最新5-单片机+外文文献+英文文献+外文翻译中英对照
单片机 外文翻译 外文文献 英文文献 51系列单片机的结构和功能
单片机外文翻译外文文献英文文献 51系列单片机的结构和功能Structure and function of the MCS-51Structure and function of the MCS-51 series one-chip computer MCS-51 is a name of a piece of one-chip computer series which Intel Company produces. This company introduced 8 top-grade one-chip computers of MCS-51 series in 1980 after introducing 8 one-chip computers of MCS-48series in 1976. It belong to a lot of kinds this line of one-chip computer the chips have,such as 8051, 8031, 8751, 80C51BH, 80C31BH,etc., their basic composition, basic performance and instruction system areall the same. 8051 daily representatives- 51 serial one-chip computers .An one-chip computer system is made up of several following parts: ( 1) One microprocessor of 8 (CPU). ( 2) At slice data memory RAM(128B/256B),it use not depositting not can reading /data that write,such as result not middle of operation, final result and data wanted to show, etc. ( 3) Procedure memory ROM/EPROM (4KB/8KB ), is used to preserve the procedure , some initial data and form in slice. But does not take ROM/EPROM within some one-chip computers, such as 8031 , 8032, 80C ,etc.. ( 4) Four 8 run side by side I/O interface P0 four P3, each mouth can use as introduction , may use as exporting too. ( 5) Two timer / counter, each timer / counter may set up and count in the way, used to count to the external incident, can set up into a timing way too, andcan according to count or result of timing realize the control of thecomputer. ( 6) Five cut off cutting off the control system of thesource . ( 7) One all duplexing serial I/O mouth of UART (universal asynchronous receiver/transmitter (UART) ), is it realize one-chip computer or one-chip computer and serial communication of computer to use for. ( 8) Stretch oscillator and clock produce circuit, quartz crystal finely tune electric capacity need outer. Allow oscillation frequency as 12 megahertas now at most. Every the above-mentioned part was joined through the inside data bus .Among them, CPU is a core of the one-chip computer, it is the control of the computer and command centre, made up of such parts as arithmetic unit and controller , etc.. The arithmetic unit can carry on 8 persons of arithmetic operation and unit ALU of logic operation while including one, the 1 storing device temporarilies of 8, storing device 2 temporarily, 8's accumulation device ACC, register B and procedure state register PSW, etc. Person who accumulate ACC count by 2 input ends entered of checking etc. temporarily as one operation often, come from person who store 1 operation is it is it make operation to go on to count temporarily , operation result and loopback ACC with another one. In addition, ACC is often regarded as the transfer station of data transmission on 8051 inside . The same as general microprocessor, it is the busiest register. Helpremembering that agreeing with A expresses in the order. The controller includes the procedure counter , the order is depositted, the order decipher, the oscillator and timing circuit, etc. The procedurecounter is made up of counter of 8 for two, amounts to 16. It is a byte address counter of the procedure in fact, the content is the next IAthat will carried out in PC. The content which changes it can change the direction that the procedure carries out . Shake the circuit in 8051one-chip computers, only need outer quartz crystal and frequency to finely tune the electric capacity, its frequency range is its 12MHZ of 1.2MHZ. This pulse signal, as 8051 basic beats of working, namely the minimum unit of time. 8051 is the same as other computers, the work in harmony under the control of the basic beat, just like an orchestra according to the beat play that is commanded.There are ROM (procedure memory , can only read ) and RAM in 8051 slices (data memory, can is it can write ) two to read, they have each independent memory address space, dispose way to be the same with general memory of computer. Procedure 8051 memory and 8751 slice procedure memory capacity 4KB, address begin from 0000H, used for preserving the procedure and form constant. Data 8051- 8751 8031 of memory data memory 128B, address false 00FH, use for middle result to deposit operation, the data are stored temporarily and the data are buffered etc.. In RAM of this 128B, there is unit of 32 byteses that can be appointed as the job register, this and general microprocessor is different, 8051 slice RAM and job register rank one formation the same to arrange the location. It is not very the same that the memory of MCS-51 series one-chip computer and general computer disposes the way in addition. General computer for first address space, ROM and RAM canarrange in different space within the range of this address at will, namely the addresses of ROM and RAM, with distributing different address space in a formation. While visiting the memory, corresponding and only an address Memory unit, can ROM, it can be RAM too, and by visiting the order similarly. This kind of memory structure is called the structure of Princeton. 8051 memories are divided into procedure memory space and data memory space on the physics structure, there are four memory spaces in all: The procedure stores in one and data memory space outside data memory and one in procedure memory space and one outside one, the structure forms of this kind of procedure device and data memory separated form data memory, called Harvard structure. But use the angle from users, 8051 memory address space is divided into three kinds: (1) In the slice, arrange blocks of FFFFH , 0000H of location , in unison outside the slice (use 16 addresses). (2) The data memory address space outside one of 64KB, the address isarranged from 0000H 64KB FFFFH (with 16 addresses ) too to the location. (3) Data memory address space of 256B (use 8 addresses). Three above-mentioned memory space addresses overlap, for distinguishing and designing the order symbol of different data transmission in the instruction system of 8051: CPU visit slice, ROM order spend MOVC ,visit block RAM order uses MOVX outside the slice, RAM order uses MOV to visit in slice.8051 one-chip computer have four 8 walk abreast I/O port, call P0,P1, P2 and P3. Each port is 8 accurate two-way mouths, accounts for 32pins altogether. Every one I/O line can be used as introduction and exported independently. Each port includes a latch (namely special function register ), one exports the driver and a introduction buffer . Make data can latch when outputting, data can buffer when making introduction , but four function of passway these self-same. Expand among the system of memory outside having slice, four port these may serve as accurate two-way mouth of I/O in common use. Expand among the system of memory outside having slice, P2 mouth see high 8 address off; P0 mouth is a two-way bus, send the introduction of 8 low addresses and data / export in timesharingOutput grade , P3 of mouth , P1 of P1 , connect with inside haveload resistance of drawing , every one of they can drive 4 Model LS TTL load to output. As while inputting the mouth, any TTL or NMOS circuit can drive P1 of 8051 one-chip computers as P3 mouth in a normal way . Because draw resistance on output grade of them have, can open a way collector too or drain-source resistance is it urge to open a way, do not need to have the resistance of drawing outerly . Mouths are all accurate two-way mouths too. When the conduct is input, must write the corresponding port latch with 1 first . As to 80C51 one-chip computer, port can only offer milliampere of output electric currents, is it output mouth go when urging one ordinary basing of transistor to regard as, should contact a resistance among the port and transistor base , in order to the electricity while restraining the high level from exporting P1~P3 Being restored to the throne is the operation of initializing ofan one-chip computer. Its main function is to turn PC into 0000Hinitially , make the one-chip computer begin to hold the conduct procedure from unit 0000H. Except that the ones that enter the system are initialized normally,as because procedure operate it make mistakes or operate there aren't mistake, in order to extricate oneself from a predicament , need to be pressed and restored to the throne the key restarting too. It is an input end which is restored to the throne the signal in 8051 China RST pin. Restore to the throne signal high level effective , should sustain 24 shake cycle (namely 2 machine cycles ) the above its effective times. If 6 of frequency ofutilization brilliant to shake, restore to the throne signalduration should exceed 4 delicate to finish restoring to the throne and operating. Produce the logic picture of circuit which is restored to the throne the signal:Restore to the throne the circuit and include two parts outside in the chip entirely. Outside that circuit produce to restore to the throne signal (RST ) hand over to Schmitt's trigger, restore to the throne circuit sample to output , Schmitt of trigger constantly in each S5P2 , machine of cycle in having one more , then just got and restored to the throne and operated the necessary signal insidly. Restore to the throne resistance of circuit generally, electric capacity parameter suitablefor 6 brilliant to shake, can is it restore to the throne signal high level duration greater than 2 machine cycles to guarantee. Being restored to the throne in the circuit is simple, its function is veryimportant. Pieces of one-chip computer system could normalrunning,should first check it can restore to the throne not succeeding. Checking and can pop one's head and monitor the pin with theoscillograph tentatively, push and is restored to the throne the key, the wave form that observes and has enough range is exported (instantaneous), can also through is it restore to the throne circuit group holding value carry on the experiment to change.Another name of MCS is embedded micro-controller, because it can be embedded into any micro-or small-scale equipment or equipment. At present, the single-chip embedded systems and Internet connectivity is a trend. However, Internet has been used as a fat server, thin machine technology users. This technology on the Internet to store and access large amounts of data is appropriate, but for control of embedded devices has become the "sledgehammer cracking a nut," the. Embedded devices to achieve and Int ernet connection, we need the Internet to the traditional theory and practice of embedded devices are reversed. In order to make complex or simple embedded devices, such as single-chip microcomputer-controlled machine tools, single-chip microcomputer-controlled door locks, can be practical and Internet connection, requires specialized equipment for the embedded microcontroller design a web server to embed devices can be connected to Internet, and through a standard Web browser to process control.At present, in order to single-chip microcomputer as the core of embedded systems and Internet connected companies, there are many morestudies in this area. More typical in this regard have emWare and TASKING company. Embedded systems companies EmWare network program - EMIT technology. This technology consists of three main parts: the emMicro, emGateway and web browser. Which, emMicroembedded devices is a 1K-byte memory capacity accounted for only a very small web servers; emGateway stronger as a function of the user or server, and it is used to achieve more than the management of embedded devices, as well as standard access the Internet communications, as well as the support of a web browser. Web browsers use to display and embedded emObjicts data transmission between devices. If sufficient resources embedded devices, while at the same time emMicro and emGateway into embedded devices, to achieve direct access to the Inter net. Otherwise, it will require a web browser emGateway and each other. EmWare's EMIT software technology using standard Internet protocol for 8-bit and 16-bit embedded devices to manage, but costs much less traditional. At present, single-chip applications, a new problem: This is how to make the 8-bit, 16-bit single-chip microcomputer to control the product, or embedded products or equipment to achieve the interconnection and the Internet? TASKING is now to solve this problem means. The company has emWare of EMIT software packages and related supporting integration, the formation of an integrated development environment, to provide users with convenient development. Embedded Internet Union ETI (embed the Internet Consortium) is to work closelywith the development of embedded Internet solutions. Results in the near future there will be published.中文译文51系列单片机的结构和功能51系列单片机是英特尔公司生产的具有一定结构和功能的单片机产品。
51单片机英文文献及翻译
Data Memory
数据存储器
Te context with microcontrollers,
术语“数据存储器”用于微控制器。
The memory which stores data,i.e.RAM,is called data memory.
用来存储数据的存储器，即RAM，被称作数据存储器
The diffenent versions of 8048 series of microcontrollers microcontrollers contain 64,128.256 bytes of RAM.
8048系列的不同版本的微控制器包含64、128、256字节的RAM。
Data Memory The term data memory is used in the context with microcontrollers,The memory which stores data,i.e.RAM,is called data memory.The diffenent versions of 8048 series of microcontrollers microcontrollers contain 64,128.256 bytes of RAM.The 8048AH,8049AH and 8050AH contain 64,128 and 256 bytes of RAM respectively.64/128/256 bytes of RAM is used either as read/write memory or general-purpose registers.
There is need of cyclical reading (lower than 1 minute periods) of the actual values from the real-time clock and the sensors for pressure and temperature, and to store the read values into the microcontroller’s memory. The communication with the real-time clock and the sensors is possible with the use of I2C interface and the previously defined in the specifications protocols for reading and writing.
5电气自动化 单片机 外文文献 英文文献 外文翻译 中英对照大学毕设论文
Single-chip1.The definition of a single-chipSingle-chip is an integrated on a single chip a complete computer system .Even though most of his features in a small chip，but it has a need to complete the majority of computer components：CPU，memory，internal and external bus system，most will have the Core.At the same time，such as integrated communication interfaces，timers，real-time clock and other peripheral equipment.And now the most powerful single-chip microcomputer system can even voice ，image，networking，input and output complex system integration on a single chip.Also known as single-chip MCU（Microcontroller），because it was first used in the field of industrial control.Only by the single-chip CPU chip developed from the dedicated processor. The design concept is the first by a large numberof peripherals and CPU in a single chip，the computer system so that smaller，more easily integrated into the complex and demanding on the volume control devices.INTEL the Z80 is one of the first design in accordance with the idea of the processor，From then on，the MCU and the development of a dedicated processor parted ways.Early single-chip 8-bit or all the four.One of the most successful is INTELs 8031，because the performance of a simple and reliable access to a lot of good praise.Since then in 8031to develop a single-chip microcomputer system MCS51 series.based on single-chip microcomputer system of the system is still widely used until now.As the field of industrial control requirements increase in the beginning of a 16-bit single-chip，but not ideal because the price has not been very widely used.After the90s with the big consumer electronics product development，single-chip technology is a huge improvement.INTEL i960 series with subsequent ARM in particular ，a broad range of application，quickly replaced by 32-bit single-chip 16-bit single-chip performance has been the rapid increase in processing power compared to the 80s to raise a few hundred times.At present，the high-end 32-bit single-chip frequency over 300MHz，the performance of the mid-90s close on the heels of a special processor，while the ordinary price of the model dropped to one U.S dollars，the most high-end models，only 10 U.S dollars.Contemporary single-chip microcomputer system is no longer only the bare-metal environment in the development and use of a large number of dedicated embedded operating system is widely used in the full range of single-chip microcomputer.In PDAs and cellphones as the coreprocessing of high-end single-chip or even a dedicated direct access to Windows and Linux operating systems.More than a dedicated single-chip processor suitable for embedded systems，so it was up to the application.In fact the number of single-chip is the worlds largest computer.Modern human life used in almost every piece of electronic and mechanical products will have a single-chip integration.Phone，telephone，calculator，home applicances，electronic toys，handheld computers and computer accessories such as a mouse in the Department are equipped with 1-2 single chip.And personal computers also have a large number of single-chip microcomputer in the workplace.Vehicles equipped with more than 40 Department of the general single-chip ，complex industrial control systems and even single-chip may have hundreds of work at the same time!SCM is not only far exceeds the number of PC and other integrated computing,even more than the number of human beings.2.single-chip introducedSingle-chip,also known as single-chip microcontroller,it is not the completion of a logic function of the chip,but a computer system integrated into a chip.Speaking in general terms: a single chip has become a computer .Its small size,light weight,cheap,for the learning,application and development of facilities provided .At the same time,learning to use the principle of single-chip computer to understand and structure the best choice.Single-chip and computer use is also similar to the module,such as CPU,memory,parallel bus, as well as the role and the same hard memory,is it different from the performance of these components are relatively weak in our home computer a lot,but the price is low ,there is generally no more than 10yuan,,can use it to make some control for a class of electrical work is not very complex is sufficient.We are using automatic drum washing machines, smoke hood,VCD and so on inside the home appliances can see its shadow! It is mainly as part of the core components of the control.It is an online real-time control computer,control-line is at the scene,we need to have a stronger anti-interference ability,low cost,and this is off-line computer(such as home PC)The main difference.By single-chip process,and can be amended.Through different procedures to achieve different functions,in particular the special unique features,this is the need to charge other devices can do a great effort,some of it is also difficult to make great efforts to do so .A function is not very complicated fi the United States the development of the 50s series of 74 or 60 during the CD4000series to get these pure hardware,the circuit must be a big PCB board !However,if the United States if the successful 70s seriesof single-chip market ,the result will be different!Simply because the adoption of single-chip preparation process you can achieve high intelligence,high efficiency and high reliability!Because of cost of single-chip is sensitive,so the dominant software or the lowest level assembly language,which is in addition to the lowest level for more than binary machine code of the language ,since such a low-level so why should we use ?Many of the seniors language has reached a level of visual programming why is it not in use ?The reason is simple ,that is,single-chip computer as there is no home of CPU,also not as hard as the mass storage device.A visualization of small high-level language program,even if there is only one button which will reach the size of dozens of K! For the home PCs hard drive is nothing,but in terms of the single-chip microcomputer is unacceptable.Single-chip in the utilization of hardware resources have to do very high ,so the compilation of the original while still in heavy use .The same token ,if the computer giants operating system and appplications run up to get the home PC,homePCcan not afford to sustain the same.It can be said that the twentieth century across the three “power”of the times,that is ,the electrical era,the electronic age and has now entered the computer age. However ,such a computer,usually refers to a personal computer,or PC.It consisits of the host ,keyboards,displays .And other components.There is also a type of computer,not how most people are familiar with . This computer is smart to give a variety of mechanical single-chip(also known as micro-controller).As the name suggests,these computer systems use only the minimum of an integrated circuit to make a simple calculation and control. Because of its small size,are usually charged with possession of machine in the “belly”in. It in the device,like the human mind plays a role, it is wrong,the entire device was paralyzed .Now,this single chip has a very wide field of use,such as smart meters,real-time industrial control,communications equipment,navigation systems,and household appliances. Once a variety of products with the use of the single-chip ,will be able to play so that the effectiveness of product upgrading,product names often adjective before the word “intelligent”,such as was hing machines and so intelligent.At present,some technical personnel of factories or other amateur electrtonics developers from engaging in certain products ,not the circuit is too complex ,that is functional and easy to be too simple imitation.The reason may be the product not on the cards or the use of single-chip programmable logic device on the other.3.single-chip historysingle-chip 70 was born in the late 20th century,experienced a SCM,MCU,SOC three stages.Single-chip micro-computer 1.SCM that(Single Chip Microcomputer)stage,is mainly a single from to find the best of the best embedded systems architecture.”Innovation model”to be successful,lay the SCM with the general-purpose computers,a completely different path of development . In embedded systems to create an independent development path,Intel Corporation credit.That is 2.MCU microcontroller(Micro Controller Unit)stage,the main direction of technology development: expanding to meet the embedded applications,the target system requirements for the various peripheral circuits and interface circuits,to highlingt the target of intelligent control.It covers all areas related with the objectSystem,therefore,the development of MCU inevitably fall on the heavy electrical,electronics manufacturers. From this point of view ,Intels development gradually MCU has its objective factors.MCU in the development ,the most famous manufacturers when the number of Philips Corporation.Philips in embedded applications for its enormous advantages,the MCS-51 from the rapid deveploment of single-chip micro-computer to the microcontroller.Therefore,when we look back at the path of development of embedded systems,Intel and Philips do not forget the historical merits.3.Single-chip is an independent embedded systems development,to the MCU an important factor in the development stage,is seeking applications to maximize the natural trend .With the mico-electronics technology,IC design,EDA tools development,based on the single-chip SOC design application systems will have greater development. Therefore,the understanding of single-chip micro-computer from a single ,monolithic single-chip microcontroller extends to applications.4.Single-chip applicationsAt present,single-chip microcomputer to infiltrate all areas of our lives,which is very difficult to find the area of almost no traces of single-chip microcomputer.Missile navigation equipment,aircraft control on a variety of instruments,compuer network communications and data transmission,industrial automation,real-time process control and data processing ,are widely used in a variety of smart IC card,limousine civilian security systems,video recorders,cameras,the control of automatic washing machines,as well as program-controllde toys,electronic pet,etc,which are inseparable from the single-chip microcomputer.Not to mention the field of robot automation ,intelligent instrumentation,medical equipment has been. Therefore,the single- chip learning ,development and application to a large number of computer applications and intelligent control of scientists,engineers.Single-chip widely used in instruments and meters,household appliances，medical equipment ,acrospace,specialized equipment and the intellingent management in areas such as process control,generally can be divided into the following areas:1.In the smart application of instrumentationSingle-chip with small size,low power consumption,control,and expansion flexibility , miniaturization and ease of sensors,can be realized,suchvoltage,power,frequency,humidity,temperature,flow,speed,thickness,angle,length,hardness,elemen t,measurement of physical pressure. SCM makes use of digital instrumentation,intelligence,miniaturization and functional than the use of electronic or digital circuitry even stronger.For example,precision measurement equipment(power meter,oscilloscope,and analyzer).2.In the industrial controlMCU can constitute a variety of control systems,data acquisition system.Such as factory assembly line of intelligent management ,intelligent control of the lift ,all kinds of alarm systems ,and computer networks constitute a secondary control system.3.In the applicationof household appliancesIt can be said that almost all home appliances are using the single-chip control,electric rice from favorable,washing machines,refrigerators,air conditioners,color TV and other audio video equipment,and then to the electronic weighing equipment,all kinds ,everywhere.4.On computer networks and communication applications in the field ofGenerally with the modern single-chip communication interface,can be easily carried out with computer carried out with computer data communications,computer networks and in inter-application communications equipment to provide an excellent material conditions,the communications equipment to provide an excellent material condition,from the mobile phone ,telephone , mini-program-controlled switchboards,buiding automated communications system call,the train wireless communications,and then you can see day-to-day work of mobile phones,Mobile communications,such as radios.5.Single-chip in the field of medical equipment applicationsSingle-chip microcomputer in medical devices have a wide range of purpose,such as medical ventilator,various analyzers,monitors,ultrasonic diagnostic equipment and hospital call systems.6.In a variety of large-scale electrical applications of modularSome special single-chip design to achieve a specific function to carry out a variety of modular circuitapplications,without requiring users to understand its internal structure.Integrated single-chip microcomputer such as music ,which seems to be simpleFunctions,a miniature electronic chip in a pure(as distinct from the principle of tape machine),would require a complex similar to the principle of the computer. Such as :music signal to digital form stored in memory(similar to ROM),read out by the microcontroller into analog music signal(similar to the sound card).In large circuits,modular applications that greatly reduces the size ,simplifying the circuit and reduce the damage,error rate ,but also to facilitate the replacement.In addition,single-chip microcomputer in the industrial,commercial,financial,scientific research ,education,defense aerospace and other fields have a wide range of uses.单片机1.单片机定义单片机是一种集成在电路芯片上的完整计算机系统。
单片机英文参考文献
单片机英文参考文献篇一：5-单片机+外文文献+英文文献+外文翻译中英对照AT89C51的介绍（原文出处：http：///resource/）描述AT89C51是一个低电压，高性能CMOS8位单片机带有4K字节的可反复擦写的程序存储器（PENROM）。
和128字节的存取数据存储器（RAM），这种器件采用ATMEL公司的高密度、不容易丢失存储技术生产，并且能够与MCS-51系列的单片机兼容。
片内含有8位中央处理器和闪烁存储单元，有较强的功能的AT89C51单片机能够被应用到控制领域中。
功能特性AT89C51提供以下的功能标准：4K字节闪烁存储器，128字节随机存取数据存储器，32个I/O口，2个16位定时/计数器，1个5向量两级中断结构，1个串行通信口，片内震荡器和时钟电路。
另外，AT89C51还可以进行0HZ的静态逻辑操作，并支持两种软件的节电模式。
闲散方式停止中央处理器的工作，能够允许随机存取数据存储器、定时/计数器、串行通信口及中断系统继续工作。
掉电方式保存随机存取数据存储器中的内容，但震荡器停止工作并禁止其它所有部件的工作直到下一个复位。
引脚描述VCC：电源电压 GND：地 P0口：P0口是一组8位漏极开路双向I/O口，即地址/数据总线复用口。
作为输出口时，每一个管脚都能够驱动8个TTL电路。
当“1”被写入P0口时，每个管脚都能够作为高阻抗输入端。
P0口还能够在访问外部数据存储器或程序存储器时，转换地址和数据总线复用，并在这时激活内部的上拉电阻。
P0口在闪烁编程时，P0口接收指令，在程序校验时，输出指令，需要接电阻。
沈阳航空工业学院电子工程系毕业设计（外文翻译）P1口：P1口一个带内部上拉电阻的8位双向I/O口，P1的输出缓冲级可驱动4个TTL电路。
对端口写“1”，通过内部的电阻把端口拉到高电平，此时可作为输入口。
因为内部有电阻，某个引脚被外部信号拉低时输出一个电流。
闪烁编程时和程序校验时，P1口接收低8位地址。
单片机英文文献及翻译
附录A英文文献翻译原文Temperature Control Using a Microcontroller:An Interdisciplinary Undergraduate Engineering Design ProjectJames S. McDonaldDepartment of Engineering ScienceTrinity UniversitySan Antonio, TX 78212AbstractThis paper describes an interdisc iplinary design project which was done under the author’s supervision by a group of four senior students in the Department of Engineering Science at Trinity University. The objective of the project was to develop a temperature control system for an air-filled chamber. The system was to allow entry of a desired chamber temperature in a prescribed range and to exhibit overshoot and steady-state temperature error of less than 1 degree Kelvin in the actual chamber temperature step response. The details of the design developed by this group of students, based on a Motorola MC68HC05 family microcontroller, are described. The pedagogical value of the problem is also discussed through a description of some of the key steps in the design process. It is shown that the solution requires broad knowledge drawn from several engineering disciplines including electrical, mechanical, and control systems engineering.1 IntroductionThe design project which is the subject of this paper originated from a real-world application.A prototype of a microscope slide dryer had been developed around an OmegaTM modelCN-390 temperature controller, and the objective was to develop a custom temperature control system to replace the Omega system. The motivation was that a custom controller targeted specifically for the application should be able to achieve the same functionality at a much lower cost, as the Omega system is unnecessarily versatile and equipped to handle a wide variety of applications.The mechanical layout of the slide dryer prototype is shown in Figure 1. The main element of the dryer is a large, insulated, air-filled chamber in which microscope slides, each with a tissue sample encased in paraffin, can be set on caddies. In order that the paraffin maintain the proper consistency, the temperature in the slide chamber must be maintained at a desired (constant) temperature. A second chamber (the electronics enclosure) houses a resistive heater and the temperature controller, and a fan mounted on the end of the dryer blows air across theheater, carrying heat into the slide chamber. This design project was carried out during academic year 1996–97 by four students under the author’s supervision as a Senior Design project in the Department of Engineering Science at Trinity University. The purpose of this paper isto describe the problem and the students’ solution in some detail, and to discuss some of the pedagogical opportunities offered by an interdisciplinary design project of this type. The students’ own report was presented a t the 1997 National Conference on Undergraduate Research [1]. Section 2 gives a more detailed statement of the problem, including performance specifications, and Section 3 describes the students’ design. Section 4 makes up the bulk of the paper, and discusses in some detail several aspects of the design process which offer unique pedagogical opportunities. Finally, Section 5 offers some conclusions.2 Problem StatementThe basic idea of the project is to replace the relevant parts of the functionality of an Omega CN-390 temperature controller using a custom-designed system. The application dictates that temperature settings are usually kept constant for long periods of time, but it’s nonetheless important that step changes be tracked in a “reasonable” manner. Thus the main requirements boil down to·allowing a chamber temperature set-point to be entered,·displaying both set-point and actual temperatures, and·tracking step changes in set-point temperature with acceptable rise time, steady-state error, and overshoot.Although not explicitly a part of the specifications in Table 1, it was clear that the customer desired digital displays of set-point and actual temperatures, and that set-point temperature entry should be digital as well (as opposed to, say, through a potentiometer setting).3 System DesignThe requirements for digital temperature displays and setpoint entry alone are enough to dictate that a microcontrollerbased design is likely the most appropriate. Figure 2 shows a block diagram of the stude nts’ design.The microcontroller, a MotorolaMC68HC705B16 (6805 for short), is the heart of the system. It accepts inputs from a simple four-key keypad which allow specification of the set-point temperature, and it displays both set-point and measured chamber temperatures using two-digit seven-segment LED displays controlled by a display driver. All these inputs and outputs are accommodated by parallel ports on the 6805. Chamber temperature is sensed using apre-calibrated thermistor and input via one of the 6805’s analog-to-digital inputs. Finally, a pulse-width modulation (PWM) output on the 6805 is used to drive a relay which switches line power to the resistive heater off and on.Figure 3 shows a more detailed schematic of the electronics and their interfacing to the 6805. The keypad, a Storm 3K041103, has four keys which are interfaced to pins PA0{ PA3 of Port A, configured as inputs. One key functions as a mode switch. Two modes are supported: set mode and run mode. In set mode two of the other keys are used to specify the set-point temperature: one increments it and one decrements. The fourth key is unused at present. The LED displays are driven by a Harris Semiconductor ICM7212 display driver interfaced to pins PB0{PB6 of Port B, configured as outputs. The temperature-sensing thermistor drives, through a voltage divider, pin AN0 (one of eight analog inputs). Finally, pin PLMA (one of two PWM outputs) drives the heater relay.Software on the 6805 implements the temperature control algorithm, maintains the temperature displays, and alters the set-point in response to keypad inputs. Because it is not complete at this writing, software will not be discussed in detail in this paper. The control algorithm in particular has not been determined, but it is likely to be a simple proportional controller and certainly not more complex than a PID. Some control design issues will be discussed in Section 4, however.4 The Design ProcessAlthough essentially the project is just to build a thermostat, it presents many nice pedagogical opportunities. The knowledge and experience base of a senior engineering undergraduate are just enough to bring him or her to the brink of a solution to various aspects of the problem. Yet, in each case, realworld considerations complicate the situation significantly.Fortunately these complications are not insurmountable, and the result is a very beneficial design experience. The remainder of this section looks at a few aspects of the problem which present the type of learning opportunity just described. Section 4.1 discusses some of the features of a simplified mathematical model of the thermal properties of the system and how it can beeasily validated experimentally. Section 4.2 describes how realistic control algorithm designs can be arrived at using introductory concepts in control design. Section 4.3 points out some important deficiencies of such a simplified modeling/control design process and how they can be overcome through simulation. Finally, Section 4.4 gives an overview of some of the microcontroller-related design issues which arise and learning opportunities offered.4.1 MathematicalModelLumped-element thermal systems are described in almost any introductory linear control systems text, and just this sort of model is applicable to the slide dryer problem. Figure 4 shows a second-order lumped-element thermal model of the slide dryer. The state variables are the temperatures Ta of the air in the box and Tb of the box itself. The inputs to the system are the power output q(t) of the heater and the ambient temperature T¥. ma and mb are the masses of the air and the box, respectively, and Ca and Cb their specific heats. μ1 and μ2 are heat transfer coefficients from the air to the box and from the box to the external world, respectively.It’s not hard to show that the (linearized) state equationscorresponding to Figure 4 areTaking Laplace transforms of (1) and (2) and solving for Ta(s), which is the output of interest, gives the following open-loop model of the thermal system:where K is a constant and D(s) is a second-order polynomial.K, tz, and the coefficients ofD(s) are functions of the variousparameters appearing in (1) and (2).Of course the various parameters in (1) and (2) are completely unknown, but it’s not hard to show that, regardless of their values, D(s) has two real zeros. Therefore the main transfer function of interest (which isthe one from Q(s), since we’ll assume constant ambient temperature) can be writtenMoreover, it’s not too hard to show that 1=tp1 <1=tz <1=tp2, i.e., that the zero lies between the two poles. Both of these are excellent exercises for the student, and the result is the openloop pole-zero diagram of Figure 5.Obtaining a complete thermal model, then, is reduced to identifying the constant K and the three unknown time constants in (3). Four unknown parameters is quite a few, but simple experiments show that 1=tp1 _ 1=tz;1=tp2 so that tz;tp2 _ 0 are good approximations. Thus the open-loop system is essentially first-order and can therefore be written(where the subscript p1 has been dropped).Simple open-loop step response experiments show that,for a wide range of initial temperatures and heat inputs, K _0:14 _=W and t _ 295 s.14.2 Control System DesignUsing the first-order model of (4) for the open-loop transfer function Gaq(s) and assuming for the moment that linear control of the heater power output q(t) is possible, the block diagram of Figure 6 represents the closed-loop system. Td(s) is the desired, or set-point, temperature,C(s) is the compensator transfer function, and Q(s) is the heater output in watts.Given this simple situation, introductory linear control design tools such as the root locus method can be used to arrive at a C(s) which meets the step response requirements on rise time, steady-state error, and overshoot specified in Table 1. The upshot, of course, is that a proportional controller with sufficient gain can meet all specifications. Overshoot is impossible, and increasing gains decreases both steady-state error and rise time.Unfortunately, sufficient gain to meet the specifications may require larger heat outputs than the heater is capable of producing. This was indeed the case for this system, and the result is that the rise time specification cannot be met. It is quite revealing to the student how useful such an oversimplified model, carefully arrived at, can be in determining overall performance limitations.4.3 Simulation ModelGross performance and its limitations can be determined using the simplified model of Figure 6, but there are a number of other aspects of the closed-loop system whose effects on performance are not so simply modeled. Chief among these are·quantization error in analog-to-digital conversion of the measured temperature and· the use of PWM to control the heater.Both of these are nonlinear and time-varying effects, and the only practical way to study them is through simulation (or experiment, of course).Figure 7 shows a SimulinkTM block diagram of the closed-loop system which incorporates these effects. A/D converter quantization and saturation are modeled using standard Simulink quantizer and saturation blocks. Modeling PWM is more complicated and requires a customS-function to represent it.This simulation model has proven particularly useful in gauging the effects of varying thebasic PWM parameters and hence selecting them appropriately. (I.e., the longer the period, the larger the temperature error PWM introduces. On the other hand, a long period is desirable to avoid excessiv e relay “chatter,” among other things.) PWM is often difficult for students to grasp, and the simulation model allows an exploration of its operation and effects which is quite revealing.4.4 The MicrocontrollerSimple closed-loop control, keypad reading, and display control are some of the classic applications of microcontrollers, and this project incorporates all three. It is therefore an excellent all-around exercise in microcontroller applications. In addition, because the project isto produce an actua l packaged prototype, it won’t do to use a simple evaluation board with theI/O pins jumpered to the target system. Instead, it’s necessary to develop a complete embedded application. This entails the choice of an appropriate part from the broad range offered in a typical microcontroller family and learning to use a fairly sophisticated development environment. Finally, a custom printed-circuit board for the microcontroller and peripherals must be designed and fabricated.Microcontroller Selection. In view of existing local expertise, the Motorola line of microcontrollers was chosen for this project. Still, this does not narrow the choice down much. A fairly disciplined study of system requirements is necessary to specify which microcontroller, out of scores of variants, is required for the job. This is difficult for students, as they generally lack the experience and intuition needed as well as the perseverance to wade through manufacturers’ selection guides.Part of the problem is in choosing methods for interfacing the various peripherals (e.g., what kind of display driver should be used?). A study of relevant Motorola application notes [2, 3, 4] proved very helpful in understandingwhat basic approaches are available, and what microcontroller/peripheral combinations should be considered.The MC68HC705B16 was finally chosen on the basis of its availableA/D inputs and PWMoutputs as well as 24 digital I/O lines. In retrospect this is probably overkill, as only oneA/D channel, one PWM channel, and 11 I/O pins are actually required (see Figure 3). The decision was made to err on the safe side because a complete development system specific to the chosen part was necessary, and the project budget did not permit a second such system to be purchased should the firstprove inadequate.Microcontroller Application Development. Breadboarding of the peripheral hardware, development of microcontroller software, and final debugging and testing of a customprinted-circuit board for the microcontroller and peripherals all require a development environment of some kind. The choice of a development environment, like that of themicrocontroller itself, can be bewildering and requires some faculty expertise. Motorola makes three grades of development environment ranging from simple evaluation boards (at around $100) to full-blown real-time in-circuit emulators (at more like $7500). The middle option was chosen for this project: the MMEVS, which consists of _ a platform board (which supports all 6805-family parts), _ an emulator module (specific to B-series parts), and _ a cable and target head adapter (package-specific). Overall, the system costs about $900 and provides, with some limitations, in-circuit emulation capability. It also comes with the simple but sufficient software development environment RAPID [5].Students find learning to use this type of system challenging, but the experience they gain in real-world microcontroller application development greatly exceeds the typical first-course experience using simple evaluation boards.Printed-Circuit Board. The layout of a simple (though definitely not trivial) printed-circuit board is another practical learning opportunity presented by this project. The final board layout, with package outlines, is shown (at 50% of actual size) in Figure 8. The relative simplicity of the circuit makes manual placement and routing practical—in fact, it likely gives better results than automatic in an application like this—and the student is therefore exposed to fundamental issues of printed-circuit layout and basic design rules. The layout software used was the very nice package pcb,2 and the board was fabricated in-house with the aid of our staff electronics technician.5 ConclusionThe aim of this paper has been to describe an interdisciplinary, undergraduate engineering design project: a microcontroller- based temperature control system with digital set-point entry and set-point/actual temperature display. A particular design of such a system has been described, and a number of design issues which arise—from a variety of engineering disciplines—have been discussed. Resolution of these issues generally requires knowledge beyond that acquired in introductory courses, but realistically accessible to advance undergraduate students, especiallywith the advice and supervision of faculty.Desirable features of the problem, from a pedagogical viewpoint, include the use of a microcontroller with simple peripherals, the opportunity to usefully apply introductorylevel modeling of physical systems and design of closed-loop controls, and the need for relatively simple experimentation (for model validation) and simulation (for detailed performance prediction). Also desirable are some of the technologyrelated aspects of the problem including practical use of resistive heaters and temperature sensors (requiring knowledge of PWM and calibration techniques, respectively), microcontroller selection and use of development systems, and printedcircuit design.AcknowledgementsThe author would like to acknowledge the hard work, dedication, and ability shown by the students involved in this project: Mark Langsdorf, Matt Rall, PamRinehart, and David Schuchmann. It is their project, and credit for its success belongs to them.References[1] M. Langsdorf, M. Rall, D. Schuchmann, and P. Rinehart,“Temperature control of a microscope slide dryer,” in1997 National Conference on Undergraduate Research,(Austin, TX), April 1997. Poster presentation.[2] Motorola, Inc., Phoenix, AZ, Temperature Measurementand Display Using the MC68HC05B4 and the MC14489,1990. Motorola SemiconductorApplicationNote AN431.[3] Motorola, Inc., Phoenix, AZ, HC05 MCU LED DriveTechniques Using the MC68HC705J1A, 1995. MotorolaSemiconductor Application Note AN1238.[4] Motorola, Inc., Phoenix, AZ, HC05MCU Keypad DecodingTechniques Using the MC68HC705J1A, 1995. MotorolaSemiconductor Application Note AN1239.[5] Motorola, Inc., Phoenix, AZ, RAPID Integrated DevelopmentEnvironment User’s Manual, 1993. (RAPID wasdeveloped by P & E Microcomputer Systems, Inc.).附录B英文文献翻译中文单片机温度控制：一个跨学科的本科生工程设计项目JamesS.McDonald工程科学系三一大学德克萨斯州圣安东尼奥市78212摘要本文所描述的是作者领导由四个三一大学高年级学生组成的团队进行的一个跨学科工程项目的设计。
关于51单片机英文文献的英文翻译
利用单片机的定时器6.1 前言这一章包含一个描述的定时器系统微控制器，包括通用定时器，该定时器，和看门狗。
6.2 总体结构和功能，计时器系统时间是必不可少的操作微控制器系统，可以生成信号的精确确定的期限，或外部事件计数。
这原因，定时器子系统，是目前所有的微控制器的实现，和涵盖的范围广泛的功能包括：•生成精确的时间间隔•测量时间的外部事件•计数外部事件。
多数微控制器提供专用定时器，或使用通用计时器实现以下功能：•实时时钟•产生的脉冲宽度调制（脉宽调制）信号•看门狗检测程序失控情况。
虽然有很大的差异在不同的实现通用定时器在不同的微控制器，有许多相似在操作的原则和结构的定时器子系统。
图6.1显示了一个定时器系统总体框图，说明原则实施最单片机定时器。
核心要素的定时器子系统是一个计数器，tcnt（8或16位在长度），这可能是读或写的软件（有时）。
时钟tcnt 得到从系统时钟，除以一个可编程分频器，或外部时钟应用到一个单片机引脚。
软件控制的计时器68使用6单片机定时器。
采用控制寄存器晶体管和信息方面的各种事件相关的计时器，可以读取状态寄存器tflg。
几种工作模式是可能的计时器：定时器溢出。
在这种模式下，如果感兴趣的是当tcnt计数器达到它的最大数量和返回到零在下一个时钟脉冲。
溢出信号这标志着这一事件是应用于中断控制逻辑（Ⅱ），这可能产生一个中断请求处理器。
之间的时间间隔连续溢出控制通过修改输入时钟频率应用到tcnt，或以书面tcnt 一初始值的计算。
•输入捕获。
在这种经营模式，内容tcnt此刻的发生外部事件，定义边缘的一个输入信号，转移在捕获寄存器（民事），和一个中断请求可能会生成。
由比较连续值捕获率，有可能确定之间的时间间隔的外部事件。
•输出比较。
在这种经营模式，内容tcnt不断比较了硬件的内容的光学字符识别（比较寄存器的输出）指数字比较器的比较。
当一个寄存器的内容比赛中，一个中断请求可能会生成。
或者，可以比较匹配通过编程改变现状的一个或多个输出线。
单片机外文文献翻译(2024)
引言：单片机（Microcontroller）是一种广泛应用于嵌入式系统中的小型计算机芯片。
它集成了处理器核心、存储器、外设接口和时钟电路等核心部件，可以独立运行。
随着全球化的发展，外文文献对于学习和研究单片机领域来说至关重要。
本文翻译的外文文献《MicrocontrollerbasedTrafficLightControlSystem》详细介绍了基于单片机的交通信号灯控制系统。
概述：交通信号灯控制是现代都市交通系统中至关重要的一环。
传统的交通信号灯控制系统通常由定时器控制，不能根据实际交通情况动态调整信号灯的时间。
而基于单片机的交通信号灯控制系统可以实现根据实时交通流量来动态调整信号灯的时间，优化交通效率。
本文将详细介绍该系统的设计和实现。
正文：一、单片机选型1.1.CPU性能：本文选择了一款高性能的32位单片机作为控制核心，它具有较高的处理能力和较大的存储器容量，可以同时处理多条交通路口的信号控制。
1.2.外设接口：该单片机具有丰富的外设接口，可以与交通信号灯、传感器和通信设备等进行连接，实现信号控制和数据交互。
1.3.低功耗设计：为了节约能源和延长系统寿命，在单片机选型时考虑了低功耗设计，降低系统运行的能耗。
二、硬件设计2.1.交通信号灯：在设计交通信号灯时，考虑了日夜可见性和能耗。
采用了高亮度LED作为信号灯光源，同时添加了光敏传感器控制信号灯的亮度，以满足不同时间段的亮度需求。
2.2.传感器：通过安装车辆感应器和行人感应器等传感器，可以在实时监测交通流量的基础上，智能调整信号灯时间，提高路口的交通效率。
2.3.通信设备：在交通信号灯控制系统中引入了通信设备，可以实现各交通路口之间的信息交互和协调控制，提高整体交通系统的效率。
三、软件设计3.1.程序架构：采用了多任务的实时操作系统，将交通信号灯控制、传感器数据处理和通信设备控制等功能分别封装成不同的任务，实现了系统的高效运行和任务调度。
单片机设计外文文献翻译(含中英文)
附录A 外文翻译——AT89S52/AT89S51技术手册AT89S52译文主要性能与MCS-51单片机产品兼容8K字节在系统可编程Flash存储器1000次擦写周期全静态操作：0Hz～33Hz三级加密程序存储器32个可编程I/O口线三个16位定时器/计数器八个中断源全双工UART串行通道低功耗空闲和掉电模式掉电后中断可唤醒看门狗定时器双数据指针掉电标识符功能特性描述AT89S52是一种低功耗、高性能CMOS8位微控制器，具有8K在系统可编程Flash 存储器。
使用Atmel公司高密度非易失性存储器技术制造，与工业80C51产品指令和引脚完全兼容。
片上Flash 允许程序存储器在系统可编程，亦适于常规编程器。
在单芯片上，拥有灵巧的8位CPU和在系统可编程Flash，使得AT89S52为众多嵌入式控制应用系统提供高灵活、超有效的解决方案。
AT89S52具有以下标准功能：8k字节Flash，256字节RAM，32位I/O口线，看门狗定时器，2个数据指针，三个16位定时器/计数器，一个6向量2级中断结构，全双工串行口，片内晶振及时钟电路。
另外，AT89S52可降至0Hz静态逻辑操作，支持2种软件可选择节电模式。
空闲模式下，CPU停止工作，允许RAM、定时器/计数器、串口、中断继续工作。
掉电保护方式下，RAM内容被保存，振荡器被冻结，单片机一切工作停止，直到下一个中断或硬件复位为止。
引脚结构方框图VCC : 电源GND :地P0口：P0口是一个8位漏极开路的双向I/O口。
作为输出口，每位能驱动8个TTL逻辑电平。
对P0端口写“1”时，引脚用作高阻抗输入。
当访问外部程序和数据存储器时，P0口也被作为低8位地址/数据复用。
在这种模式下，P0具有内部上拉电阻。
在flash编程时，P0口也用来接收指令字节；在程序校验时，输出指令字节。
程序校验时，需要外部上拉电阻。
P1口：P1 口是一个具有内部上拉电阻的8位双向I/O 口，p1 输出缓冲器能驱动4个TTL 逻辑电平。
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AT89C51的介绍12（原文出处：http：///resource/mcu.htm）345描述6AT89C51是一个低电压，高性能CMOS8位单片机带有4K字节的可反复擦写的程7序存储器（PENROM）。
和128字节的存取数据存储器（RAM），这种器件采用ATMEL公8司的高密度、不容易丢失存储技术生产，并且能够与MCS-51系列的单片机兼容。
片9内含有8位中央处理器和闪烁存储单元，有较强的功能的AT89C51单片机能够被应10用到控制领域中。
1112功能特性13AT89C51提供以下的功能标准：4K字节闪烁存储器，128字节随机存取数据存储14器，32个I/O口，2个16位定时/计数器，1个5向量两级中断结构，1个串行通信15口，片内震荡器和时钟电路。
另外，AT89C51还可以进行0HZ的静态逻辑操作，并支16持两种软件的节电模式。
闲散方式停止中央处理器的工作，能够允许随机存取数据17存储器、定时/计数器、串行通信口及中断系统继续工作。
掉电方式保存随机存取数18据存储器中的内容，但震荡器停止工作并禁止其它所有部件的工作直到下一个复位。
1920引脚描述21VCC：电源电压22GND：地- 1 -沈阳航空工业学院电子工程系毕业设计（外文翻译）23P0口：24P0口是一组8位漏极开路双向I/O口，即地址/数据总线复用口。
作为输出口时，25每一个管脚都能够驱动8个TTL电路。
当“1”被写入P0口时，每个管脚都能够作26为高阻抗输入端。
P0口还能够在访问外部数据存储器或程序存储器时，转换地址和27数据总线复用，并在这时激活内部的上拉电阻。
P0口在闪烁编程时，P0口接收指令，28在程序校验时，输出指令，需要接电阻。
29P1口：30P1口一个带内部上拉电阻的8位双向I/O口，P1的输出缓冲级可驱动4个TTL电路。
对端口写“1”，通过内部的电阻把端口拉到高电平，此时可作为输入口。
因3132为内部有电阻，某个引脚被外部信号拉低时输出一个电流。
闪烁编程时和程序校验33时，P1口接收低8位地址。
3435P2口：36P2口是一个内部带有上拉电阻的8位双向I/O口，P2的输出缓冲级可驱动4个37TTL电路。
对端口写“1”，通过内部的电阻把端口拉到高电平，此时，可作为输入38口。
因为内部有电阻，某个引脚被外部信号拉低时会输出一个电流。
在访问外部程39序存储器或16位地址的外部数据存储器时，P2口送出高8位地址数据。
在访问8位地址的外部数据存储器时，P2口线上的内容在整个运行期间不变。
闪烁编程或校验4041时，P2口接收高位地址和其它控制信号。
42P3口：4344P3口是一组带有内部电阻的8位双向I/O口，P3口输出缓冲故可驱动4个TTL电路。
对P3口写如“1”时，它们被内部电阻拉到高电平并可作为输入端时，被外4546部拉低的P3口将用电阻输出电流。
47P3口除了作为一般的I/O口外，更重要的用途是它的第二功能，如下表所示：48P3口还接收一些用于闪烁存储器编程和程序校验的控制信号。
49RST：50复位输入。
当震荡器工作时，RET引脚出现两个机器周期以上的高电平将使单片- 3 -沈阳航空工业学院电子工程系毕业设计（外文翻译）51机复位。
52ALE/PROG：53当访问外部程序存储器或数据存储器时，ALE输出脉冲用于锁存地址的低8位字54节。
即使不访问外部存储器，ALE以时钟震荡频率的1/16输出固定的正脉冲信号，55因此它可对输出时钟或用于定时目的。
要注意的是：每当访问外部数据存储器时将56跳过一个ALE脉冲时，闪烁存储器编程时，这个引脚还用于输入编程脉冲。
如果必57要，可对特殊寄存器区中的8EH单元的D0位置禁止ALE操作。
这个位置后只有一条58MOVX和MOVC指令ALE才会被应用。
此外，这个引脚会微弱拉高，单片机执行外部程59序时，应设置ALE无效。
60PSEN：61程序储存允许输出是外部程序存储器的读选通信号，当AT89C51由外部程序存62储器读取指令时，每个机器周期两次PSEN 有效，即输出两个脉冲。
在此期间，当访63问外部数据存储器时，这两次有效的PSEN 信号不出现。
64EA/VPP：65外部访问允许。
欲使中央处理器仅访问外部程序存储器，EA端必须保持低电平。
66需要注意的是：如果加密位LBI被编程，复位时内部会锁存EA端状态。
如EA端为67高电平，CPU则执行内部程序存储器中的指令。
闪烁存储器编程时，该引脚加上+12V 68的编程允许电压VPP，当然这必须是该器件是使用12V编程电压VPP。
XTAL1：震荡器反相放大器及内部时钟发生器的输入端。
6970XTAL2：震荡器反相放大器的输出端。
7172时钟震荡器73AT89C51中有一个用于构成内部震荡器的高增益反相放大器，引脚XTAL1和74XTAL2分别是该放大器的输入端和输出端。
这个放大器与作为反馈元件的片外石英晶75体或陶瓷谐振器一起构成自然震荡器。
外接石英晶体及电容C1，C2接在放大器的反馈回路中构成并联震荡电路。
对外接电容C1，C2虽然没有十分严格的要求，但电7677容容量的大小会轻微影响震荡频率的高低、震荡器工作的稳定性、起振的难易程序78及温度稳定性。
如果使用石英晶体，我们推荐电容使用30PF±10PF，而如果使用陶79瓷振荡器建议选择40PF±10PF。
用户也可以采用外部时钟。
采用外部时钟的电路如80图示。
这种情况下，外部时钟脉冲接到XTAL1端，即内部时钟发生器的输入端，XTAL281则悬空。
由于外部时钟信号是通过一个2分频触发器后作为内部时钟信号的，所以对外部时钟信号的占空比没有特殊要求，但最小高电平持续时间和最大的低电平持8283续时间应符合产品技术条件的要求。
8485内部振荡电路外部振荡电路86闲散节电模式87- 5 -沈阳航空工业学院电子工程系毕业设计（外文翻译）88AT89C51有两种可用软件编程的省电模式，它们是闲散模式和掉电工作模式。
这89两种方式是控制专用寄存器PCON中的PD和IDL位来实现的。
PD是掉电模式，当PD=1 90时，激活掉电工作模式，单片机进入掉电工作状态。
IDL是闲散等待方式，当IDL=1，激活闲散工作状态，单片机进入睡眠状态。
如需要同时进入两种工作模式，即PD和9192IDL同时为1，则先激活掉电模式。
在闲散工作模式状态，中央处理器CPU保持睡眠93状态，而所有片内的外设仍保持激活状态，这种方式由软件产生。
此时，片内随机存取数据存储器和所有特殊功能寄存器的内容保持不变。
闲散模式可由任何允许的9495中断请求或硬件复位终止。
终止闲散工作模式的方法有两种，一是任何一条被允许96中断的事件被激活，IDL被硬件清除，即刻终止闲散工作模式。
程序会首先影响中断，97进入中断服务程序，执行完中断服务程序，并紧随RETI指令后，下一条要执行的指98令就是使单片机进入闲散工作模式，那条指令后面的一条指令。
二是通过硬件复位99也可将闲散工作模式终止。
需要注意的是：当由硬件复位来终止闲散工作模式时，中央处理器CPU通常是从激活空闲模式那条指令的下一条开始继续执行程序的，要100101完成内部复位操作，硬件复位脉冲要保持两个机器周期有效，在这种情况下，内部102禁止中央处理器CPU访问片内RAM，而允许访问其他端口，为了避免可能对端口产生103的意外写入：激活闲散模式的那条指令后面的一条指令不应是一条对端口或外部存104储器的写入指令。
105106掉电模式在掉电模式下，振荡器停止工作，进入掉电模式的指令是最后一条被执行的指107108令，片内RAM和特殊功能寄存器的内容在中指掉电模式前被冻结。
退出掉电模式的109唯一方法是硬件复位，复位后将从新定义全部特殊功能寄存器但不改变RAM中的内容，在VCC恢复到正常工作电平前，复位应无效切必须保持一定时间以使振荡器从110111新启动并稳定工作。
闲散和掉电模式外部引脚状态。
112 113程序存储器的加密 114AT89C51可使用对芯片上的三个加密位LB1，LB2，LB3进行编程（P ）或不编程115（U ）得到如下表所示的功能：116沈阳航空工业学院电子工程系毕业设计（外文翻译）117118当LB1被编程时，在复位期间，EA端的电平被锁存，如果单片机上电后一直没119有复位，锁存起来的初始值是一个不确定数，这个不确定数会一直保存到真正复位120位置。
为了使单片机正常工作，被锁存的EA电平与这个引脚当前辑电平一致。
机密121位只能通过整片擦除的方法清除。
122123124125126127128129130131132133134135136137138139140141142143144145146147148149DescriptionThe AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer 150151with 4K bytes of Flash programmable and erasable read only memory (PEROM).152The device is manufactured using At mel’s high-density nonvolatile memorytechnology and is compatible with the industry-standard MCS-51 instruction 153154set and pinout. The on-chip Flash allows the program memory to be reprogrammed155in-system or by a conventional nonvolatile memory programmer. By combining156a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is157a powerful microcomputer which provides a highly-flexible and cost-effective158solution to many embedded control applications.159Function characteristic160The AT89C51 provides the following standard features: 4K bytes of Flash,161128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector162two-level interrupt architecture, a full duplex serial port, on-chip163oscillator and clock circuitry. In addition, the AT89C51 is designed with- 9 -沈阳航空工业学院电子工程系毕业设计（外文翻译）164static logic for operation down to zero frequency and supports two software 165selectable power saving modes. The Idle Mode stops the CPU while allowing 166the RAM, timer/counters, serial port and interrupt system to continue 167functioning. The Power-down Mode saves the RAM contents but freezes the 168oscillator disabling all other chip functions until the next hardware reset. 169Pin Description170VCC：Supply voltage.171GND：Ground.Port 0：172173Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, 174each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the 175pins can be used as highimpedance inputs.Port 0 may also be configured to 176be the multiplexed loworder address/data bus during accesses to external 177program and data memory. In this mode P0 has internal pullups.Port 0 also 178receives the code bytes during Flash programming,and outputs the code bytes 179during programverification. External pullups are required during 180programverification.181182183Port 1Port 1 is an 8-bit bi-directional I/O port with internal pullups.The Port 1841851 output buffers can sink/source four TTL inputs.When 1s are written to Port1 pins they are pulled high by the internal pullups and can be used as inputs. 186187As inputs,Port 1 pins that are externally being pulled low will source current188(IIL) because of the internal pullups.Port 1 also receives the low-order189address bytes during Flash programming and verification.190Port 2191Port 2 is an 8-bit bi-directional I/O port with internal pullups.The Port2 output buffers can sink/source four TTL inputs.When 1s are written to Port 1921932 pins they are pulled high by the internal pullups and can be used as inputs.194As inputs,Port 2 pins that are externally being pulled low will source current,because of the internal pullups.Port 2 emits the high-order address byte 195196during fetches from external program memory and during accesses to external197data memory that use 16-bit addresses. In this application, it uses strong198internal pullupswhen emitting 1s. During accesses to external data memory199that use 8-bit addresses, Port 2 emits the contents of the P2 Special Function200Register.Port 2 also receives the high-order address bits and some controlsignals during Flash programming and verification.201202Port 3203Port 3 is an 8-bit bi-directional I/O port with internal pullups.The Port3 output buffers can sink/source four TTL inputs.When 1s are written to Port 2042053 pins they are pulled high by the internal pullups and can be used as inputs.206As inputs,Port 3 pins that are externally being pulled low will source current207(IIL) because of the pullups.Port 3 also serves the functions of various208special features of the AT89C51 as listed below:- 11 -沈阳航空工业学院电子工程系毕业设计（外文翻译）209210Port 3 also receives some control signals for Flash programming and 211verification.212213RST214Reset input. A high on this pin for two machine cycles while the oscillator 215is running resets the device.216ALE/PROG217Address Latch Enable output pulse for latching the low byte of the address 218during accesses to external memory. This pin is also the program pulse input 219(PROG) during Flash programming.In normal operation ALE is emitted at a 220constant rate of 1/6 the oscillator frequency, and may be used for external 221timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external Data Memory.222223If desired, ALE operation can be disabled by setting bit 0 of SFR location 2248EH. With the bit set, ALE is active only during a MOVX or MOVC instruction.Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has 225226no effect if the microcontroller is in external execution mode.227PSEN228229Program Store Enable is the read strobe to external program memory.When 230the AT89C51 is executing code from external program memory, PSEN is activated 231twice each machine cycle, except that two PSEN activations are skipped during 232each access to external data memory.233EA/VPP234External Access Enable. EA must be strapped to GND in order to enable 235the device to fetch code from external program memory locations starting at 2360000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will 237be internally latched on reset.EA should be strapped to VCC for internal 238program executions.This pin also receives the 12-volt programming enable voltage(VPP) during Flash programming, for parts that require12-volt VPP. 239240241XTAL1Input to the inverting oscillator amplifier and input to the internal 242243clock operating circuit.244XTAL2Output from the inverting oscillator amplifier.245- 13 -沈阳航空工业学院电子工程系毕业设计（外文翻译）246247Oscillator Characteristics248XTAL1 and XTAL2 are the input and output, respectively,of an inverting249amplifier which can be configured for use as an on-chip oscillator, as shown250in Figure 1.Either a quartz crystal or ceramic resonator may be used. To drive251the device from an external clock source, XTAL2 should be left unconnectedwhile XTAL1 is driven as shown in Figure 2.There are no requirements on the 252253duty cycle of the external clock signal, since the input to the internalclocking circuitry is through a divide-by-two flip-flop, but minimum and 254255maximum voltage high and low time specifications must be observed.256257Figure 1. Oscillator Connections Figure 2. External Clock258Drive Configuration259Idle Mode260261In idle mode, the CPU puts itself to sleep while all the onchip peripheralsremain active. The mode is invoked by software. The content of the on-chip 262263RAM and all the special functions registers remain unchanged during this mode.264The idle mode can be terminated by any enabled interrupt or by a hardwarereset.It should be noted that when idle is terminated by a hard ware reset, 265266the device normally resumes program execution,from where it left off, up to267two machine cycles before the internal reset algorithm takes control. On-chip268hardware inhibits access to internal RAM in this event, but access to the269port pins is not inhibited. To eliminate the possibility of an unexpected270write to a port pin when Idle is terminated by reset, the instruction following271the one that invokes Idle should not be one that writes to a port pin or to272external memory.273274Power-down Mode275In the power-down mode, the oscillator is stopped, and the instruction276that invokes power-down is the last instruction executed. The on-chip RAM277and Special Function Registers retain their values until the power-down modeis terminated. The only exit from power-down is a hardware reset. Reset 278279redefines the SFRs but does not change the on-chip RAM. The reset should not280be activated before VCC is restored to its normal operating level and mustbe held active long enough to allow the oscillator to restart and stabilize. 281- 15 -沈阳航空工业学院电子工程系毕业设计（外文翻译）282283Program Memory Lock Bits284On the chip are three lock bits which can be left unprogrammed (U) or 285can be programmed (P) to obtain the additional features listed in the table 286below.287288When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during reset. If the device is powered up without a reset, the 289290latch initializes to a random value, and holds that value until reset is 291activated. It is necessary that the latched value of EA be in agreement with 292the current logic level at that pin in order for the device to function 293properly.294。