Your keymap can include keycodes that are more advanced than normal, for example shifted keys. This page documents the functions that are available to you.
Assigning Custom Names
People often define custom names using
#define. For example:
This will allow you to use
ALT_TAB in your
KEYMAP(), keeping it more readable.
Limits of these aliases
Currently, the keycodes able to used with these functions are limited to the Basic Keycodes, meaning you can't use keycodes like
KC_TILD, or anything greater than 0xFF. For a full list of the keycodes able to be used see Basic Keycodes.
Switching and toggling layers
These functions allow you to activate layers in various ways.
MO(layer)- momentary switch to layer. As soon as you let go of the key, the layer is deactivated and you pop back out to the previous layer.
LT(layer, kc)- momentary switch to layer when held, and kc when tapped.
TG(layer)- toggles a layer on or off.
TO(layer)- Goes to a layer. This code is special, because it lets you go either up or down the stack -- just goes directly to the layer you want. So while other codes only let you go up the stack (from layer 0 to layer 3, for example),
TO(2)is going to get you to layer 2, no matter where you activate it from -- even if you're currently on layer 5. This gets activated on keydown (as soon as the key is pressed).
TT(layer)- Layer Tap-Toggle. If you hold the key down, the layer becomes active, and then deactivates when you let go. And if you tap it, the layer simply becomes active (toggles on). It needs 5 taps by default, but you can set it by defining
TAPPING_TOGGLE, for example,
#define TAPPING_TOGGLE 2for just two taps.
Working With Layers
Care must be taken when switching layers, it's possible to lock yourself into a layer with no way to deactivate that layer (without unplugging your keyboard.) We've created some guidelines to help users avoid the most common problems.
If you are just getting started with QMK you will want to keep everything simple. Follow these guidelines when setting up your layers:
- Setup layer 0 as your "base" layer. This is your normal typing layer, and could be whatever layout you want (qwerty, dvorak, colemak, etc.)
- Arrange your layers in a "tree" layout, with layer 0 as the root. Do not try to enter the same layer from more than one other layer.
- Never try to stack a higher numbered layer on top of a lower numbered layer. Doing so is tricky and error prone.
Sometimes you need more than one base layer. For example, if you want to switch between QWERTY and Dvorak, switch between layouts for different countries, or switch your layout for different videogames. Your base layers should always be the lowest numbered layers. When you have multiple base layers you should always treat them as mutually exclusive. When one base layer is on the others are off.
Once you have a good feel for how layers work and what you can do, you can get more creative. The rules listed in the beginner section will help you be successful by avoiding some of the tricker details but they can be constraining, especially for ultra-compact keyboard users. Understanding how layers work will allow you to use them in more advanced ways.
Layers stack on top of each other in numerical order. When determining what a keypress does, QMK scans the layers from the top down, stopping when it reaches the first active layer that is not set to
KC_TRNS. As a result if you activate a layer that is numerically lower than your current layer, and your current layer (or another layer that is active and higher than your target layer) has something other than
KC_TRNS, that is the key that will be sent, not the key on the layer you just activated. This is the cause of most people's "why doesn't my layer get switched" problem.
Sometimes, you might want to switch between layers in a macro or as part of a tap dance routine.
layer_on activates a layer, and
layer_off deactivates it. More layer-related functions can be found in action_layer.h.
These functions allow you to combine a mod with a keycode. When pressed the keydown for the mod will be sent first, and then kc will be sent. When released the keyup for kc will be sent and then the mod will be sent.
S(kc)- applies left Shift to kc (keycode)
RSFT(kc)- applies right Shift to kc
LCTL(kc)- applies left Control to kc
RCTL(kc)- applies right Control to kc
LALT(kc)- applies left Alt to kc
RALT(kc)- applies right Alt to kc
LGUI(kc)- applies left GUI (command/win) to kc
RGUI(kc)- applies right GUI (command/win) to kc
HYPR(kc)- applies Hyper (all modifiers) to kc
MEH(kc)- applies Meh (all modifiers except Win/Cmd) to kc
LCAG(kc)- applies CtrlAltGui to kc
You can also chain these, like this:
LALT(LCTL(KC_DEL)) -- this makes a key that sends Alt, Control, and Delete in a single keypress.
The following shortcuts automatically add
LSFT() to keycodes to get commonly used symbols.
MT(mod, kc) - is mod (modifier key - MOD_LCTL, MOD_LSFT) when held, and kc when tapped. In other words, you can have a key that sends Esc (or the letter O or whatever) when you tap it, but works as a Control key or a Shift key when you hold it down.
These are the values you can use for the
These can also be combined like
MOD_LCTL | MOD_LSFT e.g.
MT(MOD_LCTL | MOD_LSFT, KC_ESC) which would activate Control and Shift when held, and send Escape when tapped. Note however, that you cannot mix right and left side modifiers.
CTL_T(kc)- is LCTL when held and kc when tapped
SFT_T(kc)- is LSFT when held and kc when tapped
ALT_T(kc)- is LALT when held and kc when tapped
ALGR_T(kc)- is AltGr when held and kc when tapped
GUI_T(kc)- is LGUI when held and kc when tapped
ALL_T(kc)- is Hyper (all mods) when held and kc when tapped. To read more about what you can do with a Hyper key, see this blog post by Brett Terpstra
LCAG_T(kc)- is CtrlAltGui when held and kc when tapped
MEH_T(kc)- is like Hyper, but not as cool -- does not include the Cmd/Win key, so just sends Alt+Ctrl+Shift.
One Shot Keys
One shot keys are keys that remain active until the next key is pressed, and then are releasd. This allows you to type keyboard combinations without pressing more than one key at a time.
For example, if you define a key as
OSM(MOD_LSFT), you can type a capital A character by first pressing and releasing shift, and then pressing and releasing A. Your computer will see the shift key being held the moment shift is pressed, and it will see the shift key being released immediately after A is released.
One shot keys also work as normal modifiers. If you hold down a one shot key and type other keys, your one shot will be released immediately after you let go of the key.
You can control the behavior of one shot keys by defining these in
OSM(mod)- Momentarily hold down mod. You must use the
MOD_*keycodes as shown in Mod Tap, not the
OSL(layer)- momentary switch to layer.
Sometimes, you want to activate a one-shot layer as part of a macro or tap dance routine. To do this, you need to call
set_oneshot_layer(LAYER, ONESHOT_START) on key down, and
set_oneshot_layer(ONESHOT_PRESSED) on key up. If you want to cancel the oneshot, call
reset_oneshot_layer(). For more complicated actions, take a look at the oneshot implementation in
As of PR#1359, there is a new
This makes it easier for fast typists to use dual-function keys. Without this, if you let go of a held key inside the tapping term, it won't register.
Example: (Tapping Term = 200ms)
- SHFT_T(KC_A) Down
- KC_X Down
- KC_X Up
- SHFT_T(KC_A) Up
With defaults, if above is typed within tapping term, this will emit
ax. With permissive hold, if above is typed within tapping term, this will emit
X (so, Shift+X).