
#define ECHO_PIN PA9
#define LED_PIN  PA5

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  Serial.begin(9600);
  Serial.println("Ultrasonic Distance Measurement Start!");
}

void loop() {
  long duration;
  float distance;

  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2;

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

  if (distance < 10) {
    digitalWrite(LED_PIN, HIGH);
    Serial.println("LED ON: Distance < 10 cm");
  } else {
    digitalWrite(LED_PIN, LOW);
    if (distance < 50) {
      analogWrite(LED_PIN, 26); // 10% Duty
      Serial.println("PWM ~10%");
    } else if (distance < 150) {
      analogWrite(LED_PIN, 102); // 40% Duty
      Serial.println("PWM ~40%");
    } else if (distance < 300) {
      analogWrite(LED_PIN, 153); // 60% Duty
      Serial.println("PWM ~60%");
    } else {
      analogWrite(LED_PIN, 0);
      Serial.println("PWM OFF");
    }
  }

  Serial.println("-----------------------------");
  delay(10000);  // 10 วินาที
}