【正文】 mode in order to limit the current through the motor windings. The CLOCK signal is supplied by the microcontroller and HALF/FULL pin should always to be low for full mode (twophaseon) of operation. The ENABLED signal is used to control the motion of the motor. When it is low, all INH1, INH2, A, B, C, D pins are brought to low. The Vref value sets the current flowing through the motor. There are two L297 ICs used and it is necessary to synchronize them. It can be done easily by using the SYNC pin of L297.Fig. . Block diagram of the systemThe shows how the input and output terminals are used in L298N. Usually 100nF noninductive capacitors are used between both Vs and Vc with the ground. The value of the current sensing resistor has to be as small as in order to avoid large voltage drops at large currents.External diode bridges provide current circulating paths when the inputs of the IC are chopped. Usually Schottky diodes are used here because they are faster in recovery.V. RESULTSThe theoretical and logical analysis of the stepper drive circuit design approach shows that it is a simple construction having several modes of operation and control.The performance of the stepper drive circuit shown in the was tested for the following capabilities:1. Speed control capability2. Current control capabilityThe and show the excitation wave forms at each phase terminal. The excitation sequences for all five phases reveal that they are working according to the requirement. shows additional orange and green phase excitation sequences to pare the black phase excitation with the others. Due to the charging and the discharging of the capacitors by the current flowing through the windings of the motor, there are some transients at each excitation points.The speed control of the motor has been achieved by varying the frequency of the excitation sequence of the five terminals. It is clearly shown that the pulse width of the voltage sequences of , gets doubled in the , same time scale of 5ms/div. It is observed that the rotating speed (speed 1) of the motor relevant to the excitation sequence shown in is half that of the speed (speed 2) of the excitation sequence shown in . Hence by varying the pulse frequency of the excitation sequence generated by the PIC microcontroller, the speed of the motor can be varied.Fig. . Drive circuit with microcontroller Voltages of the Blue, Red, Orange and Green phases at speed 1. Voltages of the Orange, Green and Black phases at speed 1. Voltages of Blue, Red, Orange and Green phases at speed 2Fig. . Voltages of the Red, Orange, Green and Black phases at speed 2 The current controlling capability of the motor drive circuit has been demonstrated in the , the sake of demonstration, only the RED phase has been considered and shows the current wave at higher Vref (=600mV) which is greater than the Vsense. Then the INH signal does not pull down to limit the current absorb by the motor. Each phase has positive and negative current ponents, because the phase voltage varies from +Vs, +Vs/2 to 0V and current to the phase varies from positive, zero to negative respectively, corresponding to the latter voltage variation. By chopping the inhibit (INH) signal to the L298N, the voltage at the motor terminals is limited to control the current through each winding. Phase Current and INH signal variation at Vref = 120 mV show the current controlling capability at two different Vref values of 200mV and 120 mV. Phase Current and INH signal variation at Vref = 200 mVFig. Phase Current and INH signal variation at Vref = 120 mVVI. CONCLUSIONSThe proposed novel drive for 5 phase stepper motor is a cost effective motor driver pared to the available stepper motor drive circuits in the market. Since the driver has necessary controlling, it can be used for five phase stepper motors for general applications.The simple construction and pacted design of the driver provides another advantage that the driver can be used for robotics applications because it requires small space. Finally the designed driver can be considered as a prototype of a low cost five phase stepper motor drive circuit having additional many functions such as current control, speed control etc. It can be introduced to the local market as a low cost pact drive circuit.REFERENCES[1] Mokhtari, “Microstep Driving for Stepper Motor: A Case Study”, Available:silab/publications/pdf/[2] Data sheet of the L297 IC, Available:[3] Data sheet of the L298N IC, Avilable:[4]Thomas L. Hopkins ‘Stepper motor driver considerations m。但是，還存在需要改進(jìn)的地方：一方面，開(kāi)關(guān)太小，不易撥動(dòng)，且沒(méi)能形成遠(yuǎn)程無(wú)線(xiàn)控制；另一方面，電路也不太穩(wěn)定，干擾太大。達(dá)到最高點(diǎn)自動(dòng)停止，將國(guó)旗上升時(shí)的高度與顯示的高度對(duì)比，多次測(cè)量。 上升高度測(cè)試結(jié)果表測(cè)試次數(shù)設(shè)置高度（cm）實(shí)際高度（cm）123關(guān)閉開(kāi)關(guān)K1，打開(kāi)開(kāi)關(guān)K2，使電機(jī)工作在反轉(zhuǎn)（即國(guó)旗下降）的模式，同樣用秒表控制在43秒的時(shí)間，國(guó)旗從最高點(diǎn)（167cm處）下降，測(cè)試國(guó)旗在指定時(shí)間停止時(shí)的實(shí)際停止點(diǎn)與參考零點(diǎn)的相差度，測(cè)量三次。 焊接實(shí)物圖焊接完成后，電機(jī)與旗桿的固定，用安裝線(xiàn)將電機(jī)與旗桿固定在一塊，注意固定的高度，要能用杜邦線(xiàn)與其連接。為了解決這個(gè)問(wèn)題，三極管換用了大功率的TIP122達(dá)林頓管，最終解決了這個(gè)難題。先測(cè)各個(gè)連線(xiàn)是否導(dǎo)通，謹(jǐn)防產(chǎn)生虛焊。布局設(shè)好之后，就是電路的焊接。4．電路的與調(diào)試與結(jié)果分析在制作電路開(kāi)始之前，先做好準(zhǔn)備工作。其他參數(shù)基本保持不變。在界面的工具欄中選擇按鈕并點(diǎn)擊，會(huì)出現(xiàn)一個(gè)對(duì)話(huà)框，在對(duì)話(huà)框中“output”，選中“Create HEX FI”,單擊“確定”。其次，在新建的工程中新建一個(gè)文件。在“Project”中選擇“New Project”，會(huì)出現(xiàn)一個(gè)“Create New Project”的對(duì)話(huà)框，keil ，輸入你要新建工程名，單擊“確定”。 音樂(lè)子程序流程圖根據(jù)升降旗子程序流程圖，利用C語(yǔ)言編程所設(shè)計(jì)的子程序見(jiàn)附錄D。 LCD1602液晶實(shí)時(shí)顯示子程序的設(shè)計(jì)一般初始化（復(fù)位）過(guò)程：，寫(xiě)指令38H（不檢測(cè)忙信號(hào)）；，寫(xiě)指令38H（不檢測(cè)忙信號(hào)）；，寫(xiě)指令38H（不檢測(cè)忙信號(hào)，以后每次寫(xiě)指令、讀/寫(xiě)數(shù)據(jù)操作均需要檢測(cè)忙信號(hào)）；：顯示模式設(shè)置；寫(xiě)指令08H：顯示關(guān)閉；寫(xiě)指令01H：顯示清屏；：顯示光標(biāo)移動(dòng)設(shè)置；寫(xiě)指令0CH：顯示開(kāi)及光標(biāo)設(shè)置。代碼中，先定義了要用到的步進(jìn)電機(jī)正轉(zhuǎn)和反轉(zhuǎn)的時(shí)序數(shù)組，以使后面的程序能夠隨時(shí)更改電機(jī)接收到的脈沖時(shí)序，以達(dá)到實(shí)時(shí)地控制電機(jī)的正轉(zhuǎn)和反轉(zhuǎn)，從而實(shí)現(xiàn)旗幟的上升與下降。下步進(jìn)電機(jī)步數(shù)的確定本設(shè)計(jì)采用的28BYJ是一個(gè)減速比為1:64的四相八拍步進(jìn)電機(jī)，電機(jī)轉(zhuǎn)動(dòng)一周實(shí)際“走”步數(shù)設(shè)為N，則N=360/=64步 cm。調(diào)整單片機(jī)發(fā)出的脈沖頻率，就可以對(duì)步進(jìn)電機(jī)進(jìn)行調(diào)速。當(dāng)步進(jìn)驅(qū)動(dòng)器接收到一個(gè)脈沖信號(hào)，它就驅(qū)動(dòng)步進(jìn)電機(jī)按設(shè)定的方向轉(zhuǎn)動(dòng)一個(gè)固定的角度（及步進(jìn)角）。所以，程序的控制主要是控制三個(gè)模塊的運(yùn)轉(zhuǎn)。要減弱這種振蕩幅度，最簡(jiǎn)單的濾波方法就是用電容，利用電容的充放電特性。將尼龍細(xì)線(xiàn)的一短纏在電機(jī)上，通過(guò)掛鉤，另一端系上國(guó)旗。用遙控器給一個(gè)脈沖信號(hào)，經(jīng)過(guò)PT2262編碼芯片進(jìn)行編碼，編碼后，經(jīng)過(guò)天線(xiàn)發(fā)射出去。 PT2262編碼芯片管腳圖 PT2272解碼芯片管腳圖PT2262和PT2272是CMOS三態(tài)編碼集成芯片，這組