Abstract

This paper describes a star-topic FMS monitoring system built using the E53-GW (470FMS22R) gateway device and E53-470FMS22S low-power node device developed by EBITE based on LoRa technology. This LoRa networking scheme is suitable for building large-scale LoRa security alarm networks.

I. Overview of LoRa Networking Scheme

With the development of wireless communication technology, the demand for data transmission stability and low power consumption is increasing. Compared with traditional FSK technology, LoRa has a longer transmission distance and stronger anti-interference capability at the same power consumption. This also determines the superiority of LoRa in more complex environments. Therefore, EBITE's IoT application experts have developed a security wireless communication network system based on the LoRa modulation format, suitable for scenarios such as smoke and fire alarms. This system includes the master-slave gateway E53-GW (470FMS22R) and low-power nodes (E53-470FMS22S). The gateway can support up to 1200 nodes.

II. LoRa Networking Solution Function Overview

Network Setup: The gateway automatically establishes the network upon power-up, and nodes automatically join the network upon power-up.

Network Management: The main gateway supports network management capabilities, including network node registration, deletion, and other network status management.

Communication Key: Users can customize network keys, greatly ensuring network communication security.

Environmental Channel Occupancy Detection: Supports environmental RSSI scanning, displaying the results graphically (line or bar chart options available).

Wireless Parameter Configuration: Users can remotely configure or read wireless module parameters by sending command data packets wirelessly.

Relay Networking: The gateway supports automatic relay networking; multi-level relaying is suitable for ultra-long-distance communication, allowing multiple networks to operate simultaneously in the same area.

Automatic Channel Avoidance: The gateway and low-power nodes support automatic channel avoidance, significantly improving data transmission stability.

Independent Heartbeat Mechanism: Supports custom heartbeat configuration; low-power nodes automatically and periodically report heartbeat frames, monitoring network status in real time and improving network stability.

Ultra-Low Power Consumption: Nodes support deep sleep mode, with total power consumption of approximately 2uA.

Abnormal Handling Mechanism: A highly efficient watchdog design ensures that the module automatically restarts and continues operating according to previous parameter settings if an abnormality occurs.

Supporting GUI: A graphical configuration tool allows for quick configuration and management of the entire network.

III. LoRa Networking System Solution Principles

1. LoRa Networking Process

① After the node powers on and initializes, it automatically initiates a network access request frame with a random delay. Active channel detection is performed before RF data transmission, and an automatic retransmission avoidance mechanism is adopted.

② The gateway receives the network access request frame and responds to the node, confirming whether the node has been registered with the gateway. The gateway will only allow registered nodes to join the network.

③ Upon receiving the gateway's response to the network access request, the node begins synchronizing its clock, frequency information, and network access status.

④ Finally, heartbeat time synchronization is initiated, completing the entire network access process. The node automatically wakes up and reports its heartbeat according to the heartbeat cycle. The flowchart is as follows:

2. Node Gateway Uplink and Downlink Data Flow

① Uplink messages from nodes include three types: Heartbeat, Alarm, and Custom Data Reporting;

② Heartbeat messages are periodically sent by the node based on its heartbeat cycle settings;

③ Alarm signals are triggered by a button on the node, simulating a fire signal. The node immediately wakes up and periodically reports alarm information, emitting an alarm sound via a buzzer. When the GUI receives an alarm signal, the corresponding node displays the alarm information;

④ Custom data reporting allows data to be reported using specific AT command formats, further expanding user scenarios. The flowchart is as follows:

2. Node Gateway Uplink and Downlink Data Flow

① Uplink messages from nodes include three types: Heartbeat, Alarm, and Custom Data Reporting;

② Heartbeat messages are periodically sent by the node based on its heartbeat cycle settings;

③ Alarm signals are triggered by a button on the node, simulating a fire signal. The node immediately wakes up and periodically reports alarm information, emitting an alarm sound via a buzzer. When the GUI receives an alarm signal, the corresponding node displays the alarm information;

④ Custom data reporting allows data to be reported using specific AT command formats, further expanding user scenarios. The flowchart is as follows: