Sensor.cpp

#include "Sensor.h"
#include <math.h>  // log()

Sensor::Sensor(int analogPin,
               float rFixed,
               float beta,
               float t0Kelvin,
               float alpha)
: pin(analogPin),
  R_FIXED(rFixed),
  B(beta),
  T0(t0Kelvin),
  alphaFilter(alpha),
  firstRun(true),
  filteredTemp(0.0f)
{
}

void Sensor::update() {
  float rawTemp = readNTCTemp();
  if (firstRun) {
    filteredTemp = rawTemp;
    firstRun = false; 
  } else {
    // Exponential Moving Average
    filteredTemp = alphaFilter * rawTemp + (1 - alphaFilter) * filteredTemp;
  }
}

float Sensor::getTemperature() const {
  return filteredTemp;
}

// Beta-Formel: ADC -> Spannung -> R_NTC -> Kelvin -> °C
float Sensor::readNTCTemp() {
  int raw = analogRead(pin);
  float rNtc = R_FIXED * (1023.0 / (float)raw - 1.0); //  float rNtc = R_FIXED / (1023.0 / (float)raw - 1.0) if NTC between GND and fixed R
  rNtc = (1.0f / T0) + (1.0f / B) * log(rNtc / R_FIXED);
  float tKelvin = 1.0f / rNtc;
  return (tKelvin - 273.15f);
}