摘 要

隨著時代的進步，電子行業(yè)的發(fā)展，定時器的應用也越來越廣泛。但傳統(tǒng)的定時器都是使用發(fā)條驅(qū)動式、電機傳動式等機械定時器。電子定時器相對機械定時器來說，體積小、重量輕、造價低、精度高、壽命長、而且安全可靠、調(diào)整方便、適于頻繁使用。本文介紹了一種以AT89C51為核心、結(jié)構(gòu)緊湊和功能齊全的多用途電子定時器，定時時間用八位數(shù)碼管顯示，并進行逆計數(shù)。定時時間可通過小按鍵在定時范圍任意設(shè)置，最大可定時24小時，能滿足各種層次答辯、各種賽事以及某些特殊定時需要。設(shè)置定時初值即可啟動倒計時，當定時器顯示為“00-00-00”時,控制器會自動啟動報警系統(tǒng)，通過蜂鳴器發(fā)出報警聲音。
倒計時定時器的用途很廣泛，它可以用作定時器，控制被定時的電器，實現(xiàn)定時開或者定時關(guān)，在定時的過程中，隨時顯示剩余時間，它還可以用作倒計時計數(shù)器，由八位數(shù)碼管直觀顯示倒計時計數(shù)狀態(tài)。當定時器定時結(jié)束即定時器顯示“00-00-00”時，控制器會自動切斷或打開用電器的電源，該定時器可替代目前一些家用電器中的機械定時器。文章對其結(jié)構(gòu)作了介紹。

關(guān)鍵詞： AT89C51 定時器 數(shù)碼管顯示 計數(shù)器 報警系統(tǒng)












ABSTRACT

As the time advances, the development of the electronics industry, the application of the timer is more extensive. However, the traditional timers are used for spring-driven timers, the motor drive type, and other mechanical timer. Electronic timer is relative to mechanical timer, it has small size, light weight, low cost, high precision, long life, and safe, reliable, easy to adjust, for frequent use. This article introduces a AT89C51 core, compact and fully functional multi-purpose electronic timer that the regular time is displayed with eight digital display, and the reverse count. Regular time can be set by the small buttons set in the time range, maximum time is 24 hours,which can meet the various levels of defense, a variety of events and needs some special time. Seting initial value to start the countdown timer when the timer is displayed as "00-00-00", the controller will automatically start alarm system, alarm through the buzzer sounds.
Countdown timer is so widely used, it can be used as a timer to control device. achieve regular time to open or shut. in the course of time, it can displays the remaining time at any time, it can be used as a countdown counter, by eight digital visual display of the countdown counter status. when the end of time , the timer display "00-00-00", the controller will automatically cut off or turn on electrical power used, the timer can replace a number of household appliances in the mechanical timer. Its structure is introduced by the article.


Keywords： AT89C51 timer digital display counter alarm system



















目 錄

第一章 緒論...．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．1
1.1 定時器的發(fā)展前景 ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．． 1
1.2 定時器的發(fā)展領(lǐng)域．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．2
第二章 定時器方案的設(shè)計．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．3
2.1 定時器方案的設(shè)想 ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．....3
2.2 定時器方案的提出 ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．....3
2.3 定時器方案的分析．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．4
第三章 定時器電路的設(shè)計..．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．7
3.1 定時器原理總圖............................................8
3.2 AT89C51單片機．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．9
3.2.1 主要特點及功能介紹.....．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．10
3.2.2 單片機中斷...............................................12
3.3 單片機最小應用系統(tǒng)設(shè)計...................................15
3.3.1 時鐘電路．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．15
3.3.2 復位電路..．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．16
3.4 按鍵控制電路.............................................16
3.4.1 按鍵接口的消抖...........................................17
3.4.2 按鍵接口的控制方式和控制流程.............................18
3.5 數(shù)碼管顯示電路...........................................19
3.5.1 數(shù)碼管分類...............................................20
3.5.2 驅(qū)動方式.................................................21
3.6 蜂鳴器報警電路...........................................24
3.6.1 電磁式蜂鳴器.............................................24
3.6.2 蜂鳴器驅(qū)動電路...........................................25
3.7 狀態(tài)顯示電路.........................