Arduino - Steinhart-Hart example

// constants for the thermistor and resistor values and the Steinhart-Hart equation
int Rt = 15000;            // Resistance of thermistor at 25 degrees c (from datasheet)
int R1 = 17790;            // Value of fixed resistor, measured using multimeter

float K0 = 0.003354016;    // Parameters for determining nominal resistance values (from datasheet)
float K1 = 0.0002744032;
float K2 = 0.000003666944;
float K3 = 0.000003666944;

float Vin = 5.06;          // Arduino output, measured using multimeter

float Abs0 = -273.15;      // 0 Kelvin in C (made it a variable, just in case it changes)

int degree_symbol = 223;  // ascii code for °

int thermistor_pin = 0;    // analogue pin 0


// Steinhart-Hart equation to convert resistance value from analogue read to temperature in Celcius
double Thermistor(int RawADC)
{
  float Vout = RawADC/1024.0*Vin;    // convert the ADC to voltage
  float Res = Vin*(R1/Vout)-R1;      // Calculate the resistance of the thermistor
  double Temp = Abs0 + 1 / (K0 + K1 * log(Res/R1) + K2 * pow(log(Res/R1),2) + K3 * pow(log(Res/R1),3));  // use Steinhart-Hart to calculate temperature;

  return Temp;
}