摘 要
这次的设计采用ATEML公司生产的AT89S51单片机为核心来设计智能电热水器。本设计也对单片机控制电热水器实现智能化的可能性进行了分析，利用温度传感器、水位检测装置、等来完成本设计。
设计分成两个部分，在硬件设计方面，主要对单片机最小系统及其扩展、电源电路、键盘显示及接口电路、LED显示电路、水温检测电路、加热电路等进行了详细介绍。还详细介绍了设计中应用到的主要芯片的性能和特点，包括AT89S51、74LS240、DS18B20、74HC245等。在软件设计方面，采用汇编语言编程，是由于其易于为单片机所识别，执行速度快。
该智能电热水器设计完善，实现方案简单易行。采用软件设计来控制，可以实现智能检测水位及水温，智能加热，并且提高了整机的可靠性及准确性。 关键词：单片机; 电热水器; 智能;
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ABSTRACT
This design USES ATEML company produces the AT89S51 as the core to design intelligent electric water heater. The design of single-chip microcomputer control and the possibility of electric water heater realize intelligent analyzed, using temperature sensors, water level detection equipment, etc to complete the design.
Design is divided into two parts, in terms of hardware design, mainly to the single chip minimize system and its extension, power supply circuit, keyboard display and interface circuit, the LED display circuit, water temperature detection circuit, heating circuit described in detail. Also introduces the main application to design characteristics and properties of the chip, including AT89S51, 74LS240, DS18B20, 74HC245 etc. In software design, use assembly language programming, is due to its easy to identify, execution by MCU fast speed. This intelligent electric water heater design perfect, the implementation scheme is simple. Using software designed to control, can realize intelligent detection levels and water temperature, intelligent heating, and improve the machine's reliability and accuracy. Keywords: single-chip microcomputer; Electric water heater; intelligence;
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目 录
摘要 ······································································································································· I ABSTRACT ······························································································································ II 目录 ·····································································································································III 1 绪论 ···································································································································1
1.1 选题的背景、目的及意义 ···················································································1 1.2 国内外的研究状况和成果 ···················································································2 2 总体方案设计 ···················································································································3
2.1 设计目标以及方案选择 ·······················································································4 2.2 芯片选择以及介绍 ·······························································································5
2.2.1 AT89S51介绍 ······························································································5 2.3 数字温度传感器DS18B20介绍 ·········································································8
2.3.1 DS18B20的主要特性···················································································8 2.3.2 DS18B20工作原理 ····················································································10 2.3.3 DS18B20有4个主要的数据部件 ····························································10 2.3.4 DS18B20的应用电路 ················································································14 2.4 74LS240简介 ········································································································16 2.4.1 74LS240特点介绍 ····················································································16 2.5 LED数码管显示 ····································································································16 2.5.1 LED数码管介绍 ······················································································16
2.5.2 LED数码管显示方式和典型应用电路 ··················································17 2.5.3 LED数码管编码方式 ··············································································18 2.6 固态继电器 ···········································································································19 2.6.1 固态继电器工作原理················································································19 3 硬件系统设计 ·················································································································20
3.1 硬件系统设计 ·····································································································20
3.1.1 电源电路 ···································································································20 3.1.2 单片机系统电路 ·······················································································21 3.1.3 键盘接口电路 ···························································································24 3.1.4 温度检测电路 ···························································································24 3.1.5 温度显示电路 ···························································································25 3.1.6 看门狗电路 ·······························································································26
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3.1.7 加热电路 ···································································································26
4 软件系统设计 ·················································································································27 4.1 主程序流程框图 ···································································································27
4.2中断流程图 ············································································································28 4.3读温度子程序流程图 ····························································································29 4.4显示子程序流程图 ································································································30 结论 ·····································································································································31 致谢 ·····································································································································32 参考文献 ·····························································································································33 附录1：硬件电路图 ··········································································································34 附录2：程序清单 ··············································································································35
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