//Measure NTC value
byte NTCPin = A0;
const long SERIESRESISTOR = 10000;

// ~~~~~~ A,B,C ~~~~~~
#define A1 0.000797110609710217//-0.2860629305E-03
#define B1 0.000213433144381270 //4.484292072E-04
#define C1 0.000000065338987554 //-8.321267622E-07  
float th_TC;

void setup()
{
	Serial.begin(9600);
	pinMode(NTCPin, INPUT);
	delay(1);
}
void loop()
{
	float ADCvalue;
	float Resistance;
	ADCvalue = analogRead(NTCPin);
	Serial.print("Analog value ");
	Serial.print(ADCvalue,0);
	Serial.print(" = ");
//convert value to resistance
	Resistance = (1023 / ADCvalue) - 1;
	Resistance = SERIESRESISTOR / Resistance;
	Serial.print(Resistance);
	Serial.print(" Ohm");
	th_TC =  f_ReadTemp_ThABC(NTCPin, SERIESRESISTOR, A1, B1, C1);  // 22k thermistor; ABC parameters were calculated using a digital precision sensor  !
	Serial.print(" | Temperature: ");
	Serial.print(th_TC);
	Serial.print(" | ");




// 	float A = 1.963175107e-3;
// float B = 0.9048811160e-4;
// float C = 32.66820892e-7;

float T = th_TC + 273.15;
float x,y;
float R;

  x = (A1 - 1/T)/C1;
  float B_C = B1/C1;
  y = sqrt(B_C*B_C*B_C/27 + x*x/4);
  R = exp(pow(y - x/2,1/3.) - pow(y + x/2,1/3.));
  // Serial.print("R = %10.4f\n",R);
	Serial.println(R);
	delay(1000);
}

// TPin = Analog Pin 
// THERMISTOR = NTC nominal value that is measured at 25*C
// R1 = R Serries
// A, B , C = the Steinhart–Hart coefficients, which vary depending on the type and model of thermistor and the temperature range of interest.
float f_ReadTemp_ThABC(byte TPin, float R1, float A, float B, float C) {

	float R2 = R1 / ((1023.0 / analogRead(TPin)) - 1);             // for pull-up configuration
	
	float logR2 = log(R2);           // Pre-Calcul for Log(R2)
	float T = (1.0 / (A + B*logR2 + C*logR2*logR2*logR2)); 
	T =  T - 273.15;             // convert Kelvin to *C
	return T;
}

//end program