Soil Information Collection System Based On ZigBee

China's water resources are insufficient,agricultural water use accounts for a large proportion of the total water consumption,reasonable irrigation played a huge role in saving water.The real-time monitoring of soil moisture is an important step to realize the reasonable irrigation.At present,the humidity measurement system is still manual operation.The workers don't regularly put historical data in sensor nodes manually into the computer,and then analyze it using related software,so the data analysis can not reflect the real-time parameters of the current soil.In view of the defects and problems,this paper uses the sensor based on FDR(frequency domain reflectometry)as a terminal node,using ZigBee wireless communication to transfer data to PC,in order to facilitate the real-time monitoring and control of soil moisture.This paper starts from the model research of sensor,carefully studies the working mechanism of the sensor,and design the structure and processing circuit of the sensor based on the FDR measuring principle.Two probes of the sensor and the measured soil is equivalent to a capacitor in the FDR hardware circuit.When soil moisture content changes,the change of dielectric constant leads to the change of capacitance value,and the output voltage of the circuit is changed,so the relationship between voltage and water content is established.The sensor can be used in the measurement of water content after calibration.ZigBee wireless communication network uses the mesh network,and consists of the four terminal nodes,a coordinator node and the host computer.Through the ZigBee wireless communication terminal node sends the data to the coordinator.the coordinator is connected to the PC through RS232.PC displays the received data and sends instructions.Through software programming,the host computer can send instructions to the terminal node such as single water content measurement,continuous water content measurement,querying node status and so on.The experiment shows that: the host computer can get the real-time data of the soil moisture after the single measurement command is sended;The terminal node sends the data to the computer every 1s when the continue measurement command sended;we cansee whether each node works normally by querying node command.Therefore,in this paper,the soil moisture acquisition system based on zigbee can effectively measure humidity data in a timely manner,which has the very high practical value.