#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);


// this constant won't change:
//Key connections with arduino
const byte  down_key = 2;    // the pin that the pushbutton is attached to
const byte  up_key = 3;
//Led connections with arduino
const int LED_RED = 10; //Red LED
const int LED_GREEN = 11; //Green LED
//thermistor
const float BETA = 3950; // should match the Beta Coefficient of the thermistor

// Variables will change:
int RELAY1 = A1; // Heater
int RELAY2 = A2; // Fan
int Range = 3; // Temp +/- Range
int SetPoint = 30; // Default temp


int buttonPushCounter_down_key = 0;   // counter for the number of button presses
boolean ButtonState_down_key = 0;         // current state of the button
boolean lastButtonState_down_key = 0;     // previous state of the button
int buttonPushCounter_up_key = 0;   // counter for the number of button presses
boolean ButtonState_up_key = 0;         // current state of the button
boolean lastButtonState_up_key = 0;     // previous state of the button

//=================================================================
//                  SETUP
//=================================================================
void setup() {
  pinMode(LED_RED, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(RELAY1, OUTPUT);
  pinMode(RELAY2, OUTPUT);
  // initialize the button pin as a input:
  pinMode(down_key, INPUT_PULLUP);
  pinMode(up_key, INPUT_PULLUP);


  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("Temp Controller");
  lcd.setCursor(0, 1); //Move coursor to second Line
  lcd.print("Version 1");
  digitalWrite(LED_GREEN, HIGH); //Green LED Off
  digitalWrite(LED_RED, LOW);    //Red LED On
  digitalWrite(RELAY1, LOW);     //Turn off Heater Relay
  digitalWrite(RELAY2, LOW);   //Turn off Fan Relay
  delay(2000);
}
//=================================================================
//                  LOOP
//=================================================================
void loop() {

  int analogValue = analogRead(A0);
  float Temperature = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;

  lcd.setCursor(0, 0);
  lcd.print("Temperature:");    //Do not display entered keys
  lcd.print(Temperature);

  static unsigned long timer = 0;
  unsigned long interval = 20;
  if (millis() - timer >= interval)
  {
    timer = millis();

    // read the pushbuttons input pin:
    ButtonState_down_key = digitalRead(down_key);
    ButtonState_up_key = digitalRead(up_key);

    // compare the ButtonState_down_key to its previous state
    if (ButtonState_down_key != lastButtonState_down_key)
    {
      // if the state has changed, increment the counter
      if (ButtonState_down_key == LOW)
      {
        // if the current state is LOW then the button went from off to on:
        buttonPushCounter_down_key++;

        if (SetPoint > 0)
        {
          SetPoint--;
        }
      }

      lastButtonState_down_key = ButtonState_down_key;
    }
    // compare the ButtonState_up_key to its previous state
    if (ButtonState_up_key != lastButtonState_up_key)
    {
      // if the state has changed, increment the counter
      if (ButtonState_up_key == LOW)
      {
        // if the current state is LOW then the button went from off to on:
        buttonPushCounter_up_key++;

        if (SetPoint < 100)
        {
          SetPoint++;
        }
      }

      lastButtonState_up_key = ButtonState_up_key;
    }
  }
  //Display Set point on LCD
  lcd.setCursor(0, 1);
  lcd.print("Set Point:");
  lcd.print(SetPoint);
  lcd.print("C   ");

  //Check Temperature is in limit
  if (Temperature == SetPoint)
  {
    digitalWrite(RELAY1, LOW);   //Turn off heater
    digitalWrite(LED_RED, LOW);   //Turn off Red LED
    digitalWrite(LED_GREEN, HIGH); //Turn on Green LED
  }
  // If temp is over limit turn on fan /Turn off heater
  if (Temperature > (SetPoint + Range))
  {
    digitalWrite(RELAY1, LOW);   //Turn off heater
    digitalWrite(RELAY2, HIGH);   //Turn on fan
    digitalWrite(LED_RED, LOW);   //Turn off Red LED
    digitalWrite(LED_GREEN, HIGH); //Turn on Green LED
  }
  //if temp is below limt turn on heater / turn off fan
  if (Temperature < (SetPoint - Range) || Temperature < SetPoint)
  {
    digitalWrite(RELAY1, HIGH);   //Turn on heater
    digitalWrite(RELAY2, LOW);   //Turn off fan
    digitalWrite(LED_GREEN, LOW); //Turn off Green LED
    digitalWrite(LED_RED, HIGH); //Turn on RED LED
  }
  delay(100); //Update at every 100mSeconds
}