kmk_firmware/docs/en/led.md

LED (Mono color backlight)

Want your keyboard to shine? Add some lights!

Enabling the extension

The only required values that you need to give the LED extension would be the led_pin. It can either be a single board pin, or a list of pins for multiple LED's.

from kmk.extensions.LED import LED
import board

led_ext = LED(led_pin=[board.GP0, board.GP1])
keyboard.extensions.append(led_ext)

[Keycodes]

Key	Aliases	Description
KC.LED_TOG()		Toggles LED's
KC.LED_INC()		Increase Brightness
KC.LED_DEC()		Decrease Brightness
KC.LED_SET()		Set Brightness
KC.LED_ANI		Increase animation speed
KC.LED_AND		Decrease animation speed
KC.LED_MODE_PLAIN	LED_M_P	Static LED's
KC.LED_MODE_BREATHE	LED_M_B	Breathing animation

Keycodes with arguments can affect all, or a selection of LED's.

# toggle all LEDs
LED_TOG_ALL = KC.LED_TOG()

# increase brightness of first LED
LED_INC_0   = KC.LED_INC(0)

# decrease brightness of second and third LED
LED_DEC_1_2 = KC.LED_DEC(1,2)

Configuration

All of these values can be set by default for when the keyboard boots.

from kmk.extensions.led import AnimationModes
led_ext = LED(
    led_pin=led_pin,
    brightness=50,
    brightness_step=5,
    brightness_limit=100,
    breathe_center=1.5,
    animation_mode=AnimationModes.STATIC,
    animation_speed=1,
    user_animation=None,
    val=100,
    )