cleanup

src/Battery.cpp

@@ -1,9 +1,33 @@
 #include "Battery.h"
+#include <Wire.h>
 
-// Meyer's singleton — guaranteed single instance across all translation units.
-// Constructed with GPIO0 (X4 ADC default). For X3, main.cpp calls
-// battery().setI2CFuelGauge() to switch to BQ27220 I2C reads instead.
-BatteryMonitor& battery() {
-  static BatteryMonitor instance(BAT_GPIO0);
+void BatteryProvider::setI2CFuelGauge(uint8_t i2cAddr, uint8_t socRegister) {
+  _useI2C = true;
+  _i2cAddr = i2cAddr;
+  _socRegister = socRegister;
+}
+
+uint16_t BatteryProvider::readPercentage() const {
+  if (_useI2C) {
+    // Read SOC directly from I2C fuel gauge (16-bit LE register).
+    // Returns 0 on I2C error so the UI shows 0% rather than crashing.
+    Wire.beginTransmission(_i2cAddr);
+    Wire.write(_socRegister);
+    if (Wire.endTransmission(false) != 0) return 0;
+    Wire.requestFrom(_i2cAddr, (uint8_t)2);
+    if (Wire.available() < 2) return 0;
+    const uint8_t lo = Wire.read();
+    const uint8_t hi = Wire.read();
+    const uint16_t soc = (hi << 8) | lo;
+    return soc > 100 ? 100 : soc;
+  }
+  // ADC path: read raw voltage, apply divider, convert via LiPo polynomial
+  return _adcMonitor.readPercentage();
+}
+
+// Meyer's singleton — single shared instance across all translation units.
+// Defaults to X4 ADC mode. For X3, main.cpp calls setI2CFuelGauge() to switch.
+BatteryProvider& battery() {
+  static BatteryProvider instance;
   return instance;
 }

src/Battery.h

@@ -1,11 +1,29 @@
 #pragma once
 #include <BatteryMonitor.h>
+#include <cstdint>
 
 #define BAT_GPIO0 0  // Battery voltage (X4 ADC pin)
 
-// Shared battery monitor singleton. Returns a single BatteryMonitor instance
-// used by all callers (themes, activities, etc.).
-//
-// - X4: reads battery voltage via ADC on GPIO0 (default, no extra setup needed)
-// - X3: reads SOC from BQ27220 fuel gauge via I2C (call setI2CFuelGauge() after Wire.begin())
-BatteryMonitor& battery();
+// Unified battery reader supporting two backends:
+//   - X4: ADC voltage divider on GPIO0 (default, no setup needed)
+//   - X3: BQ27220 fuel gauge via I2C at 0x55, SOC register 0x2C
+//         (call setI2CFuelGauge() after Wire.begin())
+class BatteryProvider {
+ public:
+  // Read battery percentage (0-100). Delegates to ADC or I2C depending on mode.
+  uint16_t readPercentage() const;
+
+  // Switch to I2C fuel gauge mode. Wire.begin() must be called first.
+  // i2cAddr: fuel gauge I2C address (e.g. 0x55 for BQ27220)
+  // socRegister: register holding state-of-charge 0-100% (e.g. 0x2C)
+  void setI2CFuelGauge(uint8_t i2cAddr, uint8_t socRegister);
+
+ private:
+  BatteryMonitor _adcMonitor{BAT_GPIO0};
+  bool _useI2C = false;
+  uint8_t _i2cAddr = 0;
+  uint8_t _socRegister = 0;
+};
+
+// Shared singleton used by themes and activities.
+BatteryProvider& battery();

src/main.cpp

@@ -255,10 +255,6 @@ void onGoHome() {
 
 void setupDisplayAndFonts() {
   if (gpio.getDeviceType() == HalGPIO::DeviceType::X3) {
-    display.setDcPin(4);
-    display.setBusyActiveHigh(false);
-    display.setBwOnly(true);
-    display.setControllerType(EInkDisplay::ControllerType::SSD1677);
     display.setDisplayDimensions(792, 528);
     // X3 has a BQ27220 fuel gauge on I2C (addr 0x55) instead of an ADC voltage
     // divider. SOC (0-100%) is read directly from register 0x2C.