Watchdog
The operation of Gluco-Monitor is monitored by a Watchdog timer to ensure system stability:
If the glucose data “age” exceeds 30 minutes, the ESP32 reboots. This is typically what happens when a patient is changing their sensor.
If the ESP32 processor freezes for more than 10 minutes, it will automatically reboot.
If no data is received from the Libreview Cloud for 20 minutes, the ESP32 reboots.
Timing
It is important to understand how this application functions in real-time.
- The patient’s CGM sensor sends data to the smartphone via Bluetooth every minute, provided they are within a few meters of each other.
- The patient’s smartphone uploads this data to the Libreview Cloud every 5 minutes (assuming a stable connection).
- Gluco-Monitor queries the Libreview Cloud every 2 minutes if the latest data is recent. It increases the frequency to every 30 seconds if the last reading is more than 5 minutes old. Note that the server can sometimes be overloaded and may not respond immediately.
In practice, this results in a variable delay between the reading shown on the Gluco-Monitor and the one on the patient’s smartphone. This same delay occurs within the official LibreLinkUp app. Always keep an eye on the color of the glucose data age: if it is White, everything is up to date.
History (Logs)
Reviewing the event history in detail can provide valuable insights into potential connection or synchronization issues.