C++ | Thermometer using Thermocouple Type-K with Arduino Uno

#include "U8glib.h"
#include <SPI.h>
#include <Wire.h>
#include "max6675.h"

// -------------------------------------------
// Thermometer using Thermocouple Type-K with Arduino Uno
// www.ardukode.blogspot.com
// -------------------------------------------

boolean centigrade = true; //Uncomment for Centigrade and Comment the  line below
//  boolean centigrade = false; // Uncomment for Fahrenheit and Comment the line above

// setup u8g object
U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE);  // I2C

double max = 215; // Maximum temperature
double min = -215; // Minimum temperature
float currentTemp = 0.00;
String thisTemp = "";
int maxTemp = 0; // Maximum temperature reached
int minTemp = 0; // Minimum temperature reached
int pad = 0;

// Thermocouple MAX 6675 Module
int thermoSO = 11;
int thermoCS = 12;
int thermoSCK = 13;
MAX6675 thermocouple(thermoSCK, thermoCS, thermoSO);
int vccPin = 20; // Vcc pin for MAX6675 module = D3
int gndPin = 22; // Gnd pin for MAX6675 = D2

void draw(void) {
  u8g.setFont(u8g_font_profont12);
  u8g.drawStr(31, 10, "Temperature");
  u8g.setFont(u8g_font_profont12);
  // Show maximum temperature reached
  u8g.drawStr(10, 25, "max");
  if (maxTemp <= int(currentTemp)) {
    maxTemp = int(currentTemp);
  }
  thisTemp = String(maxTemp);
  if (centigrade) {
    thisTemp = thisTemp + "\260C";
  }
  else {
    thisTemp = thisTemp + "\260F";
  }
  const char* maxTempC = (const char*) thisTemp.c_str();
  u8g.drawStr(30, 25, maxTempC);
  // Show the minimum temperature reached
  u8g.drawStr(80, 25, "min");
  if (minTemp >= int(currentTemp)) {
    minTemp = int(currentTemp);
  }
  thisTemp = String(minTemp);
  if (centigrade) {
    thisTemp = thisTemp + "\260C";
  }
  else {
    thisTemp = thisTemp + "\260F";
  }
  const char* minTempC = (const char*) thisTemp.c_str();
  u8g.drawStr(100, 25, minTempC);
  u8g.setFont(u8g_font_profont29);
  if (currentTemp > 99) {
    pad = 2;
  }
  if (currentTemp > 9 && currentTemp < 100) {
    pad = 10;
  }
  if (currentTemp < 10) {
    pad = 18;
  }
  thisTemp = String(currentTemp);
  if (centigrade) {
    thisTemp = thisTemp + "\260C";
  }
  else {
  }
  const char* newDispC = (const char*) thisTemp.c_str();
  u8g.drawStr(pad, 50, newDispC);
}

void setup(void) {
  pinMode(vccPin, OUTPUT); digitalWrite(vccPin, HIGH); // D3 @5V/Vcc
  pinMode(gndPin, OUTPUT); digitalWrite(gndPin, LOW); // D2@0V/GND
  Serial.begin(9600); // Serial Begin
  Wire.begin();
  delay(500); // Stabilization Time
  if (centigrade) {
    currentTemp = thermocouple.readCelsius();
    minTemp = int(thermocouple.readCelsius());
    maxTemp = int(thermocouple.readCelsius());
  }
  else {
    currentTemp = thermocouple.readFahrenheit();
    minTemp = int(thermocouple.readFahrenheit());
    maxTemp = int(thermocouple.readFahrenheit());
  }
}
void loop(void) {
  currentTemp = 0;
  for (int f = 0; f < 25; f++) {
    if (centigrade) {
      currentTemp = thermocouple.readCelsius() + currentTemp;
    }
    else {
      currentTemp = thermocouple.readFahrenheit() + currentTemp;
    }
  }
  currentTemp = currentTemp / 25; //Average 25 readings
  // Draw
  u8g.firstPage();
  do {
    draw();
  } while ( u8g.nextPage() );
  delay(50); // Refresh Time
}
// avrdude -DV -patmega328p -Pnet:192.168.4.1:23 -carduino -b115200 -U flash:w:firmware.hex:i