Hotbox Controller

// Temperature Controlled Chamber

#include <LiquidCrystalFast.h> // Library for the 4x20 LCD

LiquidCrystalFast lcd(6,7,8,9,10,11,12);

#define tempSensor A0  // TMP36 Temp sensor
#define lightSwitch 4  // Solid state relay controls the 120v lightbulb
#define indicator 5 // LED indicator to indicate when heat is on.
int readings[100];  // Array to store the last 100 ADC readings to average.
byte readingNumber=0;  // Keeps track of where we're at in the array
long averageMe = 0;  // temporary number, probably shouldn't be a global variable?
float voltage=0; // Used in the conversion from ADC to temperature
float sensor=0;  // Likewise
float celsius=0;  // Ditto
float fahrenheit=0; // Final temperature value
float targetTemp=90.0;  // TODO: Add buttons to make this user adjustable

void setup() {
  pinMode(tempSensor, INPUT);
  pinMode(lightSwitch, OUTPUT);
  pinMode(indicator, OUTPUT);
  for (int i = 0; i<100; i++) {
    readings[i] = analogRead(tempSensor); // Quickly fill the array with sane values
  }
  lcd.begin(20,4); // Initialize the LCD
  lcd.setCursor(0,0);
  lcd.print(F("Current:    F"));
  lcd.setCursor(0,1);
  lcd.print(F("Target:    F"));
}

void loop() {
  lcd.setCursor(8,1);
  lcd.print(targetTemp,1);
  lcd.print(" F");
  lcd.setCursor(9,0);
  readings[readingNumber] = analogRead(tempSensor); // Read the current temp and add it to the array
  averageMe = 0;
  for (int i=0; i<100; i++) {
    averageMe += readings[i]; // Take the array's contents and toss it all into this single number
  }
  averageMe = averageMe / 100; // Divide by the total entries to get an average of them all
            voltage=((averageMe*5000)/1024); // borrowed from examples online
            voltage=voltage-500;  // I think this one came from Tronixstuff
            celsius=voltage/10; // I thought the TMP36 was a F sensor, so why is it coming up as Celsius?
            fahrenheit=((celsius*1.8)+32); // Maybe I meant to buy the TMP35
  lcd.print(fahrenheit,1);
  lcd.setCursor(14,0);
  lcd.print('F');
  if (readingNumber==99) {
    readingNumber = 0; // Manual FOR loop..
  } else {
    readingNumber++;
  }
  if(fahrenheit < targetTemp) { // If it's not warm enough
      digitalWrite(lightSwitch,HIGH); // Turn on the light (heater)
      digitalWrite(indicator, HIGH);
  }
  else { // If it's too warm
    digitalWrite(lightSwitch,LOW); // Turn off the light (heater)
    digitalWrite(indicator, LOW);
  }
  delay(100); // Don't want to loop TOO fast..
}