In the field of intelligent hardware and the Internet of Things, the now famous ZigBee is no one knows, no one knows. In addition to wifi and Bluetooth, ZigBee is one of the most important wireless communication protocols, mainly used in the fields of Internet of Things and intelligent hardware.

Regarding ZigBee, the following questions and answers will be introduced to you in detail. It is not a boast that everything you need to know about ZigBee is here!

ZigBee Origin History

What technology does ZigBee originate from?

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, etc., and industrial automation, the demand for wireless data communication is getting stronger and stronger. Moreover, for industrial sites, such wireless data transmission must be highly reliable and resistant to various electromagnetic interferences at industrial sites.

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.

What is ZigBee?

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.

What are the characteristics of ZigBee technology?

The characteristics of ZigBee mainly include the following aspects:

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;

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 for calculation, and the full-function master node needs 32 KB. Code, sub-function nodes as little as 4KB code, and ZigBee's protocol patents are free;

Low rate: ZigBee works at 250kbps communication rate, meeting the application requirements of low-speed data transmission;

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;

Short delay: ZigBee's response speed is faster, generally only 15ms from sleep to working state, node connection into the network only 30ms, further saving energy. In comparison, Bluetooth requires 3-10s and WiFi requires 3s;

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. a large network of 65,000 nodes;

High security: ZigBee provides a three-level security model that includes no security settings, uses access control lists (ACLs) to prevent unauthorized access to data, and symmetric passwords using the Advanced Encryption Standard (AES128) to flexibly determine its security attributes;

License-exempt band: Direct sequence spread spectrum in the 2.4GHz (global) band of Industrial Science Medical.

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

ZigBee technology itself is because the Bluetooth technology cannot meet the demand for 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.

Communication technology

What kind of protocol does ZigBee use?

IEEE 802.15.4 protocol, which is a protocol for an infinite PAN with a low transfer rate. 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.

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

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 has provided the user with the number occupancy fee. This fee was charged. 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.

Is ZigBee only suitable for short-range communication?

ZigBee local area network can not only expand the network by increasing the transmit power and receiving sensitivity of each node module and increasing the number of nodes, but also can monitor the distant ZigBee control network through the traditional Internet.

However, the caveats to be considered for expansion are:

1. As the transmission power increases, the power consumption naturally increases, and only requires a large amount of power consumption, which will lose the advantage of ZigBee's own low power consumption;

2. Although 2.4Ghz is a free frequency band, it cannot exceed the maximum power limit in the radio wave method.

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