Any key
The Basic tab has a special “Any” key. This is an escape hatch, useful to enter arbitrary keycodes that are known to be supported in your build on the firmware but not otherwise accessible in the GUI. Assigning “Any” to a key opens a dialog box where you can entry an arbitrary keycode. Alternatively, double click a keymap key to open this dialog.
Textual entry
One way to enter a keycode is by its name or syntax as would be used when editing a QMK keymap.c in C, provided this name is known to the configurator. See the full list of QMK keycodes for known keycode names. Macro syntax like LSFT(kc) and MT(mod, kc) is supported as well. In this way, it is possible to enter certain keys like LM layer mod keys and modifier combinations that are not otherwise exposed.
Examples:
| Syntax | Meaning |
|---|---|
KC_ENT | Enter key |
C(KC_V) | Left Ctrl + V |
C(S(KC_V)) | Left Ctrl + Left Shift + V |
RSA(KC_V) | Right Shift + Right Alt + V |
LM(2, MOD_LSFT) | Layer 2 + Left Shift layer mod switch. |
OSM(MOD_LSFT | MOD_LGUI) | One-shot Left Shift + Left GUI |
MT(MOD_RSFT | MOD_RALT, KC_A) | Right Shift + Right Alt on hold, A on tap |
Refer to the QMK documentation for full explanation of keycode syntax.
Numeric entry
Another way to enter a key is numerically by its 16-bit keycode. Even when the key isn’t known to the configurator by name, it is yet possible to enter the key in this way. It’s a tedious process, but it does work to assign keys that would be otherwise unavailable. Of course, this only works provided you determine the correct numeric value for the keycode and your build of the firmware supports that keycode. Otherwise, the key will likely do nothing.
How to determine numeric keycodes?
One way to deduce the numeric keycode values is by referring to the firmware source files that define them. The keycodes are defined in quantum/keycodes.h, whereas preprocessor macros like LSFT(kc) are defined in quantum/quantum_keycodes.h.
Example: Suppose we have made a custom build of Vial in which Swap Hands, which Vial does not natively support, was enabled through “SWAP_HANDS_ENABLE = yes” in vial/rules.mk when building the firmware. Swap Hands defines several feature-specific keys, such as SH_MON, SH_OS, and SH_T(kc), which the configurator does not know.
Important
The numeric values of the keycodes may differ between different versions of QMK. Verify keycode values for your version of the firmware.
We can find SH_MON and SH_OS (aka QK_SWAP_HANDS_MOMENTARY_ON and QK_SWAP_HANDS_ONE_SHOT) in quantum/keycodes.h:
QK_SWAP_HANDS_MOMENTARY_ON = 0x56F2,
QK_SWAP_HANDS_MOMENTARY_OFF = 0x56F3,
QK_SWAP_HANDS_OFF = 0x56F4,
QK_SWAP_HANDS_ON = 0x56F5,
QK_SWAP_HANDS_ONE_SHOT = 0x56F6,
// (more codes...)
This shows the keycodes (expressed in hexadecimal) are SH_MON = 0x56F2 and SH_OS = 0x56F6. We can therefore assign SH_MON to a key in the configurator by first assigning Any, then entering 0x56F2. Since the configurator does not recognize the keycode, it displays as the raw numeric value 0x56F2 in the GUI. The key does nevertheless function as SH_MON on the keyboard itself.
Determining the keycode for SH_T(kc) is more complicated. Being a preprocessor macro, its definition is in quantum/quantum_keycodes.h:
#define SH_T(kc) (QK_SWAP_HANDS | ((kc)&0xFF))
in which QK_SWAP_HANDS is 0x5600 (based on referring back to quantum/keycodes.h). For the key’s “kc” placeholder, we can numerically substitute the keycode for any Basic key. For instance with KC_A = 0x0004, the full keycode for SH_T(KC_A) is 0x5604.