#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <math.h>

//LCD 
LiquidCrystal_I2C lcd(0x27 , 16, 2); //LCD I2C Screen is 0x27, 16 characters and 2 rows
//Pins
const int incButton=2; //increase button
const int decButton=3; //decrease button
const int FanPin=5; //this LED represents the fan and would be connected via a MOSFET

//setpoint control
float setPWM=0.0; //default initial PWM on switch-on
float percent=0.0;
const float step=255.0/10.0; // the amount each button press changes the set PWM
const float minPWM=0.0; // limit the settings to a minimum of 0
const float maxPWM=255.0; // limit the settings to a maximum of 255

//PWM limits. These are the maximum and minimum PWM outputs for the peltier and fan

//for debouncing of the set pins as otherwise setting the PWM is difficult
bool lastIncState=HIGH;
bool lastDecState=HIGH;

void setup() {
  // put your setup code here, to run once:
    pinMode(incButton, INPUT_PULLUP);
    pinMode(decButton, INPUT_PULLUP);
    pinMode(FanPin, OUTPUT);

    analogWrite(FanPin,0);
 
    lcd.init();
    lcd.backlight();
}

//main loop - this calls all the subroutines below it.
void loop() {
  setThePWM(); //calls the routine that sets the PWM
  updateFans(setPWM); //sets the cooling fan
  updateLCD(setPWM, percent); //calls the routine that updates the display
  delay(100); //adds a 0.1 second delay
}

void setThePWM() { // this subroutine uses the up and down buttons to set the desired PWM

    bool incState=digitalRead(incButton);
    bool decState=digitalRead(decButton);
    // increase value
    if (incState == LOW && lastIncState==HIGH) { //decrease button is pressed
      setPWM+= step; }
    if (decState==LOW && lastDecState==HIGH) { //increase button is pressed
      setPWM-=step;  }
    setPWM=constrain(setPWM, minPWM,maxPWM); //constrains to a fixed min and max PWM
   lastIncState=incState;
   lastDecState=decState;
}

// Proportional control of the peltier and fans. 
void updateFans (float setPWM) {
    analogWrite(FanPin,setPWM);
}


void updateLCD(float setPWM, float percent) { //this sends data to the LCD

percent=setPWM/maxPWM*100;

  lcd.setCursor(0,0);
  lcd.print("Set: ");
  lcd.print(setPWM,1);
  lcd.print(" PWM   ");
  
  lcd.setCursor(0,1); // displays the percentage of the PWM (0-100%)
  lcd.print("Now: ");
  lcd.print(percent,1);
  lcd.print(" %    ");



  
}