Another step towards the new SensorController. It is now also responsible for triggering the measurements based on a simple parameter (after how many seconds to trigger a measurement).

src/Data/DataController.cpp

@@ -6,34 +6,29 @@ namespace Dough
     // Constructor
     // ----------------------------------------------------------------------
 
-    DataController *DataController::_instance = nullptr;
-
     DataController *DataController::Instance()
     {
-        if (DataController::_instance == nullptr)
-        {
-            DataController::_instance = new DataController();
-        }
-        return DataController::_instance;
+        static DataController *_instance = new DataController();
+        return _instance;
     }
 
     DataController::DataController() : _temperatureMeasurements(
                                            "temperature",
                                            TemperatureSensor::Instance(),
                                            TEMPERATURE_AVG_LOOKBACK,
-                                           TEMPERATURE_SIGNIFICANT_CHANGE,
+                                           30,
                                            PUBLISH_INTERVAL),
                                        _humidityMeasurements(
                                            "humidity",
                                            HumiditySensor::Instance(),
                                            HUMIDITY_AVG_LOOKBACK,
-                                           HUMIDITY_SIGNIFICANT_CHANGE,
+                                           30,
                                            PUBLISH_INTERVAL),
                                        _distanceMeasurements(
                                            "distance",
                                            DistanceSensor::Instance(),
                                            DISTANCE_AVG_LOOKBACK,
-                                           DISTANCE_SIGNIFICANT_CHANGE,
+                                           1,
                                            PUBLISH_INTERVAL),
                                        _logger("DATA")
     {
@@ -114,7 +109,11 @@ namespace Dough
     {
         if (isConfigured())
         {
-            _sample();
+            _temperatureMeasurements.loop();
+            _humidityMeasurements.loop();
+            _distanceMeasurements.loop();
+            // Moved logic into sensor controller code.
+            //_sample();
         }
     }
 
@@ -137,7 +136,7 @@ namespace Dough
         {
             _lastSample = now;
 
-            // Quickly dip the LED to indicate that a measurement is started.
+            // Quickly dip the LED to indicate that a measurement has started.
             // This is done synchroneously, because we suspend the timer interrupts
             // in the upcoming code.
             _ui->led3.off();
@@ -152,15 +151,15 @@ namespace Dough
             switch (_sampleType)
             {
             case SAMPLE_TEMPERATURE:
-                _temperatureMeasurements.process();
+                _temperatureMeasurements.loop();
                 _sampleType = SAMPLE_HUMIDITY;
                 break;
             case SAMPLE_HUMIDITY:
-                _humidityMeasurements.process();
+                _humidityMeasurements.loop();
                 _sampleType = SAMPLE_DISTANCE;
                 break;
             case SAMPLE_DISTANCE:
-                _distanceMeasurements.process();
+                _distanceMeasurements.loop();
                 break;
             }
 

src/Data/DataController.h

@@ -16,12 +16,6 @@
 #define HUMIDITY_AVG_LOOKBACK 6          // making this a 3 minute average
 #define DISTANCE_AVG_LOOKBACK 28 * 2 * 3 // making this a 3 minute average
 
-// When significant changes occur in the sensor measurements, they are
-// published to MQTT. These definitions specify what is considered significant.
-#define TEMPERATURE_SIGNIFICANT_CHANGE 2 // to dampen flapping between two values on transition
-#define HUMIDITY_SIGNIFICANT_CHANGE 2    // also to dampen flapping behavior.
-#define DISTANCE_SIGNIFICANT_CHANGE 3    // based on the sensor specification of 3mm resolution
-
 // The minimal interval in seconds at which to forcibly publish measurements to the
 // MQTT broker. When significant changes occur in the measurements, then these will
 // be published to the MQTT broker at all times, independent from this interval.
@@ -63,7 +57,6 @@ namespace Dough
 
     private:
         DataController();
-        static DataController *_instance;
         UI *_ui;
         MQTT *_mqtt;
         SensorController _temperatureMeasurements;

src/Data/SensorController.cpp

@@ -7,15 +7,16 @@ namespace Dough
         const char *mqttKey,
         SensorBase *sensor,
         unsigned int storageSize,
-        unsigned int significantChange,
+        unsigned int minimumMeasureTime,
         unsigned int minimumPublishTime)
     {
         _mqttKey = mqttKey;
         _sensor = sensor;
         _storageSize = storageSize;
-        _significantChange = significantChange;
+        _minimumMeasureTime = minimumMeasureTime;
         _minimumPublishTime = minimumPublishTime;
         _mqtt = MQTT::Instance();
+        _ui = UI::Instance();
     }
 
     void SensorController::setup()
@@ -34,16 +35,52 @@ namespace Dough
         clearHistory();
     }
 
-    void SensorController::process()
+    void SensorController::loop()
     {
-        auto m = _sensor->read();
-        _store(m);
+        if (_mustMeasure())
+        {
+            _measure();
+        }
         if (_mustPublish())
         {
             _publish();
         }
     }
 
+    bool SensorController::_mustMeasure()
+    {
+        // When no measurement was done yet, then do one now.
+        if (_lastMeasuredAt == 0)
+        {
+            return true;
+        }
+
+        // When enough time has passed since the last measurement,
+        // then start another measurement.
+        auto now = millis();
+        auto delta = now - _lastMeasuredAt;
+        return delta >= (_minimumMeasureTime * 1000);
+    }
+
+    void SensorController::_measure()
+    {
+        _lastMeasuredAt = millis();
+        
+        // Quickly dip the LED to indicate that a measurement has started.
+        // This is done synchroneously, because we suspend the timer interrupts
+        // in the upcoming code.
+        _ui->led3.off();
+        delay(50);
+        _ui->led3.on();
+
+        // Read a measurement from the sensor. Suspend the user interface
+        // interrupts in the meanwhile, to not disturb the timing-sensitive
+        // sensor readings.
+        _ui->suspend();
+        _store(_sensor->read());
+        _ui->resume();
+    }
+
     bool SensorController::_mustPublish()
     {
         Measurement lastMeasurement = getLast();
@@ -69,8 +106,10 @@ namespace Dough
             return _lastPublishedAt == 0 || delta >= (_minimumPublishTime * 1000);
         }
 
+        auto precision = _sensor->getPrecision();
+
         // When there is a significant change in the sensor value, then publish.
-        if (abs(_lastPublished.value - lastMeasurement.value) >= _significantChange)
+        if (abs(_lastPublished.value - lastMeasurement.value) >= precision)
         {
             return true;
         }
@@ -78,7 +117,7 @@ namespace Dough
         auto average = getAverage();
 
         // When there is a significant change in the average value, then publish.
-        if (average.ok && abs(_lastPublishedAverage.value - average.value) >= _significantChange)
+        if (average.ok && abs(_lastPublishedAverage.value - average.value) >= precision)
         {
             return true;
         }
@@ -162,4 +201,4 @@ namespace Dough
             _storage[i]->clear();
         }
     }
-}
+} // namespace Dough

src/Data/SensorController.h

@@ -5,26 +5,31 @@
 #include "Sensors/SensorBase.h"
 #include "Data/Measurement.h"
 #include "Network/MQTT.h"
+#include "UI/UI.h"
 
 namespace Dough
 {
     // This class is used to store measurements for a sensor and to keep
     // track of running totals for handling average computations.
-    // It also provides functionality to decide when to publish measurements
-    // to MQTT (after significant changes occur or when the last publish
-    // was too long ago).
+    // It also provides functionality to decide when to read a measurement
+    // from a sensor and when to publish measurements to MQTT (after significant
+    // changes occur or when the last publish was too long ago).
     class SensorController
     {
     public:
         // Create a new Measurements object.
         //
+        // @param mqttKey
+        //     The key to use when publishing sensor values to MQTT.
+        //     The full key will be "<prefix>/<mqttKey>" for measurement values
+        //     and "<prefix>/<mqttKey>/average" for average values.
         // @param sensor
         //     The sensor to read, implements SensorBase.
         // @param storageSize
         //     Number of measurements to keep track of for computing an average.
-        // @param significantChange
-        //     Number that describes how much a measurement value needs to change,
-        //     before it is considered significant and must be published to MQTT.
+        // @param minimumMeasureTime
+        //     The number of seconds after which to read the next measurement
+        //     from the sensor.
         // @param minimumPublishTime
         //     The number of seconds after which to forcibly publish measurements
         //     to MQTT, even when no significant changes to measurements were seen.
@@ -32,34 +37,38 @@ namespace Dough
             const char *mqttKey,
             SensorBase *sensor,
             unsigned int storageSize,
-            unsigned int significantChange,
+            unsigned int minimumMeasureTime,
             unsigned int minimumPublishTime);
         void setup();
-        void process();
+        void loop();
         Measurement getLast();
         Measurement getAverage();
         void clearHistory();
 
     private:
         MQTT *_mqtt;
+        UI *_ui;
         const char *_mqttKey;
         char *_mqttAverageKey;
         SensorBase *_sensor;
         Measurement **_storage;
         unsigned int _storageSize;
-        unsigned int _significantChange;
-        unsigned int _minimumPublishTime;
         int _averageSum = 0;
         unsigned int _averageCount = 0;
         unsigned int _index = 0;
+        bool _mustMeasure();
+        void _measure();
+        unsigned int _minimumMeasureTime; 
+        unsigned long _lastMeasuredAt = 0;
+        bool _mustPublish();
+        void _publish();
+        unsigned int _minimumPublishTime;
         unsigned long _lastPublishedAt = 0;
         Measurement _lastPublished;
         Measurement _lastPublishedAverage;
-        bool _mustPublish();
-        void _publish();
         void _store(Measurement measurement);
         unsigned int _next();
     };
-}
+} // namespace Dough
 
 #endif

src/Network/MQTT.cpp

@@ -7,15 +7,10 @@ namespace Dough
     // Constructor
     // ----------------------------------------------------------------------
 
-    MQTT *MQTT::_instance = nullptr;
-
     MQTT *MQTT::Instance()
     {
-        if (MQTT::_instance == nullptr)
-        {
-            MQTT::_instance = new MQTT();
-        }
-        return MQTT::_instance;
+        static MQTT *_instance = new MQTT();
+        return _instance;
     }
 
     MQTT::MQTT() : _logger("MQTT") {}
@@ -81,6 +76,8 @@ namespace Dough
 
     void MQTT::procesIncomingsMessages()
     {
+        // Calling loop() on the wrapped MQTT client, will fetch the
+        // incoming messages and distribute them to the onMessage callback.
         _mqttClient.loop();
     }
 

src/Network/MQTT.h

@@ -34,7 +34,6 @@ namespace Dough
 
     private:
         MQTT();
-        static MQTT *_instance;
         MQTTClient _mqttClient;
         Logger _logger;
         MQTTConnectHandler _onConnect = nullptr;

src/Network/WiFi.cpp

@@ -6,15 +6,10 @@ namespace Dough
     // Constructor
     // ----------------------------------------------------------------------
 
-    WiFi *WiFi::_instance = nullptr;
-
     WiFi *WiFi::Instance()
     {
-        if (WiFi::_instance == nullptr)
-        {
-            WiFi::_instance = new WiFi();
-        }
-        return WiFi::_instance;
+        static WiFi *_instance = new WiFi();
+        return _instance;
     }
 
     WiFi::WiFi() : _logger("WIFI") {}

src/Network/WiFi.h

@@ -21,7 +21,6 @@ namespace Dough
 
     private:
         WiFi();
-        static WiFi *_instance;
         void _setMacAddress();
         char _macAddress[18]; // max MAC address length + 1
         Logger _logger;

src/Sensors/DistanceSensor.cpp

@@ -6,15 +6,10 @@ namespace Dough
     // Constructor
     // ----------------------------------------------------------------------
 
-    DistanceSensor *DistanceSensor::_instance = nullptr;
-
     DistanceSensor *DistanceSensor::Instance()
     {
-        if (DistanceSensor::_instance == nullptr)
-        {
-            DistanceSensor::_instance = new DistanceSensor();
-        }
-        return DistanceSensor::_instance;
+        static DistanceSensor *_instance = new DistanceSensor();
+        return _instance;
     }
 
     DistanceSensor::DistanceSensor() : _logger("DISTANCE")
@@ -59,4 +54,9 @@ namespace Dough
             return Measurement::Value(d);
         }
     }
+
+    unsigned int DistanceSensor::getPrecision()
+    {
+        return 3; // according to the sensor specifications
+    }    
 }

src/Sensors/DistanceSensor.h

@@ -14,14 +14,14 @@ namespace Dough
     {
     public:
         static DistanceSensor *Instance();
-        virtual void setup();
-        virtual Measurement read();
         void setTemperature(int temperature);
         void setHumidity(int humidity);
+        virtual void setup();
+        virtual Measurement read();
+        virtual unsigned int getPrecision();
 
     private:
         DistanceSensor();
-        static DistanceSensor *_instance;
         Logger _logger;
         SensorHCSR04 *_hcsr04;
     };

src/Sensors/HumiditySensor.cpp

@@ -6,15 +6,10 @@ namespace Dough
     // Constructor
     // ----------------------------------------------------------------------
 
-    HumiditySensor *HumiditySensor::_instance = nullptr;
-
     HumiditySensor *HumiditySensor::Instance()
     {
-        if (HumiditySensor::_instance == nullptr)
-        {
-            HumiditySensor::_instance = new HumiditySensor();
-        }
-        return HumiditySensor::_instance;
+        static HumiditySensor *_instance = new HumiditySensor();
+        return _instance;
     }
 
     HumiditySensor::HumiditySensor() : _logger("HUMIDITY") {}
@@ -47,4 +42,9 @@ namespace Dough
             return Measurement::Value(int(t));
         }
     }
+
+    unsigned int HumiditySensor::getPrecision()
+    {
+        return 2; // prevent flapping when transitioning from value A to value B
+    }    
 }

src/Sensors/HumiditySensor.h

@@ -17,10 +17,10 @@ namespace Dough
         static HumiditySensor *Instance();
         virtual void setup();
         virtual Measurement read();
+        virtual unsigned int getPrecision();
 
     private:
         HumiditySensor();
-        static HumiditySensor *_instance;
         Logger _logger;
     };
 }

src/Sensors/LowLevel/SensorDHT11.cpp

@@ -6,15 +6,13 @@ namespace Dough
     // Constructor
     // ----------------------------------------------------------------------
 
-    SensorDHT11 *SensorDHT11::_instance = nullptr;
-
+    // I am using a singleton here, to make it possible to use the physical
+    // DHT11 sensor from the two logical sensors TemperatureSensor and
+    // HumiditySensor.
     SensorDHT11 *SensorDHT11::Instance()
     {
-        if (SensorDHT11::_instance == nullptr)
-        {
-            SensorDHT11::_instance = new SensorDHT11();
-        }
-        return SensorDHT11::_instance;
+        static SensorDHT11 *_instance = new SensorDHT11();
+        return _instance;
     }
 
     SensorDHT11::SensorDHT11()

src/Sensors/LowLevel/SensorDHT11.h

@@ -17,7 +17,6 @@ namespace Dough
 
     private:
         SensorDHT11();
-        static SensorDHT11 *_instance;
         DHT *_dht;
     };
 }

src/Sensors/LowLevel/SensorHCSR04.cpp

@@ -4,6 +4,7 @@ namespace Dough
 {
     SensorHCSR04::SensorHCSR04(int triggerPin, int echoPin) : _logger("HCSR04")
     {
+        precision = 3;
         _triggerPin = triggerPin;
         _echoPin = echoPin;
         _temperature = HCSR04_INIT_TEMPERATURE;

src/Sensors/LowLevel/SensorHCSR04.h

@@ -43,6 +43,7 @@ namespace Dough
         void setTemperature(int temperature);
         void setHumidity(int humidity);
         int readDistance();
+        int precision;
 
     private:
         Logger _logger;

src/Sensors/SensorBase.h

@@ -11,6 +11,7 @@ namespace Dough
     public:
         virtual void setup();
         virtual Measurement read();
+        virtual unsigned int getPrecision();
     };
 }
 

src/Sensors/TemperatureSensor.cpp

@@ -6,15 +6,10 @@ namespace Dough
     // Constructor
     // ----------------------------------------------------------------------
 
-    TemperatureSensor *TemperatureSensor::_instance = nullptr;
-
     TemperatureSensor *TemperatureSensor::Instance()
     {
-        if (TemperatureSensor::_instance == nullptr)
-        {
-            TemperatureSensor::_instance = new TemperatureSensor();
-        }
-        return TemperatureSensor::_instance;
+        static TemperatureSensor *_instance = new TemperatureSensor();
+        return _instance;
     }
 
     TemperatureSensor::TemperatureSensor() : _logger("TEMPERATURE") {}
@@ -47,4 +42,9 @@ namespace Dough
             return Measurement::Value(int(t));
         }
     }
-}
+
+    unsigned int TemperatureSensor::getPrecision()
+    {
+        return 2; // prevent flapping when transitioning from value A to value B
+    }
+} // namespace Dough

src/Sensors/TemperatureSensor.h

@@ -17,10 +17,10 @@ namespace Dough
         static TemperatureSensor *Instance();
         virtual void setup();
         virtual Measurement read();
+        virtual unsigned int getPrecision();
 
     private:
         TemperatureSensor();
-        static TemperatureSensor *_instance;
         Logger _logger;
     };
 }

src/UI/Button.cpp

@@ -3,6 +3,7 @@
 namespace Dough
 {
     // Constructor for a button instance.
+    //
     // As a necessary evil, because of the way attachinterrupt() works in
     // Arduino, construction needs a bit of extra work to get the button
     // working. An interrupt service routine (ISR) function must be created