Document and define different RGB effects

app/include/dt-bindings/zmk/rgb.h

@@ -38,4 +38,9 @@
 #define RGB_MEFS RGB_MEFS_CMD
 #define RGB_COLOR_HSB_VAL(h, s, v) (((h) << 16) + ((s) << 8) + (v))
 #define RGB_COLOR_HSB(h, s, v) RGB_COLOR_HSB_CMD##(RGB_COLOR_HSB_VAL(h, s, v))
-#define RGB_COLOR_HSV RGB_COLOR_HSB
+#define RGB_COLOR_HSV RGB_COLOR_HSB
+
+#define RGB_EFF_SOLID 0
+#define RGB_EFF_BREATHE 1
+#define RGB_EFF_SPECTRUM 2
+#define RGB_EFF_SWIRL 3

docs/docs/behaviors/underglow.md

@@ -65,7 +65,14 @@ However the settings will only be saved after [`CONFIG_ZMK_SETTINGS_SAVE_DEBOUNC
 
 :::note Effect Selection
 
-When using the `RGB_EFS` or `RGB_MEFS` definitions you must also include a number as an argument in the keymap corresponding to the effect you want to select e.g. `RGB_EFS 0`
+When using the `RGB_EFS` or `RGB_MEFS` definitions you must also include a number as an argument in the keymap corresponding to the effect you want to select e.g. `RGB_EFS 0`. There are 4 RGB effects currently, defined in [`dt-bindings/zmk/rgb.h`](https://github.com/zmkfirmware/zmk/blob/main/app/include/dt-bindings/zmk/rgb.h). They correspond to the options for [`CONFIG_ZMK_RGB_UNDERGLOW_EFF_START`](../config/underglow.md#kconfig).
+
+| Value            | Effect                                     |
+| ---------------- | ------------------------------------------ |
+| RGB_EFF_SOLID    | Solid color (Set by HSV)                   |
+| RGB_EFF_BREATHE  | Breathe a solid colour                     |
+| RGB_EFF_SPECTRUM | Cycle all LEDs through the colour spectrum |
+| RGB_EFF_SWIRL    | Swirl a rainbow around the LEDs            |
 
 If the `RGB_MEFS` key is held down for longer than [`CONFIG_ZMK_SETTINGS_SAVE_DEBOUNCE`](../config/system.md#general) milliseconds and the board is reset prior to releasing the key the temporary effect will have been saved to flash memory and will be restored after resetting/power cycling