LED indicators using an RGB LED

This is a ZMK module containing a simple widget that utilizes a (typically built-in) RGB LED controlled by three separate GPIOs. It is used to indicate battery level and BLE connection status in a minimalist way.

Features

Short video demo

See below video for a short demo, running through power on, profile switching and power offs.

rgbled_widget.mp4

Currently the widget does the following:

• Blink 🟢/🟡/🔴 on boot depending on battery level (for both central/peripherals), thresholds set by CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_HIGH and CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_LOW
• Blink 🔴 on every battery level change if below critical battery level (CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_CRITICAL)
• Blink 🔵 for connected, 🟡 for open (advertising), 🔴 for disconnected profiles on every BT profile switch (on central side for splits)
• Blink 🔵 for connected, 🔴 for disconnected on peripheral side of splits

If you enable CONFIG_RGBLED_WIDGET_SHOW_LAYER_CHANGE, the LED will show the highest active layer on every layer activation using a sequence of N cyan color blinks, where N is the zero-based index of the layer.

In addition, there are keymap behaviors you can use to show the status on demand, see below.

Installation

To use, first add this module to your config/west.yml by adding a new entry to remotes and projects:

manifest:
  remotes:
    - name: zmkfirmware
      url-base: https://github.com/zmkfirmware
    - name: caksoylar  # <-- new entry
      url-base: https://github.com/caksoylar
  projects:
    - name: zmk
      remote: zmkfirmware
      revision: main
      import: app/west.yml
    - name: zmk-rgbled-widget  # <-- new entry
      remote: caksoylar
      revision: main
  self:
    path: config

For more information, including instructions for building locally, check out the ZMK docs on building with modules.

Then, if you are using one of the boards supported by the rgbled_adapter shield such as Xiao BLE, just add the rgbled_adapter as an additional shield to your build, e.g. in build.yaml:

---
include:
  - board: seeeduino_xiao_ble
    shield: hummingbird rgbled_adapter

For other keyboards, see the "Adding support" section below.

Showing status on demand

This module also defines keymap behaviors to let you show battery or connection status on demand:

#include <behaviors/rgbled_widget.dtsi>  // needed to use the behaviors

/ {
    keymap {
        ...
        some_layer {
            bindings = <
                ...
                &ind_bat  // indicate battery level
                &ind_con  // indicate connectivity status
                ...
            >;
        };
    };
};

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

Expand to see available configuration options

Name	Description	Default
CONFIG_RGBLED_WIDGET_INTERVAL_MS	Minimum wait duration between two blinks in ms	500
CONFIG_RGBLED_WIDGET_BATTERY_BLINK_MS	Duration of battery level blink in ms	2000
CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_HIGH	High battery level percentage	80
CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_LOW	Low battery level percentage	20
CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_CRITICAL	Critical battery level percentage, blink periodically if under	5
CONFIG_RGBLED_WIDGET_BATTERY_COLOR_HIGH	Color for high battery level (above LEVEL_HIGH)	Green (2)
CONFIG_RGBLED_WIDGET_BATTERY_COLOR_MEDIUM	Color for medium battery level (between LEVEL_LOW and LEVEL_HIGH)	Yellow (3)
CONFIG_RGBLED_WIDGET_BATTERY_COLOR_LOW	Color for low battery level (below LEVEL_LOW)	Red (1)
CONFIG_RGBLED_WIDGET_BATTERY_COLOR_CRITICAL	Color for critical battery level (below LEVEL_CRITICAL)	Red (1)
CONFIG_RGBLED_WIDGET_CONN_BLINK_MS	Duration of BLE connection status blink in ms	1000
CONFIG_RGBLED_WIDGET_CONN_COLOR_CONNECTED	Color for connected BLE connection status	Blue (4)
CONFIG_RGBLED_WIDGET_CONN_COLOR_ADVERTISING	Color for advertising BLE connection status	Yellow (3)
CONFIG_RGBLED_WIDGET_CONN_COLOR_DISCONNECTED	Color for disconnected BLE connection status	Red (1)
CONFIG_RGBLED_WIDGET_SHOW_LAYER_CHANGE	Indicate highest active layer on each layer change with a sequence of blinks	n
CONFIG_RGBLED_WIDGET_LAYER_BLINK_MS	Blink and wait duration for layer indicator	100
CONFIG_RGBLED_WIDGET_LAYER_COLOR	Color to use for layer indicator	Cyan (6)
CONFIG_RGBLED_WIDGET_LAYER_DEBOUNCE_MS	Wait duration after a layer change before showing the highest active layer	100

Color settings use the following integer values:

Color	Value
Black (none)	0
Red	1
Green	2
Yellow	3
Blue	4
Magenta	5
Cyan	6
White	7

You can add these settings to your keyboard conf file to modify the config values, e.g. in config/hummingbird.conf:

CONFIG_RGBLED_WIDGET_INTERVAL_MS=250
CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_HIGH=50
CONFIG_RGBLED_WIDGET_BATTERY_LEVEL_CRITICAL=10

Adding support in custom boards/shields

To be able to use this widget, you need three LEDs controlled by GPIOs (not smart LEDs), ideally red, green and blue colors. Once you have these LED definitions in your board/shield, simply set the appropriate aliases to the RGB LED node labels.

As an example, here is a definition for three LEDs connected to VCC and separate GPIOs for a nRF52840 controller:

/ {
    aliases {
        led-red = &led0;
        led-green = &led1;
        led-blue = &led2;
    };

    leds {
        compatible = "gpio-leds";
        status = "okay";
        led0: led_0 {
            gpios = <&gpio0 26 GPIO_ACTIVE_LOW>;  // red LED, connected to P0.26
        };
        led1: led_1 {
            gpios = <&gpio0 30 GPIO_ACTIVE_LOW>;  // green LED, connected to P0.30
        };
        led2: led_2 {
            gpios = <&gpio0 6 GPIO_ACTIVE_LOW>;  // blue LED, connected to P0.06
        };
    };
};

(If the LEDs are wired between GPIO and GND instead, use GPIO_ACTIVE_HIGH flag.)

Finally, turn on the widget in the configuration:

CONFIG_RGBLED_WIDGET=y