基于串口通信的字符顯示終端的設計 外文翻譯

1、<p><b>　　本科畢業(yè)設計</b></p><p><b>　　英文翻譯</b></p><p>　　專業(yè)名稱 電子信息工程 </p><p>　　學生姓名 ****** </p><p>　　指導教師 *****

2、 </p><p>　　完成時間 2013.06 </p><p>　　本科畢業(yè)設計英文翻譯</p><p><b>　　指導教師評閱意見</b></p><p>　　學生姓名：****** 班級：122902 得分： </p><p>　　

3、Serial Communication Based Character Display Terminal </p><p>　　To introduce</p><p>　　With microcontroller and microprocessor technology continues to evolve, especially in the field of network t

4、echnology widely used in the monitoring and control by the PC and multi-single chip consisting of multi-machine network monitoring and control system has become the SCM technology development in one direction. Computer a

5、nd computer or computer data transfer between the terminal can use a serial communications and parallel communications in two ways. Since the serial communication line with</p><p>　　Microcontroller hardware

6、structure and communication system </p><p>　　Microcontroller and PC serial communication generally use RS-232, RS-422, or B3-485 bus standard interface, there is also a non-standard 20nnJL current loop. To e

7、nsure reliable communications, the choice of interface must be noted: (1) the rate of communication; (2) Communication distance: (3) anti-jamming capability; (4) networking. This paper describes the use of RS-232 interfa

8、ce to communicate with the microcontroller method.</p><p>　　1, RS-232 level converter and PC interface circuit</p><p>　　RS-232 is an early data communication to the public telephone network and

9、established standards, the logic level and ITL \ CMOS power almost entirely different. Logic "0" is defined as +5- +15 V between logic "1, defined as between -5 ~-15V Since RS-232 transmit and receive betw

10、een common ground transmission using non-equilibrium model, so a total of mode noise is coupled to the signal system, the standard recommended maximum communication distance of 15 meters, but the practical application of

11、 </p><p>　　RS-232 level and the general provisions of the microprocessor logic level inconsistent, must be level conversion, logic-level translators can use the following three ways.</p><p>　　Th

12、e conversion interface using MAX232 MAX232 chip is produced by MAXIM, including two-way driver and receiver RS-232 converter chip. Figure 2 is a practical circuit. Chip has an internal voltage converter, you can convert

13、the input voltage is +5 v RS-232 interface ± 10V voltage required, especially for no ± 12V single supply system. With this principle, the same chip as well MAx202, AD's ADDtl01 and INl2 only SIL's ICl23

14、2 chips.</p><p>　　Implemented using discrete components Figure 3 shows the conversion interface implemented using discrete components RS-232-TTL level conversion interface circuit, which is characterized by

15、the use of PC-BS-232 interface signal ③ feet out (also available ④, ⑦ feet ) to supply the negative supply, FC machine ③, ④, ⑦ feet in the non-transmission logic "0" level are one level (-10V or so), the drive

16、capacity of 20mA, using this characteristic, with a diode and an electrolytic capacitors, electrolyti</p><p>　　The introduction of the RS. 232 to TTL level conversion method can be applied to most of the com

17、munication system, in some special applications such as electrostatic protection needs, multi-transceiver (eg with MODEM connected) can be used when MAX238 (4 drive, four receiving) or MAX3221t t15Kv electrostatic protec

18、tion) and other chips.</p><p>　　2, single-chip serial communication design</p><p>　　SCM string works the widely used 51 series microcontroller serial communication can operate in synchronous or

19、asynchronous mode, most compatible with the 8051 series has one or more UART asynchronous serial interface, which is designed for users communication program provides good facilities. When the application system requires

20、 multiple serial communication interface, we can use the following methods: (a) multi-chip serial port, such as Winbond WW77E58 there are two serial interfaces; (2) adopt</p><p>　　Microcontroller serial port

21、 rate setting microcontroller and PC communication, the communication rate by timer T1 or T2 timer generates (52 series), at work in the way 2:00 T1 communication rate is calculated as: Porter String = (SMOD × Fosc)

22、 / (32 × 12 × [256-TH1]). Which crystal frequency Fosc, in order to obtain accurate communication rate, Fosc usually 11.0592MH2. The T1 timer communication system, the rate can not be too high, generally up to

23、19200bit / s. If in order to obtain a higher com</p><p>　　Single-chip serial communication program implementations practical applications, SCM communication procedures generally use interrupt communication w

24、ith the computer, the computer do the main prosecution. When the microcontroller receives address signals sent by computer, they transferred to the interrupt service routine, the computer sends data. Its interrupt servic

25、e program flow shown in Figure 4, the interrupt service procedure also applies to multi-machine communication systems. See the deta</p><p>　　General principles of design requirements:</p><p>　　T

26、he entire control system to send data from the PC to operate, using 51 microcontroller system and PC RS232 serial port, two-way data communications, and then use visual programming preparing serial debugging software, fu

27、rther serial port to send "1", "2", "3 "......" 8 "," 9 "," 0 "and other characters, the circuit board receives the data via lcd1602 LCD display, feedback to th

28、e PC, and it will show the successful confirmation signal that the PC serial port debugging software receive buffer wil</p><p>　　基于串口通信的字符顯示終端的設計 </p><p><b>　　介紹</b></p><

29、p>　　隨著單片機和微機技術的不斷發(fā)展，特別是網(wǎng)絡技術在測控領域的廣泛應用，由PC機和多臺單片機構成的多機網(wǎng)絡測控系統(tǒng)已成為單片機技術發(fā)展的一個方向。計算機與計算機或計算機與終端之間的數(shù)據(jù)傳送可以采用串行通訊和并行通訊二種方式。由于串行通訊方式具有使用線路少、成本低，特別是在遠程傳輸時，避免了多條線路特性的不一致而被廣泛采用。 在串行通訊時，要求通訊雙方都采用一個標準接口，使不同的設備可以方便地連接起來進行通訊。

30、0;RS-232-C接口(又稱 EIA RS-232-C)是目前最常用的一種串行通訊接口。它是在1970年由美國電子工業(yè)協(xié)會(EIA)聯(lián)合貝爾系統(tǒng)、 調(diào)制解調(diào)器廠家及計算機終端生產(chǎn)廠家共同制定的用于串行通訊的標 準。它的全名是“數(shù)據(jù)終端設備(DTE)和數(shù)據(jù)通訊設備(DCE)之間 串行二進制數(shù)據(jù)交換接口技術標準”該標準規(guī)定采用一個25個腳的 DB25連接器，對連接器的每個引腳的信

31、號內(nèi)容加以規(guī)定，還對各種信 號的電平加以規(guī)定。串口通信結合了單片機在實時數(shù)據(jù)采集和微機對圖形處理、顯示的優(yōu)點。同時，windows環(huán)境下后臺微機在數(shù)據(jù)庫管理上具有明顯的優(yōu)勢。使得單片機的應用已不僅僅局限于傳統(tǒng)意義上</p><p>　　硬件結構和單片機的通信系統(tǒng)設計</p><p>　　單片機和PC機的串行通信一般采用RS-232、RS-422或B3-485總線標準接口，也有采用

32、非標準的20nnJL電流環(huán)的。為保證通信的可靠，在選擇接口時必須注意：（1）通信的速率；（2）通信距離：（3）抗干擾能力；（4）組網(wǎng)方式。本文主要介紹采用RS-232接口與單片機通信的方法。</p><p>　　1、 RS-232電平轉換和PC機的接口電路</p><p>　　RS-232是早期為公用電話網(wǎng)絡數(shù)據(jù)通信而制定的標準，其邏輯電平與ITL＼CMOS電乎完全不同。邏輯“0”規(guī)定為+

33、5- +15V之間，邏輯“1，，規(guī)定為-5～-15V之間。由于RS-232發(fā)送和接收之間有公共地，傳輸采用非平衡模式，因此共模噪聲會耦合到信號系統(tǒng)中，其標準建議的最大通信距離為15米．但實際應用中我們在300bi／s的速率下可以達到300米。</p><p>　　RS-232規(guī)定的電平和一般微處理器的邏輯電平不一致，必須進行電平轉換，實現(xiàn)邏輯電平轉換可以采用以下三種方式。</p><p>

34、　　采用MAX232芯片的轉換接口 MAX232是MAXIM公司生產(chǎn)的，包含兩路驅動器和接收器的RS-232轉換芯片。圖2為實際電路。芯片內(nèi)部有一個電壓轉換器，可以把輸入的+5v電壓轉換為RS-232接口所需的±10V電壓，尤其適用于沒有±12V的單電源系統(tǒng)。與此原理相同的芯片還有MAx202、AD公司的ADDtl01以及 INl2只SIL公司的ICl232芯片。</p><p>　　采用分立

35、元件實現(xiàn)的轉換接口圖3為采用分立元件實現(xiàn)的RS-232-TTL電平的轉換接口電路，其特點是利用PC機的BS-232接口的③腳信號出（也可用④、⑦腳）來供給負電源，F(xiàn)C機的③、④、⑦腳在非發(fā)送邏輯”0“電平時均為1電平（-10V左右），其驅動能力為20mA，利用這個特性，用一個二極管和電解電容，即在電解電容上獲取了RS-232通信所需的負電源。該電路簡單、功耗小，在沒有專用芯片時不失為一種替代方法。</p><p>

36、;　　上述介紹的RS。232至TTL電平轉換的方法可以適用于大多數(shù)通信系統(tǒng)，在一些特殊應用場合需要諸如靜電保護、多收發(fā)器（如與MODEM連接）時可采用MAX238（4驅動、4接收）或MAX3221t t15Kv靜電保護）等芯片。</p><p>　　2、單片機串口通信設計</p><p>　　單片機串工作方式目前廣泛應用的51系列單片機的串行通信可工作于同步或異步方式，多數(shù)與8031兼容的

37、51系列單片機都有一個或多個UART異步串行接口，這就為用戶設計通信程序提供了很好的便利條件。當應用系統(tǒng)中需要多個串行通信接口時，可采用以下幾種方法：（1）采用多串口的單片機，如華邦的WW77E58就有2個串行接口；（2）采用通用異步串口擴展芯片，如TLl6c552（2路）、LCl6C554（4路）；（3）采用普通I／O模擬實現(xiàn)通信。這是最簡單經(jīng)濟的方法，并且可以實現(xiàn)高速串通信，實現(xiàn)方法詳見《電子世界）雜志以前刊登的有關文章。本文僅討論

38、采用一個異步串行通信的設計方法，單片機串口的控制方式MCS-51系列單片機對串口的控制是通過對串行口控制寄存器SCON和功率控制寄存器PCON的設置來實現(xiàn)的。SCON是一個可位尋址的特殊功能寄存器，通過設置SGON的SM0和SMI，可以使單片機有四種不同的工作方式。SCON的格式可參見有關手冊說明。在用于和PC機實現(xiàn)串行通信時，一般設置為方式1或方式3，主要區(qū)別是方式1的數(shù)據(jù)格式為8位，方式3的數(shù)據(jù)格式為9位，其中第9位SM2為多機通信

39、位，‘可實現(xiàn)單片機的多</p><p>　　單片機串口的速率設置單片機和PC機通信時，其通信速率由定時器T1或定時器T2產(chǎn)生（52系列），在T1工作在方式2時的通信速率的計算公式為：波特串＝（SMOD× Fosc）／（32×12×［256－TH1］）。其中Fosc晶振頻率，為獲得準確的通信速率，F(xiàn)osc通常為11．0592MH2。采用T1定時器通信的系統(tǒng)，速率不可能過高，一般情況下最

40、高為19200bit／s。如為了獲得更高的通信速率可利用52系列單片機的定時器T2，最高速率可達 115200bjt／s。實際應用中我們曾經(jīng)在6MH2晶振的單片機系統(tǒng)中實現(xiàn)了38400bit／s的高速通信。</p><p>　　單片機串口通信程序的實現(xiàn)方法實際應用中，單片機通信程序一般采用中斷方式與微機通信，微機做為主控方。當單片機收到微機發(fā)送的地址信號時，便轉入中斷服務程序，向微機發(fā)送數(shù)據(jù)。其中斷服務于程序流程

41、見圖4，該中斷服務于程序也適用于多機通信的系統(tǒng)。詳細的程序清單請參見本刊網(wǎng)站COMMON．ASM，單片機的晶振為11． 0592MHz，通信速率為9600bit／s，幀格式為N．8．1。</p><p><b>　　總設計要求原理：</b></p><p>　　整個控制系統(tǒng)由PC機發(fā)送數(shù)據(jù)進行操作，利用51單片機系統(tǒng)與PC機RS232串口相連，實現(xiàn)雙向數(shù)據(jù)通信，然后利