Thermistor on A0, degrees on an LCD (pins 4, 6, 10 to 13), on an Arduino Uno

// A thermometer: a thermistor on A0, Celsius and Fahrenheit on the LCD.
//
//   5V -> 10k resistor -> A0 -> thermistor -> GND
//   LCD RS -> pin 4    LCD E -> pin 6
//   LCD D4 -> pin 10   D5 -> pin 11   D6 -> pin 12   D7 -> pin 13
//   LCD RW, VSS, K -> GND     VDD, A -> 5V
//   LCD V0 (contrast) -> GND here; on the bench, the middle leg of a pot
//
// The thermistor is at the bottom of the divider: as it warms its resistance
// falls, and so does the reading on A0. From the reading the sketch works out
// the thermistor's resistance,
//
//   R = 10000 * reading / (1023 - reading)
//
// and the beta equation (10k at 25 C, beta 3950) turns it into kelvin.
//
// Drag the thermistor's temperature and watch the display.

#include <LiquidCrystal.h>
#include <math.h>

const int SENSOR = A0;
const float BETA = 3950.0;
const float R25 = 10000.0;

LiquidCrystal lcd(4, 6, 10, 11, 12, 13);

void setup() {
  lcd.begin(16, 2);
  Serial.begin(9600);
  Serial.println("Mokxi Uno: thermistor on A0, LCD on pins 4, 6 and 10 to 13");
}

void loop() {
  int reading = analogRead(SENSOR);
  if (reading < 1) reading = 1;
  if (reading > 1022) reading = 1022;
  float resistance = R25 * reading / (1023.0 - reading);
  float kelvin = 1.0 / (1.0 / 298.15 + log(resistance / R25) / BETA);
  float celsius = kelvin - 273.15;
  float fahrenheit = celsius * 1.8 + 32.0;
  lcd.setCursor(0, 0);
  lcd.print("Temp:        C ");
  lcd.setCursor(6, 0);
  lcd.print(celsius, 1);
  lcd.setCursor(0, 1);
  lcd.print("Fahr:        F ");
  lcd.setCursor(6, 1);
  lcd.print(fahrenheit, 1);
  Serial.print(celsius, 1);
  Serial.println(" C");
  delay(500);
}