单片机实现AD9850 DDS
目录
摘  要  …………………………………………………………………… 3
第一章  方案论证…………………………………………………………4
1.1  系统框图…………………………………………………………4
1.2  系统模块…………………………………………………………4
1.2.1  主控制器………………………………………………………4
1.2.2  正弦信号的产生………………………………………………7
1.2.3   电压放大…………………………………………………… 10
第二章   系统硬件设计………………………………………………… 10
2.1  硬件系统总体框图………………………………………………10
2.2  硬件模块设计……………………………………………………11
2.2.1  正弦信号产生模块……………………………………………11
2.2.2   带负载输出………………………………………………… 13
2.2.3   DDS技术的实现 …………………………………………… 14
2.2.4   键盘显示…………………………………………………… 15
第三章  系统软件设计……………………………………………… 16
3.1  初始化9850………………………………………………………17
3.2  初始化LCD……………………………………………………… 18
3.3  初始化PIC16F877程序…………………………………………19
3.4   AD9850控制字的写入…………………….……………………20
3.5  键盘扫描显示………………………………………………… 21
3.6  LCD显示……………………………………………………….24
总结 ………………………………………………………………… 26
参考文献………………………………………………………………… 27
致谢…………………………………………………

计算机毕业设计摘要
本系统设计一个正弦信号发生器。，使用PIC16F877单片机作为中央控制器，PIC（Peripheral Interface Controller）是一种用来开发的去控制外围设备的集成电路（IC）。一种具有分散作用（多任务）功能的CPU。它的最高操作频率大约都在20MHz左右，存储器容量用做写程序的大约1K—4K字节。
传统的频率合成器，通常从一排晶振荡器产生的各种频率通过开关进行频率混合。也有的采用众所周知的锁相环(PLL)技术实现频率合成。随着数字技术的飞速发展，用数字控制方法从一个参考频率源产生多种频率，即直接数字合成技术(DDS)异军突起。本设计使用世界流行的美国ADI公司生产的AD9850频率合成器正是应用这种DDS技术的典型热门产品之一，AD9850采用先地蝗CMOS工艺，其功耗在3.3V供电时仅为155mW，扩展工业级温度范围为-40～80℃，采用28脚SSOP表面封装形式，结合DDS芯片AD9850，产生0～15MHz频率可调的正弦信号；调制信号为1KHz的正弦波，调制信号的产生采用DDS技术；系统采用全中文菜单操作方式，操作简单，快捷，且系统的精度和稳定性高。
关键字：正弦信号  PIC16F877  AD9850  DDS技术 
ABSTRACT
The system design a sine signal generator. Using PIC16F877 microchip as a central controller, PIC (Peripheral Interface Controller) is the method which used to control peripherals development of Integrated Circuits (IC). A CPU with scattered (multi-task) function . Its maximum operating frequency is 20MHz approximately about. The memory capacity of theprocedures used to write about 1K-4K bytes.
The traditional frequency synthesizers, usually form a row of crystal oscillator frequency by switching from a variety of frequency mixed. Some used the well-known PLL technology to achieve frequency synthetic. With the rapid development of digital technology, using digital control methods form a variety of sources in a frequency reference frequency, direct digital synthesis techniques (DDS) sudden appearance as a new way. The design use the  popular American ADI cmopany’s production AD9850 frequency synthesizers. DDS technology is the application of this popular products typically . AD9850 used to control CMOS first, the power loss is only 155mW at 3.3V supply, the expansion of industrial grade temperature range for -40~80 degrees, 28 feet SSOP surface packaging used form of DDS chip AD9850, a 0~15MHz frequency communications signals to the neighboring letter; preparation of the sinusoidal wave 1KHz, a modem signals used DDS technology; Chinese menu system used throughout the operation, the operation simple, fast and high system accuracy and stability  
Key words: Sine signal ；PIC16F877 ；AD9850；DDS technology

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