Persist time and steps across reboots

Author: mark9064

src/components/motion/MotionController.cpp

@@ -38,12 +38,15 @@ namespace {
 void MotionController::AdvanceDay() {
   --nbSteps; // Higher index = further in the past
   SetSteps(Days::Today, 0);
+  carrySteps = 0;
   if (service != nullptr) {
     service->OnNewStepCountValue(NbSteps(Days::Today));
   }
 }
 
 void MotionController::Update(int16_t x, int16_t y, int16_t z, uint32_t nbSteps) {
+  // Offset the sensor value by whatever we are carrying forward
+  nbSteps += carrySteps;
   uint32_t oldSteps = NbSteps(Days::Today);
   if (oldSteps != nbSteps && service != nullptr) {
     service->OnNewStepCountValue(nbSteps);
@@ -160,3 +163,9 @@ void MotionController::Init(Pinetime::Drivers::Bma421::DeviceTypes types) {
       break;
   }
 }
+
+void MotionController::Restore(uint32_t carrySteps, uint32_t carryTripSteps) {
+  this->carrySteps = carrySteps;
+  SetSteps(Days::Today, carrySteps);
+  currentTripSteps = carryTripSteps;
+}

src/components/motion/MotionController.h

@@ -66,6 +66,8 @@ namespace Pinetime {
 
       void Init(Pinetime::Drivers::Bma421::DeviceTypes types);
 
+      void Restore(uint32_t carrySteps, uint32_t carryTripSteps);
+
       void SetService(Pinetime::Controllers::MotionService* service) {
         this->service = service;
       }
@@ -76,6 +78,7 @@ namespace Pinetime {
 
     private:
       Utility::CircularBuffer<uint32_t, stepHistorySize> nbSteps = {0};
+      uint32_t carrySteps = 0;
       uint32_t currentTripSteps = 0;
 
       void SetSteps(Days day, uint32_t steps) {

src/components/persistence/RebootPersist.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <cstdint>
+
+namespace Pinetime {
+  namespace Components {
+    class RebootPersist {
+    public:
+      [[nodiscard]] bool IsValid() const volatile {
+        return canary == magic;
+      }
+
+      void SetValid() volatile {
+        canary = magic;
+      }
+
+      // layout of time point is implementation defined
+      // instead store milliseconds since epoch
+      uint64_t timeMillis;
+      uint32_t steps;
+      uint32_t tripSteps;
+
+    private:
+      // The canary determines whether memory has been kept or not after a reset,
+      // since the NRF52832 doesn't guarantee RAM retention
+      // See https://docs.nordicsemi.com/bundle/ps_nrf52832/page/power.html#d935e523
+      // If the magic value is still in the canary when booting,
+      // we assume that memory is intact from the previous boot
+
+      // Increment magic upon changing members of this class
+      // Otherwise garbage values will be loaded after DFU
+      static constexpr uint32_t magic = 0xDEAD0001;
+      uint32_t canary;
+    };
+  }
+}

src/main.cpp

@@ -36,6 +36,7 @@
 #include "components/datetime/DateTimeController.h"
 #include "components/heartrate/HeartRateController.h"
 #include "components/stopwatch/StopWatchController.h"
+#include "components/persistence/RebootPersist.h"
 #include "components/fs/FS.h"
 #include "drivers/Spi.h"
 #include "drivers/SpiMaster.h"
@@ -161,14 +162,10 @@ void vApplicationStackOverflowHook(TaskHandle_t /*xTask*/, char* /*pcTaskName*/)
   stackOverflowCount++;
 }
 }
-/* Variable Declarations for variables in noinit SRAM
-   Increment NoInit_MagicValue upon adding variables to this area
-*/
+// Variable Declarations for variables in noinit SRAM
 extern uint32_t __start_noinit_data;
 extern uint32_t __stop_noinit_data;
-static constexpr uint32_t NoInit_MagicValue = 0xDEAD0000;
-uint32_t NoInit_MagicWord __attribute__((section(".noinit")));
-std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> NoInit_BackUpTime __attribute__((section(".noinit")));
+volatile Pinetime::Components::RebootPersist NoInit_Persistence __attribute__((section(".noinit")));
 
 void nrfx_gpiote_evt_handler(nrfx_gpiote_pin_t pin, nrf_gpiote_polarity_t action) {
   if (pin == Pinetime::PinMap::Cst816sIrq) {
@@ -352,12 +349,14 @@ int main() {
   // retrieve version stored by bootloader
   Pinetime::BootloaderVersion::SetVersion(NRF_TIMER2->CC[0]);
 
-  if (NoInit_MagicWord == NoInit_MagicValue) {
-    dateTimeController.SetCurrentTime(NoInit_BackUpTime);
+  if (NoInit_Persistence.IsValid()) {
+    dateTimeController.SetCurrentTime(
+      std::chrono::time_point<std::chrono::system_clock>(std::chrono::milliseconds(NoInit_Persistence.timeMillis)));
+    motionController.Restore(NoInit_Persistence.steps, NoInit_Persistence.tripSteps);
   } else {
     // Clear Memory to known state
     memset(&__start_noinit_data, 0, (uintptr_t) &__stop_noinit_data - (uintptr_t) &__start_noinit_data);
-    NoInit_MagicWord = NoInit_MagicValue;
+    NoInit_Persistence.SetValid();
   }
 
   systemTask.Start();

src/systemtask/SystemTask.cpp

@@ -391,7 +391,11 @@ void SystemTask::Work() {
         }
       }
       monitor.Process();
-      NoInit_BackUpTime = dateTimeController.CurrentDateTime();
+
+      NoInit_Persistence.steps = motionController.NbSteps();
+      NoInit_Persistence.tripSteps = motionController.GetTripSteps();
+      NoInit_Persistence.timeMillis =
+        std::chrono::duration_cast<std::chrono::milliseconds>(dateTimeController.CurrentDateTime().time_since_epoch()).count();
       if (nrf_gpio_pin_read(PinMap::Button) == 0) {
         watchdog.Reload();
       }

src/systemtask/SystemTask.h

@@ -18,6 +18,7 @@
 #include "components/stopwatch/StopWatchController.h"
 #include "components/alarm/AlarmController.h"
 #include "components/fs/FS.h"
+#include "components/persistence/RebootPersist.h"
 #include "touchhandler/TouchHandler.h"
 #include "buttonhandler/ButtonHandler.h"
 #include "buttonhandler/ButtonActions.h"
@@ -32,7 +33,7 @@
 #include "drivers/Watchdog.h"
 #include "systemtask/Messages.h"
 
-extern std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> NoInit_BackUpTime;
+extern volatile Pinetime::Components::RebootPersist NoInit_Persistence;
 
 namespace Pinetime {
   namespace Drivers {