//This program reads 3 NTC100K thermistors on the Nano's analog inputs and controls 3 SSRs on its digital outputs.
// By rotating the knob of the encoder and pressing the button at each of the 3 stages, a different temperature target can be set from room temperature to 300 °C.
// If the set temperature is higher than the one measured by the corresponding thermistor, then the SSR receives a signal to turn on.
// After setting a target temperature, the measured (rising) temperature is shown instead of the target.
// PID control implementation is yet to be done.

//Libraries used for the program
#include <LiquidCrystal_I2C.h>
#include <math.h>

//LCD screen parameters
#define I2C_ADDR    0x27  //I2C address of the LCD
#define LCD_COLUMNS 16  //Horizontal digits
#define LCD_LINES   2 //Vertical digits
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

//Menu variables
int menuCounter = 0; //counts the crotations of the rotary encoder between menu items (0-2 in this case)
int menu1_Value = 0; //value within (below) TH1
int menu2_Value = 0;
int menu3_Value = 0;
bool menu1_selected = false; //enable/disable to change the value of menu item
bool menu2_selected = false;
bool menu3_selected = false;

const int RotaryCLK = 2; //CLK pin on the rotary encoder, interrupt pin
const int RotaryDT = 4; //DT pin on the rotary encoder
const int PushButton = 3; //Button to enter/exit menu, interrupt pin

//Statuses for the rotary encoder
int CLKNow;
int CLKPrevious;
int DTNow;
int DTPrevious;

bool refreshLCD = true; //refreshes values
bool refreshSelection = false; //refreshes selection (> / X)

//Temperature measurement variables
#define therm_pin1 = A0;

float T1_approx;

float V_0 = 3.3; // reference voltage 


float R_1 = 220000.0; // TH1 resistor value for voltage divider

float a = 283786.2; // fit coefficients
float b = 0.06593;
float c = 49886.0;

int avg_size = 10; // averaging size

//SSR output pins
const int relayPin1 = 8; // SSR1 connected to digital pin 8
const int relayPin2 = 9; // SSR2 connected to digital pin 9
const int relayPin3 = 10; // SSR3 connected to digital pin 10


void setup() {

  pinMode( therm_pin1 ,INPUT);



  analogReference(EXTERNAL);

  pinMode(2, INPUT_PULLUP); //RotaryCLK
  pinMode(3, INPUT_PULLUP); //RotaryDT
  pinMode(4, INPUT_PULLUP); //Button

  pinMode(relayPin1, OUTPUT);
  pinMode(relayPin2, OUTPUT);
  pinMode(relayPin3, OUTPUT);

  lcd.begin(16, 2);
  lcd.backlight();

  printLCD(); //print the stationary parts on the screen

  //Store states of the rotary encoder
  CLKPrevious = digitalRead(RotaryCLK);
  DTPrevious = digitalRead(RotaryDT);

  attachInterrupt(digitalPinToInterrupt(RotaryCLK), rotate, CHANGE); //CLK pin is an interrupt pin
  attachInterrupt(digitalPinToInterrupt(PushButton), pushButton, FALLING); //PushButton pin is an interrupt pin

}

//--------------------Temperature measurement--------------------------------------

void loop() {


// loop over several values to lower noise
  float T_sum = 0.0;
  for (int ii;ii<avg_size;ii++){
    // read the input on analog pin 0:
    int sensorValue = analogRead(therm_pin1);
    // Convert the analog reading (which goes from 0 - 1023) to voltage reference (3.3V or 5V or other):
    float voltage = (sensorValue/1023.0)*V_0;

    // this is where the thermistor conversion happens based on parameters from fit
    T_sum+=(-1.0/b)*(log(((R_1*voltage)/(a*(V_0-voltage)))-(c/a)));
  }
  
  // averaging values from loop
  T1_approx = T_sum/float(avg_size);
}


  if (refreshLCD == true)
  {
    updateLCD();

    if (menu1_selected == true || menu2_selected == true || menu3_selected == true )
    {

    }
    else
    {
      updateCursorPosition(); //update the position
    }

    refreshLCD = false; //reset the variable - wait for a new trigger
  }

  if (refreshSelection == true) //if the selection is changed
  {
    updateSelection(); //update the selection on the LCD
    refreshSelection = false; // reset the variable - wait for a new trigger
  }

}
void rotate()
{
  if (menu1_selected == true)
  {
    CLKNow = digitalRead(RotaryCLK); //Read the state of the CLK pin

    if (CLKNow != CLKPrevious  && CLKNow == 1)
    {

      if (digitalRead(RotaryDT) != CLKNow)
      {
        if (menu1_Value < 300)
        {
          menu1_Value++;
        }
        else
        {
          menu1_Value = 0;
        }
      }
      else
      {
        if (menu1_Value < 1) //we do not go below 0
        {
          menu1_Value = 300;
        }
        else
        {

          menu1_Value--;
        }
      }
    }
    CLKPrevious = CLKNow;
  }

  else if (menu2_selected == true)
  {
    CLKNow = digitalRead(RotaryCLK);

    if (CLKNow != CLKPrevious  && CLKNow == 1)
    {

      if (digitalRead(RotaryDT) != CLKNow)
      {
        if (menu2_Value < 300)
        {
          menu2_Value++;
        }
        else
        {
          menu2_Value = 0;
        }
      }
      else
      {
        if (menu2_Value < 1)
        {
          menu2_Value = 300;
        }
        else
        {

          menu2_Value--;
        }
      }
    }
    CLKPrevious = CLKNow;
  }

  else if (menu3_selected == true)
  {
    CLKNow = digitalRead(RotaryCLK);

    if (CLKNow != CLKPrevious  && CLKNow == 1)
    {

      if (digitalRead(RotaryDT) != CLKNow)
      {
        if (menu3_Value < 300)
        {
          menu3_Value++;
        }
        else
        {
          menu3_Value = 0;
        }
      }
      else
      {
        if (menu3_Value < 1)
        {
          menu3_Value = 300;
        }
        else
        {

          menu3_Value--;
        }
      }
    }
    CLKPrevious = CLKNow;
  }

  else
  {
    CLKNow = digitalRead(RotaryCLK);
    if (CLKNow != CLKPrevious  && CLKNow == 1)
    {

      if (digitalRead(RotaryDT) != CLKNow)
      {
        if (menuCounter < 2) //we do not go above 3
        {
          menuCounter++;
        }
        else
        {
          menuCounter = 0;
        }
      }
      else
      {
        if (menuCounter < 1) //we do not go below 0
        {
          menuCounter = 2;
        }
        else
        {

          menuCounter--;
        }
      }
    }
    CLKPrevious = CLKNow;
  }

  refreshLCD = true;
}

void pushButton()
{
  switch (menuCounter)
  {
    case 0:
      menu1_selected = !menu1_selected;
      break;

    case 1:
      menu2_selected = !menu2_selected;
      break;

    case 2:
      menu3_selected = !menu3_selected;
      break;

  }

  refreshLCD = true; //Refresh LCD after changing the value of the menu
  refreshSelection = true; //refresh the selection ("X")
}

void printLCD()
{
  //These are the values which are not changing the operation

  lcd.setCursor(1, 0);
  lcd.print("TH1");

  lcd.setCursor(7, 0);
  lcd.print("TH2");

  lcd.setCursor(13, 0);
  lcd.print("TH3");
}

void updateLCD()
{

  lcd.setCursor(1, 1);
  lcd.print("   "); //erase the content by printing space over it
  lcd.setCursor(1, 1);
  lcd.print(menu1_Value); //print the value of menu1_Value variable

  lcd.setCursor(7, 1);
  lcd.print("   ");
  lcd.setCursor(7, 1);
  lcd.print(menu2_Value);

  lcd.setCursor(13, 1);
  lcd.print("   ");
  lcd.setCursor(13, 1);
  lcd.print(menu3_Value);

}

void updateCursorPosition()
{
  //Clear display's ">" parts
  lcd.setCursor(0, 0); //1st line, 1st block
  lcd.print(" "); //erase by printing a space
  lcd.setCursor(6, 0);
  lcd.print(" ");
  lcd.setCursor(12, 0);
  lcd.print(" ");


  //Place cursor to the new position
  switch (menuCounter) //this checks the value of the counter (0, 1 or 2)
  {
    case 0:
      lcd.setCursor(0, 0);
      lcd.print(">");
      break;
    //-------------------------------
    case 1:
      lcd.setCursor(6, 0);
      lcd.print(">");
      break;
    //-------------------------------
    case 2:
      lcd.setCursor(12, 0);
      lcd.print(">");
      break;

  }
}

void updateSelection()
{
  //When a menu is selected ">" becomes "X"

  if (menu1_selected == true)
  {
    lcd.setCursor(0, 0); //1st line, 1st block
    lcd.print("X");
  }
  //-------------------
  if (menu2_selected == true)
  {
    lcd.setCursor(6, 0); //2nd line, 1st block
    lcd.print("X");
  }
  //-------------------
  if (menu3_selected == true)
  {
    lcd.setCursor(12, 0); //3rd line, 1st block
    lcd.print("X");
  }

  if (T1_approx < menu1_Value) {
    digitalWrite(relayPin1, HIGH);
    lcd.setCursor(1, 1);
    lcd.println(T1_approx, 0);
  }
  else {
    digitalWrite(relayPin1, LOW);
  }

  //if (T2 < menu2_Value) {
    digitalWrite(relayPin2, HIGH);
    lcd.setCursor(7, 1);
    lcd.println(T2, 0);
  }
  //else {
    digitalWrite(relayPin2, LOW);
  }

  //if (T3 < menu3_Value) {
    digitalWrite(relayPin3, HIGH);
    lcd.setCursor (13, 1);
    lcd.println(T3, 0);
  }
  //else {
    digitalWrite(relayPin3, LOW);
  }

}