#define ALARM_LED PB9
#define TRIG PB8
#define ECHO PB7
#define BREAK PB6

void setup() {
  Serial.begin(115200);
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(ALARM_LED, OUTPUT);
  pinMode(BREAK, OUTPUT);
}

int getDistance() {
  digitalWrite(TRIG, HIGH);
  delay(1);
  digitalWrite(TRIG, LOW);
  return pulseIn(ECHO, HIGH) / 58;
}

void loop() {
  digitalWrite(ALARM_LED, !digitalRead(ALARM_LED));

  int distance = getDistance();
  Serial.print("Distance in CM: ");
  Serial.println(distance);

  bool emergencyBreak = distance < 50;
  digitalWrite(BREAK, emergencyBreak);

  delay(distance);
}