Added NTCSensor

code/espurna/config/arduino.h

@@ -142,6 +142,7 @@
 //#define HCSR04_SUPPORT         1
 //#define HLW8012_SUPPORT        1
 //#define MHZ19_SUPPORT          1
+//#define NTC_SUPPORT            1
 //#define PMSX003_SUPPORT        1
 //#define PZEM004T_SUPPORT       1
 //#define SHT3X_I2C_SUPPORT      1

code/espurna/config/progmem.h

@@ -175,6 +175,9 @@ PROGMEM const char espurna_sensors[] =
     #if MHZ19_SUPPORT
         "MHZ19 "
     #endif
+    #if NTC_SUPPORT
+        "NTC "
+    #endif
     #if PMSX003_SUPPORT
         "PMSX003 "
     #endif

code/espurna/config/sensors.h

@@ -430,6 +430,43 @@
 #define MHZ19_TX_PIN                    15
 #endif
 
+//------------------------------------------------------------------------------
+// NTC sensor
+// Enable support by passing NTC_SUPPORT=1 build flag
+//--------------------------------------------------------------------------------
+
+#ifndef NTC_SUPPORT
+#define NTC_SUPPORT                     1
+#endif
+
+#ifndef NTC_SAMPLES
+#define NTC_SAMPLES                     10      // Number of samples
+#endif
+
+#ifndef NTC_DELAY
+#define NTC_DELAY                       0       // Delay between samples in micros
+#endif
+
+#ifndef NTC_R_UP
+#define NTC_R_UP                        0       // Resistor upstream, set to 0 if none
+#endif
+
+#ifndef NTC_R_DOWN
+#define NTC_R_DOWN                      10000   // Resistor downstream, set to 0 if none
+#endif
+
+#ifndef NTC_T0
+#define NTC_T0                          298.15  // 25 Celsius
+#endif
+
+#ifndef NTC_R0
+#define NTC_R0                          10000   // Resistance at T0
+#endif
+
+#ifndef NTC_BETA
+#define NTC_BETA                        3977    // Beta coeficient
+#endif
+
 //------------------------------------------------------------------------------
 // SenseAir CO2 sensor
 // Enable support by passing SENSEAIR_SUPPORT=1 build flag
@@ -589,6 +626,7 @@
     HCSR04_SUPPORT || \
     HLW8012_SUPPORT || \
     MHZ19_SUPPORT || \
+    NTC_SUPPORT || \
     SENSEAIR_SUPPORT || \
     PMSX003_SUPPORT || \
     PZEM004T_SUPPORT || \
@@ -719,6 +757,11 @@
     #include "../sensors/MHZ19Sensor.h"
 #endif
 
+#if NTC_SUPPORT
+    #include "../sensors/AnalogSensor.h"
+    #include "../sensors/NTCSensor.h"
+#endif
+
 #if SENSEAIR_SUPPORT
     #include <SoftwareSerial.h>
     #include "../sensors/SenseAirSensor.h"

code/espurna/config/types.h

@@ -268,6 +268,7 @@
 #define SENSOR_HCSR04_ID            0x23
 #define SENSOR_SENSEAIR_ID          0x24
 #define SENSOR_GEIGER_ID            0x25
+#define SENSOR_NTC_ID               0x26
 
 //--------------------------------------------------------------------------------
 // Magnitudes

code/espurna/sensor.ino

@@ -324,6 +324,8 @@ void _sensorLoad() {
     #if ANALOG_SUPPORT
     {
         AnalogSensor * sensor = new AnalogSensor();
+        sensor->setSamples(ANALOG_SAMPLES);
+        sensor->setDelay(ANALOG_DELAY);
         _sensors.push_back(sensor);
     }
     #endif
@@ -500,6 +502,20 @@ void _sensorLoad() {
     }
     #endif
 
+    #if NTC_SUPPORT
+    {
+        NTCSensor * sensor = new NTCSensor();
+        sensor->setSamples(NTC_SAMPLES);
+        sensor->setDelay(NTC_DELAY);
+        sensor->setUpstreamResistor(NTC_R_UP);
+        sensor->setDownstreamResistor(NTC_R_DOWN);
+        sensor->setBeta(NTC_BETA);
+        sensor->setR0(NTC_R0);
+        sensor->setT0(NTC_T0);
+        _sensors.push_back(sensor);
+    }
+    #endif
+
     #if SENSEAIR_SUPPORT
     {
         SenseAirSensor * sensor = new SenseAirSensor();

code/espurna/sensors/AnalogSensor.h

@@ -3,7 +3,7 @@
 // Copyright (C) 2017-2018 by Xose Pérez <xose dot perez at gmail dot com>
 // -----------------------------------------------------------------------------
 
-#if SENSOR_SUPPORT && ANALOG_SUPPORT
+#if SENSOR_SUPPORT && (ANALOG_SUPPORT || NTC_SUPPORT)
 
 #pragma once
 

code/espurna/sensors/NTCSensor.h

@@ -0,0 +1,125 @@
+// -----------------------------------------------------------------------------
+// NTC Sensor (maps to a NTCSensor)
+// Copyright (C) 2018 by Xose Pérez <xose dot perez at gmail dot com>
+// -----------------------------------------------------------------------------
+
+#if SENSOR_SUPPORT && NTC_SUPPORT
+
+#pragma once
+
+// Set ADC to TOUT pin
+#undef ADC_MODE_VALUE
+#define ADC_MODE_VALUE ADC_TOUT
+
+#include "Arduino.h"
+#include "AnalogSensor.h"
+
+extern "C" {
+    #include "../libs/fs_math.h"
+}
+
+class NTCSensor : public AnalogSensor {
+
+    public:
+
+        // ---------------------------------------------------------------------
+        // Public
+        // ---------------------------------------------------------------------
+
+        NTCSensor(): AnalogSensor() {
+            _count = 1;
+            _sensor_id = SENSOR_NTC_ID;
+        }
+
+        void setBeta(unsigned long beta) {
+            if (beta > 0) _beta = beta;
+        }
+
+        void setUpstreamResistor(unsigned long resistance) {
+            _resistance_up = resistance;
+            if (_resistance_up > 0) _resistance_down = 0;
+        }
+
+        void setDownstreamResistor(unsigned long resistance) {
+            _resistance_down = resistance;
+            if (_resistance_down > 0) _resistance_up = 0;
+        }
+
+        void setR0(unsigned long resistance) {
+            if (resistance > 0) _R0 = resistance;
+        }
+
+        void setT0(double temperature) {
+            if (temperature > 0) _T0 = temperature;
+        }
+
+        // ---------------------------------------------------------------------
+
+        // ---------------------------------------------------------------------
+        // Sensor API
+        // ---------------------------------------------------------------------
+
+        // Descriptive name of the sensor
+        String description() {
+            return String("NTC @ TOUT");
+        }
+
+        // Descriptive name of the slot # index
+        String slot(unsigned char index) {
+            return description();
+        };
+
+        // Address of the sensor (it could be the GPIO or I2C address)
+        String address(unsigned char index) {
+            return String("0");
+        }
+
+        // Type for slot # index
+        unsigned char type(unsigned char index) {
+            if (index == 0) return MAGNITUDE_TEMPERATURE;
+            return MAGNITUDE_NONE;
+        }
+
+        // Current value for slot # index
+        double value(unsigned char index) {
+
+            double temperature = 0;
+
+            if (index == 0) {
+
+                // sampled reading
+                double read = _read();
+
+                // Ru = (1023/c - 1) * Rd
+                double resistance;
+                double alpha = (1023.0 / read) - 1;
+                if (_resistance_down > 0) {
+                    resistance = _resistance_down * alpha;
+                } else if (0 == alpha) {
+                    resistance = _R0;
+                } else {
+                    resistance = _resistance_up / alpha;
+                }
+
+                // 1/T = 1/T0 + 1/B * ln(R/R0)
+                temperature = fs_log(resistance / _R0);
+                temperature = (1.0 / _T0) + (temperature / _beta);
+                temperature = 1.0 / temperature - 273.15;
+
+            }
+
+            return temperature;
+
+        }
+
+    protected:
+
+        unsigned long _beta = NTC_BETA;
+        unsigned long _resistance_up = NTC_R_UP;
+        unsigned long _resistance_down = NTC_R_DOWN;
+        unsigned long _R0 = NTC_R0;
+        double _T0 = NTC_T0;
+
+};
+
+#endif // SENSOR_SUPPORT && NTC_SUPPORT