Design And Implementation Of Solenoid Valve Control System For Central Pivot Variable Irrigation System

China lacks water resources,has a large area of cultivated land,and has a low utilization rate of irrigation water.Traditional irrigation methods relying on manual control are gradually replaced with the development of modern agriculture.The purpose of this paper is to develop a solenoid valve control system in the "central shaft variable irrigation system",which automatically controls the opening and closing time of each solenoid valve in one cycle according to the variable irrigation level data to realize variable irrigation.The system uses the 433 MHz wireless communication technology network to trigger the transmission of the corresponding partition variable irrigation level data through the sprinkler angle,and realizes the solenoid valve control based on the STM32F103C8T6 microprocessor chip.The specific contents are as follows:(1)Design and implementation of solenoid valve control function module.It consists of three parts: control center,data communication and solenoid valve controller.In the system,there is only one control center and the number of solenoid valve controllers is 15.The control center is based on the STM32F103C8T6 microprocessor chip design,including 433 MHz wireless module,corner measurement module,GPS positioning module and 4G network module.Data communication uses 433 MHz radio frequency technology,using E31-433T17 S module,data transmission in broadcast transparent transmission mode.The solenoid valve controller is based on the STM32F103C8T6 microprocessor chip design,which is mainly composed of 433 MHz wireless module,solenoid valve drive circuit,USB power supply circuit and so on.The control center receives all variable irrigation level data sent by the client software,and sends corresponding partition variable irrigation level data to each solenoid valve controller according to the current corner.The solenoid valve controller controls the solenoid valve according to the received variable irrigation level.The time of opening and closing in one cycle,which in turn controls the amount of irrigation.Data communication between the control center and the solenoid valve controller is performed by a 433 MHz wireless module in a broadcast transparent transmission mode.(2)Design and implementation of the corner measurement function module.In the solenoid valve control system,the control center sends the corresponding zone variable irrigation level data to all the solenoid valve controllers according to the current sprinkler angle.Therefore,the function module of the angle measurement is indispensable.Using the magnetometer module HMC5983 with the principle of applying magnetic effect,the module communicates with the control center through the IIC serial bus.The transmission rate is high and the stability is strong.The module is in absolute north direction in the north direction and supports the continuous measurement mode.Get the corner value in real time.(3)System performance test.The solenoid valve control system designed in this paper is tested by sub-module and the system is tested for overall performance.The results show that the 433 MHz wireless module sends and receives data normally.Under the communication distance of 200 meters,the communication delay is 50-70 milliseconds.The angle measurement module can measure the current corner of the sprinkler in real time,and the measurement accuracy is 1 degree,which satisfies the system requirements.The control center realizes the transmission of the irrigation level data corresponding to the partition variable according to the corner trigger.The solenoid valve controller can control the opening and closing time of the solenoid valve in one cycle according to the received variable irrigation level,and the time error is below 1%,and the solenoid valve control system Variable irrigation is achieved by successfully connecting to another part of the central pivot-type variable irrigation system.