Merge pull request #661 from mestafin/constant_sensor

added constant_sensor class

.github/workflows/test.yml

@@ -21,6 +21,7 @@ jobs:
           - examples/repeat_sensor_analog_input.cpp
           - examples/freertos_tasks.cpp
           - examples/raw_json.cpp
+          - examples/constant_sensor.cpp
         target_device:
           - esp32dev
     steps:

examples/constant_sensor.cpp

@@ -0,0 +1,45 @@
+/**
+ * @file constant_sensor.cpp
+ * @brief Example of a ConstantSensor that outputs a constant value at given
+ *   time intervals.
+ *
+ * ConstantSensor is a "sensor" that outputs a constant value at given time
+ * intervals. The interval, output value and the path can be set in the
+ * user interface.
+ *
+ * This example outputs a fresh water tank capacity of 100 litres (0.1 m3) every
+ * 10 seconds.
+ */
+
+#include "sensesp/sensors/constant_sensor.h"
+#include "sensesp_app_builder.h"
+
+using namespace sensesp;
+
+reactesp::ReactESP app;
+
+void setup() {
+  // Some initialization boilerplate when in debug mode...
+#ifndef SERIAL_DEBUG_DISABLED
+  SetupSerialDebug(115200);
+#endif
+
+  // Create the builder object
+  SensESPAppBuilder builder;
+  sensesp_app = builder.get_app();
+
+  // Create the ConstantSensor object
+  auto* constant_sensor =
+      new FloatConstantSensor(0.1, 10, "/Sensors/Frash Water Tank Capacity");
+
+  // create and connect the output object
+
+  constant_sensor->connect_to(
+      new SKOutputFloat("tanks.freshWater.capacity", "",
+                        new SKMetadata("m3", "Fresh Water Tank Capacity")));
+
+  // Start the SensESP application running
+  sensesp_app->start();
+}
+
+void loop() { app.tick(); }

src/sensesp/sensors/constant_sensor.h

@@ -0,0 +1,102 @@
+#ifndef CONSTANT_SENSOR_H_
+#define CONSTANT_SENSOR_H_
+
+#include "Arduino.h"
+#include "sensesp/sensors/sensor.h"
+
+namespace sensesp {
+
+/**
+ * @brief ConstantSensor is the base class for virtual sensors that periodically
+ * emit a constant value.
+ *
+ * The virtual sensors are typically used to send a constant value to SignalK.
+ * Typical example is the capacity of a tank or the length of an anchor rode;
+ *
+ * The sensors can be connected to all the standard SKOutput consumers.
+ *
+ * The sensor value and send delay can be configured via the web ui.
+ *
+ * The sensor has a get_value() and a set_value() method to interact with the
+ * sensor from normal code.
+ *
+ * Example: send the water tank capacity every 30 seconds to SignalK:
+ *
+ *    int send_delay = 30;
+ *    const char* config_path = "/tanks.water_capacity";
+ *    auto *capacity = new ConstantFloatSensor(send_delay,config_path);
+ *    capacity->connect_to(new SKOutputFloat(sk_path, sk_config_path, sk_metadata));
+ *
+ * To set or get the the value of the virtual sensor for use in your code:
+ *
+ *    capacity->set_value(value);
+ *
+ *    value = capacity->get_value();
+ *
+ * @param send_interval[in] Time interval in seconds between consecutive
+ * emissions of the sensor value.
+ *
+ * @param[in] config_path Configuration path for the sensor.
+ */
+
+static const char SCHEMA_CONSTANT_SENSOR[] PROGMEM = R"###({
+        "type": "object",
+        "properties": {
+            "value": { "title": "Constant Value", "type": "number", "description": "Constant value" }
+        }
+    })###";
+
+/**
+ * @brief Base class for constant value sensors.
+ */
+template <class T>
+class ConstantSensor : public SensorT<T> {
+ public:
+  ConstantSensor(T value, int send_interval = 30, String config_path = "")
+      : SensorT<T>(config_path), value_{value}, send_interval_{send_interval} {
+    this->load_configuration();
+  }
+  void start() override {
+    ReactESP::app->onRepeat(send_interval_ * 1000,
+                            [this]() { this->emit(value_); });
+  }
+
+  void set_value(T value) { value_ = value; }
+  T get_value() { return value_; }
+
+ protected:
+  virtual void get_configuration(JsonObject &doc) override {
+    doc["value"] = value_;
+    doc["interval"] = send_interval_;
+  }
+  virtual bool set_configuration(const JsonObject &config) override {
+    // Neither of the configuration parameters are mandatory
+    if (config.containsKey("value")) {
+      value_ = config["value"];
+    }
+    if (config.containsKey("interval")) {
+      send_interval_ = config["interval"];
+    }
+    return true;
+  }
+  virtual String get_config_schema() override {
+    return FPSTR(SCHEMA_CONSTANT_SENSOR);
+  }
+  void update() { this->emit(value_); }
+
+  T value_;
+  int send_interval_;  // seconds
+};
+
+// ..........................................
+//  constant value sensors
+// ..........................................
+
+typedef ConstantSensor<float> FloatConstantSensor;
+typedef ConstantSensor<int> IntConstantSensor;
+typedef ConstantSensor<bool> BoolConstantSensor;
+typedef ConstantSensor<String> StringConstantSensor;
+
+}  // namespace sensesp
+
+#endif