Problem

Build a reliable, maintainable environmental-monitoring system rather than a single sensor demo. The platform needed to support multiple nodes, local display and alerts, backend-controlled configuration, persistent data storage, browser-based visibility, and firmware updates without repeated physical access.

System requirements

  • Collect temperature and humidity from multiple ESP32 nodes.
  • Display local status and thresholds.
  • Transmit authenticated telemetry over Wi-Fi.
  • Persist measurements and configuration.
  • Allow device-specific configuration from the backend.
  • Support OTA firmware updates and repeatable testing.

Architecture

Sensor node (ESP32 + sensor + OLED)
        | authenticated REST telemetry
        v
FastAPI ingestion and configuration service
        |
        +--> SQLite persistence
        +--> browser dashboard
        +--> device-specific thresholds and intervals
        +--> OTA and version-management workflow

Implemented capabilities

  • Multi-node reporting with device identity and backend-controlled settings.
  • API-key authentication, device allowlisting, input validation, and secrets separation.
  • FastAPI ingestion, SQLite persistence, dashboarding, and configuration endpoints.
  • OTA firmware updates and repeatable validation evidence.
  • Local OLED status, alerts, threshold visibility, and telemetry health indicators.

Testing

Testing has focused on configuration changes, device reporting, invalid inputs, authentication behavior, persistence, dashboard display, OTA reliability, and recovery from common integration errors. Future releases will formalize automated regression tests and hardware-in-the-loop fault injection.

Current limitations

  • The current sensor class is appropriate for prototyping, not precision environmental metrology.
  • Cloud deployment and fleet-scale device management remain future releases.
  • Enclosure airflow, thermal bias, and long-duration reliability still require measured validation.

Next release

V2 will evolve the platform toward a workshop or greenhouse controller with separate temperature and humidity configuration, actuator control, reliability monitoring, enclosure design, failure detection, and digital-twin integration.

Publication rule: Source code, diagrams, screenshots, and measurements will be added only after an OPSEC/security review and removal of all credentials, internal addresses, and sensitive operational information.