#define THERMISTORPIN1 34
#define THERMISTORPIN2 32
#define THERMISTORPIN3 35
#define THERMISTORPIN4 33

const double VCC = 3.3;             // NodeMCU on board 3.3v vcc
const double R2 = 10000;            // 10k ohm series resistor
const double adc_resolution = 4096; // 12-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, Rth1, Rth2, Rth3, Rth4, temperature1, temperature2, temperature3, temperature4, adc_value1, adc_value2, adc_value3, adc_value4;

  adc_value1 = adc_resolution - analogRead(THERMISTORPIN1) + 0.5; // switch direction
  adc_value2 = adc_resolution - analogRead(THERMISTORPIN2) + 0.5;
  adc_value3 = adc_resolution - analogRead(THERMISTORPIN3) + 0.5;
  adc_value4 = adc_resolution - analogRead(THERMISTORPIN4) + 0.5;

  Vout = (adc_value1 * VCC) / adc_resolution;
  Rth1 = (VCC * R2 / Vout) - R2;

  Vout = (adc_value2 * VCC) / adc_resolution;
  Rth2 = (VCC * R2 / Vout) - R2;

  Vout = (adc_value3 * VCC) / adc_resolution;
  Rth3 = (VCC * R2 / Vout) - R2;

  Vout = (adc_value4 * VCC) / adc_resolution;
  Rth4 = (VCC * R2 / Vout) - R2;

  temperature1 = (1 / (A + (B * log(Rth1)) + (C * pow((log(Rth1)), 3))));
  temperature2 = (1 / (A + (B * log(Rth2)) + (C * pow((log(Rth2)), 3))));
  temperature3 = (1 / (A + (B * log(Rth3)) + (C * pow((log(Rth3)), 3))));
  temperature4 = (1 / (A + (B * log(Rth4)) + (C * pow((log(Rth4)), 3))));

  temperature1 = temperature1 - 273.15;  // Temperature in degree celsius
  temperature2 = temperature2 - 273.15;
  temperature3 = temperature3 - 273.15;
  temperature4 = temperature4 - 273.15;

  Serial.print("Rth1:");
  Serial.print(Rth1);
  Serial.print(" Temperature1 = ");
  Serial.print(temperature1);
  Serial.println(" degree celsius");

  Serial.print("Rth2:");
  Serial.print(Rth2);
  Serial.print(" Temperature2 = ");
  Serial.print(temperature2);
  Serial.println(" degree celsius");

  Serial.print("Rth3:");
  Serial.print(Rth3);
  Serial.print(" Temperature3 = ");
  Serial.print(temperature3);
  Serial.println(" degree celsius");

  Serial.print("Rth4:");
  Serial.print(Rth4);
  Serial.print(" Temperature4 = ");
  Serial.print(temperature4);
  Serial.println(" degree celsius");

  delay(5000);
}