FacePlant/src/sensors/BatterySensor.h

#pragma once
#include <Arduino.h>

class BatterySensor {
public:
  void begin();
  void loop();

  // Battery status
  int percent() const { return _percent; }
  float voltage() const { return _voltage; }
  bool isLow() const { return _isLow; }
  bool isCharging() const { return _isCharging; }
  bool shouldBlink() const;

  // For display
  int iconFillWidth(int maxWidth) const;

private:
  static constexpr int PIN_BATTERY_ADC = 2;  // Voltage divider input
  static constexpr int PIN_LBO = 5;          // PowerBoost LBO pin
  static constexpr int PIN_CHG = 4;          // PowerBoost CHG pin (LOW when charging)

  static constexpr unsigned long CHECK_INTERVAL_MS = 2000;
  static constexpr int SAMPLES = 10;  // Number of ADC samples to average

  // LiPo voltage thresholds
  static constexpr float VOLTAGE_MIN = 3.0;   // 0%
  static constexpr float VOLTAGE_MAX = 4.2;   // 100%
  static constexpr float VOLTAGE_LOW = 3.2;   // Low battery threshold

  // Voltage divider: R1=100k, R2=100k (2:1 ratio)
  static constexpr float DIVIDER_RATIO = 2.0;

  int _percent = 100;
  float _voltage = 3.7;
  bool _isLow = false;
  bool _isCharging = false;
  unsigned long _lastCheckMs = 0;

  float readBatteryVoltage();
  int voltageToPercent(float voltage);
};