Tianjin University of Technology and Education
毕 业 设 计
二○一一年 六 月
智能灌溉系统的设计
Design of Intelligent Irrigation System
2011年6月
摘 要
近几年来，随着全球水资源的日趋紧张，世界各国都在积极探索行之有效的节水途径和措施。自动控制节水灌溉技术的高低代表着农业现代化的发展状况，灌溉系统自动化水平较低是制约我国高效农业发展的主要原因，节水灌溉作为一项现代化的工
程技术，无论是工程节水、农业节水，还是管理节水都必须建立在节水灌溉设备实现产业化生产的基础上。节水灌溉技术是为了解决水资源不足，提高灌溉效率而发展起来的现代灌溉技术之一。
本课题设计了一个智能灌溉系统，该系统以AT89S52单片机为控制核心，采用模块化的设计方案，由温湿度采集模块、时钟模块、步进电机控制模块、键盘接口模块和液晶显示模块组成。温湿度采集模块以DHT11温湿度传感器为核心，时钟模块主要由DS1302和32.768kHz的晶体组成，步进电机控制电路模块采用了达林顿驱动芯片ULN2003，显示电路模块主要由LCD12864构成。在闭环（自动）模式下，该系统能自动对土壤的温湿度进行检测，当实际湿度低于警戒值时单片机自动启动步进电机进行灌溉。
关键词：AT89S52；DHT11温湿度传感器；ULN2003达林顿驱动；LCD12864 ；DS1302
ABSTRACT
In recent years, along with the global water resources is nervous, countries in the world explore actively effective ways and measures of water-saving. Automatic control the discretion of water-saving irrigation technologies represents the agricultural
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modernization, low level of the development situation of irrigation system automation become the main cause of restricting high-efficient agriculture development, water-saving irrigation is a modern engineering technology, whether engineering section water, water saving, or management of agricultural water must be based on the basis of water-saving irrigation equipment realizing industrialization production. Water-saving irrigation technique is used to deal with the water shortage, improve irrigation efficiency and be developed into one of the modern irrigation techniques.
This topic design an intelligent irrigation system, this system select the AT89S52 SCM as control core, adopt the modularizing design scheme, which contain the temperature and humidity acquisition module, PH value detection module, clock module, stepping motor control module, keyboard interface module and LCD module.DHT11 and humidity sensor is selected as the core of temperature and humidity acquisition module, clock module is mainly composed of the clock DS1302 and crystal of 32.768kHz, stepping motor control circuit module adopted reach linton drive chip ULN2003, display circuit module is mainly consisted of the LCD12864 constitutes. In the loop (automatically) mode, the system can automatically detect on soil temperature and humidity, when actual humidity under alert value single-chip microcomputer automatic start stepping motor for irrigation.
Key Words：AT89S52; DHT11 temperature and humidity sensor; ULN2003
Darlington Driver; LCD12864;DS1302
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目 录
1 绪论........................................................................................................................ 1
1.1 引言............................................................................................................. 1 1.2 课题来源..................................................................................................... 1 1.3 国内外现状................................................................................................. 2 2 方案设计与论证.................................................................................................... 4
2.1 总体方案论证............................................................................................. 4 2.2 键盘电路..................................................................................................... 5 2.3温湿度传感器的选取.................................................................................. 6
2.3.1湿度传感器原理............................................................................... 6 2.3.2数字温湿度传感器DHT11 ............................................................. 7
3 系统硬件电路设计.............................................................................................. 9
3.1 AT89S52单片机的硬件结构 .................................................................. 9
3.1.1单片机的结构及信号引脚............................................................... 9 3.1.2 AT89S52最小系统 ..................................................................... 12 3.2 直流稳压电源的设计............................................................................... 13 3.3 湿度采集模块........................................................................................... 14
3.3.1 温湿度传感器的原理.................................................................... 14 3.4 pH值检测装置......................................................................................... 17 3.5时钟模块.................................................................................................... 19
3.5.1时钟模块接线图............................................................................. 19 3.5.2 DS1302 内部寄存器 ..................................................................... 21 3.6液晶显示模块............................................................................................ 22
3.6.1液晶显示模块概述......................................................................... 22 3.6.2模块主要硬件构成说明................................................................. 23 3.7步进电机驱动模块.................................................................................... 25
3.7.1步进电机简介和原理..................................................................... 25 3.7.2 ULN2003驱动芯片 ....................................................................... 25 3.7.3步进电机驱动模块......................................................................... 26
4 系统软件设计.................................................................................................... 27
4.1 程序设计................................................................................................... 27