128 lines
5.2 KiB
Markdown
128 lines
5.2 KiB
Markdown
# LED Indicators
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::: tip
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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#data-sync-options) for more details.
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:::
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QMK provides methods to read 5 of the LEDs defined in the HID spec:
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* Num Lock
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* Caps Lock
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* Scroll Lock
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* Compose
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* Kana
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There are three ways to get the lock LED state:
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* Configuration options in `config.h`
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* Implement `led_update_*` function
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* Call `led_t host_keyboard_led_state()`
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::: warning
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The `host_keyboard_led_state()` may reflect an updated state before `led_update_user()` is called.
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:::
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Two deprecated functions that provide the LED state as `uint8_t`:
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* `uint8_t led_set_user(uint8_t usb_led)`
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* `uint8_t host_keyboard_leds()`
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## Configuration Options
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To configure the indicators, `#define` these in your `config.h`:
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|Define |Default |Description |
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|---------------------|-------------|-------------------------------------------|
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|`LED_NUM_LOCK_PIN` |*Not defined*|The pin that controls the `Num Lock` LED |
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|`LED_CAPS_LOCK_PIN` |*Not defined*|The pin that controls the `Caps Lock` LED |
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|`LED_SCROLL_LOCK_PIN`|*Not defined*|The pin that controls the `Scroll Lock` LED|
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|`LED_COMPOSE_PIN` |*Not defined*|The pin that controls the `Compose` LED |
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|`LED_KANA_PIN` |*Not defined*|The pin that controls the `Kana` LED |
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|`LED_PIN_ON_STATE` |`1` |The state of the indicator pins when the LED is "on" - `1` for high, `0` for low|
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Unless you are designing your own keyboard, you generally should not need to change the above config options.
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## LED update function
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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:
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* Keyboard/revision: `bool led_update_kb(led_t led_state)`
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* Keymap: `bool led_update_user(led_t led_state)`
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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.
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::: tip
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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.
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:::
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### Example of keyboard LED update implementation
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This is a template indicator function that can be implemented on keyboard level code:
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```c
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bool led_update_kb(led_t led_state) {
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bool res = led_update_user(led_state);
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if(res) {
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// gpio_write_pin sets the pin high for 1 and low for 0.
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// In this example the pins are inverted, setting
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// it low/0 turns it on, and high/1 turns the LED off.
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// This behavior depends on whether the LED is between the pin
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// and VCC or the pin and GND.
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gpio_write_pin(B0, !led_state.num_lock);
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gpio_write_pin(B1, !led_state.caps_lock);
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gpio_write_pin(B2, !led_state.scroll_lock);
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gpio_write_pin(B3, !led_state.compose);
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gpio_write_pin(B4, !led_state.kana);
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}
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return res;
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}
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```
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### Example of user LED update implementation
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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.
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```c
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#ifdef AUDIO_ENABLE
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float caps_on[][2] = SONG(CAPS_LOCK_ON_SOUND);
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float caps_off[][2] = SONG(CAPS_LOCK_OFF_SOUND);
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#endif
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bool led_update_user(led_t led_state) {
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#ifdef AUDIO_ENABLE
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static uint8_t caps_state = 0;
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if (caps_state != led_state.caps_lock) {
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led_state.caps_lock ? PLAY_SONG(caps_on) : PLAY_SONG(caps_off);
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caps_state = led_state.caps_lock;
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}
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#endif
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return true;
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}
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```
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## Host keyboard LED state
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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:
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```c
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bool caps = host_keyboard_led_state().caps_lock;
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```
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## `led_update_ports()`
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This function writes the LED state to the actual hardware. Call it manually
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from your `led_update_*()` callbacks to modify the handling of the standard
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keyboard LEDs.
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For example when repurposing a standard LED indicator as layer indicator.
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## Setting Physical LED State
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Some keyboard implementations provide convenient methods for setting the state of the physical LEDs.
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### Ergodox Boards
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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.
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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)`.
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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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