kmk_firmware/docs/oneshot.md

OneShot Keycodes

OneShot keys or sticky keys enable you to have keys that keep staying pressed for a certain time or until another key is pressed and released. If the timeout expires or other keys are pressed, and the sticky key wasn't released, it is handled as a regular key hold.

Enable OneShot Keys

from kmk.modules.oneshot import OneShot
oneshot = OneShot()
# optional: set a custom tap timeout in ms (default: 1000ms)
# oneshot.tap_time = 1500
keyboard.modules.append(modtap)

Keycodes

Keycode	Aliases	Description
KC.OS(KC.ANY)	KC.ONESHOT	make a sticky version of KC.ANY

KC.ONESHOT accepts any valid key code as argument, including modifiers and KMK internal keys like momentary layer shifts.

Custom OneShot Behavior

The full OneShot signature is as follows:

KC.OS(
    KC.TAP, # the sticky keycode
    tap_time=None # length of the tap timeout in milliseconds
    )

OneShot Modifier Combinations

The OneShot module by default cannot apply two OneShot modifiers to another key. To get around this you can use the Combos module. Below is a minimal example that allows for multiple OneShot modifiers to apply to the next key pressed. In this example you can tap either of the OneShot keys then tap the other and finally tap p and that will send ctrl+shift+p.

from kmk.modules.combos import Chord, Combos
from kmk.modules.oneshot import OneShot

oneshot = OneShot()
keyboard.modules.append(oneshot)

OS_LCTL = KC.OS(KC.LCTL, tap_time=None)
OS_LSFT = KC.OS(KC.LSFT, tap_time=None)

combos = Combos()
keyboard.modules.append(combos)

combos.combos = [
    Chord((OS_LCTL, OS_LSFT), OS_LCTL_LSFT, timeout=1000),
]

keyboard.keymap = [[OS_LSFT, OS_LCTL, KC.P]]

Below is the complete list of OneShot and Chords you need to allow any combination of modifiers (left modifiers only).

Long code chunk (click to load)

```python
OS_LCTL = KC.OS(KC.LCTL, tap_time=None)
OS_LSFT = KC.OS(KC.LSFT, tap_time=None)
OS_LGUI = KC.OS(KC.LGUI, tap_time=None)
OS_LALT = KC.OS(KC.LALT, tap_time=None)

OS_LCTL_LSFT = KC.OS(KC.LCTL(OS_LSFT), tap_time=None)
OS_LCTL_LALT = KC.OS(KC.LCTL(OS_LALT), tap_time=None)
OS_LCTL_LGUI = KC.OS(KC.LCTL(OS_LGUI), tap_time=None)
OS_LSFT_LALT = KC.OS(KC.LSFT(OS_LALT), tap_time=None)
OS_LSFT_LGUI = KC.OS(KC.LSFT(OS_LGUI), tap_time=None)
OS_LALT_LGUI = KC.OS(KC.LALT(OS_LGUI), tap_time=None)

OS_LCTL_LSFT_LGUI = KC.OS(KC.LCTL(KC.LSFT(OS_LGUI)), tap_time=None)
OS_LCTL_LSFT_LALT = KC.OS(KC.LCTL(KC.LSFT(OS_LALT)), tap_time=None)
OS_LCTL_LALT_LGUI = KC.OS(KC.LCTL(KC.LALT(OS_LGUI)), tap_time=None)
OS_LSFT_LALT_LGUI = KC.OS(KC.LSFT(KC.LALT(OS_LGUI)), tap_time=None)

OS_LCTL_LSFT_LALT_LGUI = KC.OS(KC.LCTL(KC.LSFT(KC.LALT(OS_LGUI))), tap_time=None)

combos.combos = [
    Chord((OS_LCTL, OS_LSFT), OS_LCTL_LSFT, timeout=1000),
    Chord((OS_LCTL, OS_LALT), OS_LCTL_LALT, timeout=1000),
    Chord((OS_LCTL, OS_LGUI), OS_LCTL_LGUI, timeout=1000),
    Chord((OS_LSFT, OS_LALT), OS_LSFT_LALT, timeout=1000),
    Chord((OS_LSFT, OS_LGUI), OS_LSFT_LGUI, timeout=1000),
    Chord((OS_LALT, OS_LGUI), OS_LALT_LGUI, timeout=1000),

    Chord((OS_LCTL, OS_LSFT, OS_LGUI), OS_LCTL_LSFT_LGUI, timeout=1000),
    Chord((OS_LCTL, OS_LSFT, OS_LALT), OS_LCTL_LSFT_LALT, timeout=1000),
    Chord((OS_LCTL, OS_LALT, OS_LGUI), OS_LCTL_LALT_LGUI, timeout=1000),
    Chord((OS_LSFT, OS_LALT, OS_LGUI), OS_LSFT_LALT_LGUI, timeout=1000),

    Chord((OS_LCTL, OS_LSFT, OS_LALT, OS_LGUI), OS_LCTL_LSFT_LALT_LGUI, timeout=1000),
]
```