Making Things Interactive

May 12, 2008

The Light-o-Stat

Filed under: Assignments,Brian Kish,Final Project,Term Paper — bkish @ 10:22 am

Hello All:

Please take a look at my final term paper for my Light-o-Stat Project by following the attached link.


The majority of my documentation can be seen in the paper, but here are some other things too.

 The Guts of the Project:                          The Mess that I made with an Arduino and Breadboard
The Guts of the ProjectThe Mess that I made with an Arduino and Breadboard
int servoPin = 2;     // Control pin for servo motor
int minPulse = 800;   // Minimum servo position
int maxPulse = 2300;  // Maximum servo position
int neutralPulse = 1500;  //neutral servo
int pulse = 0;        // Amount to pulse the servo
int prevPhotosensor;  //last reading of sensor-last state
int increment = 50;   //pwm changes
int goodLED= 6;
int darkLED= 7;
int brightLED = 5;

long lastPulse = 0;    // the time in milliseconds of the last pulse
int refreshTime = 20; // the time needed in between pulses

int photoSensor = 0;  // the value returned from the analog sensor
int sensorPin = 1;    // the analog pin that the sensor's on
int average = 10;      // reads per cycle
int potSwitch = 0;     //potentiometer switch
int potMin = 0;
int potMax = 0;
int potPin = 0;

void setup() {
  pinMode(servoPin, OUTPUT);  // Set servo pin as an output pin
  pinMode(potSwitch, INPUT);
  pinMode(goodLED, OUTPUT);
  pinMode(darkLED, OUTPUT);
  pinMode(brightLED, OUTPUT);
  pulse = neutralPulse;           // Set the motor position value to the minimum
  digitalWrite(goodLED, LOW);
  digitalWrite(darkLED, LOW);
  digitalWrite(brightLED, LOW);


void loop() {
  int x;
  int photoTotal;
  photoTotal = 0;
  for (x = 0; x<average; x++) {
    photoSensor = analogRead(sensorPin);      // read the analog input
    potSwitch = analogRead(potPin);         //pulse = (photoSensor *19)/10 + minPulse;
    photoTotal = photoSensor + photoTotal;  // convert the analog value
  photoSensor = photoTotal/average;   //average of photo sensor readings

  potMin = potSwitch-25;
  potMax = potSwitch+50;

  Serial.print("Amount of Light = ");
  Serial.print("Desired amount of light = ");

  if (millis() - lastPulse >= refreshTime) {
    digitalWrite(servoPin, HIGH);   // Turn the motor on
    delayMicroseconds(pulse);       // Length of the pulse sets the motor position
    digitalWrite(servoPin, LOW);    // Turn the motor off
    lastPulse = millis();           // save the time of the last pulse

  //good State
  if(photoSensor <= potMax && photoSensor >= potMin){  //if light value is in desired range, do the following
    digitalWrite(goodLED, HIGH);
    digitalWrite(darkLED, LOW);
    Serial.println("Light is good");
    //do nothing with pulse;
  // bright State
  if(photoSensor < potMin){   // if the actual light is greater than desired, do this...remember that the values are reversed, larger number=darker and smaller number = brighter
    digitalWrite(goodLED, LOW);
    digitalWrite(darkLED, LOW);
    Serial.println("Too Bright");

    //pulse clockwise
    if(prevPhotosensor > photoSensor) {  // if moving the shades makes it darker, it i doing the right thing, continue in this direction
      prevPhotosensor = photoSensor;
      pulse = pulse - increment;
      if (pulse < minPulse)
        pulse = minPulse;


  // dark State
  if(photoSensor > potMax){              // if level of light is below the minimum desired, it is too dark
    digitalWrite(goodLED, LOW);
    digitalWrite(darkLED, HIGH);
    Serial.println("Too Dark");
    //pulse counter-clockwise
    if(prevPhotosensor < photoSensor) {   //if moving the shades makes it lighter, it is doin the right thing
      prevPhotosensor = photoSensor;
      pulse = pulse + increment;
      if (pulse > maxPulse)
        pulse = maxPulse;



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