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One of the biggest flaws in my original design for the Garage Parking Assistant was not including a mechanism to turn off the LEDs in the event there was no change over a specified period of time. There is a lot of wasted energy having the green lights on all day long while I’m at work, or having the red lights on through the night. The easiest solution to the problem was to count the number of times a zone was selected in the conditional statement. As the car moves into the garage to be parked it will not stay in anyone zone for more then a minute, so we use this as the base measurement. There is a 50 millisecond delay at the end of the application, so the program will count 1000 cycles before turning off all the LEDs. The following illustration provides a rough idea of the software process.

Updated Source Code:

 #include 
 #include 
 #define TRIGGER_PIN 5
 #define ECHO_PIN 6
 const int red = 4; // Red bank of LEDs
 const int yellow = 3; // Yellow bank of LEDs
 const int green = 2; // Green bank of LEDs
 const int calibration = 11;  // Calibration button
 int threshold = 0;
 int redcount = 0;
 int yellowcount = 0;
 int greencount = 0;
 int toclosecount = 0;
 int tofarcount = 0;
  
 Ultrasonic ultrasonic(TRIGGER_PIN, ECHO_PIN);
 
 /******************************************************************************************
  * Setup Area
  ******************************************************************************************/
 void setup()
{
  Serial.begin(9600);
 // I don't set the ref pin and the analogread pin because 
 // Arduino automatically sets them
 pinMode(red, OUTPUT);
 pinMode(yellow, OUTPUT);
 pinMode(green, OUTPUT);
 pinMode(calibration, OUTPUT);
 digitalWrite(calibration, HIGH);
 
 // When the device gets reset, it needs to reset the total counts
 int redcount = 0;
 int yellowcount = 0;
 int greencount = 0;
 int toclosecount = 0;
 int tofarcount = 0;
 
 // Sets the threshold value equal to the value in EEPROM
    threshold = EEPROM.read(0); 
 
 for(int i = 0; i < 6; i++) // When the system first resets it should flash the leds
   {
     digitalWrite(red, HIGH);
     digitalWrite(yellow, HIGH);
     digitalWrite(green, HIGH);

     delay(100);

     digitalWrite(red, LOW);
     digitalWrite(yellow, LOW);
     digitalWrite(green, LOW);

     delay(100);
    }
}

 /******************************************************************************************
  * Run Loop Starts
  ******************************************************************************************/
 void loop()
{
  // Inlude the code for taking a sensor sample and converting it to a measurement
  float cmMsec, inMsec;
  long microsec = ultrasonic.timing();
  
  cmMsec = ultrasonic.convert(microsec, Ultrasonic::CM);
  inMsec = ultrasonic.convert(microsec, Ultrasonic::IN);
  
  int currentDistance = (int)inMsec;
    
  /******************************************************************************************
  * Calibration Button
  ******************************************************************************************/
  // Execute the calibration function
  if (analogRead(5) > 800)
   {
    // Earse the current value in the EEPROM
    EEPROM.write(0, 0);
     
    // Write the current distance measurement to the first byte in EEPROM
    EEPROM.write(0, currentDistance);  
    
  // Send the program back to the setup function to start the system over,
  // the flashing at the end of setup will let you know that the calibration when okay
   setup();
   }
        
  /******************************************************************************************
  * Determine what zone the car is in
  ******************************************************************************************/  
  else 
   {              
     if (currentDistance > ( 125 + threshold) && tofarcount < 6000)
          {
          digitalWrite(green, LOW);
          digitalWrite(yellow, LOW);
          digitalWrite(red, LOW);
          tofarcount += 1;
          greencount = 0;
          yellowcount = 0;
          redcount = 0;
          toclosecount = 0;
          tofarcount = 0;
        }   
     
     if (currentDistance <= (124 + threshold) && currentDistance > (threshold + 40) && greencount < 1000)
          {
          digitalWrite(green, HIGH);
          digitalWrite(yellow, LOW);
          digitalWrite(red, LOW);
          greencount += 1;
          yellowcount = 0;
          redcount = 0;
          toclosecount = 0;
          tofarcount = 0;
        }
        if (currentDistance <= (39 + threshold) && currentDistance > (threshold + 4) && yellowcount < 1000)
          {
          digitalWrite(green, LOW);
          digitalWrite(yellow, HIGH);
          digitalWrite(red, LOW);  
          yellowcount += 1;
          greencount = 0;
          redcount = 0;
          toclosecount = 0;
          tofarcount = 0;    
          }
        if (currentDistance <= (threshold + 3) && currentDistance > (threshold - 3) && redcount < 1000)
        {
          digitalWrite(green, LOW);
          digitalWrite(yellow, LOW);
          digitalWrite(red, HIGH);
          redcount += 1;
          yellowcount = 0;
          greencount = 0;
          toclosecount = 0;
          tofarcount = 0;
        }
        if (currentDistance <= (threshold - 4) && toclosecount < 1000)
        {  
          digitalWrite(green, HIGH);
          digitalWrite(yellow, HIGH);
          digitalWrite(red, HIGH);
          toclosecount += 1; 
          greencount = 0;
          yellowcount = 0;
          redcount = 0;
          tofarcount = 0;         
        } 
   
     if (greencount == 1000){
       digitalWrite(green, LOW);
       digitalWrite(yellow, LOW);
       digitalWrite(red, LOW);
    }
    if (yellowcount == 1000){
       digitalWrite(green, LOW);
       digitalWrite(yellow, LOW);
       digitalWrite(red, LOW);
    }
    if (redcount == 1000){
       digitalWrite(green, LOW);
       digitalWrite(yellow, LOW);
       digitalWrite(red, LOW); 
    }
    if (toclosecount == 1000){
       digitalWrite(green, LOW);
       digitalWrite(yellow, LOW);
       digitalWrite(red, LOW);   
    }
   } 
  delay(50);
  
}