const double VCC = 3.3; // NodeMCU on board 3.3v vcc
const double R2 = 10000; // 10k ohm series resistor
const double adc_resolution = 1023; // 10-bit adc
const double A = 0.001129148; // thermistor equation parameters
const double B = 0.000234125;
const double C = 0.0000000876741; 
void setup()
{ 
Serial.begin(9600); /* Define baud rate for serial communication */
}
void loop() 
{ 
double Vout, Rth, temperature, adc_value; 
adc_value = analogRead(15); 
Vout = (adc_value * VCC) / adc_resolution; 
Rth = (VCC * R2 / Vout) - R2;
/* Steinhart-Hart Thermistor Equation: 
• Temperature in Kelvin = 1 / (A + B[ln(R)] + C[ln(R)]^3) * 
• where A = 0.001129148, B = 0.000234125 and C = 8.76741*10^-8 */
temperature = (1 / (A + (B * log(Rth)) + (C * pow((log(Rth)),3)))); // Temperature in kelvin
temperature = temperature - 273.15; // Temperature in degree celsius
Serial.print("Temperature = "); 
Serial.print(temperature); 
Serial.println(" degree celsius"); 
delay(2500);
}