Snowflake Firmware

Zephyr-based firmware targeting Nordic nRF54L15 based snowflake circuit, found at https://github.com/JackHack96/snowflake-pcb.

Includes BLE functionality and simple animation/control logic with a small host-side utility and web controls.

Quick Start

Prerequisites

• Linux with Nordic nRF Connect SDK (NCS) v3.1.1.
• west installed and toolchain environment initialized

Build

west build -b nrf54l15dk/nrf54l15/cpuapp

Flash

west flash

Web Bluetooth Panels

Two simple Web Bluetooth tools are included under web/ to control and configure devices directly from your browser:

• snowflake-control.html: interactive control panel for a single device
• batch-program.html: configure multiple devices with the same settings

Requirements

• Use a Chromium-based browser (Chrome or Edge).
• Ensure your OS Bluetooth is enabled and you grant browser permission to access Bluetooth.

Run locally

From the repository root, start a local server and open the panel:

Single-device control (snowflake-control.html)

• Connect: Click "Connect" and select your Snowflake device.
• Identity: Set the device name (advertised over BLE).
• Effect: Choose type and tune parameters:
  • Speed (1–10), Brightness (0–255), Option (effect-specific).
• Colors: Set Primary and Secondary RGB colors.
• Timings: Effect-specific durations used by certain effects.
• Debug Mode: Enable a direct LED control mode and set color per LED index.

Changes are sent via GATT characteristics and reflected back via notifications.

Batch programming (batch-program.html)

• Scan: Add one or more devices via the Bluetooth chooser.
• Configure: Select the effect, parameters, colors, and timings once.
• Naming: Optionally set a prefix and auto-number devices (e.g., Snowflake-1, Snowflake-2, …).
• Program All: Applies the configuration to each selected device sequentially and disconnects.

Effect Catalog

All effects use Primary/Secondary colors and common parameters unless noted.

• Solid (0): Steady Primary color at the selected Brightness.
• Breathe (1): Pulsing brightness of the Primary color; Speed controls period.
• Wipe (2): Moving head over a Secondary background; Option influences step size.
• Rainbow (3): HSV rainbow across LEDs; Speed controls hue shift rate.
• Twinkle (4): Random bright sparks on a dim Secondary background; Option = number of sparks per frame.
• Comet (5): Moving bright head with fading tail; Option = tail length; Secondary used for the tail/background.
• Snowfall (6): Layered fade between Primary and Secondary; Option:
  • 0: Forward layers with blended fades
  • 1: Reverse layer order
  • 2: Focused layer transitions with background off
• Diamond (7): Random sparkle brightness over Secondary background; Option = number of sparkles per frame.
• Random Fade (8): LEDs randomly fade from Primary to Secondary.
  • Timings: Fade duration (ms) and Spawn interval (ms) control decay and new spark creation.
  • Option = number of new sparks per spawn.
• Debug (9): Renders the per-LED debug buffer; use Debug Mode and LED setter in the panel.

BLE GATT Overview

The device exposes a custom service (UUID 6e400001-b5a3-f393-e0a9-e50e24dcca9e) with characteristics used by the web panels:

• Name (6e400008…): UTF-8 string, up to 20 bytes, read/write + notify.
• Effect (6e400002…): uint8 effect ID (see catalog), read/write + notify.
• Speed (6e400003…): uint8 1–10, read/write + notify.
• Brightness (6e400004…): uint8 0–255, read/write + notify.
• Option (6e400005…): uint8 effect-specific, read/write + notify.
• Primary (6e400006…): 3 bytes RGB, read/write + notify.
• Secondary (6e400007…): 3 bytes RGB, read/write + notify.
• Timings (6e40000b…): 4 bytes little-endian: fade_ms (u16), interval_ms (u16), read/write + notify.
• Debug Mode (6e400009…): uint8 0/1, read/write + notify; enabling sets effect to Debug.
• Debug LED (6e40000a…): 4 bytes: [index,u8][R][G][B], write + notify.

Notes

• Settings persist via Zephyr settings (NVS). The device re-advertises with the configured name.
• Web Bluetooth requires a user gesture for scanning; the chooser selects one device at a time.

License

This repository may include third-party modules managed by Zephyr/NCS. Refer to upstream module licenses as needed.