【正文】 和片外數(shù)據(jù)存儲器。PDIP40 封裝形式的單片機芯片可以很方便地使用面包板來組成應(yīng)用電路。 AT89S51 單片機的封裝AT89S51 單片機 [2]具有多種封裝形式，包括 PDIPPDIP4PLCC44 和TQFP44。 本文的主要工作首先介紹設(shè)計電子鬧鐘所涉及的主要硬件和特性，然后說明軟件設(shè)計的思路，程序結(jié)構(gòu)及流程，并在測試軟件上進行調(diào)試修改，以完成電子鬧鐘的基本要求，即可隨意設(shè)定起始時間，有秒顯示功能，有 12/24 時制選擇，可設(shè)定鬧鐘，停電時由電池供電等功能。諸如定時自動報警、按時自動打鈴、時間程序自動控制、定時廣播、定時啟閉電路、定時開關(guān)烘箱、通斷動力設(shè)備，甚至各種定時電氣的自動啟用等，所有這些，都是以鐘表數(shù)字化為基礎(chǔ)的。隨時提醒這些容易忘記時間的人。手表當然是一個好的選擇，但是，隨著接受皮試的人數(shù)增加，到底是哪個人的皮試到時間卻難以判斷。尤其在醫(yī)院，每次護士都會給病人作皮試，測試病人是否對藥物過敏。但是，一旦重要事情，一時的2耽誤可能釀成大禍。 時間對人們來說總是那么寶貴，工作的忙碌性和繁雜性容易使人忘記當前的時間。采用這款芯片既克服了采用 8031 需要添加外部程序存儲器導致電路復雜的缺點，又克服了采用 8751 導致電路制作成本高的缺點。這些公司的這類產(chǎn)品也被稱為 8051 兼容芯片，這些 8051 兼容芯片在原來的基礎(chǔ)上增加了許多特性。MCS51 系列單片機優(yōu)異的性能 /價格比使得它從面世以來就獲得用戶的認可。8051 的片內(nèi)程序存儲器（ROM）是掩膜型的，即在制造芯片時已將應(yīng)用程序固化進去；8031 片內(nèi)沒有程序存儲器；8751 內(nèi)部包含有用作程序存儲器 4KB的 EPROM。該系列的基本型產(chǎn)品是 8058031 和 8751。與通用的計算機不同，單片機的指令功能是按照工業(yè)控制的要求設(shè)計，因此它又被稱為微控制器（Microcontroller） 。關(guān)鍵詞：單片機技術(shù)，AT89S51，液晶驅(qū)動，電子鬧鐘IIIABSTRACTBecause of its extremely high performanceprice ratio, the singlechip puter (SCC) has been paid great attention to ever since it came out in 1970s of 20th Century, and has gained an extensive applicable field and fast development. Among all kinds of SCCs, 51 SCC is the most typical and representative one. This design, adopting AT89S51 chip as the core part with some necessary peripheral circuits, is a simple electronic clock which uses 5V DC as the power supply. In hardware aspect, besides the CPU, six sevensegment LED digitubes are used for display, which work in a dynamically scanning display mode and driven by 74SL14 chip. The LEDs can accurately indicate hour and minute and two buttons can be used to adjust the time. While in the software aspect, the programming language is assembly language. The whole electronic clock system has functions of time display, adjustment, bellsetting and reset, etc. Choose the smallest SCM system applications,add Comparison procedures, time to adjust procedures and faint buzzing procedures, Through relatively faint buzzing trigger procedures to achieve alarm clock function, Completed the design needs of the software environment. Keil introduced and the use of SCM software simulation debugging, testing the feasibility. Keywords: technology of the onechip puter，AT89S51，the liquid crystal is driven，Electronic alarm clockIV目 錄第 1 章 緒 論 ......................................................................................................................1 單片機簡介 ................................................................................................................1 電子鬧鐘的重要意義 ................................................................................................1 本文的主要工作 ........................................................................................................2第 2 章 AT89S51 單片機的硬件系統(tǒng) ............................................................................3 AT89S51 單片機的特性 .............................................................................................3 AT89S51 單片機的封裝 ...........................................................................................3 存儲空間 ....................................................................................................................3 程序存儲空間 ..................................................................................................4 數(shù)據(jù)存儲空間 ..................................................................................................5 單片機最小應(yīng)用系統(tǒng)電路 ........................................................................................8 供電電路 .............................................................................................................8 程序存儲器選擇電路 .........................................................................................8 時鐘電路 .............................................................................................................9 復位電路 .............................................................................................................9第 3 章 電子鬧鐘的硬件設(shè)計 ...................................................................................11 系統(tǒng)要求 ...................................................................................................................11 系統(tǒng)組成 ..................................................................................................................11 系統(tǒng)設(shè)計 ...................................................................................................................11 控制器 ...............................................................................................................11V 計數(shù)器 .................................................................