// NTC B3950 Thermistor
// the formula for temp in kelvin is
//                 1
// T = ----------------------------
//     1/To + (1/beta) * ln(Rt/Ro)
//
#include "variable.h"

bool esp32 = true;       // change to false when using Arduino

int ThermistorPin;
double adcMax, Vs;

double R1 = 10000.0;   // voltage divider resistor value
double Beta = 3950.0;  // Beta value
double To = 298.15;    // Temperature in Kelvin for 25 degree Celsius
double Ro = 10000.0;   // Resistance of Thermistor at 25 degree Celsius



void setup() {
  Serial.begin(9600);
  if (esp32) {
    ThermistorPin = 34;
    adcMax = 4095.0; // ADC resolution 12-bit (0-4095)
    Vs = 3.3;        // supply voltage
  }
  else {
    ThermistorPin = A0;
    adcMax = 1023.0; // ADC resolution 10-bit (0-1023)
    Vs = 5.0;          // supply voltage
  }
}

void loop() {
  double Vout, Rt = 0;
  double T, Tc, Tf = 0;

  double adc = 0;
  if (esp32) {
    adc = analogRead(ThermistorPin);
    adc = ADC_LUT[(int)adc];
  }
  else {
    adc = analogRead(ThermistorPin);
  }
  Vout = adc * Vs/adcMax;
  Rt = R1 * Vout / (Vs - Vout);

  T = 1/(1/To + log(Rt/Ro)/Beta);    // Temperature in Kelvin
  Tc = (T - 273.15) + 4;                   // Celsius
  Serial.println(Tc);
  // Tf = Tc * 9 / 5 + 32;              // Fahrenheit
  // if (Tc > 0) Serial.println(Tc);

  delay(2000);
}