qmk_firmware/docs/drivers/battery.md
Joel Challis 6ee806f376
Implement battery level interface (#24666)
Co-authored-by: Nick Brassel <nick@tzarc.org>
2025-02-28 16:46:14 +11:00

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# Battery Driver
This driver provides support for sampling battery level.
## Usage
To use this driver, add the following to your `rules.mk`:
```make
BATTERY_DRIVER_REQUIRED = yes
```
## Basic Configuration {#basic-configuration}
Add the following to your `config.h`:
|Define |Default |Description |
|--------------------------|--------|--------------------------------------------------|
|`BATTERY_SAMPLE_INTERVAL` |`30000` |The time between battery samples in milliseconds. |
## Driver Configuration {#driver-configuration}
Driver selection can be configured in `rules.mk` as `BATTERY_DRIVER`. Valid values are `adc` (default), `vendor`, or `custom`. See below for information on individual drivers.
### ADC Driver {#adc-driver}
This is the default battery driver. The default configuration assumes the battery is connected to a ADC capable pin through a voltage divider.
```make
BATTERY_DRIVER = adc
```
The following `#define`s apply only to the `adc` driver:
|Define |Default |Description |
|-----------------------------|--------------|--------------------------------------------------------------|
|`BATTERY_PIN` |*Not defined* |The GPIO pin connected to the voltage divider. |
|`BATTERY_REF_VOLTAGE_MV` |`3300` |The ADC reverence voltage, in millivolts. |
|`BATTERY_VOLTAGE_DIVIDER_R1` |`100000` |The voltage divider resistance, in kOhm. Set to 0 to disable. |
|`BATTERY_VOLTAGE_DIVIDER_R1` |`100000` |The voltage divider resistance, in kOhm. Set to 0 to disable. |
|`BATTERY_ADC_RESOLUTION` |`10` |The ADC resolution configured for the ADC Driver. |
## Functions
### `uint8_t battery_get_percent(void)` {#api-battery-get-percent}
Sample battery level.
#### Return Value {#api-battery-get-percent-return}
The battery percentage, in the range 0-100.