Struct Adcbattery 

pub struct Adcbattery<'d> { /* private fields */ }

Battery voltage monitor using the ESP32-S3 ADC1 peripheral.

Created automatically by crate::Lilka::init and available as crate::Lilka::adc_battery.

The hardware path is:

Li-Po cell → 100 kΩ → GPIO3 (ADC1 CH2) → ESP32-S3 ADC1
                 └── 33 kΩ ──┘

The voltage divider ratio is 33 / (100 + 33) ≈ 0.248, so the ADC sees roughly 0.25× the actual battery voltage.

Example — polling battery level

use lilkaoxide::prelude::*;

loop {
    let mv = lilka.adc_battery.read_voltage_mv();
    if mv < 3_300 {
        defmt::warn!("Low battery: {} mV", mv);
    }
    // ... game logic
}

Implementations

impl<'d> Adcbattery<'d>

pub fn read(&mut self) -> u16

Reads the raw ADC sample from the battery pin.

Returns a 12-bit value in the range 0 – 4095 where:

• 0 → 0 V at the ADC input (battery deeply discharged / disconnected).
• 4095 → full-scale voltage for the configured attenuation (~3.1 V at 11 dB).

Prefer Adcbattery::read_voltage_mv for human-readable values.

Example

let raw: u16 = adc.read();
defmt::info!("Raw ADC: {}", raw);

pub fn read_voltage_mv(&mut self) -> u16

Reads the battery voltage in millivolts (mV).

Applies the voltage-divider formula to convert the raw ADC reading into the actual battery terminal voltage:

V_bat = (raw / 4095) × 3.1 V / (33 / (100 + 33))
      = (raw / 4095) × 11.73 V          [in volts]

Then multiplied by 1 000 to yield millivolts.

Accuracy notes

• The formula assumes Attenuation::_11dB (full-scale ≈ 3.1 V) and the fixed 100 kΩ / 33 kΩ divider on the Lilka PCB.
• Typical Li-Po range: 3 000 mV (empty) – 4 200 mV (full charge).
• ADC non-linearity may introduce ±50–100 mV error near the rails.

Example

let mv = adc.read_voltage_mv();
// Rough battery percentage (linear approximation)
let pct = ((mv.saturating_sub(3_000)) as u32 * 100 / 1_200) as u8;
defmt::info!("Battery: {} mV (~{}%)", mv, pct);