#define TrigPin 33
#define EchoPin 25
#define Buzzer 26

double Temperature = 20.0;

void setup()
{
  Serial.begin(115200);
  pinMode(TrigPin, OUTPUT);
  pinMode(EchoPin, INPUT);
  pinMode(Buzzer, OUTPUT);
}

void loop()
{
  double cm = readUltraSound();
  Serial.printf("Distance : %lf cm \n", cm);
  if(cm < 100)
  {
    tone(Buzzer, 1000, cm*5);
    delay(cm*5);
  }
  delay(50);
}

double readUltraSound()
{
  digitalWrite(TrigPin, 0);
  delayMicroseconds(5);
  digitalWrite(TrigPin, 1);
  delayMicroseconds(10);
  digitalWrite(TrigPin, 0);
  double Time = pulseIn(EchoPin, HIGH);
  double Speed = 331.5 + 0.6*Temperature;
  Speed = Speed / 10000;
  return Speed * Time / 2; 
}