【正文】 r applications and intelligent control of the scientists, engineers. SCM is widely used in instruments and meters, household appliances, medical equipment, aerospace, specialized equipment, intelligent management and process control fields, roughly divided into the following several areas: （ 1） In the application of Intelligent Instruments SCM has a small size, low power consumption, controlling function, expansion flexibility, the advantages of miniaturization and ease of use, widely used instrument, bining different types of sensors can be realized Zhuru voltage, power, frequency, humidity, temperature, flow, speed, thickness, angle, length, hardness, elemental, physical pressure measurement. SCM makes use of digital instruments, intelligence, miniaturization, and functionality than electronic or digital circuits more powerful. Such as precision measuring equipment (power meter, oscilloscope, various analytical instrument). （ 2） In the industrial control application With the MCU can constitute a variety of control systems, data acquisition system. Such as factory assembly line of intelligent control,all kinds of alarm systems,and puter works constitute a secondary control system. （ 3） In the Appliance of Household appliances It can be said that the appliances are basically using SCM, praise from the electric rice, washing machines, refrigerators, air conditioners, color TV, and other audio video equipment, to the electronic weighing equipment, varied, and omnipresent. （ 4） In the field of puter works and munications applications MCU general with modern munication interface, can be easy with the puter data munication, working and munications in puter applications between devices had excellent material conditions, are basically all munication equipment to achieve a controlled by MCU from mobile phone, telephone, miniprogramcontrolled switchboards, building automated munications call system, train radio munication, to the daily work can be seen everywhere in the mobile phones, trunked mobile radio, walkietalkies, etc.. （ 5） Microputer in the field of medical device applications MCU in the use of medical devices is also quite extensive, such as medical respirator, the various analyzers, monitors, ultrasound diagnostic equipment and hospital beds, etc. call system. （ 6） In a variety of major appliances in the modular applications Designed to achieve some special single specific function to be modular in a variety of circuit applications, without requiring the use of personnel to understand its internal structure. If music integrated single chip, seemingly simple function, miniature electronic chip in the (the principle is different from the tape machine), you need a puter similar to the principle of the plex. Such as: music signal to digital form stored in memory (like ROM), read by the microcontroller, analog music into electrical signals (similar to the sound card). In large circuits, modular applications that greatly reduce the volume, simplifies the circuit and reduce the damage, error rate, but also easy to replace. （ 7） Microcontroller in the application field of automotive equipment SCM in automotive electronics is widely used, such as a vehicle engine controller, CAN busbased Intelligent Electronic Control Engine, GPS navigation system, abs antilock braking system, brake system, etc.. In addition, the MCU in business, finance, research, education, national defense, aerospace and other fields has a very wide range of applications. 4 MCU introduced MCU ,also known as singlechip microcontroller, it is not plete a certain logic chips, but to a puter system integrated into a to a microputer, and puter than just the lack of a microcontroller I / O devices. General talk: a chip bees a puter. Its small size, light weight, cheap, for the study, application and development of facilities provided. At the same time, learning to use the MCU is to understand the principle and structure of the puter the best choice. MCU and the puter use is also similar to the module, such as CPU, memory, parallel bus, as well as the role and the same hard disk memory,is it different from the performance of these ponents are relatively weak in our home puter a lot ,but the price is low , there is generally no more than 10 yuan ......can use it to make some control for a class of electrical work is not very plex is are using automatic drum washing machines ,smoke hood, VCD and so on inside the home appliances can see it39。一旦 CPU 收集到數(shù)據(jù)信息和流程，它必須能夠改變外部領(lǐng)域的一部分，這些硬件設(shè)備稱作外圍設(shè)備，它們是 CPU 通往外部的窗口。這種情況下，程序可稱為輸出程序，它監(jiān)督接口的操作并完成數(shù)字 模擬轉(zhuǎn)換器（ DAC）所需數(shù)字的標(biāo)定。 編程接口： 采用控制信號的正確組合可對 Flash 閃速存儲陣列中的每一代碼字節(jié)進(jìn)行寫入和存儲器的整片擦除，寫操作周期是自身定時的，初始化后它將自動定時到操作完成。校驗(yàn)時， P0 口必須接上 10k 左右的上拉電阻。每個字節(jié)寫入周期是自身定時的，通常約為 。 AT89C52有 40個引腳， 32個外部雙向輸入 /輸出（ I/O）端口，同時內(nèi)含 2個外中端口， 3個 16位可編程定時計(jì)數(shù)器， 2個全雙工串行通信口， 2個讀寫口線， AT89C52可以按照常規(guī)方法進(jìn)行編程，也可以在線編程。 功能特性描述： AT89C52是一種低功耗、高性能 CMOS8位微控制器，具有 8K在系統(tǒng)可編程 Flash存儲器， 使用 Atmel公司的高密度、非易失性存儲技術(shù)制造，與工業(yè) 80C51產(chǎn)品指令和引腳完全兼容。用戶也可以采用外部時鐘。 要注意的是，每當(dāng)訪問外部數(shù)據(jù)存儲器時將跳過一個 ALE 脈沖。作為輸入口使用時，因?yàn)閮?nèi)部存在上拉電阻，某個引腳被外部信號拉低時會輸出一個電流（ IIL）。 P2 口： P2 是一個帶有內(nèi)部上拉電阻的 8 位雙向 I/O 口， P2 的輸出緩沖級可驅(qū)動（吸收或輸出電流） 4 個 TTL 邏輯門電路。在訪問外部數(shù)據(jù)存儲器或程序存儲器時，這組口線分時轉(zhuǎn)換地址（低 8 位）和數(shù)據(jù)總線復(fù)用，在訪問期間激活內(nèi)部上拉電阻。同時， AT89C51 降至 0Hz 的靜態(tài)邏輯操作，并支持兩種可選的節(jié)電工作模式。一旦進(jìn)入市 場，尤其任務(wù)決定性應(yīng)用諸如自動駕駛儀或反鎖制動系統(tǒng)，錯誤將是財力上所禁止的。究其原因，可能就卡在產(chǎn)品未使用單片機(jī)或其它可編程邏輯器件上。還有一類計(jì)算機(jī)，大多數(shù)人卻不怎么熟悉。 它是一種在線式實(shí)時控制計(jì)算機(jī)，在線式就是現(xiàn)場控制，需要的是有較強(qiáng)的抗干擾能力，較低的成本，這也是和離線式計(jì)算機(jī)的（比如家用 PC）的主要區(qū)別。同時，學(xué)習(xí)使用單片機(jī)是了解計(jì) 算機(jī)原理與結(jié)構(gòu)的最佳選擇。如：音樂信號以數(shù)字的形式存于存儲器中（類似于 ROM），由微控制器讀出，轉(zhuǎn)化為模擬音樂電信號（類似于聲卡）。例如精密的測量設(shè)備（ 功 率計(jì) ， 示波器 ，各種分析儀）。隨著微電子技術(shù)、 IC 設(shè)計(jì)、 EDA 工具的發(fā)展，基于 SOC 的 單片機(jī)應(yīng)用系統(tǒng)設(shè)計(jì) 會有較大的發(fā)展。在開創(chuàng)嵌入式系統(tǒng)獨(dú)立發(fā)展道路上， Intel 公司功不可沒。事實(shí)上單片機(jī)是世界上數(shù)量最多的 計(jì)算機(jī) 。隨著工業(yè)控制領(lǐng)域要求的提高，開始出現(xiàn)了 16 位單片機(jī)，但因?yàn)樾詢r比不理想并未得到很廣泛的應(yīng)用。 單片機(jī) 1 單片機(jī)定義 單片機(jī)也被稱為微控制器（ Microcontroller Unit），常用英文字母的縮寫 MCU表示單片機(jī)，它最早是被用在工業(yè)控制領(lǐng)域?；谶@一