【正文】 Finally, this system has the implementation of the output of square wave, the triangular wave and the sine wave. The frequency range from 200Hz to 1MHz,from 0 to 5V in we can drop the conclusion that the system is easy adjusting,low cost and of high value. Key words: AVR microcontroller； R2R Network； TG12864 LCD； DDS algorithm； XXXXX 大學畢業(yè)設(shè)計（論文）報告 第 3 頁 共 4 頁 目 錄 引言 ...............................................................................................................1 1 本課題要研究解決的問題 ......................................................................3 畢業(yè)設(shè)計（論文）的要求與數(shù)據(jù) .................................................................................... 3 2 系統(tǒng)設(shè)計方案 ........................................................................................3 基本設(shè)計原理 .................................................................................................................... 3 單片機 ATmega64 的簡介 ................................................................................................ 4 電源模塊設(shè)計 .................................................................................................................... 7 鍵盤模塊設(shè)計 .................................................................................................................... 7 顯示模塊 ............................................................................................................................ 8 D/A 轉(zhuǎn)換部分 ..................................................................................................................... 8 D/A 轉(zhuǎn)換器的主要性能指標 .............................................................................................. 9 A/D 轉(zhuǎn)換器說明 ............................................................................................................... 10 3 硬件電路 .............................................................................................. 11 硬件設(shè)計原則 ...................................................................................................................11 系統(tǒng)各硬件電路 .............................................................................................................. 12 電源電路 ......................................................................................................................... 12 時鐘電路 ......................................................................................................................... 12 復位電路 ......................................................................................................................... 13 鍵盤電路 ......................................................................................................................... 13 顯示電路 ......................................................................................................................... 13 D/A 轉(zhuǎn)換電路 ................................................................................................................. 15 A/D 轉(zhuǎn)換模塊 ................................................................................................................. 16 濾波器模塊的設(shè)計 ......................................................................................................... 17 系統(tǒng)硬件電路的抗干擾措施 ......................................................................................... 18 4 DDS 技術(shù)分析 ...................................................................................... 19 DDS 的基本工作原理 ....................................................................................................... 19 5 軟件設(shè)計 ................................................................................................ 22 應用軟件設(shè)計原則 ........................................................................................................... 22 編程語言的選擇 ............................................................................................................... 23 軟件設(shè)計總流程圖 ........................................................................................................... 23 程序設(shè)計的整體思路 ....................................................................................................... 24 算法實現(xiàn)改變頻率的思路 ..................................................................................... 24 液晶驅(qū)動程序設(shè)計的概括 ............................................................................................. 24 XXXXX 大學畢業(yè)設(shè)計（論文）報告 第 4 頁 共 4 頁 鍵盤掃描程序設(shè)計 ......................................................................................................... 24 6 調(diào)試過程 ................................................................................................ 26 硬件調(diào)試 ........................................................................................................................... 26 軟件調(diào)試 ........................................................................................................................... 26 7 測試結(jié)果 ................................................................................................ 27 8 總結(jié)及展望 ............................................................................................ 32 全文總結(jié) ............................................................................................................................ 32 系統(tǒng)中存在的問題、解決辦法和展望 ........................................................................... 32 謝 辭 ...................................................................................................... 33 參考文獻 ...................................................................................................... 33 附錄 ............................................................................................................. 34 附錄一 PCB 圖 ....................................................................................................................... 34 附錄二 電路原理圖 .......