//Thermostat, by fuzzy
  //turns on/off a relay based on a preset value.

  /*
  feature list:
  shrink existing code onto a attiny85
  set temp, maybe optical sensor
          will need readout
  use dual sensor for safety
  light sensor with two temps

  */

  /*
  Thermistor test sketch, will return a value between 0 and 1024.
  Uses a 10k resistor at a0/gnd, in paralell with the thermistor at a0 and 5v.
  Can play with resistor values to create a good range within the target.
     ------------10k resistor -----------------10k thermistor --------
    |                                |                                |
    gnd                             arduino                          +5V
  */
  /*
  int thermistorpin = A0; //uses pin 0 for reference pin

  void setup(){
          Serial.begin(9600); //output to serial console for testing
  }

  void loop(){
          int thermistorReading = analogRead(thermistorpin);
  Serial.println(thermistorReading);
  delay(250);//slows down output for reading
  }
  */

  /*
  tiny Thermostat, by fuzzy
  turns on/off a relay based on a preset value, using an attiny85
  uses two thermistors for safety, in case one goes out of calibration.

  */    
  // initialize pins:
  int therm1 = A0; //first thermistor, pin 1  
  int therm2 = A1;//second thermistor, pin 7
  int relay = A2; //size the relay to the heater you're driving, I'm using a
  //beefcake relay from sparkfun (10A max), pin 3
  int heatled = 13; //indicator led, tells us when we're heating and
  //when we have sensor issues, pin 2
  int settemp = 195; //set a value to heat to, this value is roughly 54deg F
  //freezing is 114, not quite boiling is 695.
  int currenttemp;

  void setup()
  {                
    pinMode(therm1, INPUT);
    pinMode(therm2, INPUT);
    pinMode(relay, OUTPUT);
    pinMode(heatled, OUTPUT);
    digitalWrite(relay, LOW);
    digitalWrite(heatled, LOW);
  Serial.begin(9600);
  }

  void loop()
  {
    delay(500);//don't start right away so we can get the serial monitor running
  //read the sensors with the averaging functions, and average that
    currenttemp = (averagetemp1() + averagetemp2()) / 2 ;
    //safety loop: if temp sensors are different or unplugged, blink and turn relay off
    //first, check if unplugged; then check if shorted;
    //next check if sensors read roughly the same(+-20). If all checks out, proceed.

   if (currenttemp > 500 || currenttemp < 100 || abs(averagetemp1() - averagetemp2()) >= 20)
  {//blink like hell if there's an error
    Serial.println("error");
    Serial.print("Thermistor 1: ");
    Serial.println(averagetemp1());
    Serial.print("Thermistor 2: ");
    Serial.println(averagetemp2());
    Serial.print("Current temp: ");
    Serial.println(currenttemp);
   digitalWrite(heatled, HIGH);
   delay(100);
   digitalWrite(heatled, LOW);
   digitalWrite(relay, LOW);
   delay(100);
  }

  //logic for thermostat
    else
  {
    if (currenttemp < settemp)
  {
    digitalWrite(relay, HIGH);
    digitalWrite(heatled, HIGH);
  //debug code

   Serial.print("Heating for 5 minutes, current reading: ");
   Serial.println(currenttemp);
   Serial.print("target:");
   Serial.println(settemp);
   Serial.print("Sensor a: ");
   Serial.println(averagetemp1());
   Serial.print("Sensor b: ");
   Serial.println(averagetemp2());

  //delay(1000);//test
  delay(300000);//let it run a full five minutes so we don't fry the heater
  }
    else //if it's hot, do nothing for five minutes
    {
    digitalWrite(relay, LOW);
    digitalWrite(heatled, LOW);
  //debug code


   Serial.print("Target reached, testing again in 5 minutes, current reading: ");
   Serial.println(currenttemp);
   Serial.print("Sensor a: ");
   Serial.println(averagetemp1());
   Serial.print("Sensor b: ");
   Serial.println(averagetemp2());


    }
  //  delay(1000);
  delay(300000);    
  }} //end main loop

  int averagetemp1()
  { //read the first thermistor ten times over, then average values
  int i;
  int a = 0;
  for  (i=0; i < 10; i++)//do the following 10 times
  {
          a = a + analogRead(therm1);
  delay(5);
  }
  a = a/10;
  return a;
   }

  int averagetemp2()
  { //read the second thermistor ten times, then average values
  int i;
  int a = 0;
  for  (i=0; i < 10; i++)//do the following 10 times
  {
          a = a + analogRead(therm2);
  delay(5);
  }
  a = a/10;
  return a;
   }