Open Firenet

Local WiFi bridge for RIKA pellet stoves — replaces the proprietary Firenet 2.0 cloud dongle with an ESP32-S3 that exposes a local REST API and web interface.

No cloud account. No internet dependency. Works on your LAN.

Disclaimer — This project is not affiliated with or endorsed by RIKA Innovative Ofentechnik GmbH. The protocol was reverse-engineered for interoperability purposes only. Use at your own risk. No warranty of any kind is provided.

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What it does

RIKA stoves use a USB CDC dongle (the "Firenet 2.0" stick) to connect to RIKA's cloud. This project replaces that dongle with an ESP32-S3 that:

• Speaks the same USB CDC protocol as the original dongle
• Connects to your home WiFi
• Exposes a local web interface at http://open-firenet.local
• Exposes a REST API for home automation (Home Assistant, etc.)
• Stores all state locally — no external dependency

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Hardware

Tested hardware only — This firmware has only been tested on an ESP32-S3. Other ESP32-S3 boards will likely work. The ESP32-S2 also has native USB OTG and may work but is untested. ESP32, ESP32-C3, and other variants without native USB OTG will not work.

Required

Part	Notes
ESP32-S3 dev board with native USB	The board must expose the S3's USB OTG pins (GPIO19/20 = D+/D−) on its USB connector. Any connector type works (USB-A, USB-C, Micro-B) as long as it is wired to the S3's native USB, not to a UART bridge chip.
Cable to stove	The stove has a USB-A socket. Use whatever cable or adapter connects your board's USB port to USB-A Male (e.g. USB-C to USB-A, or USB-A to USB-A).

How it connects

The stove acts as USB host; the ESP32-S3 acts as USB device (CDC class). The firmware registers VID 0x303A / PID 0x819A to match the original dongle and be recognized by the stove's firmware.

What to look for when buying

• The board must have the ESP32-S3 chip (not ESP32, S2, or C3)
• The board must expose native USB OTG — not a UART bridge (CH340, CP2102, etc.)
• Check the schematic or product page: the native USB port is labeled "USB OTG", "USB", or connects to GPIO19/20; the UART port is labeled "UART", "COM", or connects to a bridge chip

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Flashing

Linux (recommended)

Requirements: arduino-cli, esptool, ESP32 Arduino core 3.x

chmod +x flash.sh
./flash.sh                       # serial flash via /dev/ttyACM0
./flash.sh /dev/ttyACM1          # specify serial port
./flash.sh --ota 192.168.1.x     # OTA flash via WiFi (once already running)

The script compiles then flashes bootloader + partition table + app. The NVS partition (WiFi credentials) is preserved across flashes.

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macOS

Requirements: arduino-cli, esptool, ESP32 Arduino core 3.x

Install dependencies via Homebrew:

brew install arduino-cli esptool
arduino-cli core install esp32:esp32

The serial port is named differently on macOS — find it with:

ls /dev/cu.usbmodem*

Then flash:

chmod +x flash.sh
./flash.sh /dev/cu.usbmodem14101   # adjust to your port
./flash.sh --ota 192.168.1.x       # or OTA if already running

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Windows

The flash.sh script requires a bash shell. Two options:

Option A — WSL (Windows Subsystem for Linux)

Install WSL2 then follow the Linux instructions above. To forward the USB serial port to WSL, use usbipd:

# In PowerShell (admin)
usbipd list                     # find the ESP32 busid
usbipd attach --wsl --busid <busid>

Then inside WSL:

./flash.sh /dev/ttyACM0

Option B — Flash a pre-built binary with esptool

1. Install Python and esptool:

   pip install esptool

2. Download the latest .bin from Releases (or build it on Linux/macOS).
3. Find your COM port in Device Manager (e.g. COM4).
4. Flash:

   esptool --chip esp32s3 --port COM4 --baud 460800 `
     --before default-reset --after hard-reset `
     write-flash --flash-mode dio --flash-freq 80m --flash-size 4MB `
     0x0000 open-firenet.ino.bootloader.bin `
     0x8000 open-firenet.ino.partitions.bin `
     0x10000 open-firenet.ino.bin

OTA is the easiest path on Windows — flash once via serial (Option A or B), then all subsequent updates work via ./flash.sh --ota <ip> from any platform, or directly through the /update page in the browser.

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First boot — WiFi provisioning

On first boot the bridge has no WiFi credentials and enters provisioning mode.

Two ways to provision:

Option A — Stove screen (no PC needed)

1. On the stove, go to Settings → WiFi and select your network.
2. The stove sends the credentials over USB CDC to the bridge.
3. The bridge connects and shows a connected icon on the stove screen.

Option B — Serial command (useful for testing)

Send via the serial port (/dev/ttyACM0, 115200 baud):

SETWIFI:YourSSID:YourPassword

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Web interface

Once connected, open http://open-firenet.local in a browser (or use the IP shown in the serial log).

• FR / EN language toggle in the header
• Start / Stop — disabled when the stove is already in that state
• Temperature slider — shown in Comfort mode only
• Power slider — shown in Manual and Auto modes
• Mode — Manuel / Auto / Confort (operatingMode 0 / 1 / 2)
• Log — collapsible, shows the live CDC protocol log

• OTA — firmware update via browser at /update

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REST API

Endpoint	Method	Description
/api/status	GET	JSON: wifi, ip, ssid, provisioning, mainLoop, controls
/api/sensors	GET	JSON: sensor fields from POST_SENSORS (f0 = room temp ×10)
/api/controls	GET	JSON: current setpoints (onOff, operatingMode, heatingPower, tempRoomTarget)
/api/controls	POST	Set controls — body: onOff=1; operatingMode=1; heatingPower=50; tempRoomTarget=210;
/log	GET	Plain-text log
/update	GET/POST	OTA firmware update page
/reset-wifi	GET	Erase WiFi credentials and reboot

Controls format

onOff=<0|1>; operatingMode=<0|1|2>; heatingPower=<50-100>; tempRoomTarget=<140-280>;

tempRoomTarget is ×10 (210 = 21.0 °C). heatingPower is % (50–100, values below 50 are clamped to 50).

Operating modes

Value	Mode
0	Manual (fixed power %)
1	Auto / thermostat
2	Comfort

API Explorer

docs/api-explorer.html is a standalone browser-based tool for exploring the API against your running bridge.

Open it from the repo (no server needed — it runs entirely in the browser):

open docs/api-explorer.html       # macOS
xdg-open docs/api-explorer.html   # Linux

Or, if the repo is published on GitHub Pages, the explorer is available at:

https://<your-org>.github.io/<repo>/docs/api-explorer.html

Enter your bridge address (http://open-firenet.local or the IP) in the host field at the top. The explorer checks connectivity on load and shows latency. Each endpoint has a collapsible panel with a Run button — the POST controls panel includes form fields for all setpoints.

Note: The bridge serves CORS headers (Access-Control-Allow-Origin: *) so the explorer can reach it from any origin, including file://.

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Protocol

See PROTOCOL.md for the full reverse-engineered USB CDC protocol specification.

Key facts:

• ASCII line-oriented over USB CDC
• Stove is USB host, dongle is USB device
• All commands terminated with \n or \r\n
• tempRoomTarget is always ×10 on the wire
• POST_CONTROLS does not reflect the values just written — it returns the stove's own stored values

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Home Assistant

Example REST sensor for room temperature:

sensor:
  - platform: rest
    resource: http://open-firenet.local/api/sensors
    name: Stove room temperature
    value_template: "{{ (value_json.f0 | int / 10) | round(1) }}"
    unit_of_measurement: "°C"
    scan_interval: 60

rest_command:
  rika_start:
    url: "http://open-firenet.local/api/controls"
    method: POST
    payload: "onOff=1; operatingMode=1; heatingPower=50; tempRoomTarget=210;"
    content_type: text/plain
  rika_stop:
    url: "http://open-firenet.local/api/controls"
    method: POST
    payload: "onOff=0; operatingMode=1; heatingPower=50; tempRoomTarget=210;"
    content_type: text/plain

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License

GNU Affero General Public License v3.0 or later (AGPL-3.0-or-later) — see LICENSE

Any derivative work, including commercial forks, must be distributed under the same license with the full source code made available.