(毕业设计)基于单片机at89c51的简易电子琴系统.doc

目 录
摘要······································································································Ⅰ
Abstract ·································································································Ⅱ
第一章 绪论····························································································6
　　1. 1 课题背景····················································································6
　　1. 2 本文所做的主要工作·····································································7
第二章 系统方案设计及主控芯片介绍 ·························································8
　　2. 1主体方案·····················································································8
2. 1 电子琴的总体框图········································································8
　　2．2 主控芯片AT89C51的结构与原理····················································10
　　　　2.2.1 AT89C51单片机的结构·························································10
　　　　2.2.2 AT89C51单片机的工作原理 ··················································15
第三章 硬件电路设计···············································································17
　　3. 1发声电路····················································································17
　　3. 2 数码管显示电路··········································································19
　　3. 3 电源电路设计·············································································20
　　3．4 键盘设计···················································································21
第四章 乐曲声音算法···············································································23
　　4．1音乐频率的实现···········································································23
　　4．2音乐节拍的实现···········································································24
第五章 系统软件设计···············································································28
　　5．1系统程序流程··············································································28
　　5．2 键盘扫描程序流程图···································································29
总结 ····································································································30
致谢 ····································································································31
参考文献 ······························································································32
附录1 ··································································································33
程序·····································································································34