【正文】 引腳為高電平，CPU可靠復(fù)位。它是以單片機(jī)為核心的控制電路，可以實(shí)現(xiàn)步進(jìn)電機(jī)根據(jù)設(shè)定的步數(shù)進(jìn)行自動(dòng)加減速控制，使控制系統(tǒng)以最短的時(shí)間走完所規(guī)定的步數(shù)而又不發(fā)生失步的現(xiàn)象。最后對(duì)控制系統(tǒng)各部分的電路進(jìn)行了分析和設(shè)計(jì)，并把各模塊有機(jī)組合起來形成一個(gè)較完整的電路，如附錄C所示。便于調(diào)試、連接、移植、修改。（5）經(jīng)過調(diào)試修改后的程序應(yīng)進(jìn)行規(guī)范化，除去修改“痕跡”。本系統(tǒng)的軟件采用C語言編寫，在此本文主要介紹軟件的各個(gè)模塊功能與軟件流程。單片機(jī)根據(jù)所輸入的步數(shù)判斷是否需要進(jìn)行加速啟動(dòng)，當(dāng)輸入的步數(shù)小于100時(shí)，步進(jìn)電機(jī)以最低速度25 r/min運(yùn)行。 變速控制中轉(zhuǎn)速與步長(zhǎng)之間的關(guān)系 主程序設(shè)計(jì) 主程序工作過程（1）系統(tǒng)初始化。判斷是否有按鍵按下，若有則進(jìn)行按鍵處理。（4）定時(shí)器T0啟動(dòng)。（6）步數(shù)為0判斷。 定時(shí)器T0中斷程序流程圖。 Proteus仿真界面為了防止步進(jìn)電機(jī)啟動(dòng)時(shí)發(fā)生失步，需要先以一個(gè)比較低的頻率啟動(dòng)。 （2）并行接法：使用并行接法時(shí)要對(duì)每個(gè)數(shù)碼管用I/O口單獨(dú)輸入數(shù)據(jù)，占用資源較多。在發(fā)送中斷標(biāo)志TI為0（即無效）的情況下，執(zhí)行寫串行數(shù)據(jù)輸出緩沖器SBUF指令即可將SBUF寄存器中的內(nèi)容由低位到高位依次輸出到RXD引腳，同時(shí)TXD引腳輸出移位脈沖，使外接的“串入并出”芯片逐一接受來自RXD引腳上的串行數(shù)據(jù)。顯示程序只需要將數(shù)組中的內(nèi)容一個(gè)個(gè)送入SBUF 寄存器中，就可以實(shí)現(xiàn)步數(shù)的顯示。本程序采用行、列對(duì)應(yīng)的二進(jìn)制碼來確定按鍵功能，例如讓P1輸出0FEH，如果第一按鍵按下時(shí)，第二個(gè)按鍵為0DEH，第三個(gè)按鍵為0BEH，第四個(gè)按鍵為7EH。1/150 80 mA400 pps500 pps 步進(jìn)電機(jī)轉(zhuǎn)速與頻率的關(guān)系步進(jìn)電機(jī)是機(jī)電控制中一種常用的執(zhí)行機(jī)構(gòu)，它的用途是將電脈沖轉(zhuǎn)化為角位移，通俗地說：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（步進(jìn)角）。轉(zhuǎn)一圈需要360176。 本章小結(jié)本章首先介紹了軟件設(shè)計(jì)原則，其次介紹了主程序、T0中斷程序、調(diào)速程序、顯示程序等程序的設(shè)計(jì)。通過這次設(shè)計(jì)，加深對(duì)單片機(jī)控制系統(tǒng)的了解。根據(jù)系統(tǒng)的要求確定控制系統(tǒng)的總體設(shè)計(jì)方案。用keil軟件完成程序的編寫和調(diào)試，并用Proteus軟件進(jìn)行系統(tǒng)仿真。參考文獻(xiàn)[1]唐任遠(yuǎn).《特種電機(jī)原理及應(yīng)用》.，[2]邱阿瑞.《電機(jī)與拖動(dòng)基礎(chǔ)》.，[3]王德勝.《電氣控制系統(tǒng)設(shè)計(jì)》.電子工業(yè)出版社，[4]馬忠梅.《單片機(jī)C語言應(yīng)用程序設(shè)計(jì)》.，[5]周國(guó)運(yùn).《單片機(jī)原理及應(yīng)用教程》.中國(guó)水利水電出版社，[6]王靜霞.《單片機(jī)應(yīng)用技術(shù)》.電子工業(yè)出版社，[7]溫子琪.《51單片機(jī)C語言教程》.北京航空航天大學(xué)出版社，[8]坂本正文.《步進(jìn)電機(jī)應(yīng)用技術(shù)》.科學(xué)出版社，[9]韓建國(guó).《Foundation and Application of Microcontroller》.中國(guó)質(zhì)檢出版社，[10]Dongkai Qiao,Xiangyu Yang,Jinxin of Automatic Welding Machine Based on PLC. 2011 Second International Conference on Digital Manufacturing amp。80s. We sat on the back of pickup trucks for hours. The sky was blue, and we couldn39。s performers of the troupe still tour the region39。s Liaoning province, decades ago. The solider gave the old man a handmade saddle when they bid farewell. The story inspired Nasun to write Carved Saddle, a song that later became one of his most popular numbers. Now, every year, Nasun recruits young singers and dancers for the troupe. The troupe has also designed a new repertoire, which is mostly based on the daily lives of Mongolian people, especially the lives of nomadic families, and has bined contemporary musical elements with folk songs of the region. Haimu, a 25yearold khoomei (a local variant of overtone singing) singer, joined the troupe three years ago. Along with a sixmember band, he performs fast songs and soft ones that he writes－all while playing the horsehead fiddle.Although I learned the piano since childhood and grew up listening to various kinds of music, to me, the folk music of Inner Mongolia is the root, he says. Performing in remote villages is pleasant. I feel at home on the boundless grasslands, and the warm people there make me feel fulfilled. The first round of spring auction season in Beijing ended last week, but it failed to create much spring in the art market. Although two pieces of Chinese painting fetched more than 100 million yuan, the decline in trading volume and sale rate showed a downturn this year. In the “Grand View: Chinese Painting Highlight” session at China Guardian 2015 spring auctions, Pan Tianshou’s representative work Eagle, Rock and Flora hit a record auction price of 279 million yuan, while Li Keran’s masterwork Jinggang Mountain fetched million yuan, an unexpected high in recent years. However, the trading volume fells to billion yuan from billion yuan in the same period the year before. The Huangchen 2015 Spring Auctions, which recorded million yuan in total sales, experienced the same. The section number went down to 5 from 12 pared to last year. According to expert Shao Jianwu, the art market did not attract much excitement this year due to the booming stock market and the persistent problems of forgery and fake deals. The two pieces of Chinese painting notched up high price this spring due to their own value not due to a revival in the market. The successful transaction of two works with a hammer price of more than 100 million yuan once again confirms that valuable and rare works of high quality always earn the longlasting high price. Chinese painting and calligraphy is still the pillar of the market. However, the overall sales rate has dropped slightly, which reflects the demand for the ordinary auction goods has weakened,” said the president of China Guardian’s Hu Yanyan. Besides, the entry of new buyers also makes certain changes to the direction of purchasing. In a word, the overall market trend is very unpredictable. Although China Guardian 2015 Spring Auctions has achieved remarkable results, it does not mean that the market has walked out of the predicament. We still have to wait for the big economic boom to invigorate the art market.” Even so, the hot pursuit of some special items appeared this spring. A special session of China Guardian Spring Auctions titled “Fine Gilt—Bronze Buddhist Images” achieved a great deal with total sales volume of million yuan and 92 percent sale rate. The 5th Shamar Rinpoche Statue from 1617th century of Tibet was sold for million yuan. The Beijing Chengxuan Auctions featured almost 2,800 items of coins and stamps in three sessions with good sale rate. The Huachen Auctions also set a special session of photographs under the condition of largescale decline of auction sessions. There was a palpable dull thud of disappointment that acpanied the return of the imperial entourage of Zhen Huan to her homeland. It followed a couple years of hushed excitement as Chinese fans were fed tidbits about their proud concubine who was supposed to conquer the high ground of the North American market. Zhen Huan is, of course, the title character of The Legend of Zhen Huan, a 2011 television series that swept China off its feet and later took other Asian countries by storm. Two years ago, it was reported that HBO, a premium cable service headquartered in the United States, was going to air it in North America after some modification. Now, a condensed version that provides English subtitles but no dubbing has finally been made available on Netflix for online streaming. This version, highly anti