/*thermistor parameters:
 * RT0: 10 000 Ω
 * B: 3977 K +- 0.75%
 * T0:  25 C
 * +- 5%
 */

//These values are in the datasheet
#define RT0 10000   // Ω
#define B 3977      // K
//--------------------------------------
#define VCC 5    //Supply voltage
#define R 10000  //R=10KΩ
//--------------------------------------
int Tsp=30;   // set point
int deltaT=2; // errore tollerato

int pinRele= 2;
int statoLamp= 0;
//Variables
float RT, VR, ln, TX, T0, VRT;

void setup() {
  Serial.begin(9600);
  pinMode(pinRele, OUTPUT);

  T0 = 25 + 273.15;
}

void loop() {
  VRT = analogRead(A0);
  VRT = (5.00 / 1023.00) * VRT;      //Conversion to voltage
  VR = VCC - VRT;
  RT = VRT / (VR / R);               //Resistance of RT
  ln = log(RT / RT0);
  TX =1/(ln/ B+1/T0);   //Temperature from thermistor in K
  TX = TX - 273.15;                 //Conversion to °C

  Serial.print("Temperatura: ");
  Serial.print(TX);
  Serial.println(" ℃");
 
  if (TX<(Tsp-deltaT/2)) {
    digitalWrite(pinRele, HIGH);
    Serial.println("ACCESO");
    statoLamp = 1;
  }
  else if ((TX>(Tsp+deltaT/2)))  
  {
    digitalWrite(pinRele, LOW);
    Serial.println("SPENTO");
    statoLamp = 0;
  }   
  else {
    if (statoLamp==0) {Serial.println("MANTENGO SPENTO");} 
    else {Serial.println("MANTENGO ACCESO");} 
  }

  delay(1000);
  
}