Air Quality Battery Level Data Retrieval

#include <M5Unified.h>
 
static constexpr int BAT_PIN        = 14;     
static constexpr float VREF         = 3.3f;   // ADC reference voltage
static constexpr int ADC_RESOLUTION = 4095;   // 12-bit resolution (0–4095)
static constexpr float DIVIDER      = 2.0f;   // voltage divider ratio
 
void setup() {
  // initialize M5Unified
  M5.begin();
  analogSetPinAttenuation(BAT_PIN, ADC_11db);
 
  M5.Display.clear(TFT_BLACK);
  M5.Display.setTextColor(TFT_WHITE, TFT_BLACK);
  M5.Display.setTextSize(3);
}
 
void loop() {
  // read ADC once
  int raw = analogRead(BAT_PIN);
  // calculate voltage: raw/4095 * 3.3 * 2
  float vb = (raw / float(ADC_RESOLUTION)) * VREF * DIVIDER;
 
  // display the result on the screen
  M5.Display.fillScreen(TFT_BLACK);
  M5.Display.setCursor(10, 20);
  M5.Display.printf("Battery:\n%.2f V", vb);
 
  // update every second
  delay(5000);
  M5.update();
}