【正文】 M 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。s largest puter. Modern human life used in almost every piece of electronic and mechanical products will be integrated single , telephone, calculator, home appliances, electronic toys, handheld puters and puter accessories such as a mouse with a 12 in both the Department of SCM. Personal puter will have a large number of SCM in the work. General car with more than 40 SCM, plex industrial control systems may even have hundreds of SCM in the same time work! SCM is not only far exceeds the number of PC and other puting the sum, or even more than the number of human beings. 2 MCU history Singlechip 70 was born in the late 20th century, experienced a SCM, MCU, SOC three stages. （ 1） SCM the single chip microputer (Single Chip Microputer) stage, mainly seeking the best of the best single form of embedded systems architecture. Innovation model success, laying the SCM and general puter pletely different path of development. In the open road of independent development of embedded systems, Intel Corporation contributed. （ 2） MCU the 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, highlight the object of intelligent involves the areas associated with the object system, therefore, the development of MCU39。 MCU 1 The definition of MCU Also known as singlechip MCU(Microcontroller),because it was first used in the field of industrial by the singlechip CPU chip developed from the dedicated design concept is the first by a large number of peripherals and CPU in a single chip,the puter system so that smaller,more easily integrated into the plex and demanding on the volume control 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 MCU 8bit or all of the four. One of the most successful is the INTEL 8031, because the performance of a simple and reliable access to a lot of good praise. Then developed in 8031 out of MCS51 MCU Systems. SCM systems based on this system until now is still widely used. With the increased requirements of industrial control field, began a 16bit microcontroller, because the cost is not satisfactory but have not been very widely used. After 90 years with the great development of consumer electronics, microcontroller technology has been a huge increase. With INTEL i960 series, especially the later series of widely used ARM, 32bit microcontroller quickly replace highend 16bit MCU status and enter the mainstream market. The traditional 8bit microcontroller performance have been the rapid increase capacity increase pared to 80 the number of times. Currently, highend 32bit microcontroller clocked over 300MHz, the performance catching the mid9039。一些類型的串行口單元允許 CPU 與外部設(shè)備進(jìn)行串口通信，用串口位代替平行位進(jìn)行通信需要少許的 I/O 口，這樣使通信費(fèi)用降低但 速度也相對(duì)慢些。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。當(dāng)微機(jī)要與只有打開或關(guān)閉 操作的設(shè)備相連時(shí)，這種數(shù)字形式是最有用的，這里每一位都可表示一開關(guān)或執(zhí)行器的狀態(tài)。接口電路部分的設(shè)計(jì)是使用微機(jī)的工程師所面臨最重要的任務(wù)之一。最后，信號(hào)經(jīng)調(diào)理（ 通常是放大）以形成適應(yīng)于執(zhí)行器操作的形式。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。這種情況下，信號(hào)調(diào)理單元必須將輸入信號(hào)變換成為另一信號(hào)，也可直接與接口的下一部分，即微計(jì)算機(jī)本身的輸入輸出單元相連接。模擬 數(shù)字轉(zhuǎn)換器（ ADC）用來 將連續(xù)變化信號(hào)變成相應(yīng)的數(shù)字量，這數(shù)字量可是可能性的二進(jìn)制數(shù)值中的一固定值。在計(jì)算機(jī)之外，由電子系統(tǒng)所處理的信息以一種物理信號(hào)形式存在，但在程序中，它是用數(shù)字表示的。 編程接口： 采用控制信號(hào)的正確組合可對(duì) Flash 閃速存儲(chǔ)陣列中的每一代碼字節(jié)進(jìn)行寫入和存儲(chǔ)器的整片擦除，寫操作周期是自身定時(shí)的，初始化后它將自動(dòng)定時(shí)到操作完成。 (032H) = FFH 聲明為 12V 編程電壓。讀簽名字節(jié)的過程和單元 030H、 031H 和 032H的正常校驗(yàn)相仿，只需要將 和 保持低電平，返回值意義如下： (030H) = 1EH 聲明產(chǎn)品由 ATMEL 公司制造。 : 89C51 單片機(jī)內(nèi)有 3 個(gè)簽名字節(jié) ,地址為 030H、 031H 和 032H。校驗(yàn)時(shí)， P0 口必須接上 10k 左右的上拉電阻。 : 字節(jié)編程的進(jìn)度可通過 Ready/Busy 輸出信號(hào)檢測(cè)，編程期間， ALE 變?yōu)楦唠娖健?H”后 （ Ready/Busy）端被拉低，表示正在編程狀態(tài)（忙狀態(tài)）。數(shù)據(jù)查詢 89C51 單片機(jī)用數(shù)據(jù)查詢方式來檢測(cè)一個(gè)寫周期是否結(jié)束，在一個(gè)寫周期中，如需要讀取最后寫入的那個(gè)字節(jié)，則讀出的數(shù)據(jù)的最高位（ ）是原來寫入字節(jié)的最高位的反碼。每個(gè)字節(jié)寫入周期是自身定時(shí)的，通常約為 。每對(duì) Flash 存儲(chǔ)陣列寫入一個(gè)字節(jié)或每寫入一個(gè)程序加密位，加上一個(gè) ALE/PROG 編程脈沖。激活相應(yīng)的控制信號(hào)。 6 編程方法 編程前，設(shè)置好地址、數(shù)據(jù)及控制信號(hào)，編程單元的地址加在 P1 口和 P2 口的 — （ 11 位地址范圍為 0000H—— 0FFFH），數(shù)據(jù)從 P0口輸入，引腳 、 和、 的電平設(shè)置見表 6， PSEB 為低電平， RST保持高電平， EA/Vpp 引腳是編程電源的輸入端，按要求加上編程電壓， ALE/PROG引腳輸入編程脈沖（負(fù)脈沖）。 AT89C52有 40個(gè)引腳， 32個(gè)外部雙向輸入 /輸出（ I/O）端口，同時(shí)內(nèi)含 2個(gè)外中端口， 3個(gè) 16位可編程定時(shí)計(jì)數(shù)器， 2個(gè)全雙工串行通信口， 2個(gè)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。掉電保護(hù)方式下， RAM內(nèi)容被保存，振蕩器被凍結(jié)，單片機(jī)一切工作停止，知道下一個(gè)中斷或硬件復(fù)位為止。另外， AT89C52可降至 0Hz靜態(tài)邏輯操作，支持 2種軟件可選擇節(jié)電模式。在單芯片上，擁有靈巧的 8位 CPU和在系統(tǒng)可編程 Flash，使得 AT89C52為眾多嵌入式控制應(yīng)用系統(tǒng)提供高靈活、超有效的 解決方案。 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(chǔ)