| As we all know, water resources in our country are seriously scarce. To achieve the purpose of saving water efficiently, more and more domestic units are dedicated to design the water-saving irrigation control system. Meanwhile the control technology of irrigation is also developing rapidly. Considering that the domestic irrigation control products are still few and foreign products are expensive and unsuitable for Chinese conditions, developing a functional, cost-effective irrigation controller is of great significance for water-saving irrigation."The Key Technology of Crop Water Collecting Information and Intelligent Control Irrigation Technology", as the sub project of national Twelfth-Five-Year863plan, is studied by the team of Northwest A&F University, who is responsible for the research of greenhouse intelligent irrigation system. The system consists of four parts, that is, field information acquisition device, the central server, the diagnosis and calculation of crop water deficit module and greenhouse irrigation controller. Field information acquisition device, greenhouse irrigation controller and the central server are connected through the ZigBee network using a tree topology structure to realize distributed automatic control. In this paper, design and implementation of the greenhouse irrigation controller is introduced. The following contents are mainly completed:(1) Idea of modular design is adopted according to the functions and requirements of the greenhouse irrigation controller. The overall scheme and strategy of hardware and software of the greenhouse irrigation controller is planed. The design and implementation solutions of the hardware and software and the ZigBee wireless communication module is proposed.(2) The hardware part mainly consists of ZigBee wireless communication module, power supply circuit, solenoid valve control module, solenoid valve state detection module and LED module circuit. The CC2530chip is selected as the core. The greenhouse irrigation controller receives irrigation control command from the central server. The control of the greenhouse irrigation is realized by the relay and the solenoid valve. The working state of the solenoid valve is identified and feeds back to the central server. The power and operating state of the circuit is displayed by the LED in real time. The circuit voltage and current requirements are analyzed and calculated and the device is selected according to the requirements to ensure reliable operation of the circuit. At the same time, we design the circuit diagram and PCB diagram of each circuit module. Besides, moisture-proof enclosure is used to ensure the circuit working well in wet greenhouses. Three prototypes were made and the network function was debugged.(3) According to the requirements of Z-Stack protocol stack, the software for irrigation controller is designed and coded to achieve the functions like joining of the wireless network, controlling solenoid valve ON/OFF and feeding back the operating state of the solenoid valve to the central serve. In order to realize the debugging itself, the software of coordinator nodes and router nodes in the ZigBee network are also designed.(4) The field information collection device and the central server are debugged together according to the needs of the project. Through continuous testing of168hours, the results indicate that the equipment works well, and the design is reasonable and reliable which can meet the requirements of expected design. |
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