add heart rate measurments in the background

src/heartratetask/HeartRateTask.cpp

@@ -24,52 +24,89 @@ void HeartRateTask::Process(void* instance) {
 }
 
 void HeartRateTask::Work() {
-  int lastBpm = 0;
-  while (true) {
-    Messages msg;
-    uint32_t delay;
-    if (state == States::Running) {
-      if (measurementStarted) {
-        delay = ppg.deltaTms;
-      } else {
-        delay = 100;
-      }
-    } else {
-      delay = portMAX_DELAY;
-    }
+  lastBpm = 0;
 
-    if (xQueueReceive(messageQueue, &msg, delay)) {
+  while (true) {
+    auto delay = CurrentTaskDelay();
+    Messages msg;
+
+    if (xQueueReceive(messageQueue, &msg, delay) == pdTRUE) {
       switch (msg) {
         case Messages::GoToSleep:
-          StopMeasurement();
+          if (state == States::Running) {
             state = States::Idle;
+          } else if (state == States::Measuring) {
+            state = States::BackgroundWaiting;
+            backgroundMeasurementWaitingStart = xTaskGetTickCount();
+            StopMeasurement();
+          }
           break;
         case Messages::WakeUp:
+          if (state == States::Idle) {
             state = States::Running;
-          if (measurementStarted) {
-            lastBpm = 0;
+          } else if (state == States::BackgroundMeasuring) {
+            state = States::Measuring;
+          } else if (state == States::BackgroundWaiting) {
+            state = States::Measuring;
             StartMeasurement();
           }
           break;
         case Messages::StartMeasurement:
-          if (measurementStarted) {
+          if (state == States::Measuring || state == States::BackgroundMeasuring) {
             break;
           }
+          state = States::Measuring;
           lastBpm = 0;
           StartMeasurement();
-          measurementStarted = true;
           break;
         case Messages::StopMeasurement:
-          if (!measurementStarted) {
+          if (state == States::Running || state == States::Idle) {
             break;
           }
+          if (state == States::Measuring) {
+            state = States::Running;
+          } else if (state == States::BackgroundMeasuring) {
+            state = States::Idle;
+          }
           StopMeasurement();
-          measurementStarted = false;
           break;
       }
     }
 
-    if (measurementStarted) {
+    if (state == States::BackgroundWaiting) {
+      HandleBackgroundWaiting();
+    } else if (state == States::BackgroundMeasuring || state == States::Measuring) {
+      HandleSensorData();
+    }
+  }
+}
+
+void HeartRateTask::PushMessage(HeartRateTask::Messages msg) {
+  BaseType_t xHigherPriorityTaskWoken = pdFALSE;
+  xQueueSendFromISR(messageQueue, &msg, &xHigherPriorityTaskWoken);
+  portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
+}
+
+void HeartRateTask::StartMeasurement() {
+  heartRateSensor.Enable();
+  ppg.Reset(true);
+  vTaskDelay(100);
+}
+
+void HeartRateTask::StopMeasurement() {
+  heartRateSensor.Disable();
+  ppg.Reset(true);
+  vTaskDelay(100);
+}
+
+void HeartRateTask::HandleBackgroundWaiting() {
+  if (xTaskGetTickCount() - backgroundMeasurementWaitingStart >= DURATION_BETWEEN_BACKGROUND_MEASUREMENTS) {
+    state = States::BackgroundMeasuring;
+    StartMeasurement();
+  }
+}
+
+void HeartRateTask::HandleSensorData() {
   int8_t ambient = ppg.Preprocess(heartRateSensor.ReadHrs(), heartRateSensor.ReadAls());
   int bpm = ppg.HeartRate();
 
@@ -95,25 +132,24 @@ void HeartRateTask::Work() {
   if (bpm != 0) {
     lastBpm = bpm;
     controller.Update(Controllers::HeartRateController::States::Running, lastBpm);
-      }
+    if (state == States::BackgroundMeasuring) {
+      StopMeasurement();
+      state = States::BackgroundWaiting;
+      backgroundMeasurementWaitingStart = xTaskGetTickCount();
     }
   }
 }
 
-void HeartRateTask::PushMessage(HeartRateTask::Messages msg) {
-  BaseType_t xHigherPriorityTaskWoken = pdFALSE;
-  xQueueSendFromISR(messageQueue, &msg, &xHigherPriorityTaskWoken);
-  portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
-}
-
-void HeartRateTask::StartMeasurement() {
-  heartRateSensor.Enable();
-  ppg.Reset(true);
-  vTaskDelay(100);
-}
-
-void HeartRateTask::StopMeasurement() {
-  heartRateSensor.Disable();
-  ppg.Reset(true);
-  vTaskDelay(100);
+int HeartRateTask::CurrentTaskDelay() {
+    switch (state) {
+      case States::Measuring:
+      case States::BackgroundMeasuring:
+        return ppg.deltaTms;
+      case States::Running:
+        return 100;
+      case States::BackgroundWaiting:
+        return 500;
+      default:
+        return portMAX_DELAY;
+    }
 }

src/heartratetask/HeartRateTask.h

@@ -4,6 +4,8 @@
 #include <queue.h>
 #include <components/heartrate/Ppg.h>
 
+#define DURATION_BETWEEN_BACKGROUND_MEASUREMENTS 5 * 60 * 1000 // 5 Minutes assuming 1 Hz
+
 namespace Pinetime {
   namespace Drivers {
     class Hrs3300;
@@ -17,7 +19,7 @@ namespace Pinetime {
     class HeartRateTask {
     public:
       enum class Messages : uint8_t { GoToSleep, WakeUp, StartMeasurement, StopMeasurement };
-      enum class States { Idle, Running };
+      enum class States { Idle, Running, Measuring, BackgroundWaiting, BackgroundMeasuring };
 
       explicit HeartRateTask(Drivers::Hrs3300& heartRateSensor, Controllers::HeartRateController& controller);
       void Start();
@@ -29,13 +31,18 @@ namespace Pinetime {
       void StartMeasurement();
       void StopMeasurement();
 
+      void HandleBackgroundWaiting();
+      void HandleSensorData();
+      int CurrentTaskDelay();
+
       TaskHandle_t taskHandle;
       QueueHandle_t messageQueue;
       States state = States::Running;
       Drivers::Hrs3300& heartRateSensor;
       Controllers::HeartRateController& controller;
       Controllers::Ppg ppg;
-      bool measurementStarted = false;
+      int lastBpm = 0;
+      TickType_t backgroundMeasurementWaitingStart;
     };
 
   }