Improve battery percentage calculation and reporting

While charging, percentage should only go up, and while discharging,
percentage should only go down.

src/components/battery/BatteryController.cpp

@@ -69,18 +69,23 @@ void Battery::SaadcEventHandler(nrfx_saadc_evt_t const* p_event) {
     // p_event->data.done.p_buffer[0] = (adc_voltage / reference_voltage) * 1024
     voltage = p_event->data.done.p_buffer[0] * (8 * 600) / 1024;
 
+    uint8_t newPercent;
     if (isFull) {
-      percentRemaining = 100;
+      newPercent = 100;
     } else if (voltage < battery_min) {
-      percentRemaining = 0;
+      newPercent = 0;
     } else {
-      percentRemaining = std::min((voltage - battery_min) * 100 / (battery_max - battery_min), isCharging ? 99 : 100);
+      newPercent = std::min((voltage - battery_min) * 100 / (battery_max - battery_min), isCharging ? 99 : 100);
+    }
+
+    if ((isPowerPresent && newPercent > percentRemaining) || (!isPowerPresent && newPercent < percentRemaining) || firstMeasurement) {
+      firstMeasurement = false;
+      percentRemaining = newPercent;
+      systemTask->PushMessage(System::Messages::BatteryPercentageUpdated);
     }
 
     nrfx_saadc_uninit();
     isReading = false;
-
-    systemTask->PushMessage(System::Messages::BatteryMeasurementDone);
   }
 }
 

src/components/battery/BatteryController.h

@@ -42,6 +42,7 @@ namespace Pinetime {
       bool isFull = false;
       bool isCharging = false;
       bool isPowerPresent = false;
+      bool firstMeasurement = true;
 
       void SaadcInit();
 

src/systemtask/Messages.h

@@ -24,7 +24,7 @@ namespace Pinetime {
         SetOffAlarm,
         StopRinging,
         MeasureBatteryTimerExpired,
-        BatteryMeasurementDone,
+        BatteryPercentageUpdated,
       };
     }
 }

src/systemtask/SystemTask.cpp

@@ -349,14 +349,10 @@ void SystemTask::Work() {
           motorController.RunForDuration(15);
           break;
         case Messages::MeasureBatteryTimerExpired:
-          sendBatteryNotification = true;
           batteryController.Update();
           break;
-        case Messages::BatteryMeasurementDone:
-          if (sendBatteryNotification) {
-            sendBatteryNotification = false;
-            nimbleController.NotifyBatteryLevel(batteryController.PercentRemaining());
-          }
+        case Messages::BatteryPercentageUpdated:
+          nimbleController.NotifyBatteryLevel(batteryController.PercentRemaining());
           break;
 
         default:

src/systemtask/SystemTask.h

@@ -133,14 +133,12 @@ namespace Pinetime {
       TimerHandle_t dimTimer;
       TimerHandle_t idleTimer;
       TimerHandle_t measureBatteryTimer;
-      bool sendBatteryNotification = false;
       bool doNotGoToSleep = false;
 
       void GoToRunning();
       void UpdateMotion();
       bool stepCounterMustBeReset = false;
       static constexpr TickType_t batteryMeasurementPeriod = pdMS_TO_TICKS(10 * 60 * 1000);
-      TickType_t lastBatteryNotificationTime = 0;
 
 #if configUSE_TRACE_FACILITY == 1
       SystemMonitor<FreeRtosMonitor> monitor;