Get behavior to build and work in mixed board setups

Kconfig

@@ -45,10 +45,10 @@ config RGBLED_WIDGET_LAYER_DEBOUNCE_MS
 
 endif # RGBLED_WIDGET_SHOW_LAYER_CHANGE
 
+endif # RGBLED_WIDGET
+
 DT_COMPAT_ZMK_BEHAVIOR_RGBLED_WIDGET := zmk,behavior-rgbled-widget
 
 config ZMK_BEHAVIOR_RGBLED_WIDGET
     bool
     default $(dt_compat_enabled,$(DT_COMPAT_ZMK_BEHAVIOR_RGBLED_WIDGET))
-
-endif

README.md

@@ -84,6 +84,10 @@ This module also defines keymap [behaviors](https://zmk.dev/docs/keymaps/behavio
 When you invoke the behavior by pressing the corresponding key (or combo), it will trigger the LED color display.
 This will happen on all keyboard parts for split keyboards, so make sure to flash firmware to all parts after enabling.
 
+> [!NOTE]
+> The behaviors can be used even when you use split keyboards with different controllers that don't all support the widget.
+> Make sure that you use the `rgbled_adapter` shield (or enable `CONFIG_RGBLED_WIDGET`) only for the keyboard parts that support it.
+
 ## Configuration
 
 Blink durations can also be adjusted, see the [Kconfig file](Kconfig) for available config properties.

src/behaviors/behavior_rgbled_widget.c

@@ -20,6 +20,7 @@ static int behavior_rgb_wdg_init(const struct device *dev) { return 0; }
 
 static int on_keymap_binding_pressed(struct zmk_behavior_binding *binding,
                                      struct zmk_behavior_binding_event event) {
+#if IS_ENABLED(CONFIG_RGBLED_WIDGET)
     const struct device *dev = zmk_behavior_get_binding(binding->behavior_dev);
     const struct behavior_rgb_wdg_config *cfg = dev->config;
 
@@ -38,6 +39,7 @@ static int on_keymap_binding_pressed(struct zmk_behavior_binding *binding,
         indicate_layer();
     }
 #endif
+#endif // IS_ENABLED(CONFIG_RGBLED_WIDGET)
 
     return ZMK_BEHAVIOR_OPAQUE;
 }