feat(underglow): Add battery and BLE status to underglow

app/CMakeLists.txt

@@ -84,6 +84,11 @@ if ((NOT CONFIG_ZMK_SPLIT) OR CONFIG_ZMK_SPLIT_ROLE_CENTRAL)
     target_sources(app PRIVATE src/behaviors/behavior_bt.c)
     target_sources(app PRIVATE src/ble.c)
     target_sources(app PRIVATE src/hog.c)
+    target_sources_ifdef(CONFIG_ZMK_RGB_UNDERGLOW_BLE_STATUS app PRIVATE src/rgb_underglow/ble_status.c)
+  endif()
+else()
+  if (CONFIG_ZMK_BLE)
+    target_sources_ifdef(CONFIG_ZMK_RGB_UNDERGLOW_BLE_STATUS app PRIVATE src/rgb_underglow/ble_peripheral_status.c)
   endif()
 endif()
 
@@ -100,7 +105,21 @@ add_subdirectory_ifdef(CONFIG_ZMK_SPLIT src/split)
 
 target_sources_ifdef(CONFIG_USB_DEVICE_STACK app PRIVATE src/usb.c)
 target_sources_ifdef(CONFIG_ZMK_USB app PRIVATE src/usb_hid.c)
-target_sources_ifdef(CONFIG_ZMK_RGB_UNDERGLOW app PRIVATE src/rgb_underglow.c)
+
+if (CONFIG_ZMK_RGB_UNDERGLOW)
+  target_sources(app PRIVATE src/rgb_underglow/current_status.c)
+  target_sources(app PRIVATE src/rgb_underglow/rgb_underglow_base.c)
+  target_sources(app PRIVATE src/rgb_underglow/init.c)
+  target_sources(app PRIVATE src/rgb_underglow/state.c)
+  if (CONFIG_ZMK_RGB_UNDERGLOW_BLE_STATUS OR CONFIG_ZMK_RGB_UNDERGLOW_BATTERY_STATUS)
+    target_sources( app PRIVATE src/rgb_underglow/startup_mutex.c)
+    target_sources( app PRIVATE src/rgb_underglow/status_on_startup.c)
+  endif()
+  if (CONFIG_ZMK_RGB_UNDERGLOW_BATTERY_STATUS)
+    target_sources( app PRIVATE src/rgb_underglow/battery_status.c)
+  endif()
+endif()
+
 target_sources_ifdef(CONFIG_ZMK_BACKLIGHT app PRIVATE src/backlight.c)
 target_sources_ifdef(CONFIG_ZMK_LOW_PRIORITY_WORK_QUEUE app PRIVATE src/workqueue.c)
 target_sources(app PRIVATE src/main.c)

app/Kconfig

@@ -335,6 +335,32 @@ config ZMK_RGB_UNDERGLOW_AUTO_OFF_USB
     bool "Turn off RGB underglow when USB is disconnected"
     depends on USB_DEVICE_STACK
 
+if ZMK_BATTERY_REPORTING
+config ZMK_RGB_UNDERGLOW_BATTERY_STATUS
+    bool "Reflect the battery status with underglow"
+    default n
+
+config ZMK_RGB_UNDERGLOW_BATTERY_CRIT
+    int "Threshold for showing the RGB value for critically low battery charge"
+    range 0 100
+    default 5
+
+config ZMK_RGB_UNDERGLOW_BATTERY_LOW
+    int "Threshold for showing the RGB value for low battery charge"
+    range 0 100
+    default 15
+
+#ZMK_BATTERY_REPORTING
+endif
+
+if ZMK_BLE
+config ZMK_RGB_UNDERGLOW_BLE_STATUS
+    bool "Reflect the ble connection states with underglow"
+    default n
+
+#ZMK_BLE
+endif
+
 endif # ZMK_RGB_UNDERGLOW
 
 menuconfig ZMK_BACKLIGHT

app/include/zmk/rgb_underglow/battery_status.h

@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+int rgb_underglow_set_color_battery(uint8_t state_of_charge);

app/include/zmk/rgb_underglow/ble_peripheral_status.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr/kernel.h>
+
+struct peripheral_ble_state {
+    bool connected;
+};
+
+struct peripheral_ble_state zmk_get_ble_peripheral_state();
+int zmk_rgb_underglow_set_color_ble_peripheral(struct peripheral_ble_state ps);

app/include/zmk/rgb_underglow/ble_status.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zmk/endpoints.h>
+#include <zmk/event_manager.h>
+
+struct output_state {
+    struct zmk_endpoint_instance selected_endpoint;
+    bool active_profile_connected;
+    bool active_profile_bonded;
+};
+
+struct output_state zmk_get_output_state(void);
+int zmk_rgb_underglow_set_color_ble(struct output_state os);

app/include/zmk/rgb_underglow.h → app/include/zmk/rgb_underglow/current_status.h

@@ -1,16 +1,12 @@
 /*
- * Copyright (c) 2020 The ZMK Contributors
+ * Copyright (c) 2025 The ZMK Contributors
  *
  * SPDX-License-Identifier: MIT
  */
 
 #pragma once
 
-struct zmk_led_hsb {
-    uint16_t h;
-    uint8_t s;
-    uint8_t b;
-};
+#include <zmk/rgb_underglow/rgb_underglow_base.h>
 
 int zmk_rgb_underglow_toggle(void);
 int zmk_rgb_underglow_get_state(bool *state);
@@ -27,3 +23,5 @@ int zmk_rgb_underglow_change_sat(int direction);
 int zmk_rgb_underglow_change_brt(int direction);
 int zmk_rgb_underglow_change_spd(int direction);
 int zmk_rgb_underglow_set_hsb(struct zmk_led_hsb color);
+int zmk_rgb_underglow_apply_current_state(void);
+void zmk_rgb_underglow_init(void);

app/include/zmk/rgb_underglow/init.h

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+int zmk_rgb_ug_on(void);
+int zmk_rgb_ug_off(void);

app/include/zmk/rgb_underglow/rgb_underglow_base.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr/kernel.h>
+#include <zephyr/devicetree.h>
+#include <zmk/rgb_underglow/state.h>
+
+#if !DT_HAS_CHOSEN(zmk_underglow)
+
+#error "A zmk,underglow chosen node must be declared"
+
+#endif
+
+#define STRIP_CHOSEN DT_CHOSEN(zmk_underglow)
+#define STRIP_NUM_PIXELS DT_PROP(STRIP_CHOSEN, chain_length)
+
+int zmk_rgb_ug_select_effect(int effect);
+int zmk_rgb_ug_set_spd(int speed);
+int zmk_rgb_ug_set_hsb(struct zmk_led_hsb color);
+void zmk_rgb_ug_tick(struct k_work *work);
+void zmk_rgb_ug_tools_init(const struct device *led_strip);

app/include/zmk/rgb_underglow/startup_mutex.h

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr/kernel.h>
+
+bool is_starting_up(void);
+bool start_startup(void);
+void stop_startup(void);

app/include/zmk/rgb_underglow/state.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr/kernel.h>
+
+#define HUE_MAX 360
+#define SAT_MAX 100
+#define BRT_MAX 100
+
+struct zmk_led_hsb {
+    uint16_t h;
+    uint8_t s;
+    uint8_t b;
+};
+
+struct rgb_underglow_state {
+    struct zmk_led_hsb color;
+    uint8_t animation_speed;
+    uint8_t current_effect;
+    uint16_t animation_step;
+    bool on;
+};
+
+enum rgb_underglow_effect {
+    UNDERGLOW_EFFECT_SOLID,
+    UNDERGLOW_EFFECT_BREATHE,
+    UNDERGLOW_EFFECT_SPECTRUM,
+    UNDERGLOW_EFFECT_SWIRL,
+    UNDERGLOW_EFFECT_NUMBER // Used to track number of underglow effects
+};
+
+static const struct rgb_underglow_state default_rgb_settings = (struct rgb_underglow_state){
+    color : {
+        h : CONFIG_ZMK_RGB_UNDERGLOW_HUE_START,
+        s : CONFIG_ZMK_RGB_UNDERGLOW_SAT_START,
+        b : CONFIG_ZMK_RGB_UNDERGLOW_BRT_START,
+    },
+    animation_speed : CONFIG_ZMK_RGB_UNDERGLOW_SPD_START,
+    current_effect : CONFIG_ZMK_RGB_UNDERGLOW_EFF_START,
+    animation_step : 0,
+    on : IS_ENABLED(CONFIG_ZMK_RGB_UNDERGLOW_ON_START)
+};
+
+struct rgb_underglow_state *zmk_rgb_ug_get_state(void);
+struct rgb_underglow_state *zmk_rgb_ug_get_save_state(void);
+int zmk_rgb_ug_save_state(void);
+int zmk_rgb_ug_state_init(void);

app/src/behaviors/behavior_rgb_underglow.c

@@ -11,7 +11,7 @@
 #include <zephyr/logging/log.h>
 
 #include <dt-bindings/zmk/rgb.h>
-#include <zmk/rgb_underglow.h>
+#include <zmk/rgb_underglow/current_status.h>
 #include <zmk/keymap.h>
 
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);