Bed Vacancy Alarm

/*
*Little Bed Vacancy Alarm
*Platform: Arduino UNO/ATmega328P-PU/IDE0022
*/
const int ledAlert = 13; // Pin 19 of IC2
const int ledStby = 12; // Pin 18 of IC2
const int beepAlert = 11; // Pin 17 of IC2
int fsrPin = 0; // FSR Input A0 / Pin 23 of IC2
int fsrReading; // Analog Reading-FSR input
int curCounter = 0; // Wake-Up Counter
void setup(void) /* This function is used to initialise
control pin as digital O/P */
{
pinMode(ledAlert, OUTPUT);
pinMode(ledStby, OUTPUT);
pinMode(beepAlert, OUTPUT);
}
void loop(void) /* This function is used to read FSR output and
generate an alarm, depending on the threshold value */ 
{
int fsrReading = analogRead(fsrPin);
  if (curCounter >=15)//Wake-Up Delay
  { 
  digitalWrite(ledAlert, HIGH); //Bed Vacancy-Alert ON
  digitalWrite(ledStby, LOW);
  playTone(500, 600);
  delay(100);
  playTone(500, 800);
  delay(100);
  }
  if (fsrReading < 100)// Bed Vacany Threshold (empirically-selected value/see text)
  { 
  curCounter++; // Increment Counter-Wake Up Mode
  }
else if (fsrReading > 600) // Bed Occupancy Threshold (empirically-selected value/see text)
  { 
  digitalWrite(ledAlert, LOW);
  curCounter = 0; // Reset Counter-Sleep Mode
  digitalWrite(ledStby, HIGH);
  playTone(0, 0);
  }
delay(100);
}
void playTone(long duration, int freq) // Alert Tone
{ 
duration *= 1000;
int period = (1.0 / freq) * 1000000;
long elapsed_time = 0;
  while (elapsed_time < duration) 
  {
  digitalWrite(beepAlert,HIGH);
  delayMicroseconds(period / 2);
  digitalWrite(beepAlert, LOW);
  delayMicroseconds(period / 2);
  elapsed_time += (period);
  }
}