#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#include <SD.h>
#define CS_PIN 10
File root;
//ANALOG_PIN (READING ANALOG INPUT)
#define ANALOG_PIN A0
LiquidCrystal_I2C lcd(0x27, 20, 4);
float analogValue,celcius,prevCelcius,fahrenheit,kelvin;

float getCelcius(){
  const float BETA = 3950;
  int analogValue = analogRead(A0);
  float celcius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
  return celcius;
}

float printData(){
  lcd.clear();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Celcius: ");
  lcd.print(celcius);
  lcd.write(0xDF);
  lcd.println("C");

  lcd.setCursor(0, 1);
  lcd.print("Fahrenheit: ");
  lcd.print(fahrenheit);
  lcd.write(0xDF);
  lcd.println("F");

  lcd.setCursor(0, 2);
  lcd.print("Kelvin: ");
  lcd.print(kelvin);
  lcd.write(0xDF);
  lcd.println("K");
}

void readFile(){
  
    File textFile = SD.open("angel.txt");
    if (textFile) {
      while (textFile.available()) {
        Serial.write(textFile.read());
      }
      textFile.close();
      Serial.println();
    } else {
      Serial.println("error opening angel.txt!");
    }
}

void setup(){
  Serial.begin(9600);
  pinMode(ANALOG_PIN, INPUT);
  Serial.print("Initializing SD card... ");
  if (!SD.begin(CS_PIN)) {
    Serial.println("Card initialization failed!");
    while (true);
  }
  Serial.println("initialization done.");
  Serial.println("Files in the card:");
  Serial.println("");
  lcd.begin(20,4);
}

void loop(){
  analogValue = analogRead(ANALOG_PIN);
  celcius = getCelcius();
  fahrenheit = (celcius*(9/5))+32;
  kelvin = (celcius + 273.15);
  if(celcius!=prevCelcius){
    prevCelcius = celcius;
    //write
      File writeFile = SD.open("angel.txt", FILE_WRITE);
      writeFile.print("Celcius: ");
      writeFile.print(celcius);
      writeFile.print(", Fahrenheit: ");
      writeFile.print(fahrenheit);
      writeFile.print(", Kelvin: ");
      writeFile.print(kelvin);
      writeFile.print("\n");
      writeFile.close(); 
      readFile();
  }

  delay(1000);
  printData();
}