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

LiquidCrystal_I2C lcd(0x27, 16, 2); // set the LCD address to 0x27 for a 16 chars and 2 line display


int thermistor = A2;
int relay_peltier = A1;
int relay_fan = A0;

float control_temperature = 6.0;
const float BETA = 3950; // should match the Beta Coefficient of the thermistor

void setup() {
  Serial.begin(9600);
  pinMode(thermistor, INPUT);
  pinMode(relay_peltier, OUTPUT);
  pinMode(relay_fan, OUTPUT);

  lcd.init();
  lcd.backlight();
}

void loop() {

  int analogValue = analogRead(thermistor);
  float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
  Serial.println(celsius);
  lcd.setCursor(0, 0);
  lcd.print("Temperature:");
  lcd.setCursor(0, 1);
  lcd.print(celsius);
  lcd.setCursor(6, 1);
  lcd.print(char(223));
  lcd.setCursor(7, 1);
  lcd.print("C");
  delay(1000);

  if (celsius > control_temperature) {
    digitalWrite(relay_peltier, LOW);
    digitalWrite(relay_fan, LOW);
  } else if (celsius < control_temperature) {
    digitalWrite(relay_peltier, HIGH);
    digitalWrite(relay_fan, HIGH);
  }
}