---

#define TRIG_PIN 7
#define ECHO_PIN 6
#define LED_PIN 3

void setup() {
  Serial.begin(9600);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
}

void loop() {

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

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

  digitalWrite(TRIG_PIN, LOW);

  int duration, mm;

  duration = pulseIn(ECHO_PIN, HIGH);

  mm = duration * 10 / 58;

  Serial.print("Расстояние = ");
  Serial.print(mm);
  Serial.println(" мм");

  if (mm < 30) {
    int brightness = map(mm, 0, 30, 255, 0);
    analogWrite(LED_PIN, brightness);
  }
  else {
    analogWrite(LED_PIN, 0);
  }

  delay(100);
}