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基于单片机的智能电热水器毕业论文

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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