電子信息畢業(yè)設(shè)計(jì)外文翻譯--微型計(jì)算機(jī)控制系統(tǒng)（單片機(jī)控制系統(tǒng)）

1、<p><b>　　河南理工大學(xué)</b></p><p>　　Henan Polytechnic University</p><p>　　畢業(yè)設(shè)計(jì)外文資料翻譯</p><p>　　Graduation design foreign language translation</p><p>　學(xué) 院：電氣工

2、程與自動(dòng)化學(xué)院 </p><p>　專業(yè)班級(jí)：電子信息科學(xué)與技術(shù)三班 </p><p>　學(xué)生姓名：李 浩 </p><p>　學(xué) 號(hào)：310908040315 </p><p>　指導(dǎo)教師：王 帥 </p><p><b

3、>　　外文資料：</b></p><p>　　Microcomputer Systems</p><p>　　Electronic systems are used for handing information in the most general sense; this information may be telephone conversation, instr

4、ument read or a company’s accounts, but in each case the same main type of operation are involved: the processing, storage and transmission of information. in conventional electronic design these operations are combined

5、at the function level; for example a counter, whether electronic or mechanical, stores the current and increments it by one as required. A system su</p><p>　　Present day microprocessor based systems depart f

6、rom this conventional approach by separating the three functions of processing, storage, and transmission into different section of the system. This partitioning into three main functions was devised by Von Neumann durin

7、g the 1940s, and was not conceived especially for microcomputers. Almost every computer ever made has been designed with this structure, and despite the enormous range in their physical forms, they have all been of essen

8、tially the </p><p>　　In a microprocessor based system the processing will be performed in the microprocessor itself. The storage will be by means of memory circuits and the communication of information into

9、and out of the system will be by means of special input/output(I/O) circuits. It would be impossible to identify a particular piece of hardware which performed the counting in a microprocessor based clock because the tim

10、e would be stored in the memory and incremented at regular intervals but the microprocessor. H</p><p>　　The figure1-1 illustrates how these three sections within a microcomputer are connected in terms of the

11、 communication of information within the machine. The system is controlled by the microprocessor which supervises the transfer of information between itself and the memory and input/output sections. The external connecti

12、ons relate to the rest (that is, the non-computer part) of the engineering system.</p><p>　　Fig.1-1 Three Sections of a Typical Microcomputer</p><p>　　Although only one storage section has been

13、shown in the diagram, in practice two distinct types of memory RAM and ROM are used. In each case, the word ‘memory’ is rather inappropriate since a computers memory is more like a filing cabinet in concept; information

14、is stored in a set of numbered ‘boxes’ and it is referenced by the serial number of the ‘box’ in question. </p><p>　　Microcomputers use RAM (Random Access Memory) into which data can be written and from whi

15、ch data can be read again when needed. This data can be read back from the memory in any sequence desired, and not necessarily the same order in which it was written, hence the expression ‘random’ access memory. Another

16、type of ROM (Read Only Memory) is used to hold fixed patterns of information which cannot be affected by the microprocessor; these patterns are not lost when power is removed and are normally</p><p>　　The mi

17、croprocessor processes data under the control of the program, controlling the flow of information to and from memory and input/output devices. Some input/output devices are general-purpose types while others are designed

18、 for controlling special hardware such as disc drives or controlling information transmission to other computers. Most types of I/O devices are programmable to some extent, allowing different modes of operation, while so

19、me actually contain special-purpose microprocessors to</p><p>　　The microprocessor processes data under the control of the program, controlling the flow of information to and from memory and input/output dev

20、ices. Some input/output devices are general-purpose types while others are designed for controlling special hardware such as disc drives or controlling information transmission to other computers. Most types of I/O devic

21、es are programmable to some extent, allowing different modes of operation, while some actually contain special-purpose microprocessors to</p><p>　　The microprocessor , memory and input/output circuit may all

22、 be contained on the same integrated circuit provided that the application does not require too much program or data storage . This is usually the case in low-cost application such as the controllers used in microwave ov

23、ens and automatic washing machines . The use of single package allows considerable cost savings to e made when articles are manufactured in large quantities . As technology develops , more and more powerful processors an

24、</p><p>　　Another major engineering application of microcomputers is in process control. Here the presence of the microcomputer is usually more apparent to the user because provision is normally made for pro

25、gramming the microcomputer for the particular application. In process control applications the benefits lf fitting the entire system on to single chip are usually outweighed by the high design cost involved, because this

26、 sort lf equipment is produced in smaller quantities. Moreover, process controllers</p><p>　　The working instruments in the plant usually include simple pressure gauges, precision recorders and indicators, a

27、nd pneumatic and electronic pressure transmitters. A pressure transmitter makes a pressure measurement and generates either a pneumatic or electrical signal output that is proportional to the pressure being sensed.</p

28、><p>　　In the process plant, it is impractical to locate the control instruments out in the place near the process. It is also true that most measurements are not easily transmitted from some remote location. P

29、ressure measurement is an exception, but if a high pressure of some dangerous chemical is to be indicated or recorded several hundred feet from the point of measurement, a hazard may be from the pressure or from the chem

30、ical carried.</p><p>　　To eliminate this problem, a signal transmission system was developed. This system is usually either pneumatic or electrical. And control instruments in one location. This makes it pra

31、ctical for a minimum number of operators to run the plant efficiently.</p><p>　　When a pneumatic transmission system is employed, the measurement signal is converted into pneumatic signal by the transmitter

32、scaled from 0 to 100 percent of the measurement value. This transmitter is mounted close to the point of measurement in the process. The transmitter output-air pressure for a pneumatic transmitter-is piped to the recordi

33、ng or control instrument. The standard output range for a pneumatic transmitter is 20 to 100kPa, which is almost universally used.</p><p>　　When an electronic pressure transmitter is used, the pressure is co

34、nverted to electrical signal that may be current or voltage. Its standard range is from 4 to 20mA DC for current signal or from 1 to 5V DC for voltage signal. Nowadays, another type of electrical signal, which is becomin

35、g common, is the digital or discrete signal. The use of instruments and control systems based on computer or forcing increased use of this type of signal.</p><p>　　Sometimes it is important for analysis to o

36、btain the parameters that describe the sensor/transmitter behavior. The gain is fairly simple to obtain once the span is known. Consider an electronic pressure transmitter with a range of 0～600kPa.The gain is </p>

37、<p>　　defined as the change in output divided by the change in input. In this case, the output is electrical signal (4～20mA DC) and the input is process pressure (0～600kPa). Thus the gain. Beside we must measure Te

38、mperature Temperature measurement is important in industrial control, as direct indications of system or product state and as indirect indications of such factors as reaction rates, energy flow, turbine efficiency, and l

39、ubricant quality. Present temperature scales have been in use for about </p><p>　　Advantages of electrical systems include high accuracy and sensitivity, practicality of switching or scanning several measur

40、ements points, larger distances possible between measuring elements and controllers, replacement of components(rather than complete system), fast response, and ability to measure higher temperature. Among the electrical

41、temperature sensors, thermocouples and resistance temperature detectors are most widely used.</p><p>　　Description The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flas

42、h programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pinout. Th

43、e on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a mo</p><p>　　Port 0： Port 0 is an

44、 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as highimpedance inputs.Port 0 may also be configured to be the m

45、ultiplexed loworder address/data bus during accesses to external program and data memory. In this mode P0 has internal pullups.Port 0 also receives the code bytes during Flash programming,and outputs the code bytes durin

46、g programverification. External pullups</p><p><b>　　中文翻譯：</b></p><p>　　微型計(jì)算機(jī)控制系統(tǒng)（單片機(jī)控制系統(tǒng)）</p><p>　　廣義地說，微型計(jì)算機(jī)控制系統(tǒng)（單片機(jī)控制系統(tǒng)）是用于處理信息的，這種被用于處理的信息可以是電話交談，也可以是儀器的讀數(shù)或者是一個(gè)企業(yè)的帳戶，

47、但是各種情況下都涉及到相同的主要操作：信息的處理、信息的存儲(chǔ)和信息的傳遞。在常規(guī)的電子設(shè)計(jì)中，這些操作都是以功能平臺(tái)方式組合起來的，例如計(jì)數(shù)器，無論是電子計(jì)數(shù)器還是機(jī)械計(jì)數(shù)器，都要存儲(chǔ)當(dāng)前的數(shù)值，并且按要求將該數(shù)值增加1。一個(gè)系統(tǒng)例如采用計(jì)數(shù)器的電子鐘之類的任一系統(tǒng)要使其存儲(chǔ)和處理能力遍布整個(gè)系統(tǒng)，因?yàn)槊總€(gè)計(jì)數(shù)器都能存儲(chǔ)和處理一些數(shù)字。</p><p>　　現(xiàn)如今，以微處理器為基礎(chǔ)的系統(tǒng)從常規(guī)的處理方法中分離了出

48、來，它將信息的處理，信息的存儲(chǔ)和信息的傳輸三個(gè)功能分離形成不同的系統(tǒng)單元。這種主要將系統(tǒng)分成三個(gè)主要單元的分離方法是馮-諾依曼在20世紀(jì)40年代所設(shè)想出來的，并且是針對(duì)微計(jì)算機(jī)的設(shè)想。從此以后基本上所有制成的計(jì)算機(jī)都是用這種結(jié)構(gòu)設(shè)計(jì)的，盡管他們包含著寬廣的物理形式與物理結(jié)構(gòu)，但從根本上來說他們均是具有相同基本設(shè)計(jì)的計(jì)算機(jī)。</p><p>　　在以微處理器為基礎(chǔ)的系統(tǒng)中，處理是由以微處理器為基礎(chǔ)的系統(tǒng)自身完成的。

49、存儲(chǔ)是利用存儲(chǔ)器電路，而從系統(tǒng)中輸入和輸出的信息傳輸則是利用特定的輸入/輸出（I/O）電路。要在一個(gè)以微處理器為基礎(chǔ)的時(shí)鐘中找出執(zhí)行具有計(jì)數(shù)功能的一個(gè)特殊的硬件組成部分是不可能的，因?yàn)闀r(shí)間存儲(chǔ)在存儲(chǔ)器中，而在固定的時(shí)間間隔下由微處理器控制增值。但是，規(guī)定系統(tǒng)運(yùn)轉(zhuǎn)過程的軟件卻規(guī)定了包含實(shí)現(xiàn)計(jì)數(shù)器計(jì)數(shù)功能的單元部分。由于系統(tǒng)幾乎完全由軟件所定義，所以對(duì)微處理器結(jié)構(gòu)和其輔助電路這種看起來非常抽象的處理方法使其在應(yīng)用時(shí)非常靈活。這種設(shè)計(jì)過程主要

50、是軟件工程，而且在生產(chǎn)軟件時(shí)，就會(huì)遇到產(chǎn)生于常規(guī)工程中相似的構(gòu)造和維護(hù)問題。</p><p>　　圖1-1 微型計(jì)算機(jī)的三個(gè)組成部分</p><p>　　圖1-1顯示出了微型計(jì)算機(jī)中這三個(gè)單元在一個(gè)微處理器控制系統(tǒng)中是如何按照機(jī)器中的信息通信方式而聯(lián)接起來的。該系統(tǒng)由微處理器控制，微處理器能夠?qū)ζ渥陨淼拇鎯?chǔ)器和輸入/輸出單元的信息傳輸進(jìn)行管理。外部的連接部分與工程系統(tǒng)中的其余部分（即非計(jì)算

51、機(jī)部分）有關(guān)。</p><p>　　盡管圖中顯示的只有一個(gè)存儲(chǔ)單元，但是在實(shí)際中卻有RAM和ROM兩種不同的存儲(chǔ)器被使用。在每一種情況下，由于概念上的計(jì)算機(jī)存儲(chǔ)器更像一個(gè)公文柜，上述的“存儲(chǔ)器”一詞是非常不恰當(dāng)?shù)模恍畔⒈淮娣旁谝幌盗幸褦?shù)字標(biāo)記過的的“箱子”中，而且可以按照問題由“箱子”的序列號(hào)進(jìn)行相關(guān)信息的參考定位。</p><p>　　微計(jì)算機(jī)控制系統(tǒng)經(jīng)常使用RAM（隨機(jī)存取存儲(chǔ)器），在

52、RAM中，數(shù)據(jù)可以被寫入，并且在需要的時(shí)候，可以被再次讀出。這種數(shù)據(jù)能以任意一種所希望的次序從存儲(chǔ)器中讀出，而不必按照寫入時(shí)的相同次序讀出，所以有“隨機(jī)”存取存儲(chǔ)器。另一類型ROM（只讀存儲(chǔ)器）是用來保持信息的，它們是不受微處理器影響的固定的信息標(biāo)本；這些信息在電源切斷后不會(huì)丟失，并通常用來保存規(guī)定微處理器化系統(tǒng)運(yùn)轉(zhuǎn)過程的程序。ROM可像RAM一樣被讀取，但與RAM不一樣的是不能用來存儲(chǔ)可變的信息。有些ROM在制造時(shí)將其數(shù)據(jù)標(biāo)本放入，而

53、另外的則可通過特殊的設(shè)備由用戶編程，所以稱為可編程ROM。被廣泛使用的可編程ROM可利用特殊紫外線燈察除，并被成為E</p><p>　　PROM，即可察除可編程只讀存儲(chǔ)器的縮寫。另有新類型的期器件不必用紫外線燈而用電察除，所以稱為電可察除可編程只讀存儲(chǔ)器EEPROM。</p><p>　　微處理器在程序控制下處理數(shù)據(jù)，并控制流向和來自存儲(chǔ)器和輸入/輸出裝置的信息流。有些輸入/輸出裝置是通

54、用型的，而另外一些則是設(shè)計(jì)來控制如磁盤驅(qū)動(dòng)器的特殊硬件，或控制傳給其他計(jì)算機(jī)的信息傳輸。大多數(shù)類型的I/O裝置在某種程度下可編程，允許不同形式的操作，而有些則包含特殊用途微處理器的I/O裝置不用主微處理器的直接干預(yù)，就可實(shí)施非常復(fù)雜的操作。</p><p>　　假如應(yīng)用中不需要太多的程序和數(shù)據(jù)存儲(chǔ)量，微處理器、存儲(chǔ)器和輸入/輸出可全被包含在同一集成電路中。這通常是低成本應(yīng)用情況，例如用于微波爐和自動(dòng)洗衣機(jī)的控制器

55、。當(dāng)商品被大量地生產(chǎn)時(shí)，這種單一芯片的使用就可節(jié)省相當(dāng)大的成本。當(dāng)技術(shù)進(jìn)一步發(fā)展，更強(qiáng)更強(qiáng)的處理器和更大更大數(shù)量的存儲(chǔ)器被包含形成單片微型計(jì)算機(jī)，結(jié)果使最終產(chǎn)品的裝配成本得以節(jié)省。但是在可預(yù)見的未來，當(dāng)需要大量的存儲(chǔ)器或輸入/輸出時(shí)，還是有必要繼續(xù)將許多集成電路相互聯(lián)結(jié)起來，形成微計(jì)算機(jī)。</p><p>　　微計(jì)算機(jī)的另一主要工程應(yīng)用是在過程控制中。這是，由于裝置是按特定的應(yīng)用情況由微機(jī)編程實(shí)現(xiàn)的，對(duì)用戶來說微

56、計(jì)算機(jī)的存在通常就更加明顯。在過程控制應(yīng)用中，由于這種設(shè)備以較少的數(shù)量生產(chǎn)，將整個(gè)系統(tǒng)安裝在單個(gè)芯片上所獲取的利益常比不上所涉及的高設(shè)計(jì)成本。而且，過程控制器通常更為復(fù)雜，所以要將他們做成單獨(dú)的集成電路就更為困難。可采用兩種處理，將控制器做成一種通用的微計(jì)算機(jī)，正像較強(qiáng)版本的業(yè)余計(jì)算機(jī)那樣；或者做成“包裹”式系統(tǒng)，按照像電磁繼電器那樣的較老式的技術(shù)進(jìn)行設(shè)計(jì)，來取代控制器。對(duì)前一種情況，系統(tǒng)可以用常規(guī)的編程語言來編程，正如以后要介紹的語言

57、那樣；而另一種情況，可采用特殊用途的語言，例如那種使控制器功能按照繼電器相互連接的方法進(jìn)行描述。兩種情況下，序均能存于RAM，這讓程序能按應(yīng)用情況變化時(shí)進(jìn)行相應(yīng)的變化，但是這使得總系統(tǒng)易受掉電影響而工作不正常，除非使用電池保證供電連續(xù)性。另一種選擇是將程序在ROM中，這樣他們就變成電子“硬件”的一部分并常被稱為“固件”。</p><p>　　盡管大規(guī)模集成電路的應(yīng)用使小型和微型計(jì)算機(jī)的差別變得“模糊”，更復(fù)雜的過

58、程控制器需要小型計(jì)算機(jī)實(shí)現(xiàn)他們的過程。各種類型的產(chǎn)品和過程控制器代表了當(dāng)今微計(jì)算機(jī)應(yīng)用的廣泛性，而具體的結(jié)構(gòu)取決于對(duì)“產(chǎn)品”一詞的解釋。實(shí)際上，計(jì)算機(jī)的所有工程和科學(xué)上的應(yīng)用都能指定來進(jìn)行這些種類的某一或某些工作。而在本設(shè)計(jì)中壓力和壓力變送器當(dāng)某一力加到某一面積上，就形成壓力，假如這力是1牛頓均勻地加在1平方米的面積上，這壓力被定義為1帕斯卡。壓力是一種普遍的工藝狀態(tài)，它也是這個(gè)星球上的一個(gè)生活條件：我們生活在向上延伸許多英里的大氣海洋

59、的底部?？諝馕镔|(zhì)是有重量的，而且這種下壓的重量形成大氣壓。水，是生活的必需品，也是在壓力之下提供給我們中的大多數(shù)人。在典型的過程工廠中，壓力影響沸點(diǎn)溫度、凝固點(diǎn)溫度、過程效率、消耗和其他重要因數(shù)。壓力的測(cè)量和控制，或者壓力的不足—真空，在典型的過程控制中是極為重要的。</p><p>　　工廠中的工作儀器通常包括壓力計(jì)、精密紀(jì)錄儀、以及氣動(dòng)和電動(dòng)的壓力變送器。壓力變送器實(shí)現(xiàn)壓力測(cè)量并產(chǎn)生正比于所傳感壓力的氣動(dòng)或電

60、信號(hào)輸出。</p><p>　　在過程工廠中，將控制儀表遠(yuǎn)遠(yuǎn)放在過程的附近是不現(xiàn)實(shí)的，并且大多數(shù)測(cè)量是不容易從遠(yuǎn)處傳來的。壓力測(cè)量是一個(gè)例外，但是，如果要離測(cè)量點(diǎn)幾百英尺外指示或記錄某種危險(xiǎn)化學(xué)品的高壓，就會(huì)有來自這個(gè)壓力所載的化學(xué)品所引發(fā)的危險(xiǎn)。為了消除這一問題，開發(fā)了一種信號(hào)傳輸系統(tǒng)。這種系統(tǒng)常?？墒菤鈩?dòng)或者電動(dòng)的。使用這種系統(tǒng)，就可以在某一地點(diǎn)安裝大多數(shù)的指示、記錄和控制儀器。這也是最少數(shù)量的操作者有效的運(yùn)

61、行工廠成為現(xiàn)實(shí)。</p><p>　　當(dāng)使用氣動(dòng)傳送系統(tǒng)時(shí)，測(cè)量信號(hào)就由變送器將比例為0%～100%的測(cè)量值轉(zhuǎn)換為氣動(dòng)信號(hào)。變送器安裝在靠近過程中的測(cè)量點(diǎn)上。變送器輸出—對(duì)氣動(dòng)變送器是輸出壓力—通過管道傳給記錄或控制儀表。氣動(dòng)變送器的標(biāo)準(zhǔn)輸出范圍是20～100kPa，這信號(hào)幾乎在全球使用。</p><p>　　當(dāng)使用電子壓力變送器時(shí)，壓力就被轉(zhuǎn)換成電流或電壓形式的電信號(hào)。其標(biāo)準(zhǔn)范圍對(duì)電流來

62、說是4～20mA DC，對(duì)電壓信號(hào)來說是1～5V DC。當(dāng)今，另一種電信號(hào)形式變的越來越常用，就是數(shù)字或離散信號(hào)?；谟?jì)算機(jī)或微處理器的儀器或控制系統(tǒng)的應(yīng)用正推動(dòng)這類信號(hào)的應(yīng)用不斷增加。有時(shí)，分析獲取描述傳感器/變送器特性的參數(shù)是很重要的。當(dāng)量程已知，去獲取增益就非常簡(jiǎn)單。假定電子壓力傳感器的量程為0～600kPa，增益定義為輸出變化除以輸入變化。這里，輸出的電信號(hào)（4～20mA DC），而輸入的過程壓力（0～600kPa），這樣增益就

63、為：</p><p>　　此外我們?cè)诒驹O(shè)計(jì)中還必須對(duì)溫度進(jìn)行測(cè)量，溫度測(cè)量在工業(yè)控制中是很重要的，因?yàn)樗鳛橄到y(tǒng)或產(chǎn)品狀態(tài)的直接指標(biāo)，或者作為如反應(yīng)率、能量流、渦輪機(jī)效率和潤滑質(zhì)量等間接指標(biāo)?，F(xiàn)行的溫度分度已使用了約200年，最初的儀器是基于氣體和液體的熱膨脹?，F(xiàn)在盡管有許多其他類型的儀器在使用，這些填充式系統(tǒng)仍常用于直接的溫度測(cè)量。有代表性的溫度傳感器包括：填充式熱系統(tǒng)、玻璃液體溫度計(jì)、熱電偶、電阻溫度探測(cè)器、

64、熱敏電阻、雙金屬器件、光學(xué)和輻射高溫計(jì)和熱敏涂料。</p><p>　　電氣系統(tǒng)的優(yōu)點(diǎn)包括高的精度和靈敏度，能實(shí)現(xiàn)開關(guān)切換或掃描多個(gè)測(cè)量點(diǎn)，可在測(cè)量元件和控制器之間長(zhǎng)距離傳輸，出現(xiàn)事故時(shí)可調(diào)換元件，快速響應(yīng)，以及具有測(cè)量高溫的能力。其中熱電偶和電阻溫度探測(cè)器則被最廣泛的使用。</p><p>　　說明 該AT89C51是一種低功耗，高性能CMOS 8位4K的閃存可編程和可擦除只讀存儲(chǔ)器（

65、PEROM）字節(jié)的微型計(jì)算機(jī)。該設(shè)備是采用Atmel的高密度非易失性內(nèi)存技術(shù)，并與行業(yè)標(biāo)準(zhǔn)的MCS - 51指令集和引腳兼容。片上閃存程序存儲(chǔ)器可以編程就可以在系統(tǒng)或由傳統(tǒng)的非易失性存儲(chǔ)器編程。通過將集成在一個(gè)芯片上通用的8位閃存的CPU，Atmel的AT89C51是一個(gè)強(qiáng)大的微型計(jì)算機(jī)提供了一個(gè)高度靈活和成本有效的解決方案為許多嵌入式控制應(yīng)用。 功能特點(diǎn) AT89S51內(nèi)提供了以下標(biāo)準(zhǔn)特性：4K字節(jié)閃存，128字節(jié)RAM，32個(gè)I

66、 / O線，兩個(gè)16位定時(shí)器/計(jì)數(shù)器，一個(gè)五向量?jī)杉?jí)中斷結(jié)構(gòu)，一個(gè)全雙工串行口，片上振蕩器和時(shí)鐘電路。此外，AT89C51是靜態(tài)邏輯設(shè)計(jì)與操作頻率下降到零，并支持兩種軟件可選的節(jié)電模式?？臻e模式時(shí)CPU停止工作，而RAM，定時(shí)/計(jì)數(shù)器，串行口和中斷系統(tǒng)繼續(xù)工作。掉電模式保存RAM的內(nèi)容，但凍結(jié)振蕩器關(guān)閉，直到下一個(gè)硬件復(fù)位芯片其它功能。 引腳說明 Vcc：電源電壓。 接地：接地。</p><p><b

67、>　　P0口：</b></p><p>　　P0口為一個(gè)8位漏級(jí)開路雙向I/O口，每腳可吸收8TTL門電流。當(dāng)P0口的管腳第一次寫1時(shí)，被定義為高阻輸入。P0能夠用于外部程序數(shù)據(jù)存儲(chǔ)器，它可以被定義為數(shù)據(jù)/地址的第八位。在FIASH編程時(shí)，P0 口作為原碼輸入口，當(dāng)FIASH進(jìn)行校驗(yàn)時(shí)，P0輸出原碼，此時(shí)P0外部必須被拉高。 </p><p><b>　　P1口

68、：</b></p><p>　　P1口是一個(gè)內(nèi)部提供上拉電阻的8位雙向I/O口，P1口緩沖器能接收輸出4TTL門電流。P1口管腳寫入1后，被內(nèi)部上拉為高，可用作輸入，P1口被外部下拉為低電平時(shí)，將輸出電流，這是由于內(nèi)部上拉的緣故。在FLASH編程和校驗(yàn)時(shí)，P1口作為第八位地址接收。 </p><p><b>　　P2口：</b></p>&l

69、t;p>　　P2口為一個(gè)內(nèi)部上拉電阻的8位雙向I/O口，P2口緩沖器可接收，輸出4個(gè)TTL門電流，當(dāng)P2口被寫“1”時(shí)，其管腳被內(nèi)部上拉電阻拉高，且作為輸入。并因此作為輸入時(shí)，P2口的管腳被外部拉低，將輸出電流。這是由于內(nèi)部上拉的緣故。P2口當(dāng)用于外部程序存儲(chǔ)器或16位地址外部數(shù)據(jù)存儲(chǔ)器進(jìn)行存取時(shí)，P2口輸出地址的高八位。在給出地址“1”時(shí)，它利用內(nèi)部上拉優(yōu)勢(shì)，當(dāng)對(duì)外部八位地址數(shù)據(jù)存儲(chǔ)器進(jìn)行讀寫時(shí)，P2口輸出其特殊功能寄存器的內(nèi)容

70、。P2口在FLASH編程和校驗(yàn)時(shí)接收高八位地址信號(hào)和控制信號(hào)。</p><p><b>　　P3口：</b></p><p>　　P3口管腳是8個(gè)帶內(nèi)部上拉電阻的雙向I/O口，可接收輸出4個(gè)TTL門電流。當(dāng)P3口寫入“1”后，它們被內(nèi)部上拉為高電平，并用作輸入。作為輸入，由于外部下拉為低電平，P3口將輸出電流（ILL）這是由于上拉的緣故。</p><

71、;p>　　RST 復(fù)位輸入。此管腳上出現(xiàn)兩個(gè)機(jī)器周期的高電平，而振蕩器運(yùn)行將使器件復(fù)位。 進(jìn)修/編 地址鎖存使能鎖存在訪問外部存儲(chǔ)器地址的低字節(jié)輸出脈沖。該引腳也是在flash編程脈沖輸入programming.In正常運(yùn)行的ALE（編）是在1 / 6振蕩器頻率恒定的速率發(fā)射，并可能對(duì)外部定時(shí)或時(shí)鐘的用途。請(qǐng)注意，但是，一個(gè)ALE脈沖被跳過在每次訪問外部數(shù)據(jù)存儲(chǔ)器。 如果需要時(shí)，ALE操作可以通過設(shè)置位SFR的位置8EH

72、0。隨著位設(shè)置，ALE為活躍，只有在執(zhí)行MOVX或MOVC指令。否則，腳弱拉高。設(shè)置的ALE -禁用位微控制器沒有影響，如果在外部執(zhí)行模式。</p><p>　　ALE/PROG：當(dāng)訪問外部存儲(chǔ)器時(shí)，地址鎖存允許的輸出電平用于鎖存地址的地位字節(jié)。在FLASH編程期間，此引腳用于輸入編程脈沖。在平時(shí)，ALE端以不變的頻率周期輸出正脈沖信號(hào)，此頻率為振蕩器頻率的1/6。因此它可用作對(duì)外部輸出的脈沖或用于定時(shí)目的。然而

73、要注意的是：每當(dāng)用作外部數(shù)據(jù)存儲(chǔ)器時(shí)，將跳過一個(gè)ALE脈沖。如想禁止ALE的輸出可在SFR8EH地址上置0。此時(shí)，ALE只有在執(zhí)行MOVX，MOVC指令是ALE才起作用。另外，該引腳被略微拉高。如果微處理器在外部執(zhí)行狀態(tài)ALE禁止，置位無效。</p><p>　　PSEN：外部程序存儲(chǔ)器的選通信號(hào)。在由外部程序存儲(chǔ)器取指期間，每個(gè)機(jī)器周期兩次/PSEN有效。但在訪問外部數(shù)據(jù)存儲(chǔ)器時(shí)，這兩次有效的/PSEN信號(hào)將不

74、出現(xiàn)。</p><p>　　EA/VPP：當(dāng)/EA保持低電平時(shí)，則在此期間外部程序存儲(chǔ)器（0000H-FFFFH），不管是否有內(nèi)部程序存儲(chǔ)器。注意加密方式1時(shí)，/EA將內(nèi)部鎖定為RESET；當(dāng)/EA端保持高電平時(shí)，此間內(nèi)部程序存儲(chǔ)器。在FLASH編程期間，此引腳也用于施加12V編程電源（VPP）。</p><p>　　XTAL1：反向振蕩放大器的輸入及內(nèi)部時(shí)鐘工作電路的輸入。XTAL2：來