IOT and ZigBee Wang Zhongsheng Xi'an Technological University, 2018.9

Content 1. Several Short Distance Communication 2. Consists of ZigBee Network 3. Creating a ZigBee

Overview In recent years, with the rapid development of network technology, communication and intelligent embedding technology, the word "Internet of things“(IOT) appears frequently in front of us. As an important part of the next generation network, the concept of IOT has received extensive attention all over the world, and attracted attention from developed countries such as Europe, the United States, Japan and South Korea. All countries have plans and put them into practice.

1． Several Short Distance Communication With the development and widely used of mobile communication network, satellite network and Internet, Internet of things (IOT) is being connect with them, it’s the expansion and extension of network, now long distance communication is very mature, so the problem of IOT is to solve the last “one kilometer” connection, so it is the main task of the research to short distance data communication. . Now focus on several short distance communications.

(1) Wi-Fi (Wireless Fidelity ) Wi-Fi provides wireless LAN access, nearly all smart phones, tablets and laptops support Wi-Fi, It’s one of the most widely used wireless networking technologies. The quality by Wi-Fi is not very good, the data security is a little worse than bluetooth, but the transmission speed is very fast, which meets the needs of persons and social lives. The main advantage of Wi-Fi is that it does not need wiring and can be free from the restriction conditions, so it is very suitable for the needs of mobile users. Besides, the power of transmitting signal is lower than 100mw, Wi-Fi is also relatively safe and healthy.

(2) Bluetooth Bluetooth is a standard wireless communication protocol, based on the equipment's low-cost transceiver chip, which can transmit short distance and low consumption. It is a kind of radio technology supporting the device's short distance communication, generally within 10m. It can exchange wireless information among various devices, including mobile phones, PDAs, wireless earphones, laptops, and related peripherals. This technology has been widely used in our daily life.

(3) IrDA (Infrared Data Association) IrDA is the abbreviation of the Infrared Data Association. Use infrared for point-to-point communication. It is a technology of peer-to-peer communication using infrared. It USES infrared as the medium to support wireless data transmission within a few meters. It’s Suitable for mobile phones, e-commerce, digital cameras and other portable products.

(4) ZigBee ZigBee is a short distance and low power wireless communication technology. It’s typical features are short distance, low complexity, self-organization, low power consumption, low data rate and low cost. It is mainly suitable for automatic control and remote control; it can be embedded into various devices.

ZigBee is a wireless data transmission network platform composed of more than 65,000 wireless data transmission modules. It is very similar to the existing CDMA or GSM network. Each ZigBee network data transmission module is similar to a base station of mobile network. The distance between each network node can range from the standard 75 meters, to the extended several hundred meters, or even several kilometers.

2． ZigBee Composition 2.1 ZigBee Topology ZigBee protocol defines three network topologies: star structure, tree structure and mesh structure. The star network and tree network can be regarded as a special subset of mesh. The mesh topology is the most commonly used structure. As shown in figure 1.

The ZigBee protocol only supports two physical devices; Full Function devices (FFD) and Reduced Function devices (RFD). (1) Full Function devices (FFD) The FFD module (device) can provide all services and act as any ZigBee node. It can not only send and receive data, but also has the routing function, so it can receive child nodes data.

(2) Reduced Function devices (RFD) RFD module（device）only provides partial services, can only act as the terminal node, cannot act as the coordinator and routing node, it is only responsible for sending the collected data to the coordinator and routing node, and the communication between RFD can only be completed through FFD.

2.2 Consist of of the ZigBee ZigBee defines three types of nodes: Coordination, Route and the End Module. It can be know from above that the Coordination and Router must be FFD device, and the terminal node can be FFD or RFD module (device). (1) Coordinator（中心协调器）

The Coordinator is used to create a ZigBee network The Coordinator is used to create a ZigBee network. When a node is added, an address is assigned to the node. The Coordinator is usually defined as a device that cannot be powered down without low power consumption. Each ZigBee network needs and only one Coordinator and have a PAN ID (that is the network ID number), different networks should be different PAN ID. If two of them exist in the same space, and if their original PAN ID is the same, the PAN ID of the later entered Coordinator will be automatically added one, so as not to cause PAN ID conflict.

(2) Router The Router responsible for forwarding data package, find the most suitable routing path, when a node want to join, assign address to the node, the Router is usually defined as a power supply device, can‘t enter low power consumption, each ZigBee network may need more than one Router, each Router can send and receive data and can be forwarded, when a network consists of all by the Coordinator (one) and the Router (multiple), the network is the real MESH networks, All data sent by each node is automatically routed to the target node.

(3) End Device The terminal node selects the existing ZigBee network to join in, which can send and receive data, but cannot forward data. End Device is generally defined as battery powered equipment, which can periodically wake up and perform the set task, with low power consumption. As shown in figure 2.

For the ZigBee network of data transmission, the user's configuration is usually 1 Coordinator + n Router (full function node), and a certain number of End devices can be selected according to the need. Within the same ZigBee network, all nodes must have the same PAN ID (network ID). As shown in figure 3 and the same channel.

The default node type of the ZigBee module is Router (slave node) The default node type of the ZigBee module is Router (slave node). when it leaves the factory. The configuration software can be used to set 4 parameters of the module according to requirements: PAN ID, baud rate, node type, and wireless channel; As shown in figure 4.

(4) PAN ID ZigBee protocol USES a 16-bit marker (PAN ID) to identify a network. The setting method of ZigBee module produced by different manufacturers is different. Please refer to relevant information provided by the manufacturer. Usually used ZigBee module, the manufacturer will set the ZigBee protocol stack, which can be set directly through the configuration software.

(5) Baud Rate In the same network, multiple ZigBee modules are connected to multiple devices, and it is not necessary for the whole network to have the same baud rate, as long as there is the same baud rate between modules and devices. The appropriate baud rate can be selected according to the size of the transmitted data; As shown in figure 5.

2.3 Steps of Create a ZigBee Network When we finished the setting of ZigBee module and parameter configuration, the next is to form a ZigBee network. (1) Change the node type of a module to Coordinator (main node) . uses the configuration software, as shown in figure 4. When the corresponding software is attached to the purchase of the ZigBee module, it can be used when it is opened, restart after setting, and the setting completed.

(2) Change the PAN ID of the Coordinator (main node) to a certain value (such as 0x1234) (range: 0x0001 -- 0xFF00), mainly to prevent conflict with the default value, and power down after finished; (3) Change the PAN ID of the Router that needs to be added to the Coordinator to the same value; when the space has multiple networks, you can also change the PAN ID to 0xFFFF and automatically look for any network to join. Power off after finished;

(4) First turn on the power of the Coordinator; (5) Turn on the power of other Router again, about 3 seconds, and it automatically join the network. So far, the network is complete.

Summarize This lecture introduces several short distance communication in the Internet of things, mainly introduced the structure and topology of ZigBee network, and introduces the process of the module parameter setting, the steps and matters needing attention, successfully created a ZigBee wireless sensor network, the network could communication each other and transmit data between the nodes.

Xi'an Technological University, Xi’an, 710032, China VK, id506332858 Prof. Wang Zhongsheng wzhsh1681@63.com Contact : School of Computer Science and Engineering, Xi'an Technological University, Xi’an, 710032, China VK, id506332858 Wechat: diamond-wzs QQ-mail: 59483672@qq.com