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Hold-Tap Behavior

Summary​

Hold-tap is the basis for other behaviors such as layer-tap and mod-tap.

Simply put, the hold-tap key will output the 'hold' behavior if it's held for a while, and output the 'tap' behavior when it's tapped quickly.

Hold-Tap​

The graph below shows how the hold-tap decides between a 'tap' and a 'hold'.

Simple behavior

By default, the hold-tap is configured to also select the 'hold' functionality if another key is tapped while it's active:

Hold preferred behavior

We call this the 'hold-preferred' flavor of hold-taps. While this flavor may work very well for a ctrl/escape key, it's not very well suited for home-row mods or layer-taps. That's why there are two more flavors to choose from: 'tap-preferred' and 'balanced'.

Flavors​

  • The 'hold-preferred' flavor triggers the hold behavior when the tapping-term-ms has expired or another key is pressed.
  • The 'balanced' flavor will trigger the hold behavior when the tapping-term-ms has expired or another key is pressed and released.
  • The 'tap-preferred' flavor triggers the hold behavior when the tapping-term-ms has expired. Pressing another key within tapping-term-ms does not affect the decision.
  • The 'tap-unless-interrupted' flavor triggers a hold behavior only when another key is pressed before tapping-term-ms has expired. It triggers the tap behavior in all other situations.

When the hold-tap key is released and the hold behavior has not been triggered, the tap behavior will trigger.

Hold-tap comparison

Basic usage​

For basic usage, please see the mod-tap and layer-tap pages.

Advanced Configuration​

tapping-term-ms​

Defines how long a key must be pressed to trigger Hold behavior.

quick-tap-ms​

If you press a tapped hold-tap again within quick-tap-ms milliseconds, it will always trigger the tap behavior. This is useful for things like a backspace, where a quick tap+hold holds backspace pressed. Set this to a negative value to disable. The default is -1 (disabled).

In QMK, unlike ZMK, this functionality is enabled by default, and you turn it off using TAPPING_FORCE_HOLD.

global-quick-tap​

If global-quick-tap is enabled, then quick-tap-ms will apply not only when the given hold-tap is tapped, but for any key tapped before it. This effectively disables the hold-tap when typing quickly, which can be quite useful for homerow mods. It can also have the effect of removing the input delay when typing quickly.

For example, the following hold-tap configuration enables global-quick-tap with a 125 millisecond quick-tap-ms term.

gqt: global-quick-tap {
    compatible = "zmk,behavior-hold-tap";
    label = "GLOBAL_QUICK_TAP";
    #binding-cells = <2>;
    flavor = "tap-preferred";
    tapping-term-ms = <200>;
    quick-tap-ms = <125>;
    global-quick-tap;
    bindings = <&kp>, <&kp>;
};

If you press &kp A and then &gqt LEFT_SHIFT B within 125 ms, then ab will be output. Importantly, b will be output immediately since it was within the quick-tap-ms. This quick-tap behavior will work for any key press, whether it is within a behavior like hold-tap, or a simple &kp. This means the &gqt LEFT_SHIFT B binding will only have its underlying hold-tap behavior if it is pressed 125 ms after a key press.

Note that the greater the value of quick-tap-ms is, the harder it will be to invoke the hold behavior, making this feature less applicable for use-cases like capitalizing letters while typing normally. However, if the hold behavior isn't used during fast typing, then it can be an effective way to mitigate misfires.

retro-tap​

If retro-tap is enabled, the tap behavior is triggered when releasing the hold-tap key if no other key was pressed in the meantime.

For example, if you press &mt LEFT_SHIFT A and then release it without pressing another key, it will output a.

&mt {
    retro-tap;
};

Positional hold-tap and hold-trigger-key-positions​

Including hold-trigger-key-positions in your hold-tap definition turns on the positional hold-tap feature. With positional hold-tap enabled, if you press any key NOT listed in hold-trigger-key-positions before tapping-term-ms expires, it will produce a tap.

In all other situations, positional hold-tap will not modify the behavior of your hold-tap. Positional hold-tap is useful when used with home-row modifiers: for example, if you have a home-row modifier key in the left hand, by including only key positions from the right hand in hold-trigger-key-positions, you will only get hold behaviors during cross-hand key combinations.

info

Note that hold-trigger-key-positions is an array of key position indexes. Key positions are numbered sequentially according to your keymap, starting with 0. So if the first key in your keymap is Q, this key is in position 0. The next key (probably W) will be in position 1, et cetera.

See the following example, which uses a hold-tap behavior definition, configured with the hold-preferred flavor, and with positional hold-tap enabled:

#include <dt-bindings/zmk/keys.h>
#include <behaviors.dtsi>

/ {
    behaviors {
        pht: positional_hold_tap {
            compatible = "zmk,behavior-hold-tap";
            label = "POSITIONAL_HOLD_TAP";
            #binding-cells = <2>;
            flavor = "hold-preferred";
            tapping-term-ms = <400>;
            quick-tap-ms = <200>;
            bindings = <&kp>, <&kp>;
            hold-trigger-key-positions = <1>;    // <---[[the W key]]
        };
    };
    keymap {
        compatible = "zmk,keymap";
        label ="Default keymap";
        default_layer {
            bindings = <
                //  position 0         position 1       position 2
                &pht LEFT_SHIFT Q        &kp W            &kp E
            >;
        };
    };
};
  • The sequence (pht_down, E_down, E_up, pht_up) produces qe. The normal hold behavior (LEFT_SHIFT) IS modified into a tap behavior (Q) by positional hold-tap because the first key pressed after the hold-tap key is the E key, which is in position 2, which is NOT included in hold-trigger-key-positions.
  • The sequence (pht_down, W_down, W_up, pht_up) produces W. The normal hold behavior (LEFT_SHIFT) is NOT modified into a tap behavior (Q) by positional hold-tap because the first key pressed after the hold-tap key is the W key, which is in position 1, which IS included in hold-trigger-key-positions.
  • If the LEFT_SHIFT / Q key is held by itself for longer than tapping-term-ms, a hold behavior is produced. This is because positional hold-tap only modifies the behavior of a hold-tap if another key is pressed before the tapping-term-ms period expires.

Example Use-Cases​

The following are suggested hold-tap configurations that work well with home row mods:

Option 1: cross-hand only modifiers, using tap-unless-interrupted and positional hold-tap (hold-trigger-key-positions)​
Homerow Mods: Cross-hand Example
#include <dt-bindings/zmk/keys.h>
#include <behaviors.dtsi>

/ {
    behaviors {
        lh_pht: left_hand_positional_hold_tap {
            compatible = "zmk,behavior-hold-tap";
            label = "LEFT_POSITIONAL_HOLD_TAP";
            #binding-cells = <2>;
            flavor = "tap-unless-interrupted";
            tapping-term-ms = <100>;                        // <---[[produces tap if held longer than tapping-term-ms]]
            quick-tap-ms = <200>;
            bindings = <&kp>, <&kp>;
            hold-trigger-key-positions = <5 6 7 8 9 10>;    // <---[[right-hand keys]]
        };
    };

    keymap {
        compatible = "zmk,keymap";
        default_layer {
            bindings = <
                // position 0     pos 1             pos 2             pos 3             pos 4    pos 5    pos 6    pos 7    pos 8    pos 9    pos 10
                &lh_pht LSFT A    &lh_pht LGUI S    &lh_pht LALT D    &lh_pht LCTL F    &kp G    &kp H    &kp I    &kp J    &kp K    &kp L    &kp SEMI
            >;
        };
    };
};
Option 2: tap-preferred​
Homerow Mods: Tap-Preferred Example
#include <behaviors.dtsi>
#include <dt-bindings/zmk/keys.h>

/ {
    behaviors {
        hm: homerow_mods {
            compatible = "zmk,behavior-hold-tap";
            label = "HOMEROW_MODS";
            #binding-cells = <2>;
            tapping-term-ms = <150>;
            quick-tap-ms = <0>;
            flavor = "tap-preferred";
            bindings = <&kp>, <&kp>;
        };
    };

    keymap {
        compatible = "zmk,keymap";
        default_layer {
            bindings = <
                &hm LCTRL A &hm LGUI S &hm LALT D &hm LSHIFT F
            >;
        };
    };
};
Option 3: balanced​
Homerow Mods: Balanced Example
#include <behaviors.dtsi>
#include <dt-bindings/zmk/keys.h>

/ {
    behaviors {
        bhm: balanced_homerow_mods {
            compatible = "zmk,behavior-hold-tap";
            label = "HOMEROW_MODS";
            #binding-cells = <2>;
            tapping-term-ms = <200>;    // <---[[moderate duration]]
            quick-tap-ms = <0>;
            flavor = "balanced";
            bindings = <&kp>, <&kp>;
        };
    };

    keymap {
        compatible = "zmk,keymap";
        default_layer {
            bindings = <
                &bhm LCTRL A &bhm LGUI S &bhm LALT D &bhm LSHIFT F
            >;
        };
    };
};

Comparison to QMK​

The hold-preferred flavor works similar to the HOLD_ON_OTHER_KEY_PRESS setting in QMK. The 'balanced' flavor is similar to the PERMISSIVE_HOLD setting, and the tap-preferred flavor is similar to IGNORE_MOD_TAP_INTERRUPT.