【正文】 令后面的一條指令。其二是通過硬件復(fù)位也可將空閑工作模式終止，需要注意的是，當(dāng)由硬件復(fù)位來終止空閑模式時， CPU通常是從激活空閑模式那條指令的下一條指令開始繼續(xù)執(zhí)行程序的，要完成內(nèi)部復(fù)位操作，硬件復(fù)位脈沖要保持兩個機(jī)器周期（ 24 個時鐘周期）有效，在這種情況下，內(nèi)部禁止 CPU 訪問片內(nèi) RAM，而允許訪問其它端口。為了避免可能對端口產(chǎn)生以外寫入，激活空閑模式的那條指令后一條指令不應(yīng)該是一條對端口或外部存儲器的寫入指令。 在掉電模式下，震蕩器停止工作，進(jìn)入掉電模式的指令是最后一條被執(zhí)行的指令，片內(nèi) RAM 和特殊功能寄存器的內(nèi)容在終止掉電模式前被凍結(jié)。退出掉電模式的唯一方法是硬件復(fù)位，復(fù)位后將重新定義全部特殊功能寄存器但不改變 RAM 中的內(nèi)容，在 VCC 恢復(fù)到正常工作電平前，復(fù)位應(yīng)無效，且必須保持一定時間以使振蕩器重啟動并穩(wěn)定工作。 5 表 2 編程電壓 VPP=12V VPP=5V 標(biāo)志 AT89C51 XXXX YYWW AT89C51 XXXX5 YYWW 地址 (030H)=1EH (031H)=51H (032H)=FFH (030H)=1EH (031H)=51H (032H)=05H 編程方法： 編程前，需設(shè)置好地址，數(shù)據(jù)及控制信號， AT89C51 編程方法如下： 1） 在地址線上加上要編程單元的地址信號； 2） 在數(shù)據(jù)線上加上要寫入的數(shù)據(jù)字節(jié)； 3） 激活相應(yīng)的控制信號； 4） 在高電壓編程方式時，將 EA/VPP 端加上 +12V編程電壓； 5） 每對 FLASH 存儲陣列寫入一個字節(jié)或每寫入一個程序加密位，加上一個 ALE/PROG 編程脈沖，改變編程單元的地址和寫入的數(shù)據(jù)，重復(fù) 1— 5步驟，直到全部文件編程結(jié)束。每個字節(jié)寫入周期是自身定時地，通常約為。 數(shù)據(jù)查詢： AT89C51 單片機(jī)用數(shù)據(jù)查詢方式來檢測一個寫周期是否結(jié)束，在一個寫周期中，如需要讀取最后寫入的那個字節(jié)，則讀出的數(shù)據(jù)的最高位（ ）是原來寫入字節(jié)最高位的反碼。寫周期完成后，有效的數(shù)據(jù)就會出現(xiàn)在所有輸出端上，此時，可進(jìn)入下一個字節(jié)的寫周期，寫周期開始后，可在任意時刻進(jìn)行數(shù)據(jù)查詢。 READY/BUSY：字節(jié)編程的進(jìn)度可通過“ RDY/BSY”輸出信號監(jiān)測，編程期間， ALE 變?yōu)楦唠娖健?H”后 (RDY/BSY)端電平被拉低，表示正在編程狀態(tài)（忙狀態(tài)）。編程完成后， 變?yōu)楦唠娖奖硎緶?zhǔn)備就緒狀態(tài)。 程序校驗：如果加密位 LB LB2 沒有進(jìn)行編程，則代碼數(shù)據(jù)可通過地址和數(shù)據(jù)線讀回原編寫的數(shù)據(jù)。加密位不可能直接變化。證實加密位的完成通過觀察它們的特點和能力。 芯片擦除：利用控制信號的正確組合（表 1）并保持 ALE/PROG 引腳 10ms的低電平脈沖寬度即可將 PEROM 陣列（ 4k 字節(jié)）整片 擦除，代碼陣列在擦除操作中將任何非空單元寫入“ 1”，這步驟需要再編程之前進(jìn)行。 讀片內(nèi)簽名字節(jié)： AT89C51 單片機(jī)內(nèi)有 3 個簽名字節(jié)，地址為 030H、 031H和 032H。用于聲明該器件的廠商、型號和編程電壓。讀簽名字節(jié)的過程和單元西安交通大學(xué)城市學(xué)院本科生畢業(yè)設(shè)計（論文） 030H、 031H 和 032H 的正常校驗相仿，只需將 和 保持低電平，返回值意義如下：（ 030H） =1EH 聲明產(chǎn)品由 ATMEL 公司制造；（ 031H） =51H 聲明為 AT89C51 單片機(jī)；（ 032H） =FFH 聲明為 12V編程電壓；（ 032H） =05H 聲明為 5V編程電壓。 編程 接口：采用控制信號的正確組合可對 FLASH 閃速存儲陣列中的每一代碼字節(jié)進(jìn)行寫入和存儲器的整片擦除，寫操作周期是自身定時的，初始化后它將自動定時到操作完成 7 為你提供優(yōu)秀的畢業(yè)論文參考資料，請您刪除以下內(nèi)容， O(∩_∩)O謝謝！??！ 2 Many people have the same mixed feelings when planning a trip during Golden Week. With heaps of time, the sevenday Chinese為你提供優(yōu)秀的畢業(yè)論文設(shè)計參考資料，請您刪除一下內(nèi)容，O(∩_∩)O謝謝！?。?National Day holiday could be the best occasion to enjoy a destination. However, it can also be the easiest way to ruin how you feel about a place and you may bee more fatigued after the holiday, due to battling the large crowds. During peak season, a dream about a place can turn to nightmare without careful planning, especially if you travel with children and older people. As most Chinese people will take the holiday to visit domestic tourist destinations, crowds and busy traffic are inevitable at most places. Also to be expected are increasing transport and acmodation prices, with the possibility that there will be no rooms available. It is also mon that you39。 ll wait in the line for one hour to get a ticket, and another two hours at the site, to only see a tiny bit of the place due to the crowds. Last year, 428 million tourists traveled in China over the weeklong holiday in October. Traveling during this period is a matter that needs thorough preparation. If you are short on time to plan the uping Golden Week it may not be a bad idea to avoid some of the most crowded places for now. There is always a place so fascinating that everyone yearns for. Arxan is a place like this. The beauty of Arxan is everlasting regardless of the changing of four seasons. Bestowed by nature, its spectacular seasonal landscape and mountains are just beyond word. Arxan is a crucial destination for the remended travelling route, China Inner Mongolia Arxan — Hailar — Manzhouli. It is also the joint of the four prairies across the SinoMongolian border, where people gravitate towards the exotic atmosphere mixed with Chinese, Russian, and Mongolia elements. As a historic site for the Yitian Battle, Arxan still embodies the spirit of Genghis Khan. Walking into Arxan, you will be amazed by a kaleidoscope of geous colors all the year round the Spring azaleas blooming red in the snow, the Summer sea wavering blue in the breeze, the Autumn leaves painted in yellow covering volcanic traces, and the Winter woods shining white on the vast alpine snowscape. Hinggan League Arxan city is situated in the far eastern area of Inner Mongolia Autonomous Region. Its full name Haren Arxan means hot holy water in the Mongolian language. Arxan is a tourism city in the northern frontier with a blend of large forest, grand prairies, vast snowfield, heaven lake cluster, thermium, as well as volcanic cluster. It is a rare and unique ecotourism base filled with healthy sunshine, clean air and unspoiled green. Nestled close to the country39。s largest virgin forest, and known for its spring and ecological environment, Arxan is marveled at by many tourists as the purest land on earth. You cannot miss out the Autumn of Arxan. It is definitely the best with brightlycolored scenery full of emotions. Autumn in the northern part of the country es earlier than the South. A September rain followed by the footprints of Autumn brings more colors to the once emerald green mountain and blooming grassland. Shutterbugs flock to see for themselves the marvel of splendid colors around the mountains and waters, many of whom have travel a long distance and even camp here only to capture a moment of the nature wonder. The silver birch turns golden, while the larch is still proudly green. You will find yourself drowned in the intoxicating red of the wild fruits as well as the glamour of flowers in full blown. And your heart will be lingering on the woods as it39。s time for the wild fruits to ripe. The picturesque Arxan in Autumn is indeed a fairyland only exists in a dream that satisfies all your fantasies. If it rains heavily 西安交通大學(xué)城市學(xué)院本科生畢業(yè)設(shè)計（論文） on Saturday night, some elderly Chinese will say it is because Zhinu, or the Weaving Maid, is crying on the day she met her husband Niulang, or the Cowherd, on the Milky Way. Most Chinese remember being told this romantic tragedy when they were childr