Initialize SystemTask, DisplayApp and HeartRateTask as global static variable instead of variables on the heap. We don't need them on the heap as we know their size at build time, it'll reduce memory fragmentation and it'll make memory analysis easier.

src/components/timer/TimerController.cpp

@@ -12,14 +12,17 @@ using namespace Pinetime::Controllers;
 
 APP_TIMER_DEF(timerAppTimer);
 
-
-TimerController::TimerController(System::SystemTask& systemTask) : systemTask{systemTask} {
+namespace {
+  void TimerEnd(void* p_context) {
+    auto* controller = static_cast<Pinetime::Controllers::TimerController*> (p_context);
+    if(controller != nullptr)
+      controller->OnTimerEnd();
+  }
 }
 
 
 void TimerController::Init() {
-  app_timer_create(&timerAppTimer, APP_TIMER_MODE_SINGLE_SHOT, timerEnd);
-  
+  app_timer_create(&timerAppTimer, APP_TIMER_MODE_SINGLE_SHOT, TimerEnd);
 }
 
 void TimerController::StartTimer(uint32_t duration) {
@@ -47,13 +50,6 @@ uint32_t TimerController::GetTimeRemaining() {
   return (static_cast<TickType_t>(deltaTicks) / static_cast<TickType_t>(configTICK_RATE_HZ)) * 1000;
 }
 
-void TimerController::timerEnd(void* p_context) {
-  
-  auto* controller = static_cast<Controllers::TimerController*> (p_context);
-  controller->timerRunning = false;
-  controller->systemTask.PushMessage(System::SystemTask::Messages::OnTimerDone);
-}
-
 void TimerController::StopTimer() {
   app_timer_stop(timerAppTimer);
   timerRunning = false;
@@ -61,4 +57,13 @@ void TimerController::StopTimer() {
 
 bool TimerController::IsRunning() {
   return timerRunning;
-}
+}
+void TimerController::OnTimerEnd() {
+  timerRunning = false;
+  if(systemTask != nullptr)
+    systemTask->PushMessage(System::Messages::OnTimerDone);
+}
+
+void TimerController::Register(Pinetime::System::SystemTask* systemTask) {
+  this->systemTask = systemTask;
+}

src/components/timer/TimerController.h

@@ -12,7 +12,7 @@ namespace Pinetime {
     
     class TimerController {
     public:
-      TimerController(Pinetime::System::SystemTask& systemTask);
+      TimerController() = default;
       
       void Init();
       
@@ -23,12 +23,13 @@ namespace Pinetime {
       uint32_t GetTimeRemaining();
       
       bool IsRunning();
-    
+
+      void OnTimerEnd();
+
+      void Register(System::SystemTask* systemTask);
+
     private:
-      System::SystemTask& systemTask;
-      
-      static void timerEnd(void* p_context);
-  
+      System::SystemTask* systemTask = nullptr;
       TickType_t endTicks;
       bool timerRunning = false;
     };