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.

Usage

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

If you are building locally, see the instructions for building with external modules in ZMK docs.

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.

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

Experimental: Enable CONFIG_RGBLED_WIDGET_SHOW_LAYER_CHANGE to show the highest active layer on every layer change using a sequence of N cyan color blinks, where N is the zero-based index of the layer. Note that this can be noisy and distracting, especially if you use conditional layers.

Configuration

Blink durations can also be adjusted, see the Kconfig file for available config properties. 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 GND 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
        };
    };
};

Finally, turn on the widget in the configuration:

CONFIG_RGBLED_WIDGET=y