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Gluco-Monitor

Gluco-Monitor (DIY)

Gluco-Monitor is an open-source DIY glucose monitor built on an ESP32-S3 with a 320×480 touchscreen. It retrieves real-time CGM data from FreeStyle Libre, Dexcom, or NightScout and displays it on a dedicated always-on screen — no phone needed.

⚠️ Not a medical device. Do not use for medical decisions. Always rely on your official CGM device and your healthcare provider's advice.

✨ Features

Category Details
📡 Data sources FreeStyle Libre (LibreLinkUp API), Dexcom Share, NightScout REST API
🖥️ Display Real-time glucose value, trend arrow, age indicator, 8-hour bar chart; tap the glucose value to cycle through three layouts: Normal (bar chart), large gauge (altView_01), and colour-coded full-screen (altView_02)
📐 Units mg/dL or mmol/L (user-selectable)
🎯 Thresholds Configurable target range, warning levels, gauge scale
🌐 Languages English, Français, Deutsch, Español, Italiano, Polski
📊 Dashboard Real-time view at http://<device-ip>/ from any browser on your network; dark-themed unified navigation across all pages
⚙️ Web config Full device configuration at http://<device-ip>/Settings — sensor credentials, display settings, glucose thresholds, layout, day/night brightness schedule, MQTT — no cable or on-screen keyboard needed
🏠 Home Assistant MQTT auto-discovery: screen on/off switch, day/night brightness + schedule toggle, layout selector; state published as retained JSON; configurable via /Settings
🔄 OTA updates Firmware update via web interface — no cable needed
🚀 First-boot On-screen wizard or Wi-Fi AP captive portal (mobile-friendly)
💾 Persistence All settings saved to LittleFS — survive power cycles
💰 Cost ~$25 USD for components

🛠️ Hardware

Component Specification
🔲 Microcontroller ESP32-S3 (esp32-s3-devkitc-1)
🗄️ Flash 16 MB QIO
🧠 PSRAM OPI mode
📺 Display 320×480 AXS15231B TFT touchscreen
👆 Touch I2C controller (address 0x3B)
📶 Wi-Fi 802.11 b/g/n (built-in)
⚡ Power USB or battery

👉 Full hardware assembly guide: https://f1atb.fr/gluco-monitor-diy/

📦 Installation

Prerequisites

  • PlatformIO (VS Code extension or CLI)
  • ESP32-S3 board with 16 MB flash and OPI PSRAM

Build & Flash

# Clone the repository
git clone https://github.com/F1ATB/Gluco-Monitor.git
cd Gluco-Monitor

# Build firmware
pio run

# Build and flash to device
pio run -t upload

# Monitor serial output (115200 baud)
pio device monitor

Note: GFX Library for Arduino v1.6.1+ is incompatible with this project — it is pinned to ^1.5.3 in platformio.ini.

The build produces Gluco-Monitor_<version>.bin. A merged full-chip image (Gluco-Monitor_<version>.factory.bin, including bootloader and partition table) is also generated for first-time flashing with esptool.

🚀 First-Boot Setup

On first power-on (no Wi-Fi configured), the device offers two setup methods:

Option A — On-Screen Setup

  1. Select your Wi-Fi network from the on-screen list
  2. Enter the password with the on-screen keyboard
  3. Choose language, timezone, sensor type, and credentials
  4. Device connects and starts displaying glucose data

Option B — AP (Captive Portal) Mode

  1. Device broadcasts a temporary Wi-Fi network: GlucoMonit-xxxxx (password: monitor1)
  2. Connect with your phone — the setup page opens automatically
  3. Fill in: Wi-Fi credentials, sensor type & credentials, glucose thresholds, language, timezone
  4. Tap Save → device restarts in normal mode

📡 Supported Sensors

Sensor API Authentication
FreeStyle Libre LibreLinkUp Email + password + region
Dexcom Dexcom Share Username + password + region (US / Non-US / JP)
NightScout REST API v1 URL + access token (token optional for public instances)

Switch between sensors at any time in the Account screen or via the /Settings web page. Glucose history is cleared automatically when switching sources.

🖥️ Home Screen Layouts

Tap the glucose value to cycle through three display layouts:

Layout Description
Normal Semicircle gauge, 8-hour colour-coded bar chart, trend arrow, time, age indicator
altView_01 Large semicircle gauge (1.5× radius) with needle, no bar chart — easier to read at a glance
altView_02 Full-screen background colour reflects current glucose range (🔴 below target / 🟢 in range / 🟠 above target / 🟣 very high), large glucose value, no gauge or needle

A 400 ms touch-suppression window is applied after every layout or page transition, preventing ghost-taps on incoming buttons.

🌐 Web Dashboard

Open http://<device-ip>/ from any browser on the same Wi-Fi network for a real-time glucose view. All pages share a unified dark-theme design with a common navigation bar (Glucose | Settings | Data | Update | Restart | Erase).

Key endpoints:

Endpoint Description
GET / Main dashboard — real-time glucose, trend, history chart
GET /Settings Full device configuration UI (requires on-device authorization)
GET /ajaxSettings Current device config as JSON (no passwords)
POST /saveSettings Apply configuration changes immediately
POST /testConnection Test sensor credentials from the browser
GET /ajaxGlycemie Current reading (JSON, polled by UI)
GET /dataGly 8-hour glucose history (binary blob)
GET /Brute Collapsible JSON data view with syntax highlighting
GET /OTA OTA firmware upload (requires on-device authorization)
GET /Restart Restart confirmation page
POST /Restart Trigger actual device reboot
GET /eraseConfig Erase all saved configuration and restart

🏠 Home Assistant / MQTT Integration

Gluco-Monitor supports MQTT auto-discovery for Home Assistant. Once configured, the device publishes its state and registers four entities automatically — no manual YAML configuration needed.

Setup

  1. Open http://<device-ip>/Settings in your browser (requires on-device authorization)
  2. Scroll to the MQTT section
  3. Enter broker address, port (default 1883), and optional credentials
  4. Click Test Connection to verify
  5. Click Save — the device connects and publishes discovery messages immediately

Topics

Topic Direction Description
gluco_monitor/<MAC6>/state Device → HA Retained JSON: screen, brightness, brightness_day, brightness_night, night_schedule_disabled, layout
gluco_monitor/<MAC6>/cmd/screen HA → Device ON / OFF — turn display on or off
gluco_monitor/<MAC6>/cmd/brightness HA → Device 0–100 (%) — live override; not saved, does not affect the schedule
gluco_monitor/<MAC6>/cmd/brightness_day HA → Device 0–100 (%) — day brightness used by the on-device schedule
gluco_monitor/<MAC6>/cmd/brightness_night HA → Device 0–100 (%) — night brightness used by the on-device schedule
gluco_monitor/<MAC6>/cmd/night_schedule HA → Device ON / OFF — enable or disable the on-device brightness schedule
gluco_monitor/<MAC6>/cmd/layout HA → Device "Default" / "Gauge only" / "Value only"

<MAC6> is the last 6 hex digits of the device's Wi-Fi MAC address (e.g. A1B2C3).

Discovered Entities

Entity HA type Notes
Screen switch Maps to display on/off
Brightness number Live override 0–100 %; not persisted, does not affect the schedule
Day Brightness number Day-mode schedule backlight level (0–100 %)
Night Brightness number Night-mode schedule backlight level (0–100 %)
Layout select Default / Gauge only / Value only

The device auto-reconnects with a 5-second back-off if the broker becomes unavailable.

🔄 OTA Firmware Update

  1. Open http://<device-ip>/OTA in your browser
  2. Authorize the update on the physical display (touch prompt, valid for 3 minutes)
  3. Select and upload Gluco-Monitor_<version>.bin
  4. Device restarts automatically with the new firmware

🔧 Configuration Reference

All settings are stored in /parametres.json on the device's LittleFS filesystem and persist across reboots.

Key glucose thresholds (defaults in mg/dL):

Setting Default Description
glucoseRangeMin 0 mg/dL Gauge scale minimum
targetLow 70 mg/dL Lower bound of green target range
targetHigh 180 mg/dL Upper bound of green target range
glucoseWarn 300 mg/dL Upper warning threshold
glucoseRangeMax 400 mg/dL Gauge scale maximum

🏗️ Architecture Overview

src/
├── main.cpp              # Setup, loop, watchdog, sensor dispatch
├── Config.h / Config.cpp # All global state (extern declarations + definitions)
├── Stock.cpp             # LittleFS persistence (/parametres.json)
├── Libreview.cpp         # FreeStyle Libre API client
├── Dexcom.cpp            # Dexcom Share API client
├── NightScout.cpp        # NightScout REST API client
├── Server.cpp            # AsyncWebServer (port 80) — all HTTP endpoints
├── MQTT.cpp              # MQTT client: HA Discovery, state publish, command handling
├── Heure.cpp             # NTP time sync, timezone, brightness control
├── Ecran/
│   ├── Gestion.cpp       # Display driver init, touch, page routing
│   ├── pageAccueil.cpp   # Home screen — three tap-selectable layouts: Normal (bar chart),
│   │                     #   altView_01 (large semicircle gauge + needle),
│   │                     #   altView_02 (colour-coded full-screen, no gauge)
│   ├── pageCompte.cpp    # Sensor account configuration
│   ├── pageClavier.cpp   # On-screen QWERTY/AZERTY keyboard
│   └── page*.cpp         # Other configuration screens
├── Langues/              # Language strings as JSON (en/fr/de/es/it/pl)
└── HTML/                 # Embedded web assets (C string literals in .h files)
    ├── pageSettings.h    # /Settings — full browser-based device configuration
    ├── pageBrute.h       # /Brute — collapsible JSON data viewer
    ├── pageOTA.h         # /OTA — firmware update
    └── pageMain.h        # / and /Restart pages

Pages 0–2 are the rotating home / config / messages trio. Pages 10+ are fixed full-screen pages defined in Ecran/Gestion.h. Add new pages by creating a page*.h/.cpp pair and a #define constant.

🤝 Contributing

Contributions are welcome!

  • Open issues for bugs or feature requests
  • Submit pull requests
  • Add new language translations — see src/Langues/ (6 language files + update Langue.cpp and Server.cpp)
  • Port to other displays or boards

📄 License

This project is open-source. See the LICENSE file for details.

⚠️ Disclaimer

This project is not a medical device and must not be used for medical decisions.

Always rely on your official CGM device and your healthcare provider's advice for diabetes management.

❤️ Acknowledgments

  • The CGM and open-source diabetes community
  • Projects like xDrip+, Nightscout, and LibreLink Up
  • All contributors and testers

⭐ Support the Project

If this project is useful to you:

  • ⭐ Star the repository
  • Share it with the diabetes DIY community
  • Build your own and contribute improvements!

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CGM Glucose Monitoring

f1atb.fr/gluco-monitor-diy/

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