- # List of Useful Core Functions To Make Your Keyboard Better
-
- There are a lot of hidden functions in QMK that are incredible useful, or may add a bit of functionality that you've been wanting. Functions that are specific to certain features are not included here, as those will be on their respective feature page.
-
- ## (OLKB) Tri Layers :id=olkb-tri-layers
-
- There are actually separate functions that you can use there, depending on what you're after.
-
- ### `update_tri_layer(x, y, z)`
-
- The first is the `update_tri_layer(x, y, z)` function. This function check to see if layers `x` and `y` are both on. If they are both on, then it turns on layer `z`. Otherwise, if both `x` and `y` are not both on (either only one is, or neither is), then it turns off layer `z`.
-
- This function is useful if you want to create specific keys that have this functionality, but other layer keycodes won't do this.
-
- #### Example
-
- ```c
- bool process_record_user(uint16_t keycode, keyrecord_t *record) {
- switch (keycode) {
- case LOWER:
- if (record->event.pressed) {
- layer_on(_LOWER);
- update_tri_layer(_LOWER, _RAISE, _ADJUST);
- } else {
- layer_off(_LOWER);
- update_tri_layer(_LOWER, _RAISE, _ADJUST);
- }
- return false;
- case RAISE:
- if (record->event.pressed) {
- layer_on(_RAISE);
- update_tri_layer(_LOWER, _RAISE, _ADJUST);
- } else {
- layer_off(_RAISE);
- update_tri_layer(_LOWER, _RAISE, _ADJUST);
- }
- return false;
- }
- return true;
- }
- ```
-
- ### `update_tri_layer_state(state, x, y, z)`
- The other function is `update_tri_layer_state(state, x, y, z)`. This function is meant to be called from the [`layer_state_set_*` functions](custom_quantum_functions.md#layer-change-code). This means that any time that you use a keycode to change the layer, this will be checked. So you could use `LT(layer, kc)` to change the layer and it will trigger the same layer check.
-
- There are a couple of caveats to this method:
- 1. You cannot access the `z` layer without having `x` and `y` layers on, since if you try to activate just layer `z`, it will run this code and turn off layer `z` before you could use it.
- 2. Because layers are processed from the highest number `z` should be a higher layer than `x` and `y` or you may not be able to access it.
-
- #### Example
-
- ```c
- layer_state_t layer_state_set_user(layer_state_t state) {
- return update_tri_layer_state(state, _LOWER, _RAISE, _ADJUST);
- }
- ```
-
- Alternatively, you don't have to immediately "return" the value. This is useful if you want to add multiple tri layers, or if you want to add additional effects.
-
- ```c
- layer_state_t layer_state_set_user(layer_state_t state) {
- state = update_tri_layer_state(state, _LOWER, _RAISE, _ADJUST);
- state = update_tri_layer_state(state, _RAISE, _SYMB, _SPECIAL);
- return state;
- }
- ```
-
- ## Setting the Persistent Default Layer
-
- Do you want to set the default layer, so that it's retained even after you unplug the board? If so, this is the function for you.
-
- To use this, you would use `set_single_persistent_default_layer(layer)`. If you have a name defined for your layer, you can use that instead (such as _QWERTY, _DVORAK or _COLEMAK).
-
- This will set the default layer, update the persistent settings, and play a tune if you have [Audio](feature_audio.md) enabled on your board, and the default layer sounds set.
-
- To configure the default layer sounds, you would want to define this in your `config.h` file, like this:
-
- ```c
- #define DEFAULT_LAYER_SONGS { SONG(QWERTY_SOUND), \
- SONG(COLEMAK_SOUND), \
- SONG(DVORAK_SOUND) \
- }
- ```
-
-
- ?> There are a large number of predefined songs in [quantum/audio/song_list.h](https://github.com/qmk/qmk_firmware/blob/master/quantum/audio/song_list.h) that you can use.
-
- ## Reseting the keyboard
-
- There is the `RESET` quantum keycode that you can use. But if you want to reset the board as part of a macro, rather than hitting a key separately, you can do that.
-
- And to do so, add `reset_keyboard()` to your function or macro, and this will reset to bootloader.
-
- ## Wiping the EEPROM (Persistent Storage)
-
- If you're having issues with Audio, RGB Underglow, backlighting or keys acting weird, then you can reset the EEPROM (persistent setting storage). To force an EEPROM reset, use the [`EEP_RST` keycode](quantum_keycodes.md) or [Bootmagic Lite](feature_bootmagic.md) functionality. If neither of those are an option, then you can use a custom macro to do so.
-
- To wipe the EEPROM, run `eeconfig_init()` from your function or macro to reset most of the settings to default.
-
- ## Tap random key
-
- If you want to send a random character to the host computer, you can use the `tap_random_base64()` function. This [pseudorandomly](https://en.wikipedia.org/wiki/Pseudorandom_number_generator) selects a number between 0 and 63, and then sends a key press based on that selection. (0–25 is `A`–`Z`, 26–51 is `a`–`z`, 52–61 is `0`–`9`, 62 is `+` and 63 is `/`).
-
- ?> Needless to say, but this is _not_ a cryptographically secure method of generating random Base64 keys or passwords.
-
- ## Software Timers
-
- It's possible to start timers and read values for time-specific events. Here's an example:
-
- ```c
- static uint16_t key_timer;
- key_timer = timer_read();
-
- if (timer_elapsed(key_timer) < 100) {
- // do something if less than 100ms have passed
- } else {
- // do something if 100ms or more have passed
- }
- ```
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