单片机文献翻译

A. 求基于单片机的全自动洗衣机外文翻译

Abstract ：This engineering design is to regard AT89C2051 as the key component , because there are few pins of AT89C2051, the memory is not big in capacity, so, the function of the washing machines controlled has certain restriction , but, because the basic function of the washing machine is to the washing of the clothes, so, the key lies in carrying on the control of the laundry procere. Proceed from this angle, analyse , the main function of the automatic washing machine designed has the following seven items to the function of the washing machine : Have strong , weak washing functions; Four laundry working routine, already standardization program , economic procere, procere drain off water procere enter , drainage system trouble diagnose the function automatically alone; Safe protection while dehydrating and defending the vibration function; Drive way of the
intermittence ; Suspend the function; The sound only shows the function.
Key word： AT89C2051, full-automatic washing machine, engineering design , control circuit

B. 求单片机参考文献，中文的有相应的外文翻译

[1]杨十元.模拟系统故障诊断与可靠性设计，清华人学出版社，2004
[2]童诗白.模拟电子技术基础，高教出版社，2006
[3]周航慈.单片机应用程序设计技术，北京航空航大大学出版社，2005
[4]李刚.ADuC812系列单片机原理和应用技术，北京航空航天山版社，2005
[5]胡诞康.在线测试技术的发展与展望，计量与测试技术，2001
[6]星河科技开发公司，印刷电路板在线测试系统的发展与应用，电子标准化与测量，2003
[7]季华.PCB测试技术的综合利用，电子产品世界，2007-12
[8]鲜坛.组装测试技术应用前景分析，世界电子元器件，2008-1
[9]张金敏.基于单片机控制的智能电阻电容在线测试仪，甘肃科技，2006
[10]庄绍雄王济浩张迎春.智能阻容在线测试技术，山东工业大学学报，
[11]陈国顺陈春沙王格芳等.通用电路板在线测试仪设计与开发，仪器仪表学报，2001
[12]Nancy Hplland.Automated Instruments Smooth Rapid Test System Development.Test & Measurement World,AUGUST 2001
[13]卢育强.如何设定ICT的上下限，电子生产设备，2003 142-143
[14]赵悦 沈青松 终玉军.路板的测试技术，辽宁工学院学报，2008-1
[15]程亚黎 曾周末.电路故障自动测试与诊断系统，中国仪器仪表，2007

C. 单片机毕业论文外文文献怎么找去哪个网站

网络学术，将你所需要的关键词翻译成英文，再搜索就可以，还可以直接查看哪里可以下载全文。

D. 单片机外文翻译

我的网络文库里有很多单片机方面的英文文献带翻译的的 大多符合你的要求，你可以去挑选下！

E. 文献求助，毕设是基于单片机的智能小车设计，现在需要一片相关外文文献做外文翻译1.0～1.5万外文印刷字符

基于单片机的智能小车设计
OK 我可以指导。

F. 单片机的英文全称

“单片机”是我们国人的称呼，即single chip microcomputer (SCM)，但国际上的说法应该是Micro Control Unit（MCU），即微控制单元。

单片机是一种集成电路芯片。

单片机是采用超大规模集成电路技术把具有数据处理能力的中央处理器CPU、随机存储器RAM、只读存储器ROM、多种I/O口和中断系统、定时器/计数器等功能。

（可能还包括显示驱动电路、脉宽调制电路、模拟多路转换器、A/D转换器等电路）集成到一块硅片上构成的一个小而完善的微型计算机系统，在工业控制领域广泛应用。从上世纪80年代，由当时的4位、8位单片机，发展到现在的300M的高速单片机。

硬件特征

1、单片机的体积比较小， 内部芯片作为计算机系统，其结构简单，但是功能完善，使用起来十分方便，可以模块化应用。

2、单片机有着较高的集成度，可靠性比较强，即使单片机处于长时间的工作也不会存在故障问题。

3、单片机在应用时低电压、低能耗，是人们在日常生活中的首要选择， 为生产与研发提供便利。

4、单片机对数据的处理能力和运算能力较强，可以在各种环境中应用，且有着较强的控制能力。

G. 单片机英文文献及翻译，2200字左右

Single-Chip Microcomputer
有的时候，也可以用SingleChip来代替
下面链接的第六章有讲单片机Single Chip Microcmputer 第148页开始
http://books.google.co.nz/books?id=AUtTx3TgO7IC&pg=PT41&lpg=PT41&dq=what+is+Single+Chip+Microcomputer&source=web&ots=QQqVentmyy&sig=ZPBVtVXwiQakAtCIXJqzRw_BobE&hl=en&sa=X&oi=book_result&resnum=8&ct=result#PPT41,M1

这是一段中汉对照的。
中文:
单片机是把主要计算机功能部件都集成在一块芯片上的微型计算机。它是一种集计数和多中接口于一体的微控制器，被广泛应用在智能产品和工业自动化上，而51单片机是个单片机中最为典型和最有代表性的一种。
本课题选择89S51为核心控制元件，设计了一个日常生活中用到的电子音乐门铃系统。当功能按键按下，音乐响起，发光二极管随着音乐的节拍进行闪烁，LED显示相应的定时器初值。音乐演奏过程中再次按下按键无效，只有当音乐段结束再次按下才有效。如果是电子音乐门铃在响，按下复位按键就终止，显示初始状态。经过实践证明，本系统运行稳定，具有一定的实用价值。
-------------
翻译:
SCM is a major piece of computer components are integrated into the chip micro-computer. It is a multi-interface and counting on the micro-controller integration, and intelligence procts are widely used in instrial automation. and MCS-51 microcontroller is a typical and representative.

The topics chosen for the 89S51 control of the core components used in the design of a daily electronic music doorbell system. When the function button is pressed, the music sounded and the music beats with light emitting diodes for flickered. Initial corresponding LED timer. Musical process again pressed the button ineffective, and only when pressed again before the end of the music effectively. If the doorbell ring for electronic music, press the button on the rection and termination, showed initial state. Practice has proved that the system is stable and has some practical value.

本设计是以凌阳16位单片机为重心，介绍语音控制在机械手中的应用，实现微型舵机的运作，完成所指定的动作。其中通过凌阳16位单片机输出的脉冲信号来准确的控制机械手的摆动角度，机械手的捏拿动作由电磁铁完成，电磁铁的通断由凌阳16位单片机的I/O口控制，硬件和软件都在具体的实验中证明了其可行性
This design is take insults the positive 16 monolithic integrated circuits as a center of gravity, introced the pronunciation control in manipulator's application, the realization miniature servo operation, completes the movement which assigns. Through insults the pulse signal which the positive 16 monolithic integrated circuits outputs to come the accurate control manipulator to swing the angle, the manipulator pinches takes the movement to complete by the electro-magnet, the electro-magnet passes the legal reason for judgment to insult the positive 16 monolithic integrated circuits I/O control, the hardware and the software all have proven its feasibility in the concrete experiment

H. 需要一篇自动控制方面的英文文献

本毕业设计课题是属于教师拟定性课题，主要是研究基于单片机的对步进电机的有效控制。步进电机是一种能将数字输入脉冲转换成旋转举察或直线增量运动的电磁执行元件，每输入蠢虚一个脉冲电机转轴步进一个步距角增量。电机总的回转角与输入脉冲数成正比例，相应的转速取决于输入脉冲频率。

步进电机是机正档茄电一体化产品中关键部件之一，通常被用作定位控制和定速控制。步进电机惯量低、定位精度高、无累积误差、控制简单等特点。广泛应用于机电一体化产品中，如：数控机床、包装机械、计算机外围设备、复印机、传真机等。

Abstract
This article mainly elaborated has been hanging the movement control system merit, introced was hanging the movement control system function, the principle and the design process. Is hanging the movement control system is one of in control engineering domain important applications, its main target is to is controlled the object the movement condition, including path, speed and position implementation check. The movement control system compares with other control systems, has the system model simply, the check algorithm is unitary, also not complex characteristic and so on non-linearity and coupling situation. Also is precisely because the movement control system can implement to the path, the running rate, the pointing accuracy as well as the repetition precision accuracy control requirement, has the broad application foreground in each category of control engineering, therefore the movement control system has at present become in the check study application domain very much significant the research direction. Through the monolithic integrated circuit to stepping monitor check, implemented the motor-driven to cause the object at on the board which inclined the movement, The control section is the SST89E52 monolithic microcomputer which SST Corporation proces primarily, with when the 1602LCD liquid crystal screen and according to turned has implemented with the user interactive, through the keyboard entry different control command, the liquid-crystal display was allowed to display the setting value and the run the coordinates. The electrical machinery control section used LM324N four to transport puts and is connected the electronic primary device voluntarily to develop the 42BYG205 stepping monitor actuation electric circuit to implement the electrical machinery accuracy control. The algorithm partially for will suit the monolithic integrated circuit system to operate carries on optimizes many times, will rece the microprocessor the operand. Has completed the object voluntarily the movement and according to the different setup path movement.
Key words Magneto; 1602LCD; LM324N; Drive circuit

选择步进电机时，首先要保证步进电机的输出功率大于负载所需的功率。而在选用功率步进电机时，首先要计算机械系统的负载转矩，电机的矩频特性能满足机械负载并有一定的余量保证其运行可靠。在实际工作过程中，各种频率下的负载力矩必须在矩频特性曲线的范围内。一般地说最大静力矩Mjmax大的电机，负载力矩大[1 ]。

选择步进电机时，应使步距角和机械系统匹配，这样可以得到机床所需的脉冲当量。在机械传动过程中为了使得有更小的脉冲当量，一是可以改变丝杆的导程，二是可以通过步进电机的细分驱动来完成。但细分只能改变其分辨率，不改变其精度。精度是由电机的固有特性所决定。

选择功率步进电机时，应当估算机械负载的负载惯量和机床要求的启动频率，使之与步进电机的惯性频率特性相匹配还有一定的余量，使之最高速连续工作频率能满足机床快速移动的需要。
基于单片机的悬挂运动控制系统，具有硬件电路结构简单，精确度高，抗干扰性强等优点。

1.2 课题目的
培养综合运用四年大学所学知识去分析问题和解决实际问题的能力。在实践中检验所学知识,从而加强理论与实践的相结合。 体验一个科研项目开发的全过程，学会单片机开发应用方法,锻炼应用能力,动手能力。本课题设计是具有一定难度的基于单片机的应用系统开发项目，培养学生创新精神和创新能力。通过这次毕业论文及设计，检验的综合素质和专业教育的培养效果，并且使学会阅读、利用英文文献资料，阅读并翻译外文资料的能力，学会设计报告和论文。

1.3 课题意义
随着社会的发展、科技的进步以及人们生活水平的逐步提高，各种方便于生活的自动控制系统开始进入了人们的生活，以单片机为核心的自动门系统就是其中之一。同时也标志了自动控制领域成为了数字化时代的一员[ 3]。它实用性强，功能齐全，技术先进，使人们相信这是科技进步的成果。它更让人类懂得，数字时代的发展将改变人类的生活，将加快科学技术的发展。
通过对“微机控制自动门系统”的研究和设计，精心撰写了微机控制自动门系统论文。本论文着重阐述了以单片机为主体，LED点阵显示芯片及步进电机为核心的系统。
本设计主要应用SST89E58作为控制核心，LED点阵显示芯片、步进电机、压力传感器、电位器相结合的系统。充分发挥了单片机的性能。其优点硬件电路简单，软件功能完善，控制系统可靠，性价比较高等特点，具有一定的使用和参考价值。

1.4 应解决的主要问题
在基于单片机的悬挂运动控制系统中，主要分三个部分设计，一个是输入和键盘显示模块；另一个是步进电机驱动模块；第三个是最小系统和输出模块设计。主要解决的问题是：
1. 单片机最小系统硬件设计；
2. 步进电机驱动模块设计；
3. 输出部分的软硬件设计；
4. 主程序设计；
5. 绘图板的设计。

1.5 技术要求
设计一电机控制系统，控制物体在倾斜（仰角≤100度）的板上运动。
在一白色底板上固定两个滑轮，两只电机（固定在板上）通过穿过滑轮的吊绳控制一物体在板上运动，运动范围为80cm×100cm。物体的形状不限，质量大于100克。物体上固定有浅色画笔，以便运动时能在板上画出运动轨迹。板上标有间距为1cm的浅色坐标线（不同于画笔颜色），左下角为直角坐标原点。

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I. 单片机英文文献及翻译，5000字左右 急需 谢谢 [email protected]

Introction of Programmable controllers
From a simple heritage, these remarkable systems have evolved to not only replace electromechanical devices, but to solve an ever-increasing array of control problems in both process and nonprocess instries. By all indications, these microprocessor powered giants will continue to break new ground in the automated factory into the 1990s.
HISTORY
In the 1960s, electromechanical devices were the order of the day ass far as control was concerned. These devices, commonly known as relays, were being used by the thousands to control many sequential-type manufacturing processes and stand-along machines. Many of these relays were in use in the transportation instry, more specifically, the automotive instry. These relays used hundreds of wires and their interconnections to effect a control solution. The performance of a relay was basically reliable - at least as a single device. But the common applications for relay panels called for 300 to 500 or more relays, and the reliability and maintenance issues associated with supporting these panels became a very great challenge. Cost became another issue, for in spite of the low cost of the relay itself, the installed cost of the panel could be quite high. The total cost including purchased parts, wiring, and installation labor, could range from $30~$50 per relay. To make matters worse, the constantly changing needs of a process called for recurring modifications of a control panel. With relays, this was a costly prospect, as it was accomplished by a major rewiring effort on the panel. In addition these changes were sometimes poorly documented, causing a second-shift maintenance nightmare months later. In light of this, it was not uncommon to discard an entire control panel in favor of a new one with the appropriate components wired in a manner suited for the new process. Add to this the unpredictable, and potentially high, cost of maintaining these systems as on high-volume motor vehicle proction lines, and it became clear that something was needed to improve the control process – to make it more reliable, easier to troubleshoot, and more adaptable to changing control needs.
That something, in the late 1960s, was the first programmable controller. This first ‘revolutionary’ system wan developed as a specific response to the needs of the major automotive manufacturers in the United States. These early controllers, or programmable logic controllers (PLC), represented the first systems that 1 could be used on the factory floor, 2 could have there ‘logic’ changed without extensive rewiring or component changes, and 3 were easy to diagnose and repair when problems occurred.
It is interesting to observe the progress that has been made in the past 15 years in the programmable controller area. The pioneer procts of the late 1960s must have been confusing and frightening to a great number of people. For example, what happened to the hardwired and electromechanical devices that maintenance personnel were used to repairing with hand tools? They were replaced with ‘computers’ disguised as electronics designed to replace relays. Even the programming tools were designed to appear as relay equivalent presentations. We have the opportunity now to examine the promise, in retrospect, that the programmable controller brought to manufacturing.
All programmable controllers consist of the basic functional blocks shown in Fig. 10. 1. We’ll examine each block to understand the relationship to the control system. First we look at the center, as it is the heart ( or at least the brain ) of the system. It consists of a microprocessor, logic memory for the storage of the actual control logic, storage or variable memory for use with data that will ordinarily change as a function power for the processor and memory. Next comes the I/O block. This function takes the control level signals for the CPU and converts them to voltage and current levels suitable for connection with factory grade sensors and actuators. The I/O type can range from digital (discrete or on / off), analog (continuously variable), or a variety of special purpose ‘smart’ I/O which are dedicated to a certain application task. The programmer is shown here, but it is normally used only to initially configure and program a system and is not required for the system to operate. It is also used in troubleshooting a system, and can prove to be a valuable tool in pinpointing the exact cause of a problem. The field devices shown here represent the various sensors and actuators connected to the I/O. These are the arms, legs, eyes, and ears of the system, including push buttons, limit switches, proximity switches, photosensors, thermocouples, RTDS, position sensing devices, and bar code reader as input; and pilot lights, display devices, motor starters, DC and AC drives, solenoids, and printers as outputs.
No single attempt could cover its rapidly changing scope, but three basic characteristics can be examined to give classify an instrial control device as a programmable controller.
(1) Its basic internal operation is to solve logic from the beginning of memory to some specified point, such as end of memory or end of program. Once the end is reached, the operation begins again at the beginning of memory. This scanning process continues from the time power is supplied to the time it it removed.
(2) The programming logic is a form of a relay ladder diagram. Normally open, normally closed contacts, and relay coils are used within a format utilizing a left and a right vertical rail. Power flow (symbolic positive electron flow) is used to determine which coil or outputs are energized or deenergized.
(3) The machine is designed for the instrial environment from its basic concept; this protection is not added at a later date. The instrial environment includes unreliable AC power, high temperatures (0 to 60 degree Celsius), extremes of humidity, vibrations, RF noise, and other similar parameters.
General application areas
The programmable controller is used in a wide variety of control applications today, many of which were not economically possible just a few years ago. This is true for two general reasons: 1 there cost effectiveness (that is, the cost per I/O point) has improved dramatically with the falling prices of microprocessors and related components, and 2 the ability of the controller to solve complex computation and communication tasks has made it possible to use it where a dedicated computer was previously used.
Applications for programmable controllers can be categorized in a number of different ways, including general and instrial application categories. But it is important to understand the framework in which controllers are presently understood and used so that the full scope of present and future evolution can be examined. It is through the power of applications that controllers can be seen in their full light. Instrial applications include many in both discrete manufacturing and process instries. Automotive instry applications, the genesis of the programmable controller, continue to provide the largest base of opportunity. Other instries, such as food processing and utilities, provide current development opportunities.
There are five general application areas in which programmable controllers are used. A typical installation will use one or more of these integrated to the control system problem. The five general areas are explained briefly below.

Description
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the instry-standard MCS-51 instruction set and pinout. The 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 monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications.
Function characteristic
The AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full plex serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.
Pin Description
VCC：Supply voltage.
GND：Ground.
Port 0：
Port 0 is an 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 multiplexed loworder address/data bus ring accesses to external program and data memory. In this mode P0 has internal pullups.Port 0 also receives the code bytes ring Flash programming,and outputs the code bytes ring programverification. External pullups are required ring programverification.

Port 1
Port 1 is an 8-bit bi-directional I/O port with internal pullups.The Port 1 output buffers can sink/source four TTL inputs.When 1s are written to Port 1 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups.Port 1 also receives the low-order address bytes ring Flash programming and verification.
Port 2
Port 2 is an 8-bit bi-directional I/O port with internal pullups.The Port 2 output buffers can sink/source four TTL inputs.When 1s are written to Port 2 pins they are pulled high by the internal pullups and can be used as inputs. As 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 ring fetches from external program memory and ring accesses to external data memory that use 16-bit addresses. In this application, it uses strong internal pullupswhen emitting 1s. During accesses to external data memory that use 8-bit addresses, Port 2 emits the contents of the P2 Special Function Register.Port 2 also receives the high-order address bits and some control signals ring Flash programming and verification.
Port 3
Port 3 is an 8-bit bi-directional I/O port with internal pullups.The Port 3 output buffers can sink/source four TTL inputs.When 1s are written to Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups.Port 3 also serves the functions of various special features of the AT89C51 as listed below:

Port 3 also receives some control signals for Flash programming and verification.

RST
Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device.
ALE/PROG
Address Latch Enable output pulse for latching the low byte of the address ring accesses to external memory. This pin is also the program pulse input (PROG) ring Flash programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped ring each access to external Data Memory.
If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only ring a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.

PSEN
Program Store Enable is the read strobe to external program memory.When the AT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped ring each access to external data memory.
EA/VPP
External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset.EA should be strapped to VCC for internal program executions.This pin also receives the 12-volt programming enable voltage(VPP) ring Flash programming, for parts that require12-volt VPP.

XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.

Oscillator Characteristics
XTAL1 and XTAL2 are the input and output, respectively,of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 1.Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2.There are no requirements on the ty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.

Figure 1. Oscillator Connections Figure 2. External Clock Drive Configuration

Idle Mode
In idle mode, the CPU puts itself to sleep while all the onchip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged ring this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset.It should be noted that when idle is terminated by a hard ware reset, the device normally resumes program execution,from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when Idle is terminated by reset, the instruction following the one that invokes Idle should not be one that writes to a port pin or to external memory.

Power-down Mode
In the power-down mode, the oscillator is stopped, and the instruction that invokes power-down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power-down mode is terminated. The only exit from power-down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.

Program Memory Lock Bits
On the chip are three lock bits which can be left unprogrammed (U) or can be programmed (P) to obtain the additional features listed in the table below.

When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched ring reset. If the device is powered up without a reset, the latch initializes to a random value, and holds that value until reset is activated. It is necessary that the latched value of EA be in agreement with the current logic level at that pin in order for the device to function properly

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8-Bit Microcontroller-AT89C51

Features
Compatible with MCS-51 Procts
4 Kbytes of In-System Reprogrammable Flash Memory
Enrance: 1,000 Write/Erase Cycles
Fully Static Operation: 0 Hz to 24 MHz
Three-Level Program Memory Lock
128 x 8-Bit Internal RAM
32 Programmable I/O Lines
Two 16-Bit Timer/Counters
Six Interrupt Sources
Programmable Serial Channel
Low Power Idle and Power Down Mode
Description
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4Kbytes of Flash Programmable and Erasable Read Only Memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the instry standard MCS-51instruction set and pinout. The 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 monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.
The AT89C51 provides the following standard features: 4Kbytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full plex serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The idle Mode stops the CPU while allowing the RAM, timer/count- ers, serial port and interrupt system to continue functioning. The Power Down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.
Pin Configurations

Pin Description
VCC：Supply voltage.
GND：Ground.
Port 0
Port 0 is an 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 high-impedance inputs.
Port 0 may also be configured to be the multiplexed low- order address/data bus ring accesses to external program and data memory. In this mode P0 has internal pullups.
Port 0 also receives the code bytes ring Flash programming, and outputs the code bytes ring program verification. External pullups are required ring program verification.
Port 1
Port 1 is an 8-bit bidirectional I/O port with internal pullups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal pullups and can be used as inputs. As inputs.
Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups.
Port 1 also receives the low-order address bytes ring Flash programming and program verification.
Port 2
Port 2 is an 8-bit bidirectional I/O port with internal pullups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to port 2 pins they are pulled high by the internal pullups and can be used as inputs. As 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 ring fetches from external program memory and ring accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, it uses strong internal data memory that use 8-bit addresses (MOVX @ RI). Port 2 emits the cintents of the P2 special Function Register.
Port 2 also receives the high-order address bits and some control signals ring Flash programming and verification.
Port 3
Port 3 is an 8-bit bidirectional I/O port with internal pullups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups.
Port 3 also serves the functions of various special features of the AT89C51 as listed below:

Port 3 also receives some control signals for Flash programming and programming verification.
RST
Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device.
ALE/PROG
Address Latch Enable output pulse for latching the low byte of the address ring accesses to external memory. This pin is also the program pulse input (PROG) ring Flash programming.
In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes.. Note ,however, that one ALE pulse is skipped ring each access to external Data Memory.If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.
PSEN
Program Store Enable is the read strobe to external pro- gram memory. When the AT89C51is executing code from external pro- gram memory, PSEN is ac tivated twice each machine cycle, except that two PSEN activations are skipped ring each access to external data memory.
EA/VPP
External Access Enable. must be strapped to GND in order to enable the device to fetch code from external pro- gram memory locations starting at 0000H up to FFFFFH. Note, however, that if lock bit 1 is programmed, will be internally latched on reset. EA should be strapped to VCC for internal program execu tions. This pin also receives the 12-volt programming enable voltage (VPP) ring Flash programming, for parts that re- quire 12-volt VPP.
XTAL1: Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2: Output from the inverting oscillator amplifier.
Oscillator Characteristics
XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven. There are no requirements on the ty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.
Power Down Mode
In the power down mode the oscillator is stopped, and the instruction that invokes power down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power down mode is terminated. The only exit from power down is a hardware reset. The only exit from power down is a hardware reset. Reset redefines the SFRs but does not change the on- chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.
Data Memory
The AT89C52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel address space to the Special Function Registers. That means the upper 128 bytes have the same addresses as the SFR space but are physically separate from SFR space.
When an instruction accesses an internal location above address 7FH, the address mode used in the instruction specifies whether the CPU accesses the upper 128 bytes of RAM or the SFR space. Instructions that use direct addressing access SFR space.
For example, the following direct addressing instruction accesses the SFR at location 0A0H (which is P2).
MOV 0A0H, #data Instructions that use indirect addressing access the upper 128 bytes of RAM. For example, the following indirect addressing instruction, where R0 contains 0A0H, accesses the data byte at address 0A0H, rather than P2 (whose address is 0A0H).
MOV @R0, #data
Note that stack operations are examples of indirect addressing, so the upper 128 bytes of data RAM are available as stack space.
Timer 0 and 1
Timer 0 and Timer 1 in the AT89C52 operate the same way as Timer 0 and Timer 1 in the AT89C51.
Timer 2
Timer 2 is a 16-bit Timer/Counter that can operate as either a timer or an event counter. The type of operation is selected by bit C/T2 in the SFR T2CON (shown in Table 2). Timer 2 has three operating modes: capture, auto-reload (up or down counting), and baud rate generator. The modes are selected by bits in T2CON, as shown in Table 3.
Timer 2 consists of two 8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is incremented every machine cycle. Since a machine cycle consists of 12 oscillator periods, the count rate is 1/12 of the oscillator frequency.
In the Counter function, the register is incremented in response to a l-to-0 transition at its corresponding external input pin, T2. In this function, the external input is sampled ring S5P2 of every machine cycle. When the samples show a high in one cycle and a low in the next cycle, the count is incremented. The new count value appears in the register ring S3P1 of the cycle following the one in which the transition was detected. Since two machine cycles (24 oscillator periods) are required to recognize a 1-to-0 transition, the maximum count rate is 1/24 of the oscillator frequency. To ensure that a given level is sampled at least once before it changes, the level should be held for at least one full machine cycle.
Special Function Registers
A map of the on-chip memory area called the Special Function Register (SFR) space is shown in Table 1.
Note that not all of the addresses are occupied, and unoccupied addresses may not be implemented on the chip. Read accesses to these addresses will in general return random data, and write accesses will have an indeterminate effect.
User software should not write 1s to these unlisted locations, since they may be used in future procts to invoke new features. In that case, the reset or inactive values of the new bits will always be 0.
Timer 2 Registers Control and status bits are contained in registers
T2CON (shown in Table 2) and T2MOD (shown in Table 4) for Timer 2. The register pair (RCAP2H, RCAP2L) are the Capture/Reload registers for Timer 2 in 16-bit capture mode or 16-bit auto-reload mode. Interrupt Registers The indivial interrupt enable bits are in the IE register. Two priorities can be set for each of the six interrupt sources in the IP register.