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121 lines
3.4 KiB
121 lines
3.4 KiB
// -----------------------------------------------------------------------------
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// NTC Sensor (maps to a NTCSensor)
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// Copyright (C) 2019 by Xose Pérez <xose dot perez at gmail dot com>
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// -----------------------------------------------------------------------------
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#if SENSOR_SUPPORT && NTC_SUPPORT
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#pragma once
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#include <Arduino.h>
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#include "AnalogSensor.h"
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extern "C" {
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#include "../libs/fs_math.h"
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}
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class NTCSensor : public AnalogSensor {
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public:
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// ---------------------------------------------------------------------
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// Public
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// ---------------------------------------------------------------------
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NTCSensor() {
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_count = 1;
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_sensor_id = SENSOR_NTC_ID;
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}
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void setBeta(unsigned long beta) {
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if (beta > 0) _beta = beta;
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}
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void setUpstreamResistor(unsigned long resistance) {
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_resistance_up = resistance;
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if (_resistance_up > 0) _resistance_down = 0;
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}
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void setDownstreamResistor(unsigned long resistance) {
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_resistance_down = resistance;
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if (_resistance_down > 0) _resistance_up = 0;
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}
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void setR0(unsigned long resistance) {
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if (resistance > 0) _R0 = resistance;
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}
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void setT0(double temperature) {
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if (temperature > 0) _T0 = temperature;
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}
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// ---------------------------------------------------------------------
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// ---------------------------------------------------------------------
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// Sensor API
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// ---------------------------------------------------------------------
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// Descriptive name of the sensor
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String description() {
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return String("NTC @ TOUT");
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}
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// Descriptive name of the slot # index
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String slot(unsigned char index) {
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return description();
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}
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// Address of the sensor (it could be the GPIO or I2C address)
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String address(unsigned char index) {
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return String("0");
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}
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// Type for slot # index
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unsigned char type(unsigned char index) {
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if (index == 0) return MAGNITUDE_TEMPERATURE;
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return MAGNITUDE_NONE;
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}
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// Current value for slot # index
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double value(unsigned char index) {
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double temperature = 0;
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if (index == 0) {
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// sampled reading
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double read = _read();
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// Ru = (1023/c - 1) * Rd
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double resistance;
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double alpha = (1023.0 / read) - 1;
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if (_resistance_down > 0) {
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resistance = _resistance_down * alpha;
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} else if (0 == alpha) {
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resistance = _R0;
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} else {
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resistance = _resistance_up / alpha;
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}
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// 1/T = 1/T0 + 1/B * ln(R/R0)
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temperature = fs_log(resistance / _R0);
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temperature = (1.0 / _T0) + (temperature / _beta);
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temperature = 1.0 / temperature - 273.15;
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}
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return temperature;
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}
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protected:
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unsigned long _beta = NTC_BETA;
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unsigned long _resistance_up = NTC_R_UP;
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unsigned long _resistance_down = NTC_R_DOWN;
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unsigned long _R0 = NTC_R0;
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double _T0 = NTC_T0;
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};
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#endif // SENSOR_SUPPORT && NTC_SUPPORT
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