Engineers must know the summary of ZigBee technology Q&A

Core Tips for Electronic Enthusiasts : This article is a summary of some of the basic knowledge of ZigBee technology and industry applications. I hope that through the analysis of this article, we can have a comprehensive and intuitive understanding of the origin, development, characteristics, prospects of ZigBee technology and related applications in the communication network.

1, basic knowledge articles

Q1-1 What technology does ZigBee originate from?

A: During the use of Bluetooth technology, Bluetooth technology has been found to have many drawbacks despite its many advantages. For industrial, home automation control and industrial telemetry and remote control, Bluetooth technology is too complicated, power consumption, distance is too close, network size is too small, and industrial automation is increasingly demanding wireless data communication. This wireless data transmission in the field must be highly reliable and resistant to various electromagnetic interferences in the industrial field. Therefore, after long-term efforts, the ZigBee protocol was officially released in 2003. In addition, ZigBee uses Home RF Lite, a communication protocol for home networks that it has studied before.

Q1-2: What is ZigBee?

A: First of all, ZigBee is synonymous with the IEEE802.15.4 protocol. The technology specified in this protocol is a two-way wireless communication technology with close proximity, low complexity, low power consumption, low data rate and low cost. It is mainly suitable for automatic control and remote control, and can be embedded in various devices. Support for geolocation. Because bees rely on flying and "zig" to shake the wings of the "dance" to convey the position and near-far information of the pollen with the companion, that is, the bees rely on such a way to constitute communication in the group. "Network", so the inventors of ZigBee visually use this behavior of bees to visually describe this wireless information transmission technology.

Q1-3: What are the characteristics of ZigBee technology?

A: The characteristics of ZigBee mainly include the following aspects:

(1) Low power consumption: In the low power standby mode, 2 No. 5 dry batteries can support 1 node for 6-24 months or even longer. This is the outstanding advantage of ZigBee. In contrast, Bluetooth can work for several weeks, and WiFi can work for hours;

(2) Low cost: By greatly simplifying the protocol, the cost is very low (less than 1/10 of Bluetooth), and the requirements for the communication controller are reduced. According to the prediction analysis, the 8051 8-bit microcontroller is used to calculate the full-featured master. Nodes require 32KB of code, sub-function nodes as little as 4KB of code, and ZigBee's protocol patents are free;

(3) Low rate: ZigBee works at a communication rate of 250 kbps, meeting the application requirements of transmitting data at a low rate;

(4) Close range: The transmission range is generally between 10 and 100 m. After increasing the RF transmission power, it can also be increased to 1-3 km. This refers to the distance between adjacent nodes. If the relay is used by routing and communication between nodes, the transmission distance will be farther;

(5) Short delay: ZigBee's response speed is faster. Generally, it takes only 15ms from sleep to working state, and the node connection enters the network only takes 30ms, which further saves energy. In comparison, Bluetooth requires 3-10s and WiFi requires 3s;

(6) High capacity: ZigBee can adopt star, patch and mesh network structure. One master node manages several child nodes, and at most one master node can manage 254 child nodes. At the same time, the master node can also be managed by the upper layer network node. , can form a large network of up to 65,000 nodes;

(7) High security: ZigBee provides a three-level security mode, including no security settings, the use of access control lists (ACLs) to prevent illegal access to data, and symmetric passwords using the Advanced Encryption Standard (AES128) for flexible determination of security attributes. ;

(8) License-free frequency band: Direct sequence spread spectrum is used in the 2.4 GHz (global) frequency band of Industrial Science Medical.

Q1-4: Why is ZigBee compliant with the growing demand for reliable wireless data transmission from industrial automation?

A: ZigBee technology itself is because the Bluetooth technology cannot meet the demand of low data volume, low cost, low power consumption and high reliability wireless data communication in industrial automation. Because, for industrial sites, this wireless data transmission must be highly reliable and resistant to various electromagnetic interferences in the industrial field. In ZigBee technology, mesh topology, automatic routing, dynamic networking, and direct sequence spread spectrum are used. It is to meet this need of industrial automation control sites.

2, communication technology articles

Q2-1: Which protocol does ZigBee use?

A: IEEE 802.15.4 protocol, which is a protocol with a low transfer rate of unlimited PAN. In terms of standardization, the IEEE802.15.4 working group is mainly responsible for the development of the physical layer and MAC layer protocols. The remaining protocols mainly refer to and adopt existing standards. The work of high-level applications, testing and marketing will be handled by the ZigBee Alliance.

Q2-2: Why is ZigBee wireless communication using the 2, 4G band as a free band?

A: In China and most other countries in the world, the general use of radio equipment is subject to frequency usage fees, including mobile communication, but the mobile operator has already paid the fee to the state and adopted the number occupancy fee. The user is charged this fee. When using other wireless devices, you must first apply for a frequency license from the relevant national authorities, and then charge the amount and amount of power according to the frequency, amount and amount of wireless devices used by your wireless device. This is not a small fee. Generally, equipment costs a few thousand dollars a year. The free frequency band refers to a frequency band that each country divides according to its actual situation and considers the consistency with other countries in the world as much as possible. It is used exclusively for industrial, medical and scientific research (ISM band). A frequency band that can be used free of charge if required. Our country's 2.4G band is such a frequency band. However, in order to ensure that everyone can use it reasonably, the state has limited the use of wireless transceiver equipment in this frequency band in different environments. For example, in an urban environment, the transmission power cannot exceed 100 mW.

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