tmk_core/doc/keymap.md

   1 Keymap framework - how to define your keymap
   2 ============================================
   3 ***NOTE: This is not final version, may be inconsistent with source code and changed occasionally for a while.***
   4
   5 ## 0. Keymap and layers
   6 The **keymap** is an array composed of one or more layers.
   7 Each **layer** is an array of **keycodes**, defining **actions** for each physical key.
   8 Layers can be activated and deactivated independently. Multiple layers may be active at once, resulting in the currently-active **layer state**. Each layer has an index between 0-31. As active layers are stacked together, higher layers take precedence over lower layers.
   9
  10     Keymap: 32 Layers                   Layer: Keycode matrix
  11     -----------------                   ---------------------
  12     stack of layers                     array_of_keycode[row][column]
  13            ____________ precedence               _______________________
  14           /           / | high                  / ESC / F1  / F2  / F3   ....
  15       31 /___________// |                      /-----/-----/-----/-----
  16       30 /___________// |                     / TAB /  Q  /  W  /  E   ....
  17       29 /___________/  |                    /-----/-----/-----/-----
  18        :   _:_:_:_:_:__ |               :   /LCtrl/  A  /  S  /  D   ....
  19        :  / : : : : : / |               :  /  :     :     :     :
  20        2 /___________// |               2 `--------------------------
  21        1 /___________// |               1 `--------------------------
  22        0 /___________/  V low           0 `--------------------------
  23
  24 **Note:** The keymap array is limited to **32 layers**.
  25
  26
  27
  28 ### 0.1 Layer state
  29 The current keymap layer state is determined by two parameters: the *default layer*, and the individual *layer states*. Changing the default layer is useful for switching key layouts completely; for example, switching to Dvorak, Colemak or Workman instead of QWERTY. Individual layer states, on the other hand, can be used to overlay the base layer with other functions such as navigation keys, function keys (F1-F12), media keys or other actions.
  30
  31 Because the default layer is really just a special case affecting the overall layer state, it is important to first understand how the layer state is determined.
  32
  33 #### 0.1.1 The layer state
  34 The **layer state** indicates the current on/off status of all layers. It is defined in the firmware by a 32-bit integer, `layer_state`, which stores each layer's on/off status in a single bit: 0 for off, 1 for on. As layers are activated and deactivated, their respective bits are flipped, changing the value of `layer_state`.
  35
  36     Overlay feature layer
  37     ---------------------      bit|status
  38            ____________        ---+------
  39       31  /           /        31 |   0
  40       30 /___________// -----> 30 |   1
  41       29 /___________/  -----> 29 |   1
  42        :                        : |   :
  43        :   ____________         : |   :
  44        2  /           /         2 |   0
  45     ,->1 /___________/  ----->  1 |   1
  46     |  0                        0 |   0
  47     |                                 +
  48     `--- default_layer = 1            |
  49          layer_state   = 0x60000002 <-'
  50
  51 #### 0.1.2 The default layer
  52 The **default layer** is the base keymap layer (0-31) which is always active and considered the "bottom" of the stack. When the firmware boots, the default layer is the only active layer. It is set to layer 0 by default, though this can be changed ~~in *config.h*~~ via Boot Magic settings.
  53
  54     Initial state of Keymap          Change base layout
  55     -----------------------          ------------------
  56
  57       31                               31
  58       30                               30
  59       29                               29
  60        :                                :
  61        :                                :   ____________
  62        2   ____________                 2  /           /
  63        1  /           /              ,->1 /___________/
  64     ,->0 /___________/               |  0
  65     |                                |
  66     `--- default_layer = 0           `--- default_layer = 1
  67          layer_state   = 0x00000001       layer_state   = 0x00000002
  68
  69 Note that the `default_layer_state` variable only determines the lowest value to which `layer_state` may be set, and that `default_layer_state` is used by the core firmware when determining the starting value of `layer_state` before applying changes. In other words, the default layer will *always* be set to *on* in `layer_state`.
  70
  71 The default layer is defined in the firmware by the `default_layer_state` variable, which is identical in format to the `layer_state` variable exlpained above. The value may be changed using the following functions:
  72
  73 - `default_layer_state_set(state)` sets the state to the specified 32-bit integer value.
  74 - AND/OR/XOR functions set the state based on a boolean logic comparison between the current state and the specified 32-bit integer value:
  75     - `default_layer_state_and(state)`
  76     - `default_layer_state_or(state)`
  77     - `default_layer_state_xor(state)`
  78
  79 For example, to set layer 3 as the default layer:
  80
  81 ```C
  82 // convert 3 to a 32-bit unsigned long value, and set the default layer
  83 default_layer_state_set(1UL<<3);
  84 ```
  85
  86
  87
  88 ### 0.2 Layer Precedence and Transparency
  89 Note that ***higher layers have priority in the layer stack***. The firmware starts at the topmost active layer, and works down to the bottom to find the an active keycode. Once the search encounters any keycode other than **`KC_TRNS`** (transparent) on an active layer, the search is halted and the remaining lower layers aren't examined, even if they are active.
  90
  91 **Note:** a layer must be activated before it may be included in the stack search.
  92
  93 `KC_TRNS` is a special placeholder which can be used on overlay layers. This allows for the creation of "partial" layers which fall back on the lower layers, eliminating a good deal of repetition in keymap files.
  94
  95
  96
  97 ### 0.3 Keymap Example
  98 The keymap is defined in the **`uint8_t keymaps[]`** array, a 2-dimensional array of rows and columns corresponding to positions in the keyboard matrix. But most often the layers are defined using C macros to allow for easier reading and editing of the keymap files. To use complex actions you need to define `Fn` action in the **`action_t fn_actions[]`** array.
  99
 100 This is a keymap example for the [HHKB](http://en.wikipedia.org/wiki/Happy_Hacking_Keyboard) keyboard.
 101 This example has three layers: the QWERTY base layer, and two overlay layers for cursor and mousekey control, respectively.
 102 In this example,
 103
 104  `Fn0` is a **momentary layer switching** key--you can use keys on the Cursor layer while holding the key.
 105
 106  `Fn1` is a momentary layer switching key with tapping function--tapping the key as one would normally use it, sends the semicolon **';'** keycode, while holding the key down switches layers.
 107
 108  `Fn2` is a **toggle layer switch** key--pressing the key toggles the layer on until you press it again.
 109
 110 You can find other keymap definitions in file `keymap.c` located on project directories.
 111
 112     const uint8_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
 113         /* 0: Qwerty
 114          * ,-----------------------------------------------------------.
 115          * |Esc|  1|  2|  3|  4|  5|  6|  7|  8|  9|  0|  -|  =|  \|  `|
 116          * |-----------------------------------------------------------|
 117          * |Tab  |  Q|  W|  E|  R|  T|  Y|  U|  I|  O|  P|  [|  ]|Backs|
 118          * |-----------------------------------------------------------|
 119          * |Contro|  A|  S|  D|  F|  G|  H|  J|  K|  L|Fn1|  '|Enter   |
 120          * |-----------------------------------------------------------|
 121          * |Shift   |  Z|  X|  C|  V|  B|  N|  M|  ,|  .|  /|Shift |Fn0|
 122          * `-----------------------------------------------------------'
 123          *       |Gui|Alt  |Space                  |Alt  |Fn2|
 124          *       `-------------------------------------------'
 125          */
 126         KEYMAP(ESC, 1,   2,   3,   4,   5,   6,   7,   8,   9,   0,   MINS,EQL, BSLS,GRV, \
 127                TAB, Q,   W,   E,   R,   T,   Y,   U,   I,   O,   P,   LBRC,RBRC,BSPC, \
 128                LCTL,A,   S,   D,   F,   G,   H,   J,   K,   L,   FN1, QUOT,ENT, \
 129                LSFT,Z,   X,   C,   V,   B,   N,   M,   COMM,DOT, SLSH,RSFT,FN0, \
 130                     LGUI,LALT,          SPC,                RALT,FN2),
 131         /* 1: Cursor(HHKB mode)
 132          * ,-----------------------------------------------------------.
 133          * |Pwr| F1| F2| F3| F4| F5| F6| F7| F8| F9|F10|F11|F12|Ins|Del|
 134          * |-----------------------------------------------------------|
 135          * |Caps |   |   |   |   |   |   |   |Psc|Slk|Pus|Up |   |Backs|
 136          * |-----------------------------------------------------------|
 137          * |Contro|VoD|VoU|Mut|   |   |  *|  /|Hom|PgU|Lef|Rig|Enter   |
 138          * |-----------------------------------------------------------|
 139          * |Shift   |   |   |   |   |   |  +|  -|End|PgD|Dow|Shift |   |
 140          * `-----------------------------------------------------------'
 141          *      |Gui |Alt  |Space                  |Alt  |Gui|
 142          *      `--------------------------------------------'
 143          */
 144         KEYMAP(PWR, F1,  F2,  F3,  F4,  F5,  F6,  F7,  F8,  F9,  F10, F11, F12, INS, DEL, \
 145                CAPS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,PSCR,SLCK,PAUS,UP,  TRNS,BSPC, \
 146                LCTL,VOLD,VOLU,MUTE,TRNS,TRNS,PAST,PSLS,HOME,PGUP,LEFT,RGHT,ENT, \
 147                LSFT,TRNS,TRNS,TRNS,TRNS,TRNS,PPLS,PMNS,END, PGDN,DOWN,RSFT,TRNS, \
 148                     LGUI,LALT,          SPC,                RALT,RGUI),
 149         /* 2: Mousekey
 150          * ,-----------------------------------------------------------.
 151          * |Esc| F1| F2| F3| F4| F5| F6| F7| F8| F9|F10|F11|F12|Ins|Del|
 152          * |-----------------------------------------------------------|
 153          * |Tab  |   |   |   |   |   |MwL|MwD|MwU|MwR|   |   |   |Backs|
 154          * |-----------------------------------------------------------|
 155          * |Contro|   |   |   |   |   |McL|McD|McU|McR|   |   |Return  |
 156          * |-----------------------------------------------------------|
 157          * |Shift   |   |   |   |   |Mb3|Mb2|Mb1|Mb4|Mb5|   |Shift |   |
 158          * `-----------------------------------------------------------'
 159          *      |Gui |Alt  |Mb1                    |Alt  |   |
 160          *      `--------------------------------------------'
 161          * Mc: Mouse Cursor / Mb: Mouse Button / Mw: Mouse Wheel
 162          */
 163         KEYMAP(ESC, F1,  F2,  F3,  F4,  F5,  F6,  F7,  F8,  F9,  F10, F11, F12, INS, DEL, \
 164                TAB, TRNS,TRNS,TRNS,TRNS,TRNS,WH_L,WH_D,WH_U,WH_R,TRNS,TRNS,TRNS,BSPC, \
 165                LCTL,TRNS,ACL0,ACL1,ACL2,TRNS,MS_L,MS_D,MS_U,MS_R,TRNS,QUOT,ENT, \
 166                LSFT,TRNS,TRNS,TRNS,TRNS,BTN3,BTN2,BTN1,BTN4,BTN5,SLSH,RSFT,TRNS, \
 167                     LGUI,LALT,          BTN1,               RALT,TRNS),
 168     };
 169
 170     const action_t PROGMEM fn_actions[] = {
 171         ACTION_LAYER_MOMENTARY(1),                  // FN0
 172         ACTION_LAYER_TAP_KEY(2, KC_SCLN),           // FN1
 173         ACTION_LAYER_TOGGLE(2),                     // FN2
 174     };
 175
 176
 177
 178
 179 ## 1. Keycode
 180 See [`common/keycode.h`](../common/keycode.h) or keycode table below for the detail. Keycode is internal **8bit code** to indicate action performed on key in keymap. Keycode has `KC_` prefixed symbol respectively. Most of keycodes like `KC_A` have simple action registers key to host on press and unregister on release, while some of other keycodes has some special actions like `Fn` keys, Media control keys, System control keys and Mousekeys.
 181
 182  ***In `KEYMAP()` macro you should omit prefix part `KC_` of keycode to keep keymap compact.*** For example, just use `A` instead you place `KC_A` in `KEYMAP()`. Some keycodes has 4-letter **short name** in addition to descriptive name, you'll prefer short one in `KEYMAP()`.
 183
 184 ### 1.0 Other key
 185 - `KC_NO` for no action
 186 - `KC_TRNS` for layer transparency (See above)
 187
 188 ### 1.1 Normal key
 189 - `KC_A` to `KC_Z`, `KC_1` to `KC_0` for alpha numeric key
 190 - `KC_MINS`, `KC_EQL`, `KC_GRV`, `KC_RBRC`, `KC_LBRC`, `KC_COMM`, `KC_DOT`, `KC_BSLS`, `KC_SLSH`, `KC_SCLN`, `KC_QUOT`
 191 - `KC_ESC`, `KC_TAB`, `KC_SPC`, `KC_BSPC`, `KC_ENT`, `KC_DEL`, `KC_INS`
 192 - `KC_UP`, `KC_DOWN`, `KC_RGHT`, `KC_LEFT`, `KC_PGUP`, `KC_PGDN`, `KC_HOME`, `KC_END`
 193 - `KC_CAPS`, `KC_NLCK`, `KC_SLCK`, `KC_PSCR`, `KC_PAUS`, `KC_APP`, `KC_F1` to `KC_F24`
 194 - `KC_P1` to `KC_P0`, `KC_PDOT`, `KC_PCMM`, `KC_PSLS`, `KC_PAST`, `KC_PMNS`, `KC_PPLS`, `KC_PEQL`, `KC_PENT` for keypad.
 195
 196 ### 1.2 Modifier
 197 There are 8 modifiers which has discrimination between left and right.
 198
 199 - `KC_LCTL` and `KC_RCTL` for Control
 200 - `KC_LSFT` and `KC_RSFT` for Shift
 201 - `KC_LALT` and `KC_RALT` for Alt
 202 - `KC_LGUI` and `KC_RGUI` for Windows key or Command key in Mac
 203
 204 ### 1.3 Mousekey
 205 - `KC_MS_U`, `KC_MS_D`, `KC_MS_L`, `KC_MS_R` for mouse cursor
 206 - `KC_WH_U`, `KC_WH_D`, `KC_WH_L`, `KC_WH_R` for mouse wheel
 207 - `KC_BTN1`, `KC_BTN2`, `KC_BTN3`, `KC_BTN4`, `KC_BTN5` for mouse buttons
 208
 209 ### 1.4 System & Media key
 210 - `KC_PWR`, `KC_SLEP`, `KC_WAKE` for Power, Sleep, Wake
 211 - `KC_MUTE`, `KC_VOLU`, `KC_VOLD` for audio volume control
 212 - `KC_MNXT`, `KC_MPRV`, `KC_MSTP`, `KC_MPLY`, `KC_MSEL` for media control
 213 - `KC_MAIL`, `KC_CALC`, `KC_MYCM` for application launch
 214 - `KC_WSCH`, `KC_WHOM`, `KC_WBAK`, `KC_WFWD`, `KC_WSTP`, `KC_WREF`, `KC_WFAV` for web browser operation
 215
 216 ### 1.5 Fn key
 217 `KC_FNnn` are keycodes for `Fn` key which not given any actions at the beginning unlike most of keycodes has its own inborn action. To use these keycodes in `KEYMAP()` you need to assign action you want at first. Action of `Fn` key is defined in `action_t fn_actions[]` and its index of the array is identical with number part of `KC_FNnn`. Thus `KC_FN0` keycode indicates the action defined in first element of the array. ***32 `Fn` keys can be defined at most.***
 218
 219 ### 1.6 Keycode Table
 220  See keycode table in [`doc/keycode.txt`](./keycode.txt) for description of keycodes.
 221
 222  In regard to implementation side most of keycodes are identical with [HID usage][HID_usage](pdf) sent to host for real and some virtual keycodes are defined to support special actions.
 223 [HID_usage]: http://www.usb.org/developers/hidpage/Hut1_12v2.pdf
 224
 225
 226
 227 ## 2. Action
 228 See [`common/action_code.h`](../common/action_code.h). Action is a **16bit code** and defines function to perform on events of a key like press, release, holding and tapping.
 229
 230 Most of keys just register 8bit scancode to host, but to support other complex features needs 16bit extended action codes internally. However, using 16bit action codes in keymap results in double size in memory compared to using just keycodes. To avoid this waste 8bit keycodes are used in `KEYMAP()` instead of action codes.
 231
 232 ***You can just use keycodes of `Normal key`, `Modifier`, `Mousekey` and `System & Media key` in keymap*** to indicate corresponding actions instead of using action codes. While ***to use other special actions you should use keycode of `Fn` key defined in `fn_actions[]`.***
 233
 234
 235 ### 2.1 Key Action
 236 This is a simple action that registers scancodes(HID usage in fact) to host on press event of key and unregister on release.
 237
 238 #### Parameters
 239 + **mods**: { ` MOD_LCTL`, ` MOD_LSFT`, ` MOD_LALT`, ` MOD_LGUI`,
 240               ` MOD_RCTL`, ` MOD_RSFT`, ` MOD_RALT`, ` MOD_RGUI` }
 241 + **key**: keycode
 242
 243
 244 #### 2.1.1 Normal key and Modifier
 245 ***This action usually won't be used expressly in keymap*** because you can just use keycodes in `KEYMAP()` instead.
 246
 247 You can define these actions on *'A'* key and *'left shift'* modifier with:
 248
 249     ACTION_KEY(KC_A)
 250     ACTION_KEY(KC_LSFT)
 251
 252 #### 2.1.2 Modified key
 253 This action is comprised of modifiers and a key.
 254
 255 Modified keys can be defined as below. Say you want to assign a key to `Shift + 1` to get character *'!'* or `Alt + Tab` to switch application windows.
 256
 257     ACTION_MODS_KEY(MOD_LSFT, KC_1)
 258     ACTION_MODS_KEY(MOD_LALT, KC_TAB)
 259     ACTION_MODS_KEY(MOD_LALT | MOD_LSFT, KC_TAB)
 260
 261 These are identical to examples above.
 262
 263     ACTION_KEY(MOD_LSFT | KC_1)
 264     ACTION_KEY(MOD_LALT | KC_TAB)
 265     ACTION_KEY(MOD_LSFT | MOD_LALT | KC_TAB)
 266
 267 #### 2.1.3 Multiple Modifiers
 268 Registers multiple modifiers with pressing a key. To specify multiple modifiers use `|`.
 269
 270     ACTION_MODS(MOD_LALT | MOD_LSFT)
 271     ACTION_MODS(MOD_LALT | MOD_LSFT | MOD_LCTL)
 272
 273 These are identical to examples above.
 274
 275     ACTION_KEY(MOD_LALT | MOD_LSFT, KC_NO)
 276     ACTION_KEY(MOD_LALT | MOD_LSFT | MOD_LCTL, KC_NO)
 277
 278 #### 2.1.3 Modifier with Tap key([Dual role][dual_role])
 279 Works as a modifier key while holding, but registers a key on tap(press and release quickly).
 280
 281
 282     ACTION_MODS_TAP_KEY(MOD_RCTL, KC_ENT)
 283
 284
 285
 286 ### 2.2 Layer Action
 287 These actions operate layers of keymap.
 288
 289 #### Parameters
 290 You can specify a **target layer** of action and **when the action is executed**. Some actions take a **bit value** for bitwise operation.
 291
 292
 293 + **layer**: `0`-`31`
 294 + **on**: { `ON_PRESS` | `ON_RELEASE` | `ON_BOTH` }
 295 + **bits**: 4-bit value and 1-bit mask bit
 296
 297
 298 #### 2.2.1 Default Layer
 299 Default Layer is a layer which always is valid and referred to when actions is not defined on other overlay layers.
 300
 301 This sets Default Layer to given parameter `layer` and activate it.
 302
 303     ACTION_DEFAULT_LAYER_SET(layer)
 304
 305
 306 #### 2.2.2 Momentary
 307 Turns on `layer` momentarily while holding, in other words it activates when key is pressed and deactivate when released.
 308
 309     ACTION_LAYER_MOMENTARY(layer)
 310
 311
 312 #### 2.2.3 Toggle Switch
 313 Turns on `layer` with first type(press and release) and turns off with next.
 314
 315     ACTION_LAYER_TOGGLE(layer)
 316
 317
 318 #### 2.2.4 Momentary Switch with tap key
 319 Turns on `layer` momentary while holding, but registers key on tap(press and release quickly).
 320
 321     ACTION_LAYER_TAP_KEY(layer, key)
 322
 323
 324 #### 2.2.5 Momentary Switch with tap toggle
 325 Turns on `layer` momentary while holding and toggles it with serial taps.
 326
 327     ACTION_LAYER_TAP_TOGGLE(layer)
 328
 329
 330 #### 2.2.6 Invert state of layer
 331 Inverts current state of `layer`. If the layer is on it becomes off with this action.
 332
 333     ACTION_LAYER_INVERT(layer, on)
 334
 335
 336 #### 2.2.7 Turn On layer
 337 Turns on layer state.
 338
 339     ACTION_LAYER_ON(layer, on)
 340
 341 Turns on layer state on press and turns off on release.
 342
 343     ACTION_LAYER_ON_OFF(layer)
 344
 345
 346 #### 2.2.8 Turn Off layer
 347 Turns off layer state.
 348
 349     ACTION_LAYER_OFF(layer, on)
 350
 351 Turns off layer state on press and activates on release.
 352
 353     ACTION_LAYER_OFF_ON(layer)
 354
 355
 356 #### 2.2.9 Set layer
 357 Turn on layer only.
 358 `layer_state = (1<<layer) [layer: 0-31]`
 359
 360     ACTION_LAYER_SET(layer, on)
 361
 362 Turns on layer only and clear all layer on release..
 363
 364     ACTION_LAYER_SET_CLEAR(layer)
 365
 366
 367 #### 2.2.10 Bitwise operation
 368
 369 **part** indicates which part of 32bit layer state(0-7). **bits** is 5-bit value. **on** indicates when the action is executed.
 370
 371     ACTION_LAYER_BIT_AND(part, bits, on)
 372     ACTION_LAYER_BIT_OR(part, bits, on)
 373     ACTION_LAYER_BIT_XOR(part, bits, on)
 374     ACTION_LAYER_BIT_SET(part, bits, on)
 375
 376 These actions works with parameters as following code.
 377
 378     uint8_t shift = part*4;
 379     uint32_t mask = (bits&0x10) ? ~(0xf<<shift) : 0;
 380     uint32_t layer_state = layer_state <bitop> ((bits<<shift)|mask);
 381
 382
 383 Default Layer also has bitwise operations, they are executed when key is released.
 384
 385     ACTION_DEFAULT_LAYER_BIT_AND(part, bits)
 386     ACTION_DEFAULT_LAYER_BIT_OR(part, bits)
 387     ACTION_DEFAULT_LAYER_BIT_XOR(part, bits)
 388     ACTION_DEFAULT_LAYER_BIT_SET(part, bits)
 389
 390
 391 ### 2.3 Macro action
 392 `Macro` actions allow you to register a complex sequence of keystrokes when a key is pressed, where macros are simple sequences of keypresses.
 393
 394     ACTION_MACRO(id)
 395     ACTION_MACRO_TAP(id)
 396
 397 `id` is an 8-bit user-defined value the macro getter function can use to pick the specific macro.
 398
 399
 400 #### 2.3.1 Implementing Macro getter function
 401 To implement `macro` functions, the macro lookup list must be implemented:
 402
 403     const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt);
 404
 405 The function must always return a valid macro, and default implementation of `action_get_macro` always returns `MACRO_NONE` which has no effect.
 406
 407 #### 2.3.1.1 Limitations
 408 Similar to the Function Action system, the selector functions is passed  a `keyrecord_t` object, so it can inspect the key state (e.g. different macros on key press or release), and key itself.
 409
 410 Unlike the Function Action system,`macros` are pre-recorded key sequences, so you can only select from a list. If you want to use dynamic macros then you should look at the more complex function action system.
 411
 412 #### 2.3.2 Implementing/Defining Macro sequences
 413 Macros are of the form (must be wrapped by the `MACRO` function, and end with an `END` mark)
 414
 415     MACRO( ..., END )
 416
 417 Within each macro, the following commands can be used:
 418
 419 - **I()**   change interval of stroke.
 420 - **D()**   press key
 421 - **U()**   release key
 422 - **T()**   type key(press and release)
 423 - **W()**   wait
 424 - **SM()**  store modifier state
 425 - **RM()**  restore modifier state
 426 - **CM()**  clear modifier state
 427
 428 e.g.:
 429
 430     MACRO( D(LSHIFT), D(D), END )  // hold down LSHIFT and D - will print 'D'
 431     MACRO( U(D), U(LSHIFT), END )  // release U and LSHIFT keys (an event.pressed == False counterpart for the one above)
 432     MACRO( I(255), T(H), T(E), T(L), T(L), W(255), T(O), END ) // slowly print out h-e-l-l---o
 433
 434 #### 2.3.2 Examples
 435
 436 in keymap.c, define `action_get_macro`
 437
 438     const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt)
 439     {
 440         switch (id) {
 441             case 0:
 442                 return (record->event.pressed ?
 443                         MACRO( I(0), T(H), T(E), T(L), T(L), W(255), T(O), END ) :
 444                         MACRO_NONE );
 445             case 1:
 446                 return (record->event.pressed ?
 447                         MACRO( D(LALT), D(TAB), END ) :
 448                         MACRO( U(TAB), END ));
 449         }
 450         return MACRO_NONE;
 451     }
 452
 453 in keymap.c, bind items in `fn_actions` to the macro function
 454
 455     const action_t PROGMEM fn_actions[] = {
 456          [0] = ACTION_MACRO(0), // will print 'hello' for example
 457          [1] = ACTION_MACRO(1),
 458     };
 459
 460
 461 ### 2.4 Function action
 462 ***TBD***
 463
 464 There are two type of action, normal `Function` and tappable `Function`.
 465 These actions call user defined function with `id`, `opt`, and key event information as arguments.
 466
 467 #### 2.4.1 Function
 468 To define normal `Function` action in keymap use this.
 469
 470     ACTION_FUNCTION(id, opt)
 471
 472 #### 2.4.2 Function with tap
 473 To define tappable `Function` action in keymap use this.
 474
 475     ACTION_FUNCTION_TAP(id, opt)
 476
 477 #### 2.4.3 Implement user function
 478 `Function` actions can be defined freely with C by user in callback function:
 479
 480     void action_function(keyrecord_t *record, uint8_t id, uint8_t opt);
 481
 482 This C function is called every time key is operated, argument `id` selects action to be performed and `opt` can be used for option. Function `id` can be 0-255 and `opt` can be 0-15.
 483
 484  `keyrecord_t` is comprised of key event and tap count. `keyevent_t` indicates which and when key is pressed or released. From `tap_count` you can know tap state, 0 means no tap. These information will be used in user function to decide how action of key is performed.
 485
 486     typedef struct {
 487         keyevent_t  event;
 488         uint8_t     tap_count;
 489     } keyrecord_t;
 490
 491     typedef struct {
 492         key_t    key;
 493         bool     pressed;
 494         uint16_t time;
 495     } keyevent_t;
 496
 497     typedef struct {
 498         uint8_t col;
 499         uint8_t row;
 500     } key_t;
 501
 502 ***TODO: sample implementation***
 503 See `keyboard/hhkb/keymap.c` for sample.
 504
 505
 506
 507 ### 2.5 Backlight Action
 508 These actions control the backlight.
 509
 510 #### 2.5.1 Change backlight level
 511 Increase backlight level.
 512
 513     ACTION_BACKLIGHT_INCREASE()
 514
 515 Decrease backlight level.
 516
 517     ACTION_BACKLIGHT_DECREASE()
 518
 519 Step through backlight levels.
 520
 521     ACTION_BACKLIGHT_STEP()
 522
 523 Turn a specific backlight level on or off.
 524
 525     ACTION_BACKLIGHT_LEVEL(1)
 526
 527 #### 2.5.2 Turn on / off backlight
 528 Turn the backlight on and off without changing level.
 529
 530     ACTION_BACKLIGHT_TOGGLE()
 531
 532
 533
 534 ## 3. Layer switching Example
 535 There are some ways to switch layer with 'Layer' actions.
 536
 537 ### 3.1 Momentary switching
 538 Momentary switching changes layer only while holding Fn key.
 539
 540 This action makes 'Layer 1' active(valid) on key press event and inactive on release event. Namely you can overlay a layer on lower layers or default layer temporarily with this action.
 541
 542     ACTION_LAYER_MOMENTARY(1)
 543
 544
 545 Note that after switching on press the actions on destination layer(Layer 1) are performed.
 546 ***Thus you shall need to place an action to go back on destination layer***, or you will be stuck in destination layer without way to get back. Usually you need to place same action or 'KC_TRNS` on destination layer to get back.
 547
 548
 549 ### 3.2 Toggle switching
 550 Toggle switching performed after releasing a key. With this action you can keep staying on the destination layer until you type the key again to return.
 551
 552 This performs toggle switching action of 'Layer 2'.
 553
 554     ACTION_LAYER_TOGGLE(2)
 555
 556
 557
 558 ### 3.3 Momentary switching with Tap key
 559 These actions switch a layer only while holding a key but register the key on tap. **Tap** means to press and release a key quickly.
 560
 561     ACTION_LAYER_TAP_KEY(2, KC_SCLN)
 562
 563 With this you can place a layer switching action on normal key like ';' without losing its original key register function. This action allows you to have layer switching action without necessity of a dedicated key. It means you can have it even on home row of keyboard.
 564
 565
 566
 567 ### 3.4 Momentary switching with Tap Toggle
 568 This switches layer only while holding a key but toggle layer with several taps. **Tap** means to press and release key quickly.
 569
 570     ACTION_LAYER_TAP_TOGGLE(1)
 571
 572 Number of taps can be configured with `TAPPING_TOGGLE` in `config.h`, `5` by default.
 573
 574
 575
 576 ### 3.5 Momentary switching with Modifiers
 577 This registers modifier key(s) simultaneously with layer switching.
 578
 579     ACTION_LAYER_MODS(2, MOD_LSFT | MOD_LALT)
 580
 581 You can combine four modifiers at most but cannot use both left and right modifiers at a time, either left or right modiiers only can be allowed.
 582
 583
 584 ## 4. Tapping
 585 Tapping is to press and release a key quickly. Tapping speed is determined with setting of `TAPPING_TERM`, which can be defined in `config.h`, 200ms by default.
 586
 587 ### 4.1 Tap Key
 588 This is a feature to assign normal key action and modifier including layer switching to just same one physical key. This is a kind of [Dual role key][dual_role]. It works as modifier when holding the key but registers normal key when tapping.
 589
 590 Modifier with tap key:
 591
 592     ACTION_MODS_TAP_KEY(MOD_RSFT, KC_GRV)
 593
 594 Layer switching with tap key:
 595
 596     ACTION_LAYER_TAP_KEY(2, KC_SCLN)
 597
 598 [dual_role]: http://en.wikipedia.org/wiki/Modifier_key#Dual-role_keys
 599
 600
 601 ### 4.2 Tap Toggle
 602 This is a feature to assign both toggle layer and momentary switch layer action to just same one physical key. It works as momentary layer switch when holding a key but toggle switch with several taps.
 603
 604     ACTION_LAYER_TAP_TOGGLE(1)
 605
 606
 607 ### 4.3 Oneshot Modifier
 608 This runs onetime effects which modify only on just one following key. It works as normal modifier key when holding down while oneshot modifier when tapping.
 609
 610     ACTION_MODS_ONESHOT(MOD_LSFT)
 611
 612 Say you want to type 'The', you have to push and hold Shift key before type 't' then release it before type 'h' and 'e', otherwise you'll get 'THe' or 'the' unintentionally. With Oneshot Modifier you can tap Shift then type 't', 'h' and 'e' normally, you don't need to holding Shift key properly here. This mean you can release Shift before 't' is pressed down.
 613
 614 Oneshot effect is cancel unless following key is pressed down within `ONESHOT_TIMEOUT` of `config.h`. No timeout when it is `0` or not defined.
 615
 616
 617 ### 4.4 Tap Toggle Mods
 618 Similar to layer tap toggle, this works as a momentary modifier when holding, but toggles on with several taps. A single tap will 'unstick' the modifier again.
 619
 620     ACTION_MODS_TAP_TOGGLE(MOD_LSFT)
 621
 622
 623
 624
 625 ## 5. Legacy Keymap
 626 This was used in prior version and still works due to legacy support code in `common/keymap.c`. Legacy keymap doesn't support many of features that new keymap offers. ***It is not recommended to use Legacy Keymap for new project.***
 627
 628 To enable Legacy Keymap support define this macro in `config.h`.
 629
 630     #define USE_LEGACY_KEYMAP
 631
 632 Legacy Keymap uses two arrays `fn_layer[]` and `fn_keycode[]` to define Fn key. The index of arrays corresponds with postfix number of `Fn` key. Array `fn_layer[]` indicates destination layer to switch and `fn_keycode[]` has keycodes to send when tapping `Fn` key.
 633
 634 In following setting example, `Fn0`, `Fn1` and `Fn2` switch layer to 1, 2 and 2 respectively. `Fn2` registers `Space` key when tapping while `Fn0` and `Fn1` doesn't send any key.
 635
 636     const uint8_t PROGMEM fn_layer[] = {
 637         1,              // Fn0
 638         2,              // Fn1
 639         2,              // Fn2
 640     };
 641
 642     const uint8_t PROGMEM fn_keycode[] = {
 643         KC_NO,          // Fn0
 644         KC_NO,          // Fn1
 645         KC_SPC,         // Fn2
 646     };
 647
 648
 649 ## 6. Terminology
 650 ***TBD***
 651 ### keymap
 652 is comprised of multiple layers.
 653 ### layer
 654 is matrix of keycodes.
 655 ### key
 656 is physical button on keyboard or logical switch on software.
 657 ### keycode
 658 is codes used on firmware.
 659 ### action
 660 is a function assigned on a key.
 661 ### layer transparency
 662 Using transparent keycode one layer can refer key definition on other lower layer.
 663 ### layer precedence
 664 Top layer has higher precedence than lower layers.
 665 ### tapping
 666 is to press and release a key quickly.
 667 ### Fn key
 668 is key which executes a special action like layer switching, mouse key, macro or etc.
 669 ### dual role key
 670 <http://en.wikipedia.org/wiki/Modifier_key#Dual-role_keys>