Reviving your Grilleye Max thermometer with this community-driven firmware!
This project provides alternative firmware for the Grilleye Max thermometer. After the original manufacturer discontinued software support, this firmware was developed through reverse engineering to keep these capable devices functional.
Grilly+ is a fork of Free-Grilly by Epiecs and Questum, who did the reverse engineering and wrote the original firmware. This fork adds my own improvements on top. Fixes that are useful for everyone will be offered back upstream where possible.
Upgrading from Free-Grilly: Grilly+ keeps using the same settings storage (the NVS namespace is unchanged), so an OTA upgrade keeps your WiFi, probe and MQTT settings, including your existing MQTT topic prefix. Only fresh installs and factory resets use the new defaults (Grilly+ as name, grilly-plus as MQTT prefix, GrillyPlus_xxxxxx as AP name). Since your device is still running Free-Grilly the first time, flash it the normal way, through Free-Grilly's own /update page.
Grilly+ is the same firmware Free-Grilly users already know, with a new web app and a round of reliability fixes on top:
- New web app. A dashboard with a card per connected probe; tap one to set its name, target temperature or range with steppers. Settings save themselves, and it works just as well on a phone as on a desktop, in dark or light theme depending on the device.
- Firmware updates moved into the app. They now happen from the Settings view instead of the old ElegantOTA
/updatepage, and can be protected with an admin password. - A generated hotspot password on new or factory-reset devices, shown on the device's Info screen, so the local access point isn't open to anyone in range by default.
- Tighter security around settings and updates: passwords are never returned by the API, and cross-site pages can no longer change your settings or push a firmware update.
- A round of reliability fixes: the grill boots back up on its own after an update, a crash or a factory reset; a saved static IP that's missing a gateway now falls back to DHCP instead of going unreachable; empty probe sockets no longer flicker; and muted alarms stay muted when you save a probe.
- Reach it by name:
http://grilly-plus-xxxxxxxx.localinstead of looking up an IP address. - Mute from your phone: a sounding alarm can be muted from the web app or over MQTT, and the card of the probe that triggered it is highlighted.
- Calibration offset per probe, for probes that read a little high or low.
- Diagnostics: the About page shows why the grill last restarted or switched off, and the battery voltage.
- Temperature graphs: every probe card shows a graph of the whole cook, and the probe editor has a large chart with a "30 min / Whole cook" switch and a Clear history button.
- Time to target: "ready in ~1h 20m" on the card, in the editor, on the grill's own screen and over MQTT, worked out from how fast the probe has been heating up.
- Blinking alarm label on the grill's screen, so you can see which probe is beeping.
- Low-battery protection: the grill switches itself off cleanly before an empty battery causes brownouts.
See the Features list below for the full picture, and changelog.md for the detailed history.
🤖 Built with AI
Grilly+ is developed with the help of AI coding agents (Anthropic's Claude). Every change goes through a pull request with automated tests and a code review, and firmware changes are tested on a real Grilleye Max before they're merged. Still, read the changes yourself if you rely on them, and report anything that looks wrong in the Issues.
- This firmware is unofficial and NOT affiliated with or endorsed by the original manufacturer (GrillEye® by G&C).
- Flashing custom firmware onto your device carries risks. You could potentially damage or "brick" your Grilleye Max.
- You proceed entirely at your own risk. The authors and contributors are not responsible for any damage to your device.
- Flashing custom firmware will void any remaining manufacturer warranty.
- On-Device Temperature Display: Shows current probe temperatures directly on the Grilleye Max screen. The probe screen shows the time to target, and the label of a probe whose alarm is sounding blinks.
- Audible Alerts: The device beeps to notify you when temperatures go outside a set range or when food is nearing its target temperature, following the "Beep when ready" and "Beep outside target" settings, and it won't replay an alarm you already muted just because you renamed a probe or saved a setting. A sounding alarm can also be muted from the web app or over MQTT, not just the device's button, and the web app highlights the specific probe card(s) that triggered it.
- New web app: a dashboard with a card per connected probe. Tap one to set its name, target temperature or a min/max range, with large steppers for quick adjustments. Settings save themselves, network changes are applied together with one button, password fields have a show/hide button, and the app works equally well on a phone or a desktop, in a dark or light theme that follows the device.
- Dual Web Access: Access the web interface via:
- A local Access Point (AP) mode (
http://192.168.200.10) for initial setup. - Your home WiFi network (once configured) using the device's local IP address. The About page shows both addresses.
- A local Access Point (AP) mode (
- mDNS discovery: the grill is also reachable at
http://grilly-plus-xxxxxxxx.local, no IP lookup needed, both on your home WiFi and on its own hotspot. The exact address is shown on the device's Info screen and the web app's About page. Some Android versions don't resolve.localnames in the browser; the IP address still works there. - Temperature graphs: each probe card shows a graph of the whole cook with the target line or range band, the time span and the temperature range. Tap a card for a large chart with temperature labels, a "30 min / Whole cook" switch and a Clear history button (two taps). The grill keeps the last 30 minutes at 10 seconds per reading plus the whole cook at a coarser step, in a fixed ~5 KB of memory, so even a 24-hour cook fits. The history is kept until a restart, a probe is unplugged for more than 10 minutes, or you clear it.
- Time to target: in target mode the grill works out when the probe will be ready from the last 10 minutes of readings, and shows it as "ready in ~1h 20m" on the card and in the editor, as "in 1:20" on the device's probe screen, and as
eta_secondsin the API and MQTT. It restarts quickly after a drop, for example when you open the lid. - Diagnostics on the About page: battery voltage plus why the grill last restarted or was switched off (crash, watchdog, update, button, factory reset, ...), so an unexpected power-off no longer needs guesswork.
- Generated hotspot password: new and factory-reset devices get a random hotspot password, shown on the device's Info screen, instead of an open access point. Devices upgraded from an earlier version keep whatever hotspot password (or lack of one) they already had.
- Probe Flexibility:
- Custom Probe Configuration: Manually configure support for various NTC thermistor probes by entering their specific resistance (kΩ at reference temperature), reference temperature (°C), and Beta coefficient value.
- Pre-configured Probes: Includes ready-to-use settings for popular probes like the Ikea Fantast.
- Calibration offset: Fine-tune a probe that reads a little high or low with a per-probe offset (-10..10 °C), applied to every reading before it's shown, alarmed on or sent out.
- Empty probe sockets no longer flicker between connected and disconnected.
- Firmware updates from the web app: install a new
-ota.binfrom the Settings view. An optional admin password can protect updates; changing or removing it requires the current one, and it can't be changed over MQTT. - Local REST API: Provides a RESTful API endpoint on the device for integration with custom scripts, home automation systems, or other applications. Passwords are never returned by the API, and cross-site pages can't change your settings or push a firmware update.
- MQTT support: All data (grill status/probes/settings/
connected_seconds) is sent to an mqtt topic. You can also configure probes and settings via mqtt, including partial updates that only change the keys you send. - Battery Management: Includes functional battery monitoring and management based on the device's hardware. A failed fuel-gauge reading is detected and ignored instead of showing up as 65535 %. When the battery is empty (5 % or 3.2 V, not charging, confirmed for 15 seconds) the grill beeps three times and switches itself off cleanly; About then shows "Battery empty" as the reason.
- Button Functionality: The side button works for powering the device on/off and performing a factory reset (via long 10 seconds press). It's debounced, so electrical noise can't cut a long press short or fake a press.
- Persistent Settings: All your configuration settings are saved directly on the device's non-volatile memory.
- Reliability: the grill boots straight back up after a firmware update, a factory reset, or an unexpected crash, instead of needing the button held; a saved static IP with a missing gateway falls back to DHCP instead of leaving the device unreachable. The early warning beep no longer pauses probe readings, and data shared between the firmware's tasks is locked so it can't be read while it's being changed.
- Opengrill (experimental): Support for the upcoming Opengrill server by epiecs. The server is not public yet, so leave the Opengrill setting empty.
Open the grill's address in a browser on your phone or computer. The dashboard shows every connected probe with a graph of the cook; tap one for a large chart and to set its name, a target temperature or a range. Settings save themselves.
- Api documentation is include in the openapi.yaml file
- You can also view this online
GET /api/infotells an app or integration which firmware runs and which Grilly+ features (capabilities) it has.GET /api/historyreturns the temperature history of the connected probes,POST /api/history/clearclears one.
For installation please refer to the Flashing guide
- Power On: Turn on your Grilleye Max by pressing the side button. Once you hear the beeps you can release the button.
- AP Mode: The device will initially boot into Access Point (AP) mode. It will create its own WiFi network. (GrillyPlus_xxxxxx)
- If you can not see this network you can hold the side button for 2 seconds until you hear 2 beeps and then release the button. The screen will now show you the name of the wifi ap on your grilly-plus
- Connect to AP: Using your phone or computer, connect to this new WiFi network.
- Access Web Interface: Open a web browser and navigate to
http://192.168.200.10. - Configure WiFi: Find the "Settings" or "WiFi Configuration" page in the web interface. Select your home WiFi network (SSID), enter the password, and save.
- Reconnect: The Grilleye Max should now connect to your own WiFi network. Its IP address will now be assigned by your router (The local ap will keep on working as well). You can also reach it at
http://grilly-plus-xxxxxxxx.localinstead of looking up the IP; the exact address is on the device's Info screen and the web app's About page.
- Temperatures: Temperature readings from connected probes are displayed on the device's screen and updated in the web interface.
- Web Interface: Access the web interface using the IP address assigned by your router to view temperatures, change settings, etc.
- Probe Settings: Within the web interface settings, you can:
- Set minimum and target temperature alerts for each probe.
- Configure the type of probe connected (e.g., adjust settings to work with Ikea Fantast probes).
- Hold the button for 2 seconds to boot the device. You will hear 2 beeps
- If the device is booted hold the button for 2 seconds until you hear 2 beeps and then release the button to view a status screen with wifi details etc
- Tap the button to return to the temperature view
- Hold the button for 3 seconds until you hear 3 beeps to turn the device off
- Hold the button for 10 seconds until you hear 3 long beeps to factory reset
Once Grilly+ is installed, you can update to newer versions wirelessly:
- Download the latest
grilly-plus-yyyy-mm-dd-ota.binfrom Releases. - Open the web interface and go to Settings, then Firmware updates.
- Choose the downloaded
-ota.binfile and press Update. If you set an admin password, enter it under Current admin password first. - Wait while it uploads and installs. The grill restarts on its own and the page reloads.
Set an admin password in the same card so only you can install firmware. Once it is set, changing or removing it needs the current one (the web app asks for it, the API takes it as Basic auth with user admin). It can't be changed over MQTT.
Grilly+ supports more probes that the included Grilleye Iris probes. Support for the following probes is built-in:
| Probe type | ref C | ref kOhm | ref beta | notes |
|---|---|---|---|---|
| Grilleye Iris | 25 | 100 | 4250 | The best probe you can use. Fast and accurate |
| Ikea fantast | 25 | 230 | 4250 | Slow. Do not use for quick measurements |
| Maverick ET733 | 25 | 200 | 4250 | |
| Weber Igrill | 25 | 100 | 3830 |
Apart from that you can also add your own custom NTC probes if you know the 3 most important values
- Reference temperature in Celcius
- Reference beta value
- Reference resistance in kOhm
If you want you can use our handy calculator spreadsheet if you want to calculate the values for your own probes.
The Opengrill server is not publicly available yet. Once it is, enter its ip in the Opengrill field on the settings page. As long as the field is empty, Grilly+ does not try to reach an Opengrill server.
You can connect your Grilly+ to your current home assistant installation when using the mqtt broker. For this you will need to manually create the needed entities. @woutercoppens provided us/you with a decent starting point. This can also be seen in Free-Grilly issue #5.
The example uses the new default topic prefix grilly-plus. If you upgraded from Free-Grilly, your device keeps its old free-grilly prefix, so either use that in the state_topic lines or change the prefix in the settings.
# Probe 1 (Defines Anchors)
- name: "Grilly+ Probe 1 Temperature"
unique_id: "grilly_plus_probe_1_temp"
<<: &probe_temp_defaults
state_topic: "grilly-plus/7107d787-30c7-4d20-9b1b-db4cfd14fca4/grill" #Adjust
unit_of_measurement: "°C"
device_class: temperature
state_class: measurement
payload_available: "online"
payload_not_available: "offline"
device: &device_info
identifiers: "grilly_plus_7107d787" #Adjust
name: "Grilly+ Thermometer"
manufacturer: "Grilly+"
sw_version: "25.08.27"
value_template: "{{ value_json.probes[0].temperature }}"
availability_template: "{{ 'online' if value_json.probes[0].connected == true else 'offline' }}"
- name: "Grilly+ Probe 1 Target"
unique_id: "grilly_plus_probe_1_target"
<<: &probe_target_defaults
state_topic: "grilly-plus/7107d787-30c7-4d20-9b1b-db4cfd14fca4/grill" #Adjust
unit_of_measurement: "°C"
device_class: temperature
icon: mdi:target
payload_available: "online"
payload_not_available: "offline"
device: *device_info
value_template: "{{ value_json.probes[0].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[0].connected == true else 'offline' }}"
# Probe 2
- name: "Grilly+ Probe 2 Temperature"
unique_id: "grilly_plus_probe_2_temp"
<<: *probe_temp_defaults
value_template: "{{ value_json.probes[1].temperature }}"
availability_template: "{{ 'online' if value_json.probes[1].connected == true else 'offline' }}"
- name: "Grilly+ Probe 2 Target"
unique_id: "grilly_plus_probe_2_target"
<<: *probe_target_defaults
value_template: "{{ value_json.probes[1].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[1].connected == true else 'offline' }}"
# Probe 3
- name: "Grilly+ Probe 3 Temperature"
unique_id: "grilly_plus_probe_3_temp"
<<: *probe_temp_defaults
value_template: "{{ value_json.probes[2].temperature }}"
availability_template: "{{ 'online' if value_json.probes[2].connected == true else 'offline' }}"
- name: "Grilly+ Probe 3 Target"
unique_id: "grilly_plus_probe_3_target"
<<: *probe_target_defaults
value_template: "{{ value_json.probes[2].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[2].connected == true else 'offline' }}"
# Probe 4
- name: "Grilly+ Probe 4 Temperature"
unique_id: "grilly_plus_probe_4_temp"
<<: *probe_temp_defaults
value_template: "{{ value_json.probes[3].temperature }}"
availability_template: "{{ 'online' if value_json.probes[3].connected == true else 'offline' }}"
- name: "Grilly+ Probe 4 Target"
unique_id: "grilly_plus_probe_4_target"
<<: *probe_target_defaults
value_template: "{{ value_json.probes[3].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[3].connected == true else 'offline' }}"
# Probe 5
- name: "Grilly+ Probe 5 Temperature"
unique_id: "grilly_plus_probe_5_temp"
<<: *probe_temp_defaults
value_template: "{{ value_json.probes[4].temperature }}"
availability_template: "{{ 'online' if value_json.probes[4].connected == true else 'offline' }}"
- name: "Grilly+ Probe 5 Target"
unique_id: "grilly_plus_probe_5_target"
<<: *probe_target_defaults
value_template: "{{ value_json.probes[4].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[4].connected == true else 'offline' }}"
# Probe 6
- name: "Grilly+ Probe 6 Temperature"
unique_id: "grilly_plus_probe_6_temp"
<<: *probe_temp_defaults
value_template: "{{ value_json.probes[5].temperature }}"
availability_template: "{{ 'online' if value_json.probes[5].connected == true else 'offline' }}"
- name: "Grilly+ Probe 6 Target"
unique_id: "grilly_plus_probe_6_target"
<<: *probe_target_defaults
value_template: "{{ value_json.probes[5].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[5].connected == true else 'offline' }}"
# Probe 7
- name: "Grilly+ Probe 7 Temperature"
unique_id: "grilly_plus_probe_7_temp"
<<: *probe_temp_defaults
value_template: "{{ value_json.probes[6].temperature }}"
availability_template: "{{ 'online' if value_json.probes[6].connected == true else 'offline' }}"
- name: "Grilly+ Probe 7 Target"
unique_id: "grilly_plus_probe_7_target"
<<: *probe_target_defaults
value_template: "{{ value_json.probes[6].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[6].connected == true else 'offline' }}"
# Probe 8
- name: "Grilly+ Probe 8 Temperature"
unique_id: "grilly_plus_probe_8_temp"
<<: *probe_temp_defaults
value_template: "{{ value_json.probes[7].temperature }}"
availability_template: "{{ 'online' if value_json.probes[7].connected == true else 'offline' }}"
- name: "Grilly+ Probe 8 Target"
unique_id: "grilly_plus_probe_8_target"
<<: *probe_target_defaults
value_template: "{{ value_json.probes[7].target_temperature }}"
availability_template: "{{ 'online' if value_json.probes[7].connected == true else 'offline' }}"
# Battery
- name: "Grilly+ Battery"
unique_id: "grilly_plus_battery"
state_topic: "grilly-plus/7107d787-30c7-4d20-9b1b-db4cfd14fca4/grill" #Adjust
unit_of_measurement: "%"
device_class: battery
state_class: measurement
payload_available: "online"
payload_not_available: "offline"
availability_template: "{{ 'online' if value_json.wifi_connected else 'offline' }}"
value_template: "{{ value_json.battery_percentage }}"
device: *device_infoThe web app lives in web/ (plain HTML, CSS and JavaScript, no build step while developing).
- Edit the files in
web/. - Run
python tools/dev_server.py --mockfor mock data, orpython tools/dev_server.py <grill-ip>to use a real grill. - Open http://localhost:8000 and reload after each change.
Tests:
node --test "web/tests/*.test.js"
python -m unittest discover -s tools -p "test_*.py"
pio test -e native # firmware logic (history, time to target, low battery), needs a host C++ compiler
pio run builds web/ into the firmware automatically.
We welcome contributions to help improve Grilly+! Whether it's fixing bugs, adding features, improving documentation, or testing, your input is valuable.
Here's how you can contribute:
- Reporting Issues: If you find a bug or have an idea for a new feature, please check the existing Issues first. If it hasn't been reported, please open a new issue, providing as much detail as possible.
Submitting Changes (Pull Requests): If you'd like to contribute code or documentation changes:
- Fork the repository.
- Create a new branch for your changes (
git checkout -b feature/your-feature-name). - Make your changes and commit them with clear messages.
- Push your branch to your fork (
git push origin feature/your-feature-name). - Open a Pull Request against the main branch of this repository.
Thank you for considering contributing to Grilly+!