智能溫控加濕器外文翻譯

1、<p>　　本科生畢業(yè)設(shè)計（論文）專業(yè)外文翻譯</p><p>　　原 文： Intelligent temperature control humidifier</p><p>　　譯 文： 智能溫控加濕器 </p><p>　　指導(dǎo)教師 ： 鄭俊杰 職稱： 副

2、教授 </p><p>　　學(xué)生姓名 ： 王定委 學(xué)號：1102120305 </p><p>　　專 業(yè) ： 電氣工程及其自動化 </p><p>　　院（系） ： 機(jī)電工程學(xué)院 </p><p>　　2015年5月16日</p><p>　　

3、Intelligent temperature control humidifier</p><p>　　In work, study and daily life, the dry air has a lot of damage to human health, increase of air humidity and control occupies a very important position. Fi

4、rst of all, let us know about the humidifier role in daily life: increase the air humidity. Moisturize skin, raise colour beauty. Adding auxiliary agent, aroma therapy, fashion decoration, beautiful and practical. </p

5、><p>　　Human health humidity: 45-70%. In the appropriate humidity range: human physiology, the thought is in good condition, work, and rest, have a good effect. Healthy humidity can inhibit the breeding and spr

6、ead of germs, still can enhance immunity. </p><p>　　This design USES a single chip microcomputer temperature detection based on digital temperature sensor DS18B20 and heating temperature controlling system.

7、Temperature can work by the LED digital tube, real-time display the current temperature value. Heating range can be achieved by a separate button is adjustable, and through the control relay of shut off to control the he

8、ating wire is heated. System anti-interference is good, design flexible, convenient, and suitable for on-site temperature in </p><p>　　Chapter 1 Demonstration</p><p>　　The temperature detection

9、system has common features: multiple measuring points, complex environment, wiring, on-site monitoring room far from dispersion etc.. If the general temperature sensors to collect the temperature signal, you need to desi

10、gn of signal conditioning circuit, a / D conversion and the corresponding interface circuit to sensor output analog signal into digital signal is sent to the MCU to deal with. So due to a variety of factors will cause gr

11、eater detection system deviation; </p><p><b>　　Plan one:</b></p><p>　　Using thermistors, can meet the needs of 40 degrees to 90 degrees Celsius degree measurement range, but thermist

12、or precision, repeatability, reliability is poor, for the signal detection of 1 degree Celsius is not applicable. And in the temperature measurement system, the use of single-chip temperature sensor, for instance AD590,

13、LM35 etc.. But these chip output are analog signals must be after a / D conversion can be sent to the single chip microcomputer, which makes the structure of the temper</p><p>　　Scheme two:</p><p&

14、gt;　　In the temperature measurement system, traditional measuring method is analog signal remote sampling AD converter, and in order to obtain high accuracy of temperature measurement, it is necessary to adopt measures t

15、o solve by the long line transmission and measurement of switching and amplifying circuit zero drift caused by error compensation problem. The use of digital temperature chip DS18B20 temperature measurement, digital sign

16、al output. Easy to handle and control MCU, many peripheral circui</p><p>　　The temperature of the chip DS18B20 temperature measurement, can reflect the trend of system on chip. Integrated circuit, the circui

17、t more simple, faster and welding circuit circuit. Moreover, using the integrated block, effectively avoid the interference, improve the accuracy of measuring circuit. So the use of integrated chip will become a trend of

18、 the development of circuit. The application of this chip temperature, but also conform to this trend.</p><p><b>　　Plan one:</b></p><p>　　This scheme is implemented by PC. It can pro

19、gram online, online simulation function, it makes debugging more convenient. And the man-machine interaction is friendly. However, the output signal of PC can not communicate with DS18B20 directly. Needs to be compatible

20、 with the RS232 voltage converter, the synthesis of online hardware debugging, more cumbersome, very simple. And in some relatively harsh environment applications, large volume of the PC, carrying is not convenient to be

21、 installed, unst</p><p>　　Scheme two:</p><p>　　This scheme is realized by STC89C51 eight bit MCU. SCM software programming of the degrees of freedom, can realize all kinds of arithmetic and logi

22、c control algorithm by programming. And small size, hardware implementation is simple, easy to install. You can separate the DS18B20 control work, electric crossing can be integrated the advantages of packaging. Also, ST

23、C89C51 in industrial control also has a wide application, programming technology and peripheral function circuits used in conjunction</p><p>　　To sum up, the temperature sensor and the main control part adop

24、ts second schemes.</p><p>　　With single chip microcomputer as the control core, using temperature measurement, storage technology, temperature control humidification technology, the temperature sensor for me

25、asuring components, constitute the system of temperature measurement and temperature compensation.</p><p>　　The system can be divided into a temperature detection circuit, relay compensation heating temperat

26、ure control, pump supplying increased steam volatile remember display circuit and so on.</p><p>　　The system chooses the main device: temperature sensor DS18B20, relay, air pump, SCM STC89C516RC+, LED digita

27、l tube, the indicating lamp module, keys</p><p>　　Second chapter hardware circuit design</p><p>　　Circuit system function mainly includes: temperature measurement, real-time display temperature,

28、 low temperature heating temperature compensation, pump gas, electricity or running water. The hardware design mainly includes the following modules: power supply and a watchdog circuit, keyboard and display circuit, tem

29、perature testing circuit, heating circuit relay, pump supplying circuit below the circuit module is described</p><p>　　Microcomputer application system in addition to the special reset circuit reset button,

30、and the specificity of the reset function, other keys or keyboard are to switch state to set control function or input data. The keyboard is composed of a plurality of key switch matrix, it is the most commonly used inpu

31、t devices of micro computer, the user can through the keyboard to the computer input commands, addresses and data. This system adopts independent type key structure, as shown in the figure, th</p><p>　　relia

32、ble input for switching states</p><p>　　Which keyboard key contact and non contact type two, SCM application is generally made up of mechanical contact. Below, when the switch S is not pressed, the KEY input

33、 is high, the S is closed, the KEY input is low. The key is the mechanical contact, when the mechanical contact is broken, there will be the closure jitter, KEY input waveform as shown below. This jitter for people is no

34、t feel of, but to a computer is completely to the induction, because the processing speed of the computer is at m</p><p>　　The CPU can accurately read key state, on every key only for a response, it is neces

35、sary to consider how to remove the jitter and reliable input key switch state has two kinds of methods to solve. One is the hardware is key to jitter: add a latch. Another jitter for software: software method actually ve

36、ry simple is in the SCM obtain key is low, not immediately identified S1 has been pressed, but delay of 10 milliseconds or longer time tested again after the line, if still is low, that S1 indeed </p><p>　　2

37、) the function of the independent buttons</p><p>　　When no key press, the microcontroller automatically check the temperature value</p><p>　　3) select keyboard monitoring method</p><p

38、>　　The information input key is pressed on whether there are two ways to interrupt and query. The query method is adopted in this design, which is called in the keyboard scan subroutine in the CPU when idle.</p>

39、<p>　　The design uses a total of seven digital cathode cathode tube. The display of dynamic scanning and static display, the two methods are in this design. Because the static scanning refers to multiple pieces of

40、 string into and out of the chip, considering the circuit board cost calculation. I use the dynamic scan mode of hardware resource..</p><p>　　Here we use the temperature chip is DS18B20. DS18B20 is a digital

41、 temperature sensor produced by DALLAS company, with 3 pin TO92 small package. The temperature resolution can reach 0.0625 degrees, 16 digit volume is measured by temperature sign extended serial output. The power supply

42、 can be introduced in the distal, can also be produced by the parasitic power. CPU only a root port line can and many DS18B20 communication, occupy the microprocessor port less, save a lot of lead and logic circuits</

43、p><p>　　DS18B20 support "bus line" interface, measuring temperature range is - 55 degrees C~+125 DEG C, in th C, the accuracy is + 0.5 DEG C. Temperature field directly to the "first-line bus,&qu

44、ot; the digital transmission, compared with the traditional NTC thermistor temperature sensor etc, it can directly read out the temperature is to be measured, and according to the actual requirement of simple programming

45、 to achieve 9 to 12 bit digital readout mode. Greatly improve the anti-interference of the system.</p><p>　　Interface circuit between DS18b20 and MCU</p><p>　　DS18B20 can adopt two ways of power

46、 supply: a used in power supply way, at this time DS18B20 the first pin ground, second leg as a signal line, the tripod is connected with a power supply; another is parasitic power supply, the microcontroller port connec

47、ted single bus, to ensure to provide sufficient current in the effective DS18B20 clock cycle, requires a MOSFET tube to complete the bus pull. This system uses the power supply mode.</p><p>　　The design of D

48、S18B20, need to pay attention to the following issues</p><p>　　Operate on the 1-wire digital temperature sensor DS18B20 has the advantages of simple hardware structure, complete the complicated procedure. Pr

49、ogramming must be strictly according to the chip data manual provides the operation sequence, reading and writing time procedure must be strictly according to the requirements of writing. Especially in the use of DS18B20

50、 high temperature resolution, the timing and electrical parameters more demanding.</p><p>　　System using DS18B20 digital temperature sensor for temperature measurement, the temperature value by four seven se

51、gment code common cathode nixie tube display cycle. With the number of click on the corresponding points of the color light diode to use high power heating control relay.</p><p>　　In the design, but also rel

52、ated to the system of power supply circuit, reset circuit, alarm circuit, MCU watchdog circuit.</p><p>　　Because the microcontroller working power is +5V, and the bottom of a low-power circuit. Three 7805 te

53、rminal regulator can meet the requirements. </p><p>　　In order to make power with the temperature alarm value data protection, need to use a nonvolatile (off the electricity protection data) memory, and for

54、a typical application system of single-chip, the watchdog circuit design is a must. With a power down data protection function chips have many, parallel E2PROM, serial E2PROM, consider the simplicity of the structure des

55、ign, the system takes into account the serial E2PROM, commonly used have at24cxx series, AT93XX series, AT59XX series and etc.o</p><p>　　STC89S51RD2+ microcontroller with watchdog circuit. Down the electrici

56、ty protection watchdog, also known as watchdog timer, a timer circuit, generally have an input, called the dogs and a output to the MCU RST terminal, MCU normal work, every end time output a signal to feed the dog end. T

57、o reset the WDT, if more than the prescribed time do not feed the dog, generally in the program run to fly when), WDT time than to give back to a reset signal to the MCU, the MCU reset. To prevent the MCU crash</p>

58、<p>　　The computer must from time to time of the watchdog said "hello" to let the watchdog know it still in operation, if the operation fails, the action of the watchdog will caused system hardware reset

59、.</p><p>　　Third chapter software design</p><p>　　By the hardware circuit with software to realize the function of the whole system, when the basic shape of the hardware, the function of the sof

60、tware is settled. Different from the functions of the software can be points into two categories: one is monitoring software (main program), it is the core of the whole control system, designed to coordinate the relation

61、ship between the execution module and the operator. II is the implementation of the software (subroutine), it is used to complete the va</p><p>　　First of all to according to the overall function of the syst

62、em and keyboard set to select a most suitable monitoring program structure, then according to the requirements of real-time, rationally arrange the relationship between monitoring software and the execution module schedu

63、ling.</p><p>　　Main program calls the seven subroutine, digital tube display program, keyboard scanning and key process, temperature testing procedures, interrupt control program, EEPROM program memory, temp

64、erature control heating program, and an indication lamp procedures.</p><p>　　Digital display: digital display program to send the number, display control system.</p><p>　　The keyboard scanning c

65、ircuit and key processing procedures: identify the input of keyboard keys and related processing.</p><p>　　Temperature testing procedures: to deal with the temperature of the chip to send data, judge and dis

66、play.</p><p>　　Interrupt control program: interrupt service program 1 to achieve circular display function, interrupt service program 2 debounce delay.</p><p>　　EEPROM memory program: the storag

67、e of alarm limits</p><p>　　Over temperature alarm program: when a sensor temperature exceeds the set limit, alarm function</p><p>　　Indicator program: it is pointed out that the displayed temper

68、ature is a sensor detection value, or that a temperature sensor alarm setting or lower.</p><p>　　Will all function program in the form of subroutines written, when to write the main program, only need to cal

69、l the subroutine, then in the allocation of registers make a adjustment, eliminate the register conflict and I / O conflict can be. The program should as much as possible instead of using the call instruction jump instru

70、ction. Because the jump instruction makes the program difficult to understand the structural relationship between the program segments. The call instruction is different,</p><p>　　Fourth chapter system debug

71、</p><p>　　1, test environment and tools</p><p>　　Test temperature: 0~100 degrees C. (simulated multi point temperature environment)</p><p>　　The test instrument and software: digita

72、l multimeter, 0~100 degrees Celsius thermometer.</p><p>　　Test method: visual.</p><p>　　2, test method</p><p>　　The system to operate, to observe the system hardware detection is no

73、rmal (including the smallest single-chip system, keyboard circuit, display circuit, temperature measurement circuit, etc.).</p><p>　　Simultaneous measurement of multi-point temperature change (temperature va

74、lue different) using a temperature sensor and a thermometer, visual display circuit is normal. And record the temperature at each point, compared with the actual temperature, the temperature reached the index system.<

75、/p><p>　　3. Test result analysis</p><p>　　Self normal, the normal temperature display, temperature exceeds the limit alarm normally.</p><p>　　Because the chip is plastic package, so th

76、e temperature sensitivity of the sensor is not very high and need a very short time to reach a stable.</p><p><b>　　智能溫控加濕器</b></p><p>　　在工作、學(xué)習(xí)和日常生活中，空氣干燥對人身健康有著很大的傷害，對空氣濕度的適量增加及控制占據(jù)著

77、極其重要地位。首先讓我們了解一下加濕器在日常生活中的作用：增加空氣的濕度。滋潤肌膚，養(yǎng)顏美容。添加輔助劑，香薰理療,時尚擺設(shè)，美觀實(shí)用。</p><p>　　人體健康濕度：45－70％。在適宜濕度范圍內(nèi)：人體生理、思維皆處于良好狀態(tài)，工作、休息都有較好效果。健康的濕度既可抑制病菌的滋生和傳播，還可提高免疫力。</p><p>　　本設(shè)計采用的是單片機(jī)基于數(shù)字溫度傳感器DS18B20的溫度檢

78、測和控溫加熱系統(tǒng)。溫度值可以由LED數(shù)碼管工作，實(shí)時顯示當(dāng)前的溫度值。加溫范圍可以通過一位獨(dú)立按鍵實(shí)現(xiàn)可調(diào)，并通過控制繼電器的關(guān)斷來控制電熱絲加熱。系統(tǒng)的抗干擾性好、設(shè)計靈活、方便，而且適合于在較大的空間內(nèi)進(jìn)行現(xiàn)場溫度加濕。本系統(tǒng)可以應(yīng)用在大型會議廳及教室、宿舍、臥室等場合。</p><p><b>　　一 方案論證</b></p><p>　　溫度檢測系統(tǒng)有則共同

79、的特點(diǎn)：測量點(diǎn)多、環(huán)境復(fù)雜、布線分散、現(xiàn)場離監(jiān)控室遠(yuǎn)等。若采用一般溫度傳感器采集溫度信號，則需要設(shè)計信號調(diào)理電路、A/D 轉(zhuǎn)換及相應(yīng)的接口電路，才能把傳感器輸出的模擬信號轉(zhuǎn)換成數(shù)字信號送到單片機(jī)去處理。這樣，由于各種因素會造成檢測系統(tǒng)較大的偏差；又因?yàn)闄z測環(huán)境復(fù)雜、測量點(diǎn)多、信號傳輸距離遠(yuǎn)及各種干擾的影響，會使檢測系統(tǒng)的穩(wěn)定性和可靠性下降 。所以多點(diǎn)溫度檢測系統(tǒng)的設(shè)計的關(guān)鍵在于兩部分：溫度傳感器的選擇和主控單元的設(shè)計。溫度傳感器應(yīng)用范圍

80、廣泛、使用數(shù)量龐大，也高居各類傳感器之首。</p><p>　　采用熱敏電阻，可滿足40攝氏度至90攝氏度測量范圍，但熱敏電阻精度、重復(fù)性、可靠性較差，對于檢測1攝氏度的信號是不適用的。而且在溫度測量系統(tǒng)中,采用單片溫度傳感器,比如AD590,LM35等.但這些芯片輸出的都是模擬信號,必須經(jīng)過A/D轉(zhuǎn)換后才能送給單片機(jī),這樣就使得測溫裝置的結(jié)構(gòu)較復(fù)雜.</p><p>　　在測溫系統(tǒng)中，傳

81、統(tǒng)的測溫方法是將模擬信號遠(yuǎn)距離采樣進(jìn)行AD轉(zhuǎn)換，而為了獲得較高的測溫精度，就必須采用措施解決由長線傳輸，測量切換及放大電路零點(diǎn)漂移等造成的誤差補(bǔ)償問題。采用數(shù)字溫度芯片DS18B20測量溫度，輸出信號全數(shù)字化。便于單片機(jī)處理及控制，省去傳統(tǒng)的測溫方法的很多外圍電路。且該芯片的物理化學(xué)性很穩(wěn)定，它能用做工業(yè)測溫元件，此元件線形較好。在0—100攝氏度時，最大線形偏差小于1攝氏度。DS18B20的最大特點(diǎn)之一采用了單總線的數(shù)據(jù)傳輸，由數(shù)字溫

82、度計DS1820和微控制器AT89C51構(gòu)成的溫度測量裝置,它直接輸出溫度的數(shù)字信號,可通過LED數(shù)碼管顯示出來，也可直接與計算機(jī)連接。</p><p>　　采用溫度芯片DS18B20測量溫度，可以體現(xiàn)系統(tǒng)芯片化這個趨勢。部分功能電路的集成，使總體電路更簡潔，搭建電路和焊接電路時更快。而且，集成塊的使用，有效地避免外界的干擾，提高測量電路的精確度。所以集成芯片的使用將成為電路發(fā)展的一種趨勢。本方案應(yīng)用這一溫度芯片

83、，也是順應(yīng)這一趨勢。</p><p>　　此方案采用PC機(jī)實(shí)現(xiàn)。它可在線編程，可在線仿真的功能，這讓調(diào)試變得方便。且人機(jī)交互友好。但是PC機(jī)輸出信號不能直接與DS18B20通信。需要通過RS232電平轉(zhuǎn)換兼容，硬件的合成在線調(diào)試，較為繁瑣，很不簡便。而且在一些環(huán)境比較惡劣的場合，PC機(jī)的體積大，攜帶安裝不方便，性能不穩(wěn)定，給工程帶來很多麻煩！</p><p>　　此方案采用STC89C51

84、八位單片機(jī)實(shí)現(xiàn)。單片機(jī)軟件編程的自由度大，可通過編程實(shí)現(xiàn)各種各樣的算術(shù)算法和邏輯控制。而且體積小，硬件實(shí)現(xiàn)簡單，安裝方便。可以單獨(dú)對DS18B20控制工作，電過路可集成封裝等優(yōu)點(diǎn)。另外STC89C51在工業(yè)控制上也有著廣泛的應(yīng)用，編程技術(shù)及外圍功能電路的配合使用都很成熟。</p><p>　　綜上所述,溫度傳感器以及主控部分都采用第二方案。</p><p>　　以單片機(jī)為控制核心，采用溫度

85、測量，存儲技術(shù)，溫度控制加濕技術(shù)，以溫度傳感器為測量元件，構(gòu)成溫度測量及溫度補(bǔ)償系統(tǒng)。</p><p>　　該系統(tǒng)可分為溫度檢測電路，溫度控制繼電器補(bǔ)償加熱，氣泵供氣增加蒸汽揮發(fā)記顯示電路等。</p><p>　　該系統(tǒng)選用的主要器件有：溫度傳感器Ds18b20，繼電器，氣泵，STC89C516RC+單片機(jī)，LED數(shù)碼管，指示燈模塊，按鍵</p><p><b

86、>　　二 硬件電路設(shè)計</b></p><p>　　系統(tǒng)電路的功能主要包括：溫度測試，實(shí)時顯示溫度信息，低溫加熱補(bǔ)償溫度，氣泵供氣，缺水?dāng)嚯?。硬件設(shè)計主要包括以下幾個模塊：電源以及看門狗電路， 鍵盤以及顯示電路，溫度測試電路，繼電器加熱電路，氣泵供氣電路下面對電路分模塊進(jìn)行說明</p><p>　　單片機(jī)應(yīng)用系統(tǒng)中除了復(fù)位按鍵有專門的復(fù)位電路,以及專一的復(fù)位功能外,其它

87、的按鍵或鍵盤都是以開關(guān)狀態(tài)來設(shè)置控制功能或輸入數(shù)據(jù)。鍵盤是由若干按鍵組成的開關(guān)矩陣，它是微型計算機(jī)最常用的輸入設(shè)備，用戶可以通過鍵盤向計算機(jī)輸入指令、地址和數(shù)據(jù)。本系統(tǒng)中采用 獨(dú)立式按鍵結(jié)構(gòu)，如圖下所示，各按鍵相互獨(dú)立地接通一條輸入數(shù)據(jù)線，當(dāng)任何一個鍵按下時，與之相連的輸入數(shù)據(jù)線即被置0，而平時該線置1。獨(dú)立式按鍵電路配置靈活，軟件結(jié)構(gòu)簡單。當(dāng)功能鍵不很多時，采用該種方式比較合適。</p><p>　　

88、1）開關(guān)狀態(tài)的可靠輸入</p><p>　　組成鍵盤的按鍵有觸點(diǎn)式和非觸點(diǎn)式兩種，單片機(jī)中應(yīng)用的一般是由機(jī)械觸點(diǎn)構(gòu)成的。下圖中，當(dāng)開關(guān)S未被按下時，KEY輸入為高電平，S閉合后，KEY輸入為低電平。由于按鍵是機(jī)械觸點(diǎn)，當(dāng)機(jī)械觸點(diǎn)斷開、閉合時會有抖動，KEY輸入端的波形如下圖所示。這種抖動對于人來說是感覺不到的，但對計算機(jī)來說，則是完全可以感應(yīng)到的，因?yàn)橛嬎銠C(jī)處理的速度是在微秒級，而機(jī)械抖動的時間至少是毫秒級，對計

89、算機(jī)而言，這已是一個“漫長”的時間了。</p><p>　　為使CPU能正確地讀出KEY的狀態(tài)，對每一次按鍵只作一次響應(yīng)，就必須考慮如何去除抖動，鍵開關(guān)狀態(tài)的可靠輸入有兩種解決方法。一種是硬件去抖動：即為按鍵添加一個鎖存器。另一種為軟件去抖動：軟件法其實(shí)很簡單，就是在單片機(jī)獲得KEY為低信息后，不是立即認(rèn)定S1已被按下，而是延時10毫秒或更長一些時間后再次檢測該口線，如果仍為低，說明S1的確按下了，這實(shí)際上是避開

90、了按鍵按下時的抖動時間。而在檢測到按鍵釋放后（KEY為高）再延時5-10個毫秒，消除后沿的抖動，然后再對鍵值處理。</p><p>　　2）獨(dú)立按鍵的功能介紹</p><p>　　無鍵按下時，單片機(jī)自動檢查顯示溫度值</p><p>　　3）選擇鍵盤監(jiān)測方法</p><p>　　對是否有鍵按下的信息輸入方式有中斷方式與查詢方式兩種。本設(shè)計采用

91、的查詢法，即在在CPU空閑時調(diào)用鍵盤掃描子程序。</p><p>　　設(shè)計采用的是共陰極七段數(shù)碼管。顯示方式有動態(tài)掃描和靜態(tài)顯示，兩種方法在本設(shè)計中皆可。由于靜態(tài)掃描要用到多片串入并出芯片，考慮到電路板成本計算。本人采用是節(jié)約硬件資源的動態(tài)掃描方式。</p><p>　　這里我們用到溫度芯片是DS18B20。DS18B20是DALLAS公司生產(chǎn)的一線式數(shù)字溫度傳感器，具有3引腳TO－92小

92、體積封裝形式。測溫分辨率可達(dá)0.0625℃，被測溫度用符號擴(kuò)展的16位數(shù)字量方式串行輸出。其工作電源既可在遠(yuǎn)端引入，也可采用寄生電源方式產(chǎn)生。CPU只需一根端口線就能與諸多DS18B20通信，占用微處理器的端口較少，可節(jié)省大量的引線和邏輯電路。</p><p>　　DS18B20支持“一線總線”接口，測量溫度范圍為 -55°C~+125°C，在-10~+85°C范圍內(nèi),精度為

93、7;0.5°C。現(xiàn)場溫度直接以“一線總線”的數(shù)字方式傳輸，與傳統(tǒng)的熱敏電阻等測溫元件相比，它能直接讀出被測溫度，并且可根據(jù)實(shí)際要求簡單的編程實(shí)現(xiàn)9~12位的數(shù)字值讀取方式。大大提高了系統(tǒng)的抗干擾性。適合于惡劣環(huán)境的現(xiàn)場溫度測量，如：環(huán)境控制、設(shè)備或過程控制、測溫類消費(fèi)電子產(chǎn)品等。</p><p>　　DS18b20與單片機(jī)的接口電路</p><p>　　DS18b20可以采用兩種

94、方式供電：一種采用電源供電方式，此時DS18b20的第一個引腳接地，第二腳作為信號線，第三腳接電源;另一種是寄生電源供電方式，單片機(jī)端口接單總線，為保證在有效的DS18b20時鐘周期內(nèi)提供足夠的電流，需用一個MOSFET管來完成對總線的上拉。本系統(tǒng)采用的是電源供電方式。</p><p>　　對硬件結(jié)構(gòu)簡單的單線數(shù)字溫度傳感器DS18B20 進(jìn)行操作，需要用較為復(fù)雜的程序完成。編制程序時必須嚴(yán)格按芯片數(shù)據(jù)手冊提供的

95、有關(guān)操作順序進(jìn)行，讀、寫時間片程序要嚴(yán)格按要求編寫。尤其在使用DS18B20 的高測溫分辨力時，對時序及電氣特性參數(shù)要求更高。</p><p>　　系統(tǒng)中使用ds18b20數(shù)字式溫度傳感器用于檢測溫度，溫度值通過4位7段碼共陰極數(shù)碼管循環(huán)顯示。用按鍵點(diǎn)擊的次數(shù)對應(yīng)點(diǎn)顏色亮的二極管來使用繼電器控制大電源進(jìn)行加熱。</p><p>　　在本設(shè)計中，還涉及到系統(tǒng)用的電源電路，復(fù)位電路，報警電路，

96、單片機(jī)的看門狗電路等。</p><p>　　因?yàn)閱纹瑱C(jī)工作電源為+5V，且底層電路功耗很小。采用7805三端穩(wěn)壓片即可滿足要求。</p><p>　　為了使停電時具有對溫度報警值數(shù)據(jù)的保護(hù)，需要選用具有非易失性（掉電保護(hù)數(shù)據(jù)）的存儲器，而且對于一個典型的單片機(jī)應(yīng)用系統(tǒng)，看門狗電路的設(shè)計也是必須的。具有掉電保護(hù)數(shù)據(jù)功能的芯片有很多，有并行的E2PROM，有串行的E2PROM，考慮設(shè)計結(jié)構(gòu)的簡

97、單，本系統(tǒng)考慮采用串行方式的E2PROM，常用的有AT24CXX系列、AT93XX系列、AT59XX系列以及X5045等。本設(shè)計中選用了數(shù)據(jù)存儲選用X24C02，它有2048位串行E2PROM.具有掉電保護(hù)功能。</p><p>　　STC89S51RD2+單片機(jī)內(nèi)部具有看門狗電路。進(jìn)行掉電保護(hù)看門狗，又叫 watchdog timer，是一個定時器電路，一般有一個輸入，叫喂狗，一個輸出到MCU的RST端，MCU

98、正常工作的時候，每隔一端時間輸出一個信號到喂狗端，給 WDT 清零，如果超過規(guī)定的時間不喂狗，(一般在程序跑飛時)，WDT 定時超過，就回給出一個復(fù)位信號到MCU，是MCU復(fù)位. 防止MCU死機(jī)?？撮T狗的作用就是防止程序發(fā)生死循環(huán)，或者說程序跑飛。</p><p>　　計算機(jī)必須不時地對看門狗說"你好"以讓看門狗知道它依然在運(yùn)行，如果這種操作失敗，看門狗的動作就會引起系統(tǒng)硬件復(fù)位。</p

99、><p><b>　　三 軟件設(shè)計</b></p><p>　　整個系統(tǒng)的功能是由硬件電路配合軟件來實(shí)現(xiàn)的，當(dāng)硬件基本定型后，軟件的功能也就基本定下來了。從軟件的功能不同可分為兩大類：一是監(jiān)控軟件（主程序），它是整個控制系統(tǒng)的核心，專門用來協(xié)調(diào)各執(zhí)行模塊和操作者的關(guān)系。二是執(zhí)行軟件（子程序），它是用來完成各種實(shí)質(zhì)性的功能如測量、計算、顯示、通訊等。每一個執(zhí)行軟件也就是一

100、個小的功能執(zhí)行模塊。這里將各執(zhí)行模塊一一列出，并為每一個執(zhí)行模塊進(jìn)行功能定義和接口定義。各執(zhí)行模塊規(guī)劃好后，就可以規(guī)劃監(jiān)控程序了。</p><p>　　首先要根據(jù)系統(tǒng)的總體功能和鍵盤設(shè)置選擇一種最合適的監(jiān)控程序結(jié)構(gòu)，然后根據(jù)實(shí)時性的要求，合理地安排監(jiān)控軟件和各執(zhí)行模塊之間地調(diào)度關(guān)系。</p><p>　　主程序調(diào)用了7個子程序，分別是數(shù)碼管顯示程序、鍵盤掃描以及按鍵處理程序、溫度測試程序、