add state machine and simplify code

Author: patgruber

src/heartratetask/HeartRateTask.cpp

@@ -138,12 +138,12 @@ void HeartRateTask::HandleWakeUp() {
 
 void HeartRateTask::HandleStartMeasurement(int* lastBpm) {
   switch (state) {
-    case States::ScreenOffAndStopped:
     case States::ScreenOnAndStopped:
       state = States::ScreenOnAndMeasuring;
       *lastBpm = 0;
       StartMeasurement();
       break;
+    case States::ScreenOffAndStopped:
     case States::ScreenOnAndMeasuring:
     case States::ScreenOffAndMeasuring:
     case States::ScreenOffAndWaiting:
@@ -160,9 +160,6 @@ void HeartRateTask::HandleStopMeasurement() {
       break;
     case States::ScreenOffAndMeasuring:
     case States::ScreenOffAndWaiting:
-      state = States::ScreenOffAndStopped;
-      StopMeasurement();
-      break;
     case States::ScreenOnAndStopped:
     case States::ScreenOffAndStopped:
       // shouldn't happen -> ignore

src/heartratetask/HeartRateTask.h

@@ -7,6 +7,59 @@
 
 #define DURATION_UNTIL_BACKGROUND_MEASUREMENT_IS_STOPPED pdMS_TO_TICKS(30 * 1000)
 
+
+/*
+               *** Background Measurement deactivated ***                     
+                                                                              
+                                                                              
+                                                                              
+┌─────────────────────────┐                       ┌─────────────────────────┐ 
+│                         ├───StartMeasurement───►│                         │ 
+│   ScreenOnAndStopped    │                       │   ScreenOnAndMeasuring  │ 
+│                         │◄──StopMeasurement     │                         │ 
+└──▲────────────────┬─────┘                       └──▲──────────────────┬───┘ 
+   │                │                                │                  │     
+ WakeUp         GoToSleep                          WakeUp          GoToSleep  
+   │                │                                │                  │     
+┌──┴────────────────▼─────┐                       ┌──┴──────────────────▼───┐ 
+│                         │                       │                         │ 
+│   ScreenOffAndStopped   │                       │   ScreenOffAndWaiting   │ 
+│                         │                       │                         │ 
+└─────────────────────────┘                       └─────────────────────────┘ 
+                                                                              
+                                                                              
+                                                                              
+                                                                              
+                                                                              
+               *** Background Measurement activated ***                       
+                                                                              
+                                                                              
+                                                                              
+┌─────────────────────────┐                       ┌─────────────────────────┐ 
+│                         ├───StartMeasurement───►│                         │ 
+│   ScreenOnAndStopped    │                       │   ScreenOnAndMeasuring  │ 
+│                         │◄──StopMeasurement     │                         │ 
+└──▲────────────────┬─────┘                       └──▲──────────────────┬───┘ 
+   │                │                        ┌───────┘                  │     
+ WakeUp         GoToSleep                    │     WakeUp          GoToSleep  
+   │                │                        │       │                  │     
+┌──┴────────────────▼─────┐                  │    ┌──┴──────────────────▼───┐ 
+│                         │                  │    │                         │ 
+│   ScreenOffAndStopped   │                  │    │  ScreenOffAndMeasuring  │ 
+│                         │                  │    │                         │ 
+└─────────────────────────┘                  │    └───▲──────────────────┬──┘ 
+                                             │        │                  │    
+                                             │     Waited           Got sensor
+                                             │    interval             data   
+                                             │      time                 │    
+                                             │        │                  │    
+                                          WakeUp  ┌───┴──────────────────▼──┐ 
+                                             │    │                         │ 
+                                             └────┤   ScreenOffAndWaiting   │ 
+                                                  │                         │ 
+                                                  └─────────────────────────┘ 
+ */
+
 namespace Pinetime {
   namespace Drivers {
     class Hrs3300;