- # LED Indicators
-
- ?> LED indicators on split keyboards will require state information synced to the slave half (e.g. `#define SPLIT_LED_STATE_ENABLE`). See [data sync options](feature_split_keyboard.md#data-sync-options) for more details.
-
- QMK provides methods to read 5 of the LEDs defined in the HID spec:
-
- * Num Lock
- * Caps Lock
- * Scroll Lock
- * Compose
- * Kana
-
- There are three ways to get the lock LED state:
- * Configuration options in `config.h`
- * Implement `led_update_*` function
- * Call `led_t host_keyboard_led_state()`
-
- !> The `host_keyboard_led_state()` may reflect an updated state before `led_update_user()` is called.
-
- Two deprecated functions that provide the LED state as `uint8_t`:
-
- * `uint8_t led_set_kb(uint8_t usb_led)` and `_user(uint8_t usb_led)`
- * `uint8_t host_keyboard_leds()`
-
- ## Configuration Options
-
- To configure the indicators, `#define` these in your `config.h`:
-
- |Define |Default |Description |
- |---------------------|-------------|-------------------------------------------|
- |`LED_NUM_LOCK_PIN` |*Not defined*|The pin that controls the `Num Lock` LED |
- |`LED_CAPS_LOCK_PIN` |*Not defined*|The pin that controls the `Caps Lock` LED |
- |`LED_SCROLL_LOCK_PIN`|*Not defined*|The pin that controls the `Scroll Lock` LED|
- |`LED_COMPOSE_PIN` |*Not defined*|The pin that controls the `Compose` LED |
- |`LED_KANA_PIN` |*Not defined*|The pin that controls the `Kana` LED |
- |`LED_PIN_ON_STATE` |`1` |The state of the indicator pins when the LED is "on" - `1` for high, `0` for low|
-
- Unless you are designing your own keyboard, you generally should not need to change the above config options.
-
- ## LED update function
-
- When the configuration options do not provide enough flexibility, the following callbacks allow custom control of the LED behavior. These functions will be called when one of those 5 LEDs changes state:
-
- * Keyboard/revision: `bool led_update_kb(led_t led_state)`
- * Keymap: `bool led_update_user(led_t led_state)`
-
- Both receives LED state as a struct parameter. Returning `true` in `led_update_user()` will allow the keyboard level code in `led_update_kb()` to run as well. Returning `false` will override the keyboard level code, depending on how the keyboard level function is set up.
-
- ?> This boolean return type of `led_update_user` allows for overriding keyboard LED controls, and is thus recommended over the void `led_set_user` function.
-
- ### Example of keyboard LED update implementation
-
- This is a template indicator function that can be implemented on keyboard level code:
-
- ```c
- bool led_update_kb(led_t led_state) {
- bool res = led_update_user(led_state);
- if(res) {
- // writePin sets the pin high for 1 and low for 0.
- // In this example the pins are inverted, setting
- // it low/0 turns it on, and high/1 turns the LED off.
- // This behavior depends on whether the LED is between the pin
- // and VCC or the pin and GND.
- writePin(B0, !led_state.num_lock);
- writePin(B1, !led_state.caps_lock);
- writePin(B2, !led_state.scroll_lock);
- writePin(B3, !led_state.compose);
- writePin(B4, !led_state.kana);
- }
- return res;
- }
- ```
-
- ### Example of user LED update implementation
-
- This is an incomplete example will play a sound if Caps Lock is turned on or off. It returns `true` to allow keyboard LED function to maintain their state.
-
- ```c
- #ifdef AUDIO_ENABLE
- float caps_on[][2] = SONG(CAPS_LOCK_ON_SOUND);
- float caps_off[][2] = SONG(CAPS_LOCK_OFF_SOUND);
- #endif
-
- bool led_update_user(led_t led_state) {
- #ifdef AUDIO_ENABLE
- static uint8_t caps_state = 0;
- if (caps_state != led_state.caps_lock) {
- led_state.caps_lock ? PLAY_SONG(caps_on) : PLAY_SONG(caps_off);
- caps_state = led_state.caps_lock;
- }
- #endif
- return true;
- }
- ```
-
- ## Host keyboard LED state
-
- The `host_keyboard_led_state()` function will report the LED state returned from the host computer as `led_t`. This is useful for reading the LED state outside `led_update_*`. For example, you can get the boolean state of Caps Lock from the host with:
-
- ```c
- bool caps = host_keyboard_led_state().caps_lock;
- ```
-
- ## Setting Physical LED State
-
- Some keyboard implementations provide convenient methods for setting the state of the physical LEDs.
-
- ### Ergodox Boards
-
- The Ergodox implementations provide `ergodox_right_led_1`/`2`/`3_on`/`off()` to turn individual LEDs on or off, as well as `ergodox_right_led_on`/`off(uint8_t led)` to turn them on or off by their index.
-
- In addition, it is possible to specify the brightness level of all LEDs with `ergodox_led_all_set(uint8_t n)`; of individual LEDs with `ergodox_right_led_1`/`2`/`3_set(uint8_t n)`; or by index with `ergodox_right_led_set(uint8_t led, uint8_t n)`.
-
- Ergodox boards also define `LED_BRIGHTNESS_LO` for the lowest brightness and `LED_BRIGHTNESS_HI` for the highest brightness (which is the default).
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