Those who have watched Iron man will be familiar with Downey jr.'s villa "city of freedom" in the film. Whether it is the overall appearance design full of futuristic technology sense or the intelligent system with the intelligent AI "jarvis" as the core, all of them make people feel an impulse to feel for themselves. In fact, under the tide of Internet of everything, with the continuous innovation and development of technology and products, smart home has been gradually integrated into our life, subtly changing our way of life. I believe that in the near future, the life scenes shown in the film will also be reflected around us.

Now, let's take a look at how smart home works. As a specific application scenario of the concept of the Internet of things, the first step of smart home is to solve the problem of information communication between various home and electrical appliances (M2M), among which ZigBee is one of the most promising technologies.

ZigBee technology is a unified standard of short distance wireless communication technology, was born in 2003, its physical layer and data link layer protocol for the IEEE 802.15.4 standard, network layer and safety shall be formulated by the ZigBee alliance, the development and application of the application layer according to the needs of the user's application, on the development and utilization, so the technology can provide users with mobile and flexible way of networking.

According to the IEEE 802.15.4 protocol standard, ZigBee's working frequency band is divided into three frequency bands, which are widely separated and have different channel data in each frequency band. Therefore, in this technical standard, the modulation mode and transmission rate are different in each frequency band. The frequency band is a global industrial, scientific and medical (indus   -    trial, scientific and medical, ISM) frequency band. The frequency band is a radio frequency band free of charge and application. In this frequency band, the data transmission rate is 250Kb/s. The other two frequency bands are 915/868mhz, and the corresponding number of channels is 10 and 1, respectively. The transmission rates are 40Kb/s and 20Kb/s, respectively. 868MHz and 915MHz radios use direct sequence spread spectrum technology and binary phase shift keying (BPSK) modulation technology. 2.4ghz radio USES DSSS and offset normal phase shift keying (o-qpsk).

In terms of networking performance, ZigBee can be constructed as a star network or point-to-point peer-to-peer network. In each ZigBee wireless network, the connection address code is divided into 16b short address or 64b long address, and the maximum number of devices that can be accommodated is 216 and 264 respectively, with a large network capacity.

In terms of wireless communication technology, csma   -    ca mode is adopted to effectively avoid the conflict between radio carriers. In addition, in order to ensure the reliability of data transmission, a complete response communication protocol is established.

For low power consumption and ZigBee devices, usually, its output of transmission is 0 ~ 3.6 dBm, node communication distance is 30 ~ 70 m, effective communication distance can be extended by routing forwarding (ZigBee gateway), have energy detection and link quality instruction ability, according to the results of the test. The equipment can automatically adjust the transmission power, under the condition of guarantee, the quality of communication link, the minimum energy consumption equipment.

In order to ensure the security and confidentiality of communication data between ZigBee devices, ZigBee technology adopts the encryption algorithm with the key length of 128 bits to encrypt the transmitted data information.

Features such as low power consumption, low cost, independent networking and routing enable Zigbee technology to give full play to its capabilities in smart home. For ordinary families, Zigbee can be applied in the following aspects:

Air conditioning system temperature controller, automatic control of lights, curtains.

The elderly and the mobility of the emergency caller.

(3) TV and audio universal remote control, wireless keyboard, mouse, rocker, toys.

(4) smoke detector.

Smart RFID tags.

Meanwhile, the industry's upstream manufacturers are also constantly updating their products to support the development of Zigbee products. Texas instruments (TI) recently announced the launch of two new embedded processors and analog chips based on volume sound (BAW), CC2652RB Simple Link wireless microcontroller (MCU) and LMK05318 network synchronizer clock. For the first time in the industry, TI BAW resonators technology used to integrate the clock function, CC2652RB as the industry of advanced wireless MCU without external vibration semiconductor, TI in square flat pin (QFN) package integrates a BAW resonators, without external high   -    speed 48 MHZ crystal, the frequency stability of + / - 40 parts per million (PPM), at the same time, effectively reduce the PCB use space (10% ~ 15%), the support on the single chip low-power Zigbee, Thread, Bluetooth and private 2.4 GHz connection solution.

Chengdu Ebyte electronic technology co., LTD. E18 series products, based on TI CC253x series chip development, internal integration 8051 single-chip microcomputer and wireless transceiver, integrated PA + LNA, greatly extend the communication distance, enhance communication stability, the factory shipped the firmware, it can realize serial data based on ZigBee protocol passthrough, applicable to a variety of scenarios (especially in intelligent household).