E52-400/900NW22S is a wireless serial port LoRa MESH networking module based on LoRa spread spectrum technology. The maximum output power is +22 dBm, the maximum air rate can reach 62.5K, and the maximum supported baud rate is 460800 bps. The operating frequency range of the E52-400NW22S module is 410.125~509.125 MHz (default 433.125 MHz). The operating frequency range of the E52-900NW22S module is 850.125~929.125 MHz (default 868.125 MHz).

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E52-400/900NW22S adopts the new LoRa MESH networking technology, which has the functions of decentralization, self-routing, network self-healing, multi-level routing, etc. It is suitable for smart home and industrial sensors, wireless alarm security systems, building automation solutions, Smart agriculture and other application scenarios.

Related articles:

• Comparison of LoRa, LoRa MESH and LoRaWAN

• Why LoRa spread spectrum technology is so frequently applied to wireless communication

1. E52-400/900NW22S Function description

The LoRa MESH network adopts a decentralized structure. The entire network is composed of only two types of nodes: terminal nodes and routing nodes. There is no need for a central node or coordinator to participate in network management; users can also build a MESH network using only routing nodes. Routing nodes are similar to terminal nodes, but terminal nodes do not have routing functions. Terminal nodes are generally deployed at the edge of the network and are generally used to design low-power nodes, but currently do not support low-power functions. Routing nodes need to continuously receive data from the network for routing updates and data forwarding, so routing nodes cannot be used as low-power nodes.

CSMA avoidance technology is used in the MESH network. The CSMA avoidance mechanism can prevent nodes from sending wireless data at the same time as much as possible and reduce the probability of data collision errors.

The routing node will automatically collect information from surrounding nodes to form a multi-hop communication network; when a link fails or is abnormal, the routing node will re-establish a new path after several consecutive communication failures.

The network supports four communication methods, Unicast, Multicast, Broadcast and Anycast. Users can choose different communication methods according to different application scenarios. Among them, unicast and broadcast are the simplest and most basic communication methods. In unicast mode, routing will be automatically established and request responses will be returned to determine the data transmission path; in broadcast mode, all routing nodes will start a data relay after receiving data. The multicast mechanism is relatively complex and can achieve one-to-many communication. Users need to configure the multicast group address first, similar to a public address. Anycast is usually used for data exchange between different networks. Data will not be forwarded under anycast. Under anycast, two communication methods, unicast and broadcast, can be implemented depending on the target address. Users can transmit any data to any module within the communication range.

During network transmission, data will be encrypted using special algorithms by default to ensure data privacy and security. In addition, in order to avoid data errors caused by interference from other nodes, multiple verifications are performed on the data at the network layer to ensure the reliability and accuracy of the transmitted data.

1.1 Specifications
 Limit parameters

Working parameters

 Pin definition

2.Features

LoRa MESH: Using advanced LoRa modulation method, it has the advantage of long-distance anti-interference, greatly improving the coverage of the entire MESH network;
Ultra-large network capacity: The theoretical number of LoRa MESH networks is as high as 65535, and the recommended network size is about 200.
Decentralization: The entire network consists of only two types of nodes: terminal nodes and routing nodes, and does not require a central node or coordinator to participate in network management;
Automatic routing: When a data request is initiated, each routing node can automatically initiate connections with surrounding nodes to determine the data transmission path, without the need for the coordinator to participate in path planning;
Network self-healing: When a link fails, the routing node re-establishes a new path after several communication attempts fail;
Multi-level routing: Routing nodes can automatically transmit data to lower-level routing, and the automatically generated routing table controls the transmission direction of data;
Path optimization: Routing information will be continuously and automatically updated and optimized with the data transmission in the network to ensure the stability of the entire network;
Avoidance mechanism: CSMA avoidance mechanism can greatly reduce the possibility of air signal collision;
Communication method: Supports four communication methods: Unicast, Multicast, Broadcast and Anycast;
E52-400NW22S module frequency range: works in the 410.125 ~ 509.125 MHz frequency band, supports 100 channels, and the channel spacing is 1 MHz;
E52-900NW22S module frequency range: works in the 850.125 ~ 929.125 MHz frequency      band, supports 80 channels, and the channel spacing is 1 MHz;
Multiple verification: ensure the reliability and accuracy of the data transmission process;
Encrypted transmission: Special encryption algorithms are used during data transmission to ensure data security and privacy;
High throughput: The entire network is combined in time and space to achieve high concurrency performance;
Remote configuration: Supports remote changes of basic communication parameters of the entire network.

3.LoRa MESH Network topology

LoRa MESH network supports two types of devices: routing nodes and terminal nodes.
Routing node: Routing node receives data in the network for routing updates and data forwarding.
Terminal node: Terminal nodes do not have routing functions and are generally deployed at the edge of the network.

The network topology of routing nodes and terminal nodes is as shown in the figure:

4. Application scenarios

• Smart home and industrial sensors, etc.;

• Wireless alarm security system;

• Building automation solutions;

• Smart agriculture;

• Smart logistics and warehousing.
  

5. Introduction to AT commands

AT commands are divided into three categories: command commands, setting commands and query commands;

The AT command uses 115200 bps baud rate by default, without sending new lines;
Different AT commands need to input different numbers of parameters. Different parameters need to be separated by ",". The input parameters are uniformly decimal values. Please be careful.
Read the instruction set carefully; if the number of input parameters of the AT command is wrong, the serial port will return data similar to "AT+DST_ADDR=CMD_ERR".

Some AT command parameters will be restricted. If the input value of the AT command is wrong, the serial port will return data similar to "AT+DST_ADDR=CMD_VALUE_ERR";

If the parameter setting is successful, the serial port will return data similar to "AT+DST_ADDR=OK";
Data in non-AT command sets will be considered transparent transmission data, and the module will initiate a data request, so you should try to avoid sending data starting with "AT+";

After using the saved instructions, all parameters inside the current module will be saved. Most of the setting instructions will be saved directly to Flash. Only some commonly used setting instructions will be saved.

The command can choose whether to save it to Flash according to the parameters.

6. Command instruction set

There is no suffix for the command command. You only need "AT+RESET" to restart the module.

7. Query instruction set

The suffix of the query command is , for example, the query module related information command "AT+INFO=?", the module will return the main parameters of the module