XBTGC2230T 現(xiàn)在提到51單片機(jī),似乎給人一種技術(shù)落后跟不上潮流的感覺,而在我上學(xué)的時(shí)代,它可先的弄潮兒。在那時(shí),進(jìn)行實(shí)驗(yàn)所用的還是單板機(jī),外觀有些像是手提式數(shù)字電路試驗(yàn)儀,人機(jī)交互的手段則是數(shù)碼管和按鍵。編寫程序則是按機(jī)器地址,逐個(gè)鍵入機(jī)器碼。
要是有個(gè)跳轉(zhuǎn)指令,所需的偏移量都是純手工計(jì)算。后來是系主任費(fèi)力很大的力量才購進(jìn)個(gè)9臺(tái)51單片機(jī),其外觀是將整個(gè)開發(fā)板放置在一個(gè)有機(jī)玻璃的盒子里,使用時(shí)要通過單獨(dú)配置的一個(gè)5V穩(wěn)壓電源為其供電。至于程序設(shè)計(jì)是從那時(shí)起才真正進(jìn)入?yún)R編時(shí)代,無需再通過查指令表來設(shè)計(jì)程序。程序代碼也不再單純的用手敲,而是可以通過串口來下載了!
至于該單片機(jī)的結(jié)構(gòu)也與現(xiàn)在所用的單片機(jī)有很大的不同,如今的單片機(jī)才真無愧于單片機(jī)的稱號(hào),因?yàn)閷?duì)于一個(gè)最小系統(tǒng)來說,配上一套開發(fā)工具軟件,外掛一個(gè)串口通訊模塊就可以開始編程了,電源也可以從USB口獲得。那是由于CPU是不帶Flash存儲(chǔ)器的,因此盡管是一個(gè)最小系統(tǒng),那也是要三總線(數(shù)據(jù)總線、地址總線、控制總線)樣樣齊全。
CPU周圍除了晶振和復(fù)位電路外,首先連接的是一個(gè)地址鎖存器,以形成數(shù)據(jù)總線和地址總線。其次就是要配上一個(gè)3-8譯碼器,來向各個(gè)外圍器件提供片選信號(hào)以劃分他們勢力范圍(尋址空間)。由于沒有Flash存儲(chǔ)器,下載的程序是被存放到EEPROM中,要想存放數(shù)據(jù)則要另外配置RAM存儲(chǔ)器。當(dāng)然為了進(jìn)行人機(jī)交互,數(shù)碼管和陣列式按鍵也是不可或缺的。
盡管自己從十年前已開始學(xué)習(xí)和使用ARM,但對(duì)51單片機(jī)的情懷卻并未改變,那時(shí)用一段青春所做的追求,也是技術(shù)成長與跨越的橋。盡管做一些功能要求比較高的項(xiàng)目讓單片機(jī)直接來做稍顯吃力,但隨著功能模塊化的出現(xiàn),由51單片機(jī)來充當(dāng)管家還是比較方便的。
例如自己曾用51單片機(jī)做個(gè)一個(gè)音樂點(diǎn)播裝置,就是用單片機(jī)與MP3音樂播放模塊來實(shí)現(xiàn),做起來很簡單。如果換成是ARM似乎也不是件容易的事。所以搞設(shè)計(jì)不要只追求時(shí)髦,這樣使設(shè)計(jì)的效果,才是好的設(shè)計(jì)。僅以此文紀(jì)念那逝去的青春和當(dāng)年我對(duì)51單片機(jī)的狂熱追求!
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