/*
Thermistor_read.  Robert Hart June 2020.
Using  datasheet for 10k NTC thermistor (Digikey Part No.).  https://www.vishay.com/docs/29049/ntcle100.pdf
with constants A and B to calculate Temperature from Resistance.
10K resitor in series to make a simple voltage divider.
*/
int ThermistorPin = A0;
int Vo;
float R1 = 10000;
float R2, T;
float A = 3.354e-03;
float B = 2.5698e-4;

void setup() {
Serial.begin(9600);
analogReadResolution(12);                 //Using a 32-bit ATSAM microcontroller that has up to 12 bit resolution. 4095 max.
}

void loop() {

  Vo = analogRead(ThermistorPin);
  R2 = R1 * 1/(4096.0 / (float)Vo - 1.0);         //Calculate resistance of thermistor from voltage divider math.
  T = (1.0 / (A + B*log(R2/R1) ));                 // Calculate temperature using datasheet formula.
  T = T - 273.15;                                   //Convert from Kelvin to Celcius.
 

  Serial.print("Temperature: "); 
  Serial.print(T);
  Serial.println("C"); 

  delay(500);
}