【正文】 ppropriate bination of control signals. The write operation cycle is self timed and once initiated, will automatically time itself to pletion. （ 2） The sensor DS18B20 In the traditional analog signal distance temperature measuring system, need good solve lead error pensation, multipoint measurement error and amplifying circuit switching technologies such as zero drift error problem, can achieve high measuring accuracy. Another general monitoring site of the electromagic environment is very bad, all kinds of jamming signal is stronger, the simulated temperature signal interference and vulnerable to produce measurement error and measuring precision [5]. Therefore, in temperature measuring system, the strong antijamming capability of the new digital temperature sensor is the most effective to solve these problems, pared with other temperature sensor DSl820 has the following 中原工學(xué)院信息商務(wù)學(xué)院外文 翻譯 15 features: (1) the unique singleline interface way. DSl820 in connection with the microprocessor only need one interface to implement line DSl820 microprocessors and twoway munication. (2) more function simplifies distributed temperature detection application. (3) DSl820 in use without any peripheral devices. (4) power, voltage range data available from V to V. (5) can measure temperature range from 55 degrees c + + to 125, incremental value 0. 5 176。Port 2: Port 2 is an 8bit bidirectional I/O port with internal pull ups. 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 pull ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull ups. Port 2 emits the highorder address byte during fetches from external program memory and during accesses to external data memory which uses 16bit addresses (MOVX DPTR). In this application, it uses strong internal pull ups when emitting 1s. During accesses to external data memory which uses 8bit addresses (MOVX RI). Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the highorder address bits and some control signals during Flash programming and verification. Two 16bit Timer/Counters 本文摘譯自： atmel AT89C51 中文資料 DATSHEET 規(guī)格書(shū) DS18B20 的英文數(shù)據(jù)手冊(cè) DS18B20 Programmable Resolution 1Wire Digital Thermometer 中原工學(xué)院信息商務(wù)學(xué)院外文 翻譯 9 Based on SCM multifunctional temperature testing system design preface With the development of society and the technological progress, people pay more and more attention to the importance of temperature detection and display. Temperature detection and status display technology and equipment has been widely applied in industries, products on the market emerge in endlessly. Temperature testing and also gradually adopt the automatic control technology to realize the monitor. This topic is a temperature testing and status of the monitoring system. System solutions This system USES the monolithic integrated circuit AT89C51 as this system. The whole system, the hardware circuit including power supply circuit, sensor, the temperature display circuit circuit, upper alarm circuit . The alarming circuit can be measured in upper temperature range, screaming voice alarm. The basic principle for the temperature control DSl8B20: when the temperature signal acquisition to after temperature signal sent to handle, AT89C51 temperature to LCD screen, SCM according to initialize the upper temperature setting, namely, if the judgement of temperature than the highest temperature cooling fan is started, If the temperature is less than the lowest temperature setting on alarm device. The system hardware design （ 1） AT89C51 SCM are introduced The AT89C51 is a lowpower, highperformance CMOS 8bit microputer with 4K bytes of Flash programmable and erasable read only memory (PEROM) and 128 bytes of data randomaccess memory(RAM). The device is manufactured using ATMEL Co.’s highdensity nonvolatile memory technology and is patible with the industrystandard MCS51 instruction set and pinout. The onchip Flash allows the program memory to be reprogrammed insystem or by a conventional nonvolatile memory programmer. By bining a versatile 8bit CPU with Flash on a monolithic chip, the ATMEL Co.’s AT89C51 is a powerful microputer which provides a highlyflexible and costeffective solution to many embedded control applications. Features: 多功能溫度檢測(cè)顯示系統(tǒng)軟件主要包括：函數(shù)聲明、延遲時(shí)間函數(shù)、 DS18B20 初始化函數(shù)、讀出 DS18B20 當(dāng)前的溫度、溫度數(shù)據(jù)轉(zhuǎn)化成液晶字符顯示等程序。若要組成多點(diǎn)溫度檢測(cè)系統(tǒng)，可在單片機(jī)的同一根 I/O 口線上，以相同的連接方法并聯(lián)多片 DS18B20 芯片。寄生電源方式有三個(gè)好處： 1）進(jìn)行遠(yuǎn)距離測(cè)溫時(shí)，無(wú)需本地電源。圖中低溫度系數(shù)品振的振蕩頻率受溫度影響很小，用于產(chǎn)生同定頻率的脈沖信號(hào)送給計(jì)數(shù)器 l。 (5)可測(cè)量的溫度范圍從 55℃ 到 +125℃ ，增量值 0. 5℃ ；華氏溫度范圍從 67 到 +257，增量值 0． 9。 讀片內(nèi)簽名字節(jié)： 讀簽名字節(jié)的過(guò)程和單元 030H、 031H 及 032H 的正常校驗(yàn)相仿，只需將 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 (031H)=51H 聲明為 AT89C51 單片機(jī) (032H)=FFH 聲明為 12V 編程電壓 (032H)=05H 聲明為 5V 編程電壓 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。 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 。編程接口可接收高電壓（ +12V）或低電壓（ VCC）的允許編程信號(hào)。需要注意的是：當(dāng)由硬件復(fù)位來(lái)終止空閑工作模式時(shí)， CPU 通常是從激活空閑模式那條指令的下一條指令開(kāi)始繼續(xù)執(zhí)行程序的，要完成內(nèi)部復(fù)位操作，硬件復(fù)位脈沖要保持兩個(gè)機(jī)器周期有效，在這種情況下，內(nèi)部禁止CPU 訪問(wèn)片內(nèi) RAM，而允許訪問(wèn)其它端口。這個(gè)放大器與作為反饋元件的片外石英晶體 或陶瓷諧振器一起構(gòu)成自激振蕩器。需注意的是：如果加密位 LB1被編程，復(fù)位時(shí)內(nèi)部會(huì)鎖存EA 端狀態(tài)。 如有必要，可通過(guò)對(duì)特殊功能寄存器（ SFR）區(qū)中的 8EH 單元的 D0 位置位，可禁止ALE 操作。 在訪問(wèn) 8位地址的外部數(shù)據(jù)存儲(chǔ)器（如執(zhí)行 MOVXRI 指令）時(shí)， P2 口線上的內(nèi)容在整個(gè)訪問(wèn)期間不改變。對(duì)端口寫“ 1”，通過(guò)內(nèi)部的上拉電阻把端口拉到高電平，此時(shí)可作輸入口。 VCC：電源電壓 6個(gè)中斷源 與 MCS51 產(chǎn)品指令系統(tǒng)完全兼容 本課題就是一個(gè)溫度檢測(cè)及狀態(tài)顯示的監(jiān)控系統(tǒng)。 二、 系統(tǒng)方案 本系統(tǒng)采用 AT89C51 作為