This is my personal userspace for QMK Firmware. It is setup as a self-contained folder that avoids placing keymap.c source files deep inside QMK's sub-directories. All customisation required to build firmwares are configured within this space in the following manner:
- Store QMK Configurator exported layouts or wrapper based macro key map in JSON format.
- Create
rules.mk,config.hand shared source codes in this folder, with#ifdefpreprocessors for unique keyboard or feature specific functions. - Run
qmk flashon JSON layout files to build a custom firmware for each board. - See my standalone userspace guide for more details.
Clone the QMK firmware, followed by this repository into users/filterpaper:
git clone https://github.com/qmk/qmk_firmware qmk_firmware
git clone https://github.com/filterpaper/qmk_userspace qmk_firmware/users/filterpaper
- BM40 HS RGB — Per-key RGB matrix indicators.
- Planck rev6 — RGB underglow layer and modifier indicators.
- Corne Keyboard (CRKBD) — Typing animation and graphical indicators on OLEDs.
- The Mark: 65 — RGB underglow layer and modifier indicators.
| File | Description |
|---|---|
| rules.mk | QMK compile rules and hardware feature selection |
| config.h | QMK configuration variables and options, see configuring QMK |
| filterpaper.h | User specific variables and options |
| filterpaper.c | Mainj source with macro functions, see custom quantum functions |
| rgb-matrix.c | RGB matrix effect and custom codes, see RGB matrix lighting |
| mod-status.c | Graphical layer and modifier status indicators (adds ~4018 bytes) |
| luna-status.c | Luna and Felix the dog WPM animation and modifier indicators for primary OLED (adds ~6202 bytes) |
| bongocat.c | Bongocat animation using differential pixels |
| oledfont.c | Corne logo, コルネ katakana name, fonts and icon images |
| layout.h | Key map macro wrapper for shared ortholinear and Corne layouts |
| json/ | Folder of supported keyboard layouts |
| animation_frames/ | Folder of Bongocat animation images |
| archive/ | Archived files of original codes and layouts |
if (get_highest_layer(layer_state); > COLEMAK) {
uint8_t layer = get_highest_layer(layer_state);
for (uint8_t row = 0; row < MATRIX_ROWS; ++row) {
for (uint8_t col = 0; col < MATRIX_COLS; ++col) {
if (g_led_config.matrix_co[row][col] != NO_LED &&
keymap_key_to_keycode(layer, (keypos_t){col, row}) != KC_TRNS) {
rgb_matrix_set_color(g_led_config.matrix_co[row][col], RGB_LAYER);
}
}
}
}Code loops through every row and column on a per-key RGB board, scanning for configured keys (not KC_TRANS) and lighting that index location. It is configured to activate on non-default layers. This can be further customised using layer switch condition inside the last if statement.
#define W_TH LT(0, KC_W)
bool process_record_user(uint16_t keycode, keyrecord_t *record) {
switch (keycode) {
case W_TH:
// Send W on single tap
if (record->tap.count) {
if (record->event.pressed) { register_code(KC_W); }
else { unregister_code(KC_W); }
// Send macro string on hold
} else if (record->event.pressed) { SEND_STRING(":wq"); }
return false;
}
return true; // continue with unmatched keycodes
}Tap hold shortcut can be found in QMK's tap dance feature but replicated here inside process_record_user() with layer tap (LT()) and tapping term delay. It uses less firmware space than TAP_DANCE_ENABLE (~35 bytes per macro). Key macro W_TH replaces KC_W on the key map (keymap[]). The if-else statements are in a #define TAP_HOLD(_tap_, _hold_) macro.
void process_caps_word(uint16_t keycode, keyrecord_t const *record) {
// Get base key code of mod or layer tap with bitmask
if (((QK_MOD_TAP <= keycode && keycode <= QK_MOD_TAP_MAX) ||
(QK_LAYER_TAP <= keycode && keycode <= QK_LAYER_TAP_MAX)) &&
(record->tap.count)) { keycode = keycode & 0xFF; }
// Toggle caps lock with the following key codes
switch (keycode) {
case KC_ESC:
case KC_SPC:
case KC_ENT:
case KC_TAB:
case KC_DOT:
case KC_COMM:
case KC_GESC:
if (record->event.pressed) { tap_code(KC_CAPS); }
}
}Function is called inside process_record_user when caps lock is enabled to turn it off after completing a word—because caps lock is rarely used beyond capitalising one word. The first switch statement performs a bitwise AND to filter base key codes (that ranges from 0x00-0xFF) from mod/layer taps to support toggle keys on a different layer. Written by the #ergonomics enthusiasts of splitkb.com discord.
QMK will read "keyboard" and "keymap" values from the JSON file to build the firmware:
qmk flash ~/qmk_firmware/users/filterpaper/json/bm40.json
qmk flash ~/qmk_firmware/users/filterpaper/json/planck.json
qmk flash ~/qmk_firmware/users/filterpaper/json/corne.json
qmk flash ~/qmk_firmware/users/filterpaper/json/mark65.jsonCorne is configured with EE_HANDS for controllers to read left or right values off EEPROM, allowing USB-C cable to be used on either side. These are one-time flash commands to write left and right handedness bootloader into Elite-C MCUs:
qmk flash -kb crkbd/rev1/common -km default -bl dfu-split-left
qmk flash -kb crkbd/rev1/common -km default -bl dfu-split-rightSubsequently, the same firmware binary can be flashed normally to both sides. See split keyboard features for details.
QMK's split common transport.c code limits type of data sent the secondary (non-USB) controller. Animation on the secondary display can only be driven by WPM while keyboard status is limited to modifier state. My code can be built with the following rules.mk options:
Default Corne keyboard is built with Bongocat animation on primary display driven by key presses with simple modifier state on secondary OLED:
qmk compile corne.json
Bongocat code uses spacing-saving pixel differences to animate, with left and right-aligned animation arrays to support EE_HANDS configuration. Arrays for one of the sides (and its associated if-else statements) can be removed to save additional space.
Keyboard layer and modifier status on primary OLED with Bongocat animation on secondary, driven by WPM:
qmk compile -e WPM=yes corne.json
Luna the dog animation status on primary OLED with Bongocat on secondary, both driven by WPM:
qmk compile -e WPM=yes -e DOG=LUNA corne.json
White Felix the dog can be built with DOG=FELIX.
Minimal firmware with no OLED support can be built with TINY=yes preprocessor:
qmk compile -e TINY=yes corne.json
Images in glcdfont.c can be viewed and edited with:
Text-based layout (in keymap.c format) editing is supported with the use of preprocessor macros. Each layer, in text format, is created as a preprocessor macro for viewing and editing inside layout.h, example of one layer:
#define RAISE \
KC_TILD, KC_EXLM, KC_AT, KC_HASH, KC_DLR, KC_PERC, KC_CIRC, KC_AMPR, KC_ASTR, KC_LPRN, KC_RPRN, _______, \
KC_GRV, KC_1, KC_2, KC_3, KC_4, KC_5, KC_6, KC_7, KC_8, KC_9, KC_0, _______, \
_______, _______, _______, _______, S(G(A(KC_V))), _______, _______, _______, _______, _______, _______, _______
#define CORNERAISE _______, MO(4), _______, _______, _______, _______The wrapper layout name for each keyboard should be a macro mapped to the real layout inside layout.h, like this Corne example:
#define LAYOUT_wrapper_split_3x6_3(...) LAYOUT_split_3x6_3(__VA_ARGS__)Finally the keyboard's JSON file can be created by referencing the key code macros of each layer, along with the layout macro at the bottom:
{
"author": "",
"documentation": "Wrapper based keymap",
"keyboard": "crkbd/rev1/common",
"keymap": "filterpaper",
"layers": [
[ "QWERTY", "CORNEQWERTY" ],
[ "LOWER", "CORNELOWER" ],
[ "RAISE", "CORNERAISE" ],
[ "ADJUST", "CORNEBLANK" ],
],
"layout": "LAYOUT_wrapper_split_3x6_3",
"notes": "",
"version": 1
}The build process will construct a transient keymap.c from JSON file into the format [0] = LAYOUT_wrapper_split_3x6_3(QWERTY, CORNEQWERTY), and C preprocessor will use macros inside layout.h to expand that into the full layout key code for compilation.