Combine the &mo and &ht

[kaievns]

ohi folks, can I ask for an advise, please?

here is the problem. I'm using a custom keyboard layout, but it's a tricky one, because it switches to QWERTY when one of the mods are pressed. basically the point is that all the normal crtl+c, ctrl+v, ctrl+s combinations still work the way they work in QWERTY, but otherwise it's a different layout altogether.

now, I'm trying to replicate this behaviour in ZMK and apply that to home row mods. I two layers defined the custom layout and qwerty, and now I want something like mod-tap that drops into another layer when mod is pressed.

I found that I can combine a mod and a layer switch with a macro like so, I have wrapped it into a macro generator. Where I'm struggling is combining that with the hold tap behaviour, or more simply how to pass a macro into a hold-tap as an argument.

Here is what I'm trying so far, but it doesn't really compile

#define COLMAK 0
#define QWERTY 1
....

#define QWERTY_MOD_MACRO(name, mod)            \
name: name##_macro {                           \
	label = #name;                             \
	compatible = "zmk,behavior-macro";         \
	#binding-cells = <0>;                      \
	wait-ms = <0>;                             \
    bindings                                   \
        = <&macro_press &mo QWERTY &kp mod>    \
        , <&macro_pause_for_release>           \
        , <&macro_release &mo QWERTY &kp mod>; \
};

/ {
    macros {
        QWERTY_MOD_MACRO(qalt, LALT)
        QWERTY_MOD_MACRO(qgui, LGUI)
        QWERTY_MOD_MACRO(qctl, LCTRL)
    };
};

#define HOME_ROW_MOD_TAP(name, macro)      \
name: name##_mod_tap {                     \
    label = #name;                         \
    compatible = "zmk,behavior-hold-tap";  \
    #binding-cells = <2>;                  \
    flavor = "balanced";                   \
    tapping-term-ms = <200>;               \
    quick-tap-ms = <150>;                  \
    global-quick-tap;                      \
    bindings = <macro>, <&kp>;             \
};

/ {
    behaviors {
        HOME_ROW_MOD_TAP(ht_alt, &qalt)
        HOME_ROW_MOD_TAP(ht_gui, &qgui)
        HOME_ROW_MOD_TAP(ht_ctl, &qctl)
        qht: quick_hold_tap {
            label = "quick_hold_tap";
            compatible = "zmk,behavior-hold-tap";
            #binding-cells = <2>;
            flavor = "balanced";
            tapping-term-ms = <170>;
            quick-tap-ms = <130>;
            global-quick-tap;
            bindings = <&kp>, <&kp>;
        };
    };
};

#define HRML(k1,k2,k3,k4) &ht_gui k1  &ht_alt k2  &qht LSHFT k3  &ht_ctl k4
#define HRMR(k1,k2,k3,k4) &ht_ctl k1  &qht RSHFT k2  &ht_alt k3  &ht_gui k4

can you school me in the zmk ways a bit and let me know what am I doing wrong here?

Thanks!

[caksoylar]

You always need to pass two paramaters to a hold-tap behavior, even if one of the sub-behaviors do not expect one. In your case the hold binding (macro) doesn't expect one, so you can pass a dummy parameter like 0 that it will ignore:

#define HRML(k1,k2,k3,k4) &ht_gui 0 k1  &ht_alt 0 k2  &qht LSHFT 0 k3  &ht_ctl 0 k4

That being said, a mod-morph can make your life easier where you simply morph the custom layout key to C, V, S etc. when ctrl is held down.

[kaievns]

thanks, Cem, passing a dummy 0 worked like a charm!

btw, I'm still feeling about how the bindings and the #binding-cells thing work. I see there is some sort of a repeating pattern going on between the behaviours, but I'm still pretty vague on how it actually works.

Is there any piece of documentation around specifically for those properties?

[caksoylar]

btw, I'm still feeling about how the bindings and the #binding-cells thing work. I see there is some sort of a repeating pattern going on between the behaviours, but I'm still pretty vague on how it actually works.

Is there any piece of documentation around specifically for those properties?

I am not a devicetree expert myself, but keymap bindings property is a phandle array and there are some Zephyr docs explaining #X-cells and how it related to X properties: https://docs.zephyrproject.org/latest/build/dts/phandles.html#dt-phandle-arrays

In the context of ZMK, different behavior types (as specified by compatible property) have fixed #binding-cells values that cannot be changed when you create instances of them; however they still need to be specified in the node definition to those fixed values, like described in the behavior config sections.

How the behaviors handle the passed parameters I think is dependent on its implementation. Some behaviors take zero parameters like macros and mod-morphs, which are not parametrizable (so you need to create a new instance for each macro). One binding behaviors like &kp and &mo are trivially parametrized. The only behavior that has two binding cells is the hold-tap, which requires nuance on how it handles them.

[kaievns]

ah, that makes perfect sense, I didn't know that it's the zephyr's thing. I'll poke at that. thanks for the info!

[kaievns]

btw, @caksoylar, did you solve that pesky alt-tab problem somehow by any chance?

[caksoylar]

If you mean #997, then I use a custom branch with #1366 merged in and it is working well for my purposes.