音乐播放系统设计--单片机课程设计报告

单片机课程设计报告

音乐播放系统设计

姓名：陈志祥，陈琪，温雪云

班级：04电信（3）班

学号：2004358307 2004358308 2004358324 指导老师：

日期：2007.7.2～2007.7.13

华南农业大学工程学院

摘要

作为单片机的重要硬件资源之一，利用定时器可以产生各种固定频率的方波信号，也可以产生包括“Do“、“Re“、“Me“--等音阶在内的各种频率声音。在此设计中我们采用12MHz的晶振，产生的频率信号即音乐信号由P3．7口输出，信号经过放大后由喇叭发出声音。

乐曲中，每一音符对应着确定的频率，我们可以参照给出的各音符频率及其相应的时间常数来编写程序，根据表中所提供的常数，将其16进制代码送入芯片里，可以奏出音符。音符的节拍我们可以用定时器T0来控制，送入不同的初值，就可以产生不同的定时时间。便如某歌曲的节奏为每分钟94拍，即一拍为0.64秒。其它节拍与时间的对应关系也可以从两者关系表中得到。

定时器T0工作在定时方式1，改变TH0及TL0，产生不同的音频频率。要编写的乐谱按要求以音符字节数据表的形式存放在程序中，改变乐曲就是通过改变该数据表的内容来实现的。主程序的任务是按顺序读取数据表中的字节，根据情况调用音级子程序和音长子程序，启动定时器T0进行工作。

目录

1 方案比较与选择（须详细阐述创新点或新见解） (1)

2 电路仿真与分析·······································································································

2.1 电路仿真········································································································

2.2 电路分析········································································································3电路板制作、焊接、调试························································································

3.1 电路板制作·····································································································

3.2 电路板焊接·····································································································

3.3 电路板调试····································································································4讨论及进一步研究建议····························································································5课程设计心得············································································································Abstract ·························································································································参考文献·······················································································································

1．方案比较与选择

方案一：利用AT89C2051和三级管9012构成的音乐播放器

一、功能特色

本播放器可实现循环播放、上一曲、下一曲、复位等功能。为了体现乐曲播放过程中的动态效果，在P1口增加了8只LED，作随机闪烁以指示旋律的节奏。

二、硬件设计

电路以AT89C2051为主控制器，S1为复位键，S2、S3分别为上一曲、下一曲选择键。晶振采用12MHz，音乐信号由P3．7口输出，经9012放大后推动喇叭发声(电路图见图1)。

三、软件设计

程序中根音选取的是C调三个8度内的音符，共21个音。每个音符对应频率由定时器T0产生(音符频率及对应计数初值见附表)。为了程序调用方便，每个音符都对应一个编码，占用一个字节。在程序中以查表的方式加载计数初值。当值为00H时表示空拍，与节拍码配合完成节拍发音。节拍码也占一个字节，其总时间长度等于基本时间乘以节拍码的值。节拍码值为01H时，表示当前乐曲结束，为00H时，表示全部乐曲结束。为了编码简单，一般节拍码高半字节表示整拍，低半字节表示分数，只要基本延时设定恰当即可，为了及时响应键盘操作，键扫描指令安排在基本延时时间子程序中。按键每按下一次，乐曲数目计数器R5加"1"或减"1"，然后根据R5的内容转向不同的乐曲。

本程序包含4首乐曲。若要增加更多的乐曲，在存储空间许可的情况下(可直接换用4k的AT89C4051)，只要照所附的编码表将简谱转化为相应的代码附着在乐曲数据表中即可。