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摘 要

MP3是MPEG一1音频层Ⅲ的简称。MPEG音频是目前普遍应用的音频压缩标准，其中层Ⅲ的算法最为复杂，但压缩比最大，效果较好，在低码率条件下基本能达到CD的音质效果。低数据量和高播放品质的优点使其成为音乐存储、数字广播、网上音乐传输的主要方式。

单片机是一种集成电路芯片，采用超大规模技术把具有数据处理能力（如算术运算，逻辑运算，数据传送，中断处理）的微处理器，随即存取数据处理器，只读程序存储器，输入输出电路，可能还包括定时计数器，串行通信口，显示驱动电路，模拟多路转换器及A/D转换器等电路集成到一块单块芯片上，构成一个最小而又完善的计算机系统。本文介绍了一种基于ATMEL公司生产的AT89C51单片机的MP3播放器设计，分析了基于单片机的音乐播放器的工作原理，详细介绍了音乐播放器的功能以及硬件设计和软件设计的方法，以单片机为核心，由最小系统、D/A转换电路和键盘电路等完成对音乐播放器的设计与实现。

本次设计主要以AT89C51单片机为核心，对音乐播放器的设计与实现进行了硬件及软件的设计，并给出了一套完整的解决方案，实现了单片机音乐播放器对音乐的演奏。

关键词：音乐播放器；单片机；解码器；

Microcontroller-based MP3 Player Design

Abstract

MP3 is MPEG-1 Audio Layer Ⅲ for short. MPEG Audio is widely used audio compression standards, including the most complex algorithm Ⅲ level, but the maximum compression ratio, better, at lower bit rate can be achieved under the conditions of the basic CD's sound quality. Low data volume and the advantages of high playback quality make it a music store, digital broadcasting, the main form of online music transmission.

Single tablets machine is a integrated circuit chip, used Super mass technology to has data processing ability (as arithmetic operations, logic operations, data transfer, interrupt processing) of microprocessor, immediately access data processing device, only read program memory, entered output circuit, may also including scheduled counter, serial pass socket, display driven circuit, simulation more road conversion device and the A/D conversion device, circuit integrated to a single block chip Shang, constitute a minimum and and perfect of computer systems. This article describes has a based on ATMEL company production of AT89C51 single tablets machine of MP3 play device design, analysis has based on single tablets machine of music play device of work principle, more describes has music play device of function and hardware design and software design of method, to single tablets machine for core, by minimum system, and D/A conversion circuit and keyboard circuit, completed on music play device of design and implementation.

In this paper, the AT89C51 microcontroller as the core of the music player's design and implementation of hardware and software design, and gives a complete solution to achieve a single chip music player for playing music.

Key words：Music Player, Single-chip computer, Decoder

目 录

摘要 Abstract

1 绪论 ...................................................................... 1 1.1 研究现状 ................................................................ 1 1.2 课题研究的目的和意义 .................................................... 2 1.2.1 课题研究的目的 ........................................................ 2 1.2.2 课题研究的意义 ........................................................ 2 1.3 国内外概况 .............................................................. 3 1.4 课题研究内容 ............................................................ 4 2 MP3的编解码过程 .......................................................... 5 2.1 MP3的工作原理 .......................................................... 5 2.2 MP3播放器编码过程 ...................................................... 5 2.2.1 编码分析 .............................................................. 5 2.2.2 编码过程 .............................................................. 7 2.3 MP3播放器解码过程 ...................................................... 9 3 MP3播放器的硬件设计与实现 ............................................... 11 3.1 系统的总体设计 ......................................................... 11 3.2 主电路设计 ............................................................. 12 3.2.1 单片机最小系统 ....................................................... 14 3.2.2 电源部分 ............................................................. 14 3.2.3 D/A 转换部分 ......................................................... 16 3.2.4 控制部分 ............................................................. 17 3.3 单片机复位电路 ......................................................... 17 3.4 单片机晶振电路 ......................................................... 18 4 MP3播放器软件设计及实现 ................................................. 20 4.1 MP3播放器播放功能的设计 ............................................... 20 4.2 MP3功能按钮设计 ....................................................... 22