Design Of ZigBee-based Outdoor Water Monitoring Node

Measurement and control system of the nebula is the engineering background of this paper. This project is a wireless sensor network measurement and control system based on CC2530. Each station consists of a central node and a plurality of terminal acquisition node,can be measurements in the field for long-term,including the frozen soil temperature, soil moister, bridge inspection,magnetic anomaly test,the device is powered by batteries,extended node number and type. Communication method of using cluster based wireless multi-hop routing. The master node using the Android system, including display, storage, interaction,remote communication,network communication and other functions.The content of this paper is the soft and hardware design of soil moisture monitoring node. The system contains a central control node and a plurality of terminal monitoring node, the use of ZigBee wireless communication between nodes,to complete the control commands and data transmission.In this design, The terminal nodes with CC2530as the core build of wireless sensor network module.Terminal node is mainly used to collect the soil moisture content,with a sleep,wake up,low power consumption characteristics.This paper briefly introduces the basic principle of collecting soil moisture content, syste-maticly analysis of the soil moisture measuring methods. By comparing several acquisition principle and selecting the most commonly used acquisition method. The frequency domain reflection method, the principle of standing wave, time domain reflectometry. The terminal monitoring node adopts frequency type moisture sensor CS616and voltage type moisture sensor SWR3collecting soil moisture information.Monitoring node can acquire16channel frequency water signal and16channel voltage water signal.Frequency water signal channel switching using relay switching, voltage water signal channel switching using analog switch SGM4782,after two kinds of signal channel selection to respectively through different signal conditioning circuit frequency signal conditioning circuit consists of RC low pass filter and the voltage comparator together,finally to capture the frequency signals using the CC2530internal timer.The voltage signal conditioning circuit consists of a differential amplifier and phase follower together,finally use the CC2530internal ADC for collecting the voltage signal.The terminal node does not store the collected data,the collected information through ZigBee transmitted to the central control node and transmitted through the serial port to the PC or via a Bluetooth module is sent to the mobile phone.Through the experiment,that water monitoring node is designed in this paper can accurate-ly collect the soil moisture,measurement error is0.1%,and transmits the information through the transparent transmission to the PC machine.