[eAh-AVR1934] Implementare originală a funcției de citire a temperaturii pentru aplicația demo a plăcuței XMEGA-A3BU (versiunea defectă și incompletă)

gistfile1.c

/**
 * \brief Read the actual temperature from the NTC
 *
 * This function returns the temperature in Celsius by piecewise linearisation
 * of the complex transfer function between NTC resistance and ADC codes. The
 * accuracy of the temperature is somewhat limited.
 *
 * \note The result is inaccurate for temperatures outside 5-45 degrees.
 *
 * \retval the temperature in Celsius
 */
int8_t ntc_get_temperature(void)
{
  int8_t retval = 0;
  float ntc_sample = ntc_sensor_sample;
  if (ntc_sensor_sample > 697) {
    retval = (int8_t)((-0.0295 * ntc_sample) + 40.5);
  } if (ntc_sensor_sample > 420) {
    retval = (int8_t)((-0.0474 * ntc_sample) + 53.3);
  } else {
    retval = (int8_t)((-0.0777 * ntc_sample) + 65.1);
  }
  return retval;
}