DumbWaiter

//Dumbwaiter code
//adapted from MAKE; "HOT-COLD LED"
//Henry

// define pins

int SensorPinOne=13;
int SensorPinTwo=12;
int RedLedPin=6;
int YellowLedPin=5;
int GreenLedPin=3;
int pulseDuration;
int distance;
int distanceOne;
int distanceTwo;

unsigned long pulseDurationOne=0;
unsigned long pulseDurationTwo=0;

void setup() {
  pinMode(RedLedPin,OUTPUT);
  pinMode(GreenLedPin,OUTPUT);
  pinMode(YellowLedPin,OUTPUT);
}

void loop() {

  // measure distance: send "PingOne"
  pinMode(SensorPinOne, OUTPUT);
  digitalWrite(SensorPinOne, HIGH);
  delayMicroseconds(5);
  digitalWrite(SensorPinOne, LOW);

  // measure distance: listen for "PingOne"
  pinMode(SensorPinOne, INPUT);
  pulseDurationOne=pulseIn(SensorPinOne, HIGH);

delay(10);

 // measure distance: send "PingTwo"
  pinMode(SensorPinTwo, OUTPUT);
  digitalWrite(SensorPinTwo, HIGH);
  delayMicroseconds(5);
  digitalWrite(SensorPinTwo, LOW);

  // measure distance: listen for "PingTwo"
  pinMode(SensorPinTwo, INPUT);
  pulseDurationTwo=pulseIn(SensorPinTwo, HIGH);
  
  
  //Average of pulseDurationOne and pulseDurationTwo
  pulseDuration=(pulseDurationOne+pulseDurationTwo)/2;
  
  // divide by two (back/forth to single trip), divide by speed of sound = distance in in
  pulseDurationOne=pulseDurationOne/2; 
  distanceOne = int(pulseDurationOne/74);
  
    // divide by two (back/forth to single trip), divide by speed of sound = distance in in
  pulseDurationTwo=pulseDurationTwo/2; 
  distanceTwo = int(pulseDurationTwo/74);

//  distnce is lesser of both distnaces
   distance = min(distanceOne,distanceTwo);
  
  // light up red led: inverted linear of 0-15in to 0-255 eq. off to max. brightness
  if (distance > 0 && distance < 9.5){
    analogWrite(RedLedPin, 0); 
  } 
  else {
    analogWrite(RedLedPin, 255);
  }

  // light up yellow led: 0-25in ^= 0-255, 25-50in ^= 255-0 on YellowLedPin
  if (distance > 9.5 && distance <= 16.5){
    analogWrite(YellowLedPin, 0);
  } 
  else {
    analogWrite(YellowLedPin, 255);
  }

  // light up green led: 0-25in ^= 0-255, 25-50in ^= 255-0 on greenLedPin
  if (distance > 16.5 && distance <= 24){
 
    analogWrite(GreenLedPin, 0);  
  } 
  else {
    analogWrite(GreenLedPin, 255);
  }

  // wait a little... 
  delay(200);

}