The Study Of Wireless Temperature Monitoring System Based On ZigBee Technology

The acquisition of temperature and other environmental parameters in the industrial control area has a very important application. The traditional monitoring system generally uses the wired way to transmit the data collected by sensors to PC. But, when the environment of the site is bad, more complex, or need to monitor more data, the sensor network system in the wired way will be severely constrained. The wireless sensor network uses a way of wireless transmission to construct corresponding wireless data acquisition network. The nodes in the wireless sensor network also have adaptive and self-organizing ability; therefore, the advantage is pretty obvious in the application of data collection and transmission.ZigBee protocol as a kind of brand-new wireless sensor technology arises at the historic moment. Comparing with other short-range wireless communication protocol, it has low cost, low power consumption, low rate, low complexity and networking flexible characteristics. Many manufacturers prefer to choose the protocol because of its characteristics. Based on physical layer and medium access control layer provided by IEEE802.15.4, ZigBee technology adds network layer, network security and the application layer software, supports star network, tree network and mesh network. ZigBee technology also can realize network coverage in the large area and expand multi-point network., which can avoid a single point breakdown. ZigBee technology has very broad development prospect in industry, agriculture, building automation, military defense, biological and medical treatment, intelligent household, environmental monitoring, etc.This paper deeply studies IEEE802.15.4 / ZigBee protocol standards and the specific function of each layer of the protocol. The design of embedded node based on ZigBee protocol mainly uses an 8 bit wireless microcontroller- MC13213 offered by Freescale Company, which is highly integrated by wireless RF module and the HCS08 series microprocessor, and simplifies the design of the peripheral circuit and greatly reduces system cost. The temperature PT100 and humidity sensor DHT11 are chosen to collect data of the environment; the circuits are designed to filter and amplify the advanced signal collected by the sensors, and then are connected to network terminal nodes.In the software design, IEEE802.15.4 standard software based on MC13213 is researched and analyzed. On the basis of underlying code, the paper separately programs the application layer function and interface function of each layer of coordinator node and child nodes. The program of coordinator includes system initialization, channel scanning, coordinator building networks, allowing child nodes accessing network and receiving child nodes data. The program of child nodes includes accessing network, whether or not to join the routing functions, data acquisition and processing, wireless data transmission, etc. The procedure is respectively transplanted to different network nodes. Therefore, a small temperature and humidity monitoring network system is finally realized. The coordinate and the child nodes are connected with PC through RS232; the paper can realize the display of wireless data transmission on the computer through setting the attribute value of the serial port. The collected data can also be displayed on the LCD module of the coordination, with the contrast of the data displayed on the PC; the reason is the same, which illustrates that the network system is successful.The experiment tests several indicators of the system and the experimental results show that the wireless sensor network based on ZigBee technology designed by the paper can be used in wireless sensor network system that has requirements of low power consumption, networking flexible, small data transmission quantity and short distance transmission.