Arduino dust sensor

dusty.h

// Based on instructions at:
//   http://www.instructables.com/id/How-to-Interface-With-Optical-Dust-Sensor/
int measurePin = A3; int ledPower = 12; int samplingTime = 280;int deltaTime = 40;
int sleepTime = 9680; float voMeasured = 0; float calcVoltage = 0;
float dustDensity = 0;

float readDust(){
  digitalWrite(ledPower,LOW); // power on the LED
  delayMicroseconds(samplingTime);
  voMeasured = analogRead(measurePin); // read the dust value
  delayMicroseconds(deltaTime);
  digitalWrite(ledPower,HIGH); // turn the LED off
  delayMicroseconds(sleepTime);
  calcVoltage = voMeasured * (5.0 / 1024);

  // linear eqaution taken from http://www.howmuchsnow.com/arduino/airquality/
  // Chris Nafis (c) 2012
  return (0.17 * calcVoltage - 0.1)*1000;
}