Implemented a circular buffer and added an average alg for batter remaining percentage.

2 files changed, 33 insertions, 3 deletions

diff --git a/src/components/battery/BatteryController.cpp b/src/components/battery/BatteryController.cpp
index 3e3d65b4..e0042f5c 100644
--- a/src/components/battery/BatteryController.cpp
+++ b/src/components/battery/BatteryController.cpp
@@ -34,10 +34,12 @@ void Battery::Update() {
 
   // see https://forum.pine64.org/showthread.php?tid=8147
   voltage = (value * 2.0f) / (1024/3.0f);
-  percentRemaining = ((voltage - 3.55f)*100.0f)*3.9f;
+  float percentRemaining = ((voltage - 3.55f)*100.0f)*3.9f;
   percentRemaining = std::max(percentRemaining, 0.0f);
   percentRemaining = std::min(percentRemaining, 100.0f);
 
+  percentRemainingBuffer.insert(percentRemaining);
+
 //  NRF_LOG_INFO("BATTERY " NRF_LOG_FLOAT_MARKER " %% - " NRF_LOG_FLOAT_MARKER " v", NRF_LOG_FLOAT(percentRemaining), NRF_LOG_FLOAT(voltage));
 //  NRF_LOG_INFO("POWER Charging : %d - Power : %d", isCharging, isPowerPresent);
 }
diff --git a/src/components/battery/BatteryController.h b/src/components/battery/BatteryController.h
index 7cc964e4..a94adaad 100644
--- a/src/components/battery/BatteryController.h
+++ b/src/components/battery/BatteryController.h
@@ -1,14 +1,41 @@
 #pragma once
 #include <cstdint>
 #include <drivers/include/nrfx_saadc.h>
+#include <array>
+#include <numeric>
 
 namespace Pinetime {
   namespace Controllers {
+  // A simple circular buffer that can be used to average 
+  // out sensor values
+  template <int N> 
+  class CircBuffer {
+  public:
+    CircBuffer() : arr{}, sz{}, cap{N}, loc{} {}
+    void insert(const float num) {
+      loc %= cap;
+      arr[loc++] = num;
+      if (sz != cap) {
+        sz++;
+      }
+    }
+
+    float GetAverage() const {
+      float sum = std::accumulate(arr.begin(), arr.end(), 0);
+      return (sum / sz);
+    }
+
+  private:
+    std::array<float, N> arr;
+    uint8_t sz;
+    uint8_t cap;
+    uint8_t loc;
+  };
     class Battery {
       public:
         void Init();
         void Update();
-        float PercentRemaining() const { return percentRemaining; }
+        float PercentRemaining() const { return percentRemainingBuffer.GetAverage(); }
         float Voltage() const { return voltage; }
         bool IsCharging() const { return isCharging; }
         bool IsPowerPresent() const { return isPowerPresent; }
@@ -17,8 +44,9 @@ namespace Pinetime {
         static constexpr uint32_t chargingPin = 12;
         static constexpr uint32_t powerPresentPin = 19;
         static constexpr nrf_saadc_input_t batteryVoltageAdcInput = NRF_SAADC_INPUT_AIN7;
+        static constexpr uint8_t percentRemainingSamples = 10;
         static void SaadcEventHandler(nrfx_saadc_evt_t const * p_event);
-        float percentRemaining = 0.0f;
+        CircBuffer<percentRemainingSamples> percentRemainingBuffer {};
         float voltage = 0.0f;
         bool isCharging = false;
         bool isPowerPresent = false;