#define PIN_TRIG 3
#define PIN_ECHO 2

void setup(){
  pinMode(8, OUTPUT); // Set buzzer - pin 9 as an output

  Serial.begin(115200);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
}

void loop(){
  // Start a new measurement:
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);

  // Read the result:
  int duration = pulseIn(PIN_ECHO, HIGH);
  Serial.print("Distance in CM: ");
  int distance = duration / 58;
  Serial.println(distance);

  if(distance<25){
    tone(8, 350, 100);
    delay(125);
  }else if(distance<50){
    tone(8, 300, 250);
    delay(500);
  }
}