【正文】 南京工程學院本科畢業(yè)設計（論文） 1 摘 要 當今社會，單片機已經(jīng)普及到我們生活、工作的各個方面，已經(jīng)發(fā)展成為一門比較成熟的技術。 定時器在日常生活、工業(yè)控制、交通燈管理、檢測、報警等方面的應用越來越廣泛，同時人們對定時器的要求也越來越高。本課題設計一個基于 STC89C52 構成的實用定時器，這在某些應用中具有一定的實用價值。 本課題設計了一個基于 STC89C52 的定時器，首先介紹了設計內容及要求，介紹了定時器的設計思路以及功能模塊的劃分，并對各模塊實現(xiàn)的具體功能進行了說明。然后結合框圖，介紹了定時器的工作原理，之后詳細介紹了定時器具體單元電路 的設計與分析。 該定時器除具有基本的定時功能外，還具有定時時間連續(xù)可調、倒計時顯示和定時開關功能。它造價低，功能全，整體功能性價比高，配以 LED 顯示器，它適應各種場合的定時預警之用。而且設計巧妙，體積小，功能強，計時范圍大，用途廣泛，操作攜帶方便，是一種較理想的定時工具。 關鍵詞： 定時器； STC89C52；連續(xù)可調；倒計時顯示 南京工程學院本科畢業(yè)設計（論文） 1 ABSTRACT Today, the monolithic integrated circuits has been popular in our daily life and work ,and has bee a relatively mature timer in our daily lives, industrial control, traffic lights management, detection, alarm and so on, while people on the timer there are increasingly high requirements. The design of a subject with a practical STC89C52 timer, which in some applications has some practical values. This paper first introduced the design of the content and requirements on the design of the timer and the delineation of functional modules, each module and the specific functions of the note. Then with diagram, on the principle of the timer, after details of the specific unit timer circuit design and analysis. The timer in addition to a basic function of the timing, but also with adjustable timing consecutive time, the countdown display and regularly switching function. it is low cost, fullfeatured, costeffective overall function, together with a LED display, it is adapt to a variety of occasions for use in varieties of warning. And cleverly designed, small, strong function, wide time range, wide range of uses, easy to carry and operate, is an ideal timing tool. Keywords: Timer。 STC89C52。 continuously adjustable。 the countdown show 南京工程學院本科畢業(yè)設計（論文） 1 目 錄 第一章 緒論 ...........................................................................................1 設計背景 ........................................................................................................... 3 論文研究內容 ................................................................................................... 5 論文結構安排 .................................................................................................. 5 第二章 整體方案設計 ............................................................................6 設計任務及要求 ............................................................................................... 6 系統(tǒng)設計整體方案 ........................................................................................... 6 時鐘計時的方案選擇 ............................................................................. 6 時鐘顯示的方案選擇 ............................................................................. 8 系統(tǒng)硬件的整體設計 ............................................................................. 8 主控制模塊的方案選擇與設計 ............................................................. 9 第三章 硬件電路設計 .......................................................................... 10 STC 單片機 ..................................................................................................... 10 STC 單片機模塊介紹 ..................................................................................... 12 復位電路 .............................................................................................. 12 晶振電路 .............................................................................................. 14 電源電路 .............................................................................................. 14 下載電路 .............................................................................................. 15 LED 與單片機接口電路 ................................................................................ 16 發(fā)光二級管電路設計 ..................................................................................... 18 器件選擇 ......................................................................................................... 19 接口連接設計 ................................................................................................ 20 功能簡介 ........................................................................................................ 20 第四章 軟件設計 .................................................................................. 20 主程序 ............................................................................................................. 20 發(fā)光二極管指示程序 ..................................................................................... 21 鍵掃描程序 ..................................................................................................... 22 定時器中斷程序 ............................................................................................. 24 第五章 設計調試 .................................................................................. 25 南京工程學院本科畢業(yè)設計（論文） 1 軟件調試 ........................................................................................................ 25 Keil 軟件及其調試功能簡介 ............................................................... 25 C 語言簡介 ............................................................................................ 27 軟件調試 ........................................................................................ 28 硬件調試 ........................................................................................................ 32 Protel 99 SE 簡介 ................................................................................. 32 Protel 99 SE 繪制原理圖見附錄 C ..................................................... 34 Protel 99 SE 繪制 PCB 圖見附錄 D.................................................... 34 調試結 果 ........................................................................................................ 34 第六章 總結 .............................................................................