nicla-system: Add sketch that shows how to charge the battery.

Author: sebromero

libraries/Nicla_System/examples/NiclaSenseME_BatteryChargingSimple/NiclaSenseME_BatteryChargingSimple.ino

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+/*
+ * This example shows how to use the Nicla Sense ME library to charge a battery.
+ * 
+ * The LED colors will change depending on the battery's operating status:
+ * - Blue: Ready
+ * - Yellow: Charging
+ * - Green: Charging complete
+ * - Red: Error
+ * 
+ * Instructions:
+ * 1. Connect a battery to the board.
+ * 2. Configure the charge current in the setup() function.
+ * 3. Upload this sketch to your Nicla Sense ME board.
+ * 
+ * Initial author: Sebastian Romero @sebromero
+ */
+
+#include "Nicla_System.h"
+
+constexpr auto printInterval { 10000ul };
+float voltage = -1.0f;
+
+void setup(){
+  Serial.begin(115200);
+  for (const auto timeout = millis() + 2500; millis() < timeout && !Serial; delay(250));
+  nicla::begin(); // Initialise library
+  nicla::leds.begin(); // Start I2C connection to LED driver
+  nicla::setBatteryNTCEnabled(true); // Set to false if your battery doesn't have a NTC.
+  
+  /* 
+  A safe default charging current value that works for most common LiPo batteries is 0.5C, 
+  which means charging at a rate equal to half of the battery's capacity.
+  For example, a 200mAh battery could be charged at 100mA (0.1A). 
+  */
+  nicla::enableCharging(100);
+  nicla::leds.setColor(blue);
+}
+
+void loop(){
+
+  static auto updateTimestamp = millis();
+
+  if (millis() - updateTimestamp >= printInterval) {
+    updateTimestamp = millis();
+
+    float currentVoltage = nicla::getCurrentBatteryVoltage();
+    if(currentVoltage != voltage){
+      voltage = currentVoltage;    
+      Serial.print("\nVoltage: ");
+      Serial.println(voltage);      
+    } else {
+      Serial.print(".");
+    }
+
+    auto operatingStatus = nicla::getOperatingStatus();
+
+    switch(operatingStatus) {
+      case OperatingStatus::Charging:
+      nicla::leds.setColor(255,100,0); // Yellow
+        break;
+      case OperatingStatus::ChargingComplete:
+        nicla::leds.setColor(green);
+        
+        // This will stop further charging until enableCharging() is called again.
+        nicla::disableCharging();
+        break;
+      case OperatingStatus::Error:
+        nicla::leds.setColor(red);
+        break;
+      case OperatingStatus::Ready:
+        nicla::leds.setColor(blue);
+        break;
+      default:
+        nicla::leds.setColor(off);
+        break;
+    }
+
+  }
+}