目录
摘 要 .................................................................................................................................................1
Abstract.............................................................................................................................................2
1. 引言 ...........................................................................................................................................4
1.1. 主要功能 .......................................................................................................................4
1.2. 系统的可行性分析 .......................................................................................................4
1.2.1. 总体设计分析 ...................................................................................................4
1.2.2. 模块功能简介 ...................................................................................................4
2. 功能模块的设计 .......................................................................................................................6
2.1. 用户线接口模块 ...........................................................................................................6
2.1.1. AM79R70 的引脚定义.....................................................................................6
2.1.2. AM79R70 的工作方式....................................................................................8
2.1.3. AM79R70 的应用...........................................................................................10
2.2. 信号音发生模块 .........................................................................................................11
2.2.1. NE555 简介.....................................................................................................11
2.2.2. 450HZ 信号发生电路.....................................................................................12
2.2.3. 铃流信号发生电路 .........................................................................................13
2.3. DTMF 双音频识别模块.............................................................................................14
2.3.1. MT8870 工作原理 ..........................................................................................14
2.3.2. MT8870 应用 ..................................................................................................14
2.4. 电话交换模块 .............................................................................................................17
2.4.1. MT8816 简介 ..................................................................................................18
2.4.2. MT8816 应用电路 ..........................................................................................21
2.5. 控制模块和电源模块 .................................................................................................22
2.5.1. 控制模块 .........................................................................................................23
2.5.2. 电源模块 .........................................................................................................23
3. 系统的工作原理 .....................................................................................................................24
4. 总结与展望 .............................................................................................................................24
参考文献 .........................................................................................................................................25
致谢 .................................................................................................................................................26
附录 交换机原理图 ...................................................................................................................27
