外文翻譯中英對照--基于RS-232的串行通信.doc

外文翻譯 專業(yè)： 班級： 姓名： 基于RS-232的串行通信摘要這篇文章論述了串行通信的主要原則，提出了在RS232的基礎(chǔ)上，設(shè)計串行通訊硬電路的方法。實現(xiàn)了分別在PC微機(jī)和單片機(jī)中使用匯編語言和C+Builder編程。關(guān)鍵詞：串行通信；單片機(jī)；程序設(shè)一緒論在控制系統(tǒng)的工作中，PC微機(jī)發(fā)送指令到步進(jìn)電機(jī)中來收集圖像信息。因此，PC微機(jī)和驅(qū)動系統(tǒng)之間的通信是系統(tǒng)通信所必需的。一般來說，一個完整的通信系統(tǒng)由發(fā)射器、接收器、轉(zhuǎn)換數(shù)據(jù)接口和傳輸數(shù)據(jù)通道所構(gòu)成。該步進(jìn)電機(jī)是通過單芯片來實現(xiàn)微機(jī)控制脈沖分配的。在電機(jī)的控制系統(tǒng)中，PC微機(jī)被稱為上位機(jī)，而由單片機(jī)所控制的步進(jìn)電機(jī)被稱為下位機(jī)。上位機(jī)與下位機(jī)之間的通信有兩個方法，他們分別是串行通信和并行通信。并行通信可以同時傳輸大量的數(shù)據(jù)，具有傳送速度快的優(yōu)點。但是當(dāng)傳輸距離遠(yuǎn)，并且傳輸數(shù)據(jù)的數(shù)量很多時，它需要的傳輸線的數(shù)目也更多。此外，電壓等級會因為輸電線路的因素和電壓干擾而改變。串行通信是一個數(shù)據(jù)按一個個序位單向傳輸?shù)耐ǖ?，其中兩個過渡線是需要實現(xiàn)雙向通信傳輸。正是考慮到在控制系統(tǒng)中需傳遞的數(shù)據(jù)多，而單次傳輸?shù)臄?shù)量少，因此在控制系統(tǒng)中選擇串口通信的方法，從而簡化了硬件結(jié)構(gòu)并節(jié)約了所需的成本。二串口通訊的簡述每次一個二進(jìn)制位移動的。它的優(yōu)點是只需一對傳輸線進(jìn)行傳送信息，因此其成本低，適用于遠(yuǎn)距離通信；它的缺點是傳送速度低。串行通信有異步通信和同步通信兩種基本通信方式。同步通信適用于傳送速度高的情況，它的硬件復(fù)雜。而異步通信應(yīng)用于傳送速度在50到19200波特之間。是比較常用的傳送方式。在異步通信中，數(shù)據(jù)是一幀一幀傳送的，每一串行幀的數(shù)據(jù)格式由一位起始位，5-8位的數(shù)據(jù)位，一位奇偶校驗位（可省略）和一位停止位四部分組成。在串行通信前，發(fā)送方和接收方要約定具體的數(shù)據(jù)格式和波特率（通信協(xié)議），PC機(jī)采用可編程串行異步通信控制器8250來實現(xiàn)異步串行通信。通過對8250的初始化編程，可以控制串行數(shù)據(jù)傳送格式和速度。在PC機(jī)中一般有兩個標(biāo)準(zhǔn)RS-232C串行接口COM1和COM21MCS51系列單片機(jī)內(nèi)含有一個全雙工的串行接口，通過編程也可實現(xiàn)串行通信功能。智能傳感器的CMOS芯片應(yīng)為其低成本，小型化，智能化和標(biāo)準(zhǔn)化的特點已得到廣泛應(yīng)用。在智能傳感器IC設(shè)計中，在傳感器和信號處理電路以外，通信接口電路也可發(fā)揮重要角色。串行通信擁有很多的標(biāo)準(zhǔn)接口，如RS-232，RS_485，USB接口和IEEE-1394。它們各自都有著自身的特點，同時也分別適用于不同的應(yīng)用領(lǐng)域。RS-485具有抗噪聲數(shù)據(jù)傳輸?shù)奶攸c，因此它通常用于工業(yè)生產(chǎn)。USB接口和IEEE-1394具有傳輸速度快的優(yōu)點，但是有一些電腦和操作系統(tǒng)并不支持這種接口。RS-232是在PC機(jī)中和通信行業(yè)中應(yīng)用最廣泛的串行接口。RS-232C標(biāo)準(zhǔn)是異步串行協(xié)議溝通，并已廣泛應(yīng)用于個人電腦和通信產(chǎn)業(yè)。許多短距離打印機(jī)等電腦外設(shè)交際，所以磁盤和終端與PC機(jī)通過RS232通信串行接口。RS-232標(biāo)準(zhǔn)RS-232是美國電子工業(yè)協(xié)會（EIA）正式公布的，在異步串行通信中應(yīng)用最廣泛的標(biāo)準(zhǔn)總線。該標(biāo)準(zhǔn)適用于DCE和DTE間的串行二進(jìn)制通信，最高數(shù)據(jù)傳輸速率可達(dá)19.2kbps，最長傳送電纜可達(dá)15米IRS-232C標(biāo)準(zhǔn)定義了25根引線。對于一般的雙向通信，只需使用串行輸入RXD，串行輸出TXD和地線GND1RS-232C標(biāo)準(zhǔn)的電平采用負(fù)邏輯，規(guī)定+3V-+15V之間的任意電平為邏輯“0”電平，-3V-15V之間的任意電平為邏輯“1”電平，與TTL和CMOS電平是不同的。在接口電路和計算機(jī)接口芯片中大多為TTL或CMOS電平，所以在通信時，必須進(jìn)行電平轉(zhuǎn)換，以便與RS-232C標(biāo)準(zhǔn)的電平匹配1MAX232芯片可以完成電平轉(zhuǎn)換這一工作。RS-232C被定義為單端標(biāo)準(zhǔn)，它具有許多的優(yōu)點，如更低速的串行通信，通信距離遠(yuǎn)，適中的價格和良好的系統(tǒng)適用性，所以它是最試用的一個通信端口。RS-232是一個基本現(xiàn)代化的計算機(jī)接口，它包括COM1和COM2端口，該端口COM1有9針連接器。新一代的計算機(jī)有一個9針連接器（DB9），這樣就可以通過這個9針連接器來連接RS-232串行端口。為了實現(xiàn)可靠的，實時的傳輸，該系統(tǒng)采用三線連接方式，即RS-232端口的GND引腳，RXD引腳和TXD引腳與外部端口連接，如圖1所示。連接端口電腦端口 圖1.RS-232端口三串口通信的軟件設(shè)計該單片機(jī)與PC機(jī)之間通過中斷與PC機(jī)通信程序通信被稱為主控制器。當(dāng)單片機(jī)接收通過PC電腦發(fā)送的數(shù)據(jù)信號時，它就會調(diào)用中斷服務(wù)程序。為了充分利用單片機(jī)，以減少CPU的占用時間，提高溝通效率，控制程序?qū)⑹俏覀儠皶r響應(yīng)和控制的對象。通訊程序?qū)⒌玫絻?yōu)化。子程序的串口接收數(shù)據(jù)，逐個發(fā)送脈沖，為判斷指令子程序和中斷子程序發(fā)送數(shù)據(jù)。A串口中斷子程序用于接收數(shù)據(jù)對用于接收數(shù)據(jù)的串行端口的中斷子程序主要是由PC接收和發(fā)送的數(shù)據(jù)存儲到分配的內(nèi)存中的數(shù)據(jù)（不與數(shù)據(jù)處理，以減少由中斷注冊的時間）負(fù)責(zé)。由單片機(jī)接收到的數(shù)據(jù)包括一些信息，如速度，步驟和開/關(guān)指示，由于緩沖區(qū)的大小足夠把這些數(shù)據(jù)發(fā)送到電腦中，所以省略了軟件握手協(xié)議，以提高CPU利用率。當(dāng)串口中斷程序接收到指定的數(shù)據(jù)時，便退出串行口中斷。B發(fā)送步進(jìn)脈沖子程序使用反單晶片微控制器定時器0定時器，作為固定的時間完成，能使P1.5端口被否定，從而產(chǎn)生周期性的驅(qū)動脈沖。定時器從0開始計數(shù)初始值65535，然后中斷分項計劃的定時器0被調(diào)用，在其中P1.5端口被否定產(chǎn)生驅(qū)動脈沖。同時，單片機(jī)重新載入PC機(jī)通過串行通信微機(jī)發(fā)送的初始值。C判斷指令的子程序教學(xué)計劃的判斷上設(shè)置被稱為串行口中斷的程序。PC微機(jī)發(fā)送數(shù)據(jù)到單片機(jī)。經(jīng)過單片機(jī)接收數(shù)據(jù)，并調(diào)用串口中斷子程序，其中第一次發(fā)送的數(shù)據(jù)被處理。如果第一個數(shù)據(jù)是一個數(shù)字symble“48”，串行口中斷分程序設(shè)置P1.4腳高，那么接下來的五個字節(jié)的數(shù)據(jù)用于確保步進(jìn)電機(jī)的速度和步驟。如果第一個數(shù)據(jù)是一個數(shù)字symble“49”，這意味著步進(jìn)電機(jī)反轉(zhuǎn)，則單片機(jī)接收到發(fā)送來的速度和步驟信息。否則，單片機(jī)判定接收到的數(shù)據(jù)是不是“STOP”指令，如果是這樣，它發(fā)出“停止”指令驅(qū)動系統(tǒng)，如果沒有，他便推出中斷。D發(fā)送中斷處理子程序在發(fā)送中斷處理子程序負(fù)責(zé)將數(shù)據(jù)發(fā)送到計算機(jī)，發(fā)送中斷狀態(tài)一般是關(guān)閉的。當(dāng)通信方案完全由PC微機(jī)發(fā)送的數(shù)據(jù)交易，代碼為“1”可寫入發(fā)送緩沖區(qū)，隨著計算機(jī)接收符號“1”，這是說，單片機(jī)上執(zhí)行完全由PC微機(jī)發(fā)送的介紹。因此，串口中斷設(shè)置為“關(guān)閉”狀態(tài)的單片機(jī)，他設(shè)定為“開”狀態(tài)的數(shù)據(jù)后再發(fā)送。因此，單片機(jī)返回到主程序和等待接收指令。4 PC和單片機(jī)通信程序的設(shè)計 為了方便地實現(xiàn)系統(tǒng)軟件移植和統(tǒng)一，上位機(jī)程序的設(shè)計使用作為控制系統(tǒng)編程工具博蘭的C+Builder的5.0是一個PC編程的編程工具。串行口通信可以利用兩種方式：一是注冊組件，生成的C+本身并不提供單獨的串行通訊組件，但是它可通過已注冊的Microsoft MSComm32成分，其中相對簡單的VB，VC的這種方式。第二種方法是調(diào)用Window API（應(yīng)用程序接口）函數(shù)，此函數(shù)是由操作系統(tǒng)提供，以提供大量的行政職能。該計劃的步驟是如下：（1） 設(shè)置的通信協(xié)議，打開串行端口，這是所謂的初始化，然后阻止其他的程序使用串行端口。（2） 配置串口。（3） 傳遞串口轉(zhuǎn)來的數(shù)據(jù)，驗證數(shù)據(jù)的傳輸過程。（4） 關(guān)閉串口，使其他程序試用。 子接口很簡單，其中的子接口的設(shè)置，如波特率通信模塊的單芯片已被設(shè)置為2400Bps和波特率設(shè)置為在計算機(jī)上的端口的默認(rèn)設(shè)置2400Bps。微機(jī)具有兩個串口，一般稱為COM1和COM2，以便程序可以自動識別串行端口，利于端口可以成功的發(fā)送和接收數(shù)據(jù)和指令。串行通信程序包括兩個方面，一方面是MCS-51單片機(jī)的通信程序，另一方面為PC機(jī)的通信程序。在編寫程序之前，制定其雙方通信協(xié)議是十分重要的，否則將無法保證通信數(shù)據(jù)的可靠性，從而失去通信的意義?，F(xiàn)約定其通信協(xié)議如下：（1） 串行通信波特率為1200bps。（2） 幀格式為：一位起始位，八位數(shù)據(jù)位，一位可編程的第九位（此位為發(fā)送和接收的地址/數(shù)據(jù)的標(biāo)志位），一位停止位。（3） 設(shè)定單片機(jī)的地址碼為F1H。在傳送數(shù)據(jù)前先聯(lián)絡(luò)地址碼，如地址碼正確則傳送數(shù)據(jù)，否則繼續(xù)聯(lián)絡(luò)地址碼。（4） 無奇偶校驗位。數(shù)據(jù)的通信采用累加和校驗的方法，即每傳送一組數(shù)據(jù)（個數(shù)自定，設(shè)為100個），校驗一次累加和是否正確，正確則回送00H，否則回送FFH。（5） 通信可以有中斷傳送方式和查詢方式。在這里介紹查詢方式通信。（6） 聯(lián)絡(luò)方式為PC機(jī)主動聯(lián)絡(luò)MCS-51單片機(jī)。（7） PC機(jī)采用COM2通信。四結(jié)論串口通信的硬件設(shè)計基于RS-232，PC機(jī)和單片機(jī)之間進(jìn)行通信的軟件模塊使用C+編譯和匯編語言編程。該控制系統(tǒng)在產(chǎn)業(yè)領(lǐng)域運行良好，并通過控制單個步進(jìn)電機(jī)啟動/停止和正轉(zhuǎn)/反轉(zhuǎn)旋轉(zhuǎn)。PC危機(jī)通過友好的用戶界面向單片機(jī)發(fā)送控制指令。參考文獻(xiàn)【1】樊一支，姜文祥，陳梨園。串行通信控制的C+生成和RS232.北京：清華大學(xué)出版社，2002年，第2-18【2】茍?zhí)K艾。C+Builder5.0的程序員指南。北京：北京希望電子出版社，2001年，第1-6【3】劉艷玲。使用MAX232進(jìn)行的MCS-51單片機(jī)與PC機(jī)之間的通信。天津科技，1999年，第56-58【4】楊國霞。采用消息方式處理串口與主程序間的通訊。雜志：促進(jìn)科技，2001年，河北省科學(xué)院卷。18（4）：220-223頁【5】黎步銀，江盛林，盧重，周東祥?；贑語言的串行通信程序設(shè)計。作者：Transcluction技術(shù)，2002，卷。（2）第65-66【6】王志忠。單片機(jī)和PC機(jī)之間的串行通信?，F(xiàn)代電子技術(shù)，2000,119，第68-7The Designing of Serial Communication Base on RS232Abstract-This Paper discussed the principle of serial communication mainly,proposed the design method based on RS232,designed the hard circuit of serial communication,and realized the programming to PC Microcomputer and single chip microcomputer by using assembly language and C+ Builder separately,Keywords-serial communication;single chip microcomputer;program designI.INTRODUCTIONDuring working in the control system,the PC microcomputer sends instructions for step-by-step motor to collect the image information.Therefore the communication between the PC microcomputer and the driving system is needed for the communication system.In general,a complete communication system consists of transmitter,receiver,converting the data interface and transmitting data channel.The control of tne step-by step motor is realized through the pulse distribution by single chip microcomputer.On the motor control system,the PC microcomputer is called as upper computer,and the single chip microcomputer for driving step_by_step motor is called as lower computer.The communication between the upper computer and the lower computer has two methods,that si to say the parallel interface can transmit much data at the same time and has the fast speed,but when the transmission distance is far and the number of data is much,it needs more the number of transmission lines.In addition,the voltage level may be changed by the transmission line factor and electromagnetic interference.Serial communication is utilized in the control system so as to simplify the hardware and save the cost. II. THE BRIEF DESCRIPTION OF SERIAL PORT COMMUNITION Serial communication is the communication between sender and receiver data line,to move each time a bit.The advantage is that only a pair of transmission lines to send information,so its low cost,suitable for long-distance communication;its disadvantage is that transmission speed is low.Serial communication with asynchronous communication and synchronous communication are two basic means of communication.Synchronous communication for the case of high transmission speed,the hardware complexity.The asynchronous communication used in transmission speed between 50 and 19200 baud.Transmission is relatively common.In asynchronous communication,data is transmitted frame by frame,each frame of serial data format by a start bit,5 to 8 data bits,a parity bit(optional) and a Stop bit of four parts.Before the serial communication,the sender and receiver to agree the specific data format and baud rate(communication protocol).PC-programmable serial asynchronous communication controller 8250 to implement asynchronous serial communication.By 8250 the initial programming,you can control serial data transmission format and speed.In the PC,in general there are two standard RS-232C serial interface COM1 and COM21MCS-51 serial micro-controller chip includes a full-duple serial interface,can also be realized by programming the serial communications. CMOS smart sensor IC has received wide application for low cost,miniaturization,intelligence and standardization.In smart sensor IC designs,the communication interface circuits also play an important role other than sensors and signal processing circuits.There are more serial communication standard interfaces,such as RS-232,RS-485,USB Interface,IEEE-1394,which has itself good features and also has focused on areas of application.RS-485 has a anti-noise capacity transmitting data,so it is commonly used in industrial production.USB interface and IEEE-1394 have fast speed,but some computers and operating systems do not support such interfaces.RS-232C standard is a protocol of asynchronous serial communication and has been widely used in PC and communication industries.Many short distance communicational peripherals of PC such as printers,disks and terminals all communicate with PC via RS232 serial interface. RS-32C standard RS-232C is the American Electronics Industry Association(EIA) formally announced,in the asynchronous serial communication,the most widely used standard bus.The standard for DCE and DTE serial binary communication between the maximum data transfer rate of up to 19.2kbps,the longest transmission cables up to 15 meters RS-232C standard defines the 25-lead,two-way communication in general,just Serial input RXD,serial output TXD and ground GND1RS-232C standard levels using negative logic,the provisions of +3V+15V at any level between a logic ”1” level,with TTL and CMOS levels are different.In the interface circuit and computer interface chip in the mostly level TTL or CMOS,so the communication,the need for level conversion,so with RS-232C standard level matching 1MAX232 chip level conversion can be done in this work. RS-232 is defined as the single-ended standards,which has much characteristic,such as more communication distance in a low-speed serial communication,moderate price and good practically of the system,so it is most appropriate to be a communication port.RS-232 is an essential modern computer interface,it includes ports COM1 and COM2,the port COM1 has 9-pin connector.The new generation computer has a 9-pin connector(DB9)so as to connect with the RS-232 communication port.In order to achieve reliable and realtime transmission,the system adopt a three-wire connection method,that is to say that the GND pin,RXD pin and TXD pin of RS-232 port is connected with the external port,it is shown in Figure 1: Figure 1. The RS-232 port III. THE SOFTWARE DESIGN OF SERIAL PORT COMMUNICATION The communication program of the single chip microcomputer communications with PC computer by interrupt and PC computer is called as main controller.When the single chip computer receives the data singles sent by PC computer,then it calls interrupt service program.The flowchart of the interrupt service main subprogram is shown in Figure 3.In order to fully exploit the efficiency of single chip computer to minimize CPU time occupied by communication,the control program will be we will promptly respond to and control objects.The communication program will be optimized.The subprogram of serial port interrupt for receiving data,the subprogram for sending step-by-step impulse,the subprogram for judging instruction and the subprogram foe sending data.A.The subprogram of serial port interrupts for receiving dataThe subprogram of serial port interrupt for receiving data is mainly responsible for receiving data send by PC microcomputer and storing the data into allocated memory(it does not deal with data so as to reduce the time taken up by interruptions). The data received by the single chip microcomputer includes little information ,such as speed,steps and on/off instructions,and the buffers is large enough to send the computer,so the software shake hands protocol is omit so as to raises the CPU utilization.When the program of serial port interrupt receives the specified data,it exits the serial port interrupt.B.The subprogram of sending the step-by-step impulseUsing counter-timer of the single chip microcomputer time 0,as the fixed times complete,the p1.5 port is negated so as to periodically generate the driving pulses.The time 0 begins to count from initial value which to 65535,then the interrupt sub-program of timer 0 is called, in which the p1.5 port is negated to generate a driving pulse.Meanwhile,the single chip microcomputer loads again the initial value which is send by the PC microcomputer by serial communication.C.The subprograms of judging instruction The program of judging instruction is set on the serial port interrupt program to be called.The PC microcomputer sends data to the single chip microcomputer.After the single chip microcomputer receives data,it sets the RI higher and called the serial port interrupt sub-program,in which the first data is processed.If the first data is a digital symbol “48”,the serial port interrupt sub-program sets P1.4 higher,then the next five bytes data is used to ensure the step-by-step motor speed and steps.If the first data is a digital symbol “49”,it means that the step-by-step motor reverses,then the single chip microcomputer receives the speed and steps information.Otherwise the single chip microcomputer judges that the received data is not “STOP” instruction,if so,it sends “stop” instruction to the drive system;if not,it quits the interrupt.D.The processing subprogram of send interrupts The processing subprogram of send interrupts is responsible to send data to the computer,sending interrupt state is off in the general.When the communication program completely deals with data with data sent by PC microcomputer,the symbol “1”can be written to send buffer.As the computer receives the symbol ”1”,it is said that single chip computer executes completely the introduction sent by PC microcomputer.Therefore the serial port interrupt is set as “off” state by the single chip microcomputer and it is set “on” state again after data are sent.So the single chip microcomputer returns to main program and waits for receiving instructions.IV.THE DESIGN OF COMMUNICATION PROGRAM OF PC MICROCOMPUTER AND SINGLE CHIP MICROCOMPUTERIn order to realize the system software easily grafted and uniformity,the program of upper computer is designed using the Boland C+ Builder 5.0 as a programming tool in the control system s the Boland C+ Builder 5.0 as a programming tool for PC programming.The serial port communication can be utilized in two ways:First,register components,C+ Builder does not in itself provide a separate serial communication component,but it can be obtained through registered Microsoft MSComm32 components,in which it is relatively simply for VB,VC in this way.The second method is called Windows API(Application Program Interface)function,in which this function is provided by the operating system in order to provide a lot of executive function.This program steps is followed:(1) Setting by communication protocol and opening the serial port,which is called initialization,then blocking the other program to use the serial port.(2) Configuring the serial port.(3) Transmitting data by the serial port to and fro,verifying data during transmission.(4) Closing the serial port as no needing it so that other program uses. The sub-interface is simple,in which the setting on sub-interface parameters are defaults,such as baud rate that single chip communication module has been set to 2400Bps and that the baud rate is set to 2400Bps in the computer setting on the ports.The PC microcomputer has two ports called as serial port COM1 and COM2 generally,so the program can automatically identify serial port so that it can send and receive data and instructions successfully.Serial communication program includes two aspects,one is MCS-51 micro-controller communication program,on the other hand for the PC,the communication process.In the preparation processes,the development of the two protocols is very important,otherwise it will not guarantee the reliability of data communications,and thus lose the meaning of communication.The communication protocol is agreed as follows:1) The serial communication baud rate is 1200bps.2) The frame format is:a start bit,eight data bits,a programmable ninth bit(this bit is sent and received address/data flag),one stop bit.3) Set the address of the micro-controller code F1H.Contact before sending the data in the address code,such as the address code is the correct transmission of data,or to contact the address code.4) No parity.The communication of data accumulation and verification of the method,that is,each