Thermostat example demonstrate advantages of source/sink vs shared in certain applications.

Author: aentinger

examples/Threading_Basics/Thermostat/SharedVariables.h

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+/* Define a data sink named 'temperature' of type 'float'. */
+SINK(temperature, float);
+
+int const LIVING_ROOM_HEATING_RELAY_PIN = 3;
+
+void setup()
+{
+  pinMode(LIVING_ROOM_HEATING_RELAY_PIN, OUTPUT);
+}
+
+void loop()
+{
+  float current_temperature_deg = temperature.pop();
+  /* Check if the temperature reported by the thermostat is above
+   * or below 22.0 °C. If the temperature is below 22.0 °C, turn
+   * on the heating.
+   */
+  if (current_temperature_deg < 22.0f)
+    digitalWrite(LIVING_ROOM_HEATING_RELAY_PIN, HIGH);
+  else
+    digitalWrite(LIVING_ROOM_HEATING_RELAY_PIN, LOW);
+}

examples/Threading_Basics/Thermostat/TemperatureControl_LivingRoom.inot

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+/* Define a data sink named 'temperature' of type 'float'. */
+SINK(temperature, float);
+
+void setup()
+{
+  Serial.begin(9600);
+}
+
+void loop()
+{
+  float current_temperature_deg = temperature.pop();
+  Serial.print("Temperature = ");
+  Serial.print(current_temperature_deg);
+  Serial.println(" °C");
+}

examples/Threading_Basics/Thermostat/TemperatureControl_SleepingRoom.inot

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+/* Define a data source named 'temperature' of type 'float'. */
+SOURCE(temperature, float);
+
+int const TEMPERATURE_SENSOR_ANALOG_IN = 0;
+
+void setup()
+{
+
+}
+
+void loop()
+{
+  /* Read temperature and convert to floating point. */
+  float const temperature_deg = analogRead(TEMPERATURE_SENSOR_ANALOG_IN) / 256.0f;
+  /* Store in temperature source variable. */
+  temperature.push(temperature_deg);
+  /* Do only one temperature sensore measurement per second. */
+  delay(1000);
+}

examples/Threading_Basics/Thermostat/TemperatureSensor.inot

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+/* Define a data sink named 'temperature' of type 'float'. */
+SINK(temperature, float);
+
+int const SLEEPING_ROOM_AC_RELAY_PIN = 2;
+
+void setup()
+{
+  pinMode(SLEEPING_ROOM_AC_RELAY_PIN, OUTPUT);
+}
+
+void loop()
+{
+  float current_temperature_deg = temperature.pop();
+  /* Check if the temperature reported by the thermostat is above
+   * or below 20.0 °C. If the temperature is above 20.0 °C, turn
+   * on the AC.
+   */
+  if (current_temperature_deg > 20.0f)
+    digitalWrite(SLEEPING_ROOM_AC_RELAY_PIN, HIGH);
+  else
+    digitalWrite(SLEEPING_ROOM_AC_RELAY_PIN, LOW);
+}

examples/Threading_Basics/Thermostat/TemperatureSensorReporter.inot

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+/* This example emulates a thermostat system which consists of
+ * a single temperature sensore and multiple heating devices
+ * or air-conditioners. The temperature sensor provides periodic
+ * temperature sensor measurements and acts as a temperature source.
+ * This temperature is consumed by various TemperatureControl_ threads
+ * which perform the act of actual room temperature control.
+ * 
+ * Note: While there is only a single temperature "source" there are
+ * multiple temperature "sinks". The source/sink paradigm is contructed
+ * in such a way, that each sink is guaranteed to see every value provided
+ * by a source. This is something that can not be modelled using the shared
+ * variable abstraction.
+ */
+
+void setup()
+{
+  /* Connect the TemperatureSensor thread providing temperature readings
+   * with the various TemperatureControl_* threads.
+   */
+  TemperatureSensor.temperature.connectTo(TemperatureControl_LivingRoom.temperature);
+  TemperatureSensor.temperature.connectTo(TemperatureControl_SleepingRoom.temperature);
+  TemperatureSensor.temperature.connectTo(TemperatureSensorReporter.temperature);
+  /* Start the individual threads for sensing the temperature
+   * and controlling heating/air-conditioning based on the sensed
+   * temperature on a per-room basis.
+   */
+  TemperatureSensor.start();
+  TemperatureControl_LivingRoom.start();
+  TemperatureControl_SleepingRoom.start();
+  TemperatureSensorReporter.start();
+}
+
+void loop()
+{
+
+}