Force backlight on when led matrix is enabled

[qmk_firmware.git] / docs / custom_quantum_functions.md

diff --git a/docs/custom_quantum_functions.md b/docs/custom_quantum_functions.md
index 5b95450f2670f45e7c6c309621db04618f13b799..d44786e2d512855dda29b60b18e0e7b982e6cd9b 100644 (file)
--- a/docs/custom_quantum_functions.md
+++ b/docs/custom_quantum_functions.md
@@ -90,7 +90,7 @@ keyrecord_t record {
 
 # LED Control
 
-This allows you to control the 5 LED's defined as part of the USB Keyboard spec. It will be called when the state of one of those 5 LEDs changes.
+QMK provides methods to read the 5 LEDs defined as part of the HID spec:
 
 * `USB_LED_NUM_LOCK`
 * `USB_LED_CAPS_LOCK`
@@ -98,31 +98,44 @@ This allows you to control the 5 LED's defined as part of the USB Keyboard spec.
 * `USB_LED_COMPOSE`
 * `USB_LED_KANA`
 
+These five constants correspond to the positional bits of the host LED state.
+There are two ways to get the host LED state:
+
+* by implementing `led_set_user()`
+* by calling `host_keyboard_leds()`
+
+## `led_set_user()`
+
+This function will be called when the state of one of those 5 LEDs changes. It receives the LED state as a parameter.
+Use the `IS_LED_ON(usb_led, led_name)` and `IS_LED_OFF(usb_led, led_name)` macros to check the LED status.
+
+!> `host_keyboard_leds()` may already reflect a new value before `led_set_user()` is called.
+
 ### Example `led_set_user()` Implementation
 
 ```c
 void led_set_user(uint8_t usb_led) {
-    if (usb_led & (1<<USB_LED_NUM_LOCK)) {
+    if (IS_LED_ON(usb_led, USB_LED_NUM_LOCK)) {
         PORTB |= (1<<0);
     } else {
         PORTB &= ~(1<<0);
     }
-    if (usb_led & (1<<USB_LED_CAPS_LOCK)) {
+    if (IS_LED_ON(usb_led, USB_LED_CAPS_LOCK)) {
         PORTB |= (1<<1);
     } else {
         PORTB &= ~(1<<1);
     }
-    if (usb_led & (1<<USB_LED_SCROLL_LOCK)) {
+    if (IS_LED_ON(usb_led, USB_LED_SCROLL_LOCK)) {
         PORTB |= (1<<2);
     } else {
         PORTB &= ~(1<<2);
     }
-    if (usb_led & (1<<USB_LED_COMPOSE)) {
+    if (IS_LED_ON(usb_led, USB_LED_COMPOSE)) {
         PORTB |= (1<<3);
     } else {
         PORTB &= ~(1<<3);
     }
-    if (usb_led & (1<<USB_LED_KANA)) {
+    if (IS_LED_ON(usb_led, USB_LED_KANA)) {
         PORTB |= (1<<4);
     } else {
         PORTB &= ~(1<<4);
@@ -135,10 +148,26 @@ void led_set_user(uint8_t usb_led) {
 * Keyboard/Revision: `void led_set_kb(uint8_t usb_led)`
 * Keymap: `void led_set_user(uint8_t usb_led)`
 
+## `host_keyboard_leds()`
+
+Call this function to get the last received LED state. This is useful for reading the LED state outside `led_set_*`, e.g. in [`matrix_scan_user()`](#matrix-scanning-code).
+For convenience, you can use the `IS_HOST_LED_ON(led_name)` and `IS_HOST_LED_OFF(led_name)` macros instead of calling and checking `host_keyboard_leds()` directly.
+
+## Setting Physical LED State
+
+Some keyboard implementations provide convenience 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).
 
 # Matrix Initialization Code
 
-Before a keyboard can be used the hardware must be initialized. QMK handles initialization of the keyboard matrix itself, but if you have other hardware like LED's or i&#xb2;c controllers you will need to set up that hardware before it can be used.
+Before a keyboard can be used the hardware must be initialized. QMK handles initialization of the keyboard matrix itself, but if you have other hardware like LEDs or i&#xb2;c controllers you will need to set up that hardware before it can be used.
 
 
 ### Example `matrix_init_user()` Implementation
@@ -176,7 +205,7 @@ This example has been deliberately omitted. You should understand enough about Q
 
 This function gets called at every matrix scan, which is basically as often as the MCU can handle. Be careful what you put here, as it will get run a lot.
 
-You should use this function if you need custom matrix scanning code. It can also be used for custom status output (such as LED's or a display) or other functionality that you want to trigger regularly even when the user isn't typing.
+You should use this function if you need custom matrix scanning code. It can also be used for custom status output (such as LEDs or a display) or other functionality that you want to trigger regularly even when the user isn't typing.
 
 
 # Keyboard Idling/Wake Code