#define ADC_PIN 10  // GPIO10 on WEMOS S2 Mini

const float R1 = 100000.0; // 100k ohms
const float R2 = 47000.0;  // 47k ohms
const float ADC_MAX = 4095.0; // 12-bit ADC resolution
const float V_REF = 3.3;    // Reference voltage for ESP32-S2 ADC

float readBatteryVoltage() {
  int rawADC = analogRead(ADC_PIN);
  float voltage = (rawADC / ADC_MAX) * V_REF;
  return voltage * (R1 + R2) / R2; // Scale to actual battery voltage
}

int batteryPercentage(float voltage) {
  if (voltage >= 4.2) return 100;
  if (voltage <= 3.0) return 0;
  return (voltage - 3.0) * 100 / (4.2 - 3.0); // Linear mapping
}