// C++ code
//
int PIR = 0;

int Distance = 0;

long readUltrasonicDistance(int triggerPin, int echoPin)
{
  pinMode(triggerPin, OUTPUT);  // Clear the trigger
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  // Sets the trigger pin to HIGH state for 10 microseconds
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);
  // Reads the echo pin, and returns the sound wave travel time in microseconds
  return pulseIn(echoPin, HIGH);
}

void setup()
{
  pinMode(15, INPUT);
  pinMode(2, OUTPUT);
  pinMode(6, OUTPUT);
}

void loop()
{
  PIR = digitalRead(15);
  delay(10); // Wait for 10 millisecond(s)
  if (PIR == HIGH) {
    digitalWrite(2, HIGH);
    delay(1); // Wait for 1 millisecond(s)
  } else {
    digitalWrite(2, LOW);
  }

  Distance = 0.01723 * readUltrasonicDistance(5, 4);
  if (Distance <= 100) {
    tone(6, 880, 125); // play tone 69 (A5 = 880 Hz)
    delay(125); // Wait for 125 millisecond(s)
  } else {
    noTone(6);
  }
}