1. Overview

With the development of wireless communication technology, the demand for data transmission stability and low power consumption is increasing day by day. Compared with traditional FSK technology, LoRa has longer transmission distance under the same power consumption and has strong anti-interference ability. This also determines LoRa's superiority in more complex environments. Therefore, our company is developing a security wireless communication network system based on the LoRa modulation format suitable for smoke and fire alarm scenarios, including a master-slave gateway (E53-GW (470FMS22R)) and a low-power node (E53-470FMS22S). A maximum of 1,200 nodes can be connected.

  1. Function introduction

lNetwork construction: The gateway automatically establishes the network when it is powered on, and the nodes automatically connect to the network when it is powered on;

lNetwork management: The main gateway supports network management capabilities. Network status management such as network node registration and deletion;

lCommunication key: Users can customize the network key, which greatly ensures the security of network communication;

lEnvironmental channel occupancy detection: supports environmental RSSI scanning. After the scanning is completed, it will be displayed in the form of a legend. You can choose a line chart or a bar chart;

lWireless parameter configuration: Users can send command data packets wirelessly to remotely configure or read wireless module parameters;

lRelay networking: The slave gateway supports automatic relay networking. Multi-level relays are suitable for ultra-long-distance communications. Multiple networks can run in the same area at the same time;

lAutomatic avoidance: Gateways and low-power nodes support automatic channel avoidance, which can greatly improve data transmission stability;

lIndependent heartbeat packet mechanism: Supports custom heartbeat packet configuration, low-power nodes automatically report heartbeat frames periodically, detect network status in real time, and improve network stability;

lUltra-low power consumption: The node supports deep sleep, and the power consumption of the whole machine in this mode is about 2uA;

lException handling mechanism: Efficient watchdog design. Once an exception occurs in the module, the module will automatically restart and continue to work according to the previous parameter settings;

lSupporting GUI: Use graphical configuration tools to quickly configure and manage the entire network;

  1. System logic

     Networking process

① After the node is powered on and initialized, it automatically initiates a network access request frame with a random delay, performs active channel detection before sending radio frequency data, and adopts an automatic avoidance and retransmission mechanism;

② The gateway receives the network access request frame data and responds to the node to confirm whether the node has been registered to the gateway. The gateway will only allow registered nodes to join the network;

③The node receives the gateway's response to the network access request and starts to synchronize the clock, frequency information, and network access status;

④ Finally enter the heartbeat packet time synchronization, the network access process is completed, and the node automatically wakes up the reporting heart according to the heartbeat packet cycle. The flow chart is as follows:

 

     Node gateway upstream and downstream data flow

①Node uplink messages include three message types: Heartbeat, Alarm, and custom data reporting;

②Heartbeat is the heartbeat message. The node wakes up periodically and sends heartbeat frames according to the heartbeat cycle setting;

③The alarm signal triggers the button through the node to simulate a fire signal. The node will wake up immediately and report the alarm information periodically, and sound the alarm sound through the buzzer. When the GUI receives an alarm signal, the corresponding node will display the alarm information;

④ Customized data reporting design, data can be reported through specific AT command format, further expanding user usage scenarios. The flow chart is as follows:

  1. Summary

Based on Sub-G FMS wireless long-distance intelligent networking technology gateway and low-power nodes, as a low-power LoRa star networking product, it can be widely used in smart homes, smart medical care, home audio and video, conference systems, photo studios, etc. Theaters, education and other industries to solve the actual needs of intelligent light control, sockets, switches, security and so on. With the rapid development of the wireless industry, the demand for wireless communication technology in smart cities will become increasingly urgent, and the market share of this networking product will gradually increase.