ZigBee is a new wireless network technology with short distance, low complexity, low power consumption, low data rate and low cost.
It is mainly used for short distance wireless connection. According to IEEE 802.15.4 standard, it realizes communication among thousands of tiny sensors.
802.15.4 emphasizes the power-saving, simple and low-cost specifications.
The physical layer (PHY) of 802.15.4 uses DSSS (direct sequence spread spectrum) technology to divide a signal into several signals, and then transmit the signal by encoding to avoid interference.
In the aspect of media access control (MAC) layer, it mainly uses the CSMA / Ca mode of 802.11 series standard in WLAN to improve the system compatibility. The so-called CSMA / CA will check whether there is data transmission in the channel before transmission. If there is no data transmission in the channel, the data transmission will be started. If there is collision, it will be retransmitted later. There are three available frequency bands, which are ISM band of 2.4GHz, 868mhz band of Europe and 915MHz frequency band of the United States, while 16, 1 and 10 channels can be used in different frequency bands.
The main application fields of ZigBee include industrial control, consumer electronic equipment, automotive automation, home and building automation, medical equipment control, etc.
Features of ZigBee
Low data transmission rate: 10KB / S ~ 250kb / s, focusing on low transmission applications
Low power consumption: in low power standby mode, two ordinary No. 5 batteries can be used for 6 ~ 24 months
Low cost: ZigBee data transmission rate is low, the protocol is simple, so the cost is greatly reduced
Large network capacity: the network can accommodate 65000 devices.
Short delay: the delay is usually between 15ms and 30ms
Security: ZigBee provides data integrity check and authentication functions, and adopts AES-128 encryption algorithm (new encryption algorithm in the United States, which is one of the best text encryption algorithms at present)
Development trend of ZigBee
With the promotion of ZigBee alliance and IEEE802.15.4 and other wireless technologies, ZigBee technology can realize ubiquitous network. It has great application value not only in industry, agriculture, military, environment, medical and other traditional fields, but also in all fields of human daily life and social production activities in the future.
As ZigBee is more and more widely used in the Internet of things, NXP, Freescale, ember, Ti and other major international MCU manufacturers have successively launched single chip solutions.
The functional requirements and networking methods of ZigBee module are different in different application situations. NXP has launched jn516x series wireless microcontrollers with high performance and ultra-low power consumption for the Internet of things market. Taking jn5168 as an example, two common communication modes of ZigBee are introduced.
Point to point and point to multipoint:
This is a simple point-to-point or point to multipoint transmission mode. The communication between nodes is equivalent to “invisible serial port”. The feature of this firmware is that it can control the module to go into sleep low power mode and wake up from sleep. And with TOF ranging and field strength ranging functions.
Based on Jennet IP network serial port transparent transmission communication protocol, Jennet IP is a kind of wireless network protocol stack based on IP specially for residential, commercial and industrial Internet of things applications. Complex tree network topology supporting multi-level routing.
At present, ZigBee has been widely used in such industries as street lamp control system, smart home, landscape light control and so on. In the future, ZigBee will develop towards the direction of lower power consumption, lower cost and lower threshold. In the era of Internet of things, ZigBee will play an important role.