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Mod-Morph Behavior

Summary

The Mod-Morph behavior sends a different keypress, depending on whether a specified modifier is being held during the keypress.

  • If you tap the key by itself, the first keycode is sent.
  • If you tap the key while holding the specified modifier, the second keycode is sent.

Mod-Morph

The Mod-Morph behavior acts as one of two keycodes, depending on if the required modifier is being held during the keypress.

Configuration

An example of how to implement the mod-morph "Grave Escape":

/ {
behaviors {
gresc: grave_escape {
compatible = "zmk,behavior-mod-morph";
#binding-cells = <0>;
bindings = <&kp ESC>, <&kp GRAVE>;
mods = <(MOD_LGUI|MOD_LSFT|MOD_RGUI|MOD_RSFT)>;
};
};
};

Note that this specific mod-morph exists in ZMK by default using code &gresc.

Behavior Binding

  • Reference: &gresc
  • Parameter: None

Example:

&gresc

Mods

This is how you determine what modifiers will activate the morphed version of the keycode.

Available Modifiers:

  • MOD_LSFT
  • MOD_RSFT
  • MOD_LCTL
  • MOD_RCTL
  • MOD_LALT
  • MOD_RALT
  • MOD_LGUI
  • MOD_RGUI

Example:

mods = <(MOD_LGUI|MOD_LSFT|MOD_RGUI|MOD_RSFT)>;

Advanced configuration

keep-mods

When a modifier specified in mods is being held, it won't be sent along with the morphed keycode unless it is also specified in keep-mods. By default keep-mods equals 0, which means no modifier specified in mods will be sent along with the morphed keycode.

For example, the following configuration morphs LEFT_SHIFT + BACKSPACE into DELETE, and morphs RIGHT_SHIFT + BACKSPACE into RIGHT_SHIFT + DELETE.

/ {
behaviors {
bspc_del: backspace_delete {
compatible = "zmk,behavior-mod-morph";
#binding-cells = <0>;
bindings = <&kp BACKSPACE>, <&kp DELETE>;
mods = <(MOD_LSFT|MOD_RSFT)>;
keep-mods = <(MOD_RSFT)>;
};
};
};
Karabiner-Elements (macOS) interfering with mod-morphs

If the first modified key press sends the modifier along with the morphed keycode and Karabiner-Elements is running, disable the "Modify Events" toggle from Karabiner's "Devices" settings page for the keyboard running ZMK.