This project focused on developing a time-synchronized embedded device for IoT-based environmental monitoring. Using a LoRa network, a gateway and sensor node communicated wirelessly to collect temperature data efficiently while adhering to real-time constraints.

Objectives

  1. Implement a gateway to transmit beacons and receive temperature data from a sensor node.
  2. Develop a sensing device to synchronize with the gateway, collect calibrated temperature data, and log it in a database.
  3. Optimize energy consumption with low-power and ultra-low-power modes.

Features

Gateway

  • Transmits 20 beacons at random intervals (2-10 seconds) with synchronization info.
  • Receives acknowledgments (acks) containing temperature data from the sensor.
  • Displays statistics on beacons sent and acks received.

Sensor Node

  • Synchronization:
    • Logs wake-up times and temperature data in EEPROM upon receiving a beacon.
    • Sends calibrated temperature as acknowledgment to the gateway.
  • Power Efficiency:
    • Enters sleep mode between transmissions and ultra-low-power mode after 20 beacons.
  • Commands via Serial Port:
    • Retrieve the latest or all recorded data, and enable low-power mode.

Challenges

  • Temperature Measurement: ADC returned incorrect values when integrated into the full system.
  • Ultra-Low-Power Mode: Difficulties reactivating the sensor from this state.
  • Real-Time Constraints: Limited by time and resources, requiring improvements in task separation and scheduling.

Conclusion

The project successfully enabled communication between the gateway and sensor node while implementing key database operations and low-power modes. Despite challenges with temperature measurement and ultra-low-power transitions, the system demonstrated essential IoT functionalities and provided a foundation for future enhancements.

Project team: Thorsten Mahieu, Cédric Chau
Time range: November 2023 - December 2023

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