/*
  Arduino Starter Kit example
  Project 3 - Love-O-Meter

  This sketch is written to accompany Project 3 in the Arduino Starter Kit

  Parts required:
  - one TMP36 temperature sensor
  - three red LEDs
  - three 220 ohm resistors

  created 13 Sep 2012
  by Scott Fitzgerald

  http://www.arduino.cc/starterKit

  This example code is part of the public domain.
*/

// named constant for the pin the sensor is connected to
const int sensorPin = A0;
// room temperature in Celsius
const float baselineTemp = 20.0;

const float BETA = 3950; // should match the Beta Coefficient of the thermistor
const double R = 10000; //R=10KΩ reference resistor
const double RT0 = 10000;//resistence of thermistor at 298.15K
const double T0 = 298.15; //25 + 273.15

void setup() {
  // open a serial connection to display values
  Serial.begin(9600);
  // set the LED pins as outputs
  // the for() loop saves some extra coding
  for (int pinNumber = 2; pinNumber < 5; pinNumber++) {
    pinMode(pinNumber, OUTPUT);
    digitalWrite(pinNumber, LOW);
  }
}

void loop() {
  // read the value on AnalogIn pin 0 and store it in a variable
  int sensorVal = analogRead(sensorPin);

  // send the 10-bit sensor value out the serial port
  Serial.print("sensor Value: ");
  Serial.print(sensorVal);

  // convert the ADC reading to voltage
  float voltage = (sensorVal / 1023.0) * 5.0;

  // Send the voltage level out the Serial port
  Serial.print(", Volts: ");
  Serial.print(voltage);
 
  Serial.print(", degrees C: ");

  double  VR = 5 - voltage; // voltage of reference resistor that connected to VCC
  double  RT = voltage / (VR/R); //current resistence of NTC thermistor
  double ln = log(RT / RT0);
  double TX = (1 / ((ln / BETA) + (1 / T0))); //Temperature from thermistor  
  float temperature = TX ;//Conversion to Celsius.Need modifying
  float celsius = TX - 273.15;  
  float fahrenheit = (celsius * 9 / 5) + 32; 

  Serial.println(temperature);
  Serial.print(celsius);  
  Serial.print("°C, ");  
  Serial.print(fahrenheit);  
  Serial.println("°F");  

  // if the current temperature is lower than the baseline turn off all LEDs
  if (celsius < baselineTemp + 2) {
    digitalWrite(2, LOW);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
  } // if the temperature rises 2-4 degrees, turn an LED on
  else if (celsius >= baselineTemp + 2 && celsius < baselineTemp + 4) {
    digitalWrite(2, HIGH);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
  } // if the temperature rises 4-6 degrees, turn a second LED on
  else if (celsius >= baselineTemp + 4 && celsius < baselineTemp + 6) {
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
  } // if the temperature rises more than 6 degrees, turn all LEDs on
  else if (celsius >= baselineTemp + 6) {
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, HIGH);
  }
  delay(1);
}