【正文】 第二章 DS18B20 資料 外文文獻(xiàn) 原文： DS18B20 Programmable Resolution 1Wire Digital Thermometer DS18B20 FEATURES Unique 1Wire interface requires only one Port pin for munication, requires no external ponents Each device has a unique 64bit serial code stored in an onboard ROM Can be powered form data line .Power supply range is （ 4） Measures temperatures form 55℃ to +125℃ , 177。由于 SP 中的值可以用指令加以改變，所以只要在程序開始階段更改了 SP 的值，就可以把堆棧設(shè)置在規(guī)定的內(nèi)存單元中，如在程序開始時，用一條MOV SP， 5FH 指令，就時把堆棧設(shè)置在從內(nèi)存單元 60H 開始的單元中。事實上‘不能作為通用 I/O 口使用’也并不是‘不能’而是（使用者）‘不會’將其作為通用 I/O 口使用。指令：由單片機芯片的設(shè)計者規(guī)定的一種數(shù)字，它與我們常用的指令助記符有著嚴(yán)格的一一對應(yīng)關(guān)系，不可以由單片機的開發(fā)者更改。器件的數(shù)據(jù)線也就被稱為數(shù)據(jù)總線，器件所有的控制線被稱為控制總線。 在大型電路中，這種模塊化應(yīng)用極大地縮小了體積，簡化了電路，降低了損壞、錯誤率，也方便于更換。 單片機在醫(yī)用設(shè)備中的用途亦相當(dāng)廣泛，例如醫(yī)用呼吸機，各種分析儀，監(jiān)護(hù)儀，超聲診斷設(shè)備及病床呼叫系統(tǒng)等等。例如精密的測量設(shè)備（功率計，示波器，各種分析儀）。更不用說自動控制領(lǐng)域的機器人、智能儀表、醫(yī)療器械了。隨著微電子技術(shù)、 IC 設(shè)計、 EDA 工具的發(fā)展，基于 SoC 的單片機應(yīng)用系統(tǒng)設(shè)計會有較大的發(fā)展。在發(fā)展 MCU 方面，最著名的廠家當(dāng)數(shù) Philips 公司。在開創(chuàng)嵌入式系統(tǒng)獨立發(fā)展道路上， Intel公司功不可沒。究其原因，可能就卡在產(chǎn)品未使用單片機或其它可編程邏輯器件上。它在整個裝置中，起著有如人類頭腦的作用，它出了毛病，整個裝置就癱瘓了。還有一類計算機，大多數(shù)人卻不怎么熟悉。一樣的道理，如果把巨型計算機上的操作系統(tǒng)和應(yīng)用軟件拿到家用 PC 上來運行，家用 PC 的也是承受不了的。通過不同的程序?qū)崿F(xiàn)不同的功能，尤其是特殊的獨特 的一些功能，這是別的器件需要費很大力氣才能做到的，有些則是花大力氣也很難做到的。 單片機內(nèi)部也用和電腦功能類似的模塊，比如 CPU，內(nèi)存，并行總線，還有和硬盤作用相同的存儲器件，不同的是它 的這些部件性能都相對我們的家用電腦弱很多，不過價錢也是低的，一般不超過 10 元即可 ......用它來做一些控制電器一類不是很復(fù)雜的工作足矣了。相當(dāng)于一個微型的計算機，和計算機相比，單片機只缺少了 I/O 設(shè)備。手機、電話、計算器、家用電器、電子玩具、掌上電腦以及鼠標(biāo)等電腦配件中都配有 12 部單片機。而在作為掌上電腦和手機核心處理的高端單片機甚至可以直接使用專用的Windows 和 Linux 操作系統(tǒng)。隨著 INTEL i960 系列特別是后來的 ARM 系列的廣泛應(yīng)用， 32 位單片機迅速取代 16 位單片機 的高端地位，并且進(jìn)入主流市場。此后在 8031 上發(fā)展出了 MCS51 系列單片機系統(tǒng)。最早的設(shè)計理念是通過將大量外圍設(shè)備和 CPU 集成在一個芯片中，使計算機系統(tǒng)更小，更容易集成進(jìn)復(fù)雜的而對體積要求嚴(yán)格的控制設(shè)備當(dāng)中。 POP 39。advanced post out backward first out 39。, the process is always from the 000039。not39。not as a generalpurpose I / O port use39。0 39。s hard drive in terms of nothing, but in terms of the MCU is not acceptable. SCM in the utilization of hardware resources to be very high for the job so although the original is still in the pilation of a lot of use. The same token, if the giant puter operating system and applications run up to get home PC, home PC, also can not afford to. Can be said that the twentieth century across the three power era, that is, the age of electricity, the electronic age and has entered into the puter age. However, this puter, usually refers to the personal puter, referred to as PC. It consists of the host, keyboard, monitor and other ponents. Another type of puter, most people do not know how. This puter is to give all kinds of intelligent machines single chip (also known as microcontroller). As the name suggests, this puter system took only a minimal integrated circuit, can be a simple operation and control. Because it is small, usually hidden in the charged mechanical stomach in. It is in the device, like the human brain plays a role, it goes wrong, the whole plant was paralyzed. Now, this microcontroller has a very broad field of use, such as smart meters, realtime industrial control, munications equipment, navigation systems, and household appliances. Once all kinds of products were using SCM, can serve to upgrade the effectiveness of products, often in the product name preceded by the adjective intelligent, such as intelligent washing machines. Now some technical personnel of factories or other amateur electronics developers to engage in out of certain products, not the circuit is too plicated, that function is too simple and can easily be copied. The reason may be stuck in the product did not use a microcontroller or other programmable logic device. SCM historySCM was born in the late 20th century, 70, experienced SCM, MCU, SoC three 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. 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 control. It involves the areas associated with the object system, therefore, the development of MCU39。s largest puter. Modern human life used in almost every piece of electronic and mechanical products will be integrated single chip. Phone, 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 Single chip, also known as singlechip microcontroller, it is not plete a certain logic chips, but to a puter system integrated into a chip. Equivalent 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. SCM and the puter functions internally with similar modules, such as CPU, memory, parallel bus, the same effect as well, and hard disk memory devices, and different is its performance of these ponents were relatively weak many of our home puter, but the price is low , usually not more than 10 yuan you can do with it ...... some control for a class is not very plicated electrical work is enough of. We are using automatic drum washing machine