【正文】 。同時(shí)，也有益于在此電路基礎(chǔ)上利用單片機(jī)的資源擴(kuò)展其它功能。 介紹了一種基于單片機(jī) AT89C2051 的速度里程表的設(shè)計(jì)方法。 另外，還應(yīng)盡量保證其它子模塊在編程時(shí)的通用性和高效性。本設(shè)計(jì)用測量脈沖頻率來計(jì)算速度，因而具有較高的測速精度。為了方便計(jì)算要顯示數(shù)據(jù)值的段碼，可再將其轉(zhuǎn)換成壓縮的 BCD 碼，然后通過查表將要顯示的數(shù)據(jù)值中每一12 位的壓縮 BCD 碼轉(zhuǎn)換成 8 段碼送到顯示緩沖區(qū)，最后經(jīng)串口送至液晶顯示模塊以顯示所測的速度或里程。單片機(jī)利用定時(shí)器 T0 的控制功能測出輸入信號(hào)的周期后，再利用單片機(jī)的算術(shù)運(yùn)算功能將周期轉(zhuǎn)換 成速度，同時(shí)每秒鐘進(jìn)行一次里程累計(jì)，從而計(jì)算出總里程。本設(shè)計(jì)用兩個(gè)按鍵來控制顯示速度或里程。 該設(shè)計(jì)能實(shí)時(shí)地將所測的速度顯示出來，同時(shí)也能夠累計(jì)顯示總里程數(shù)。本設(shè)計(jì)采用的譯碼器是 MC14499，它是 MOTOROLA 公司的高集成度 LED 顯示驅(qū)動(dòng)器，采用動(dòng)態(tài)掃描方式顯示驅(qū)動(dòng) 4 個(gè) LED 數(shù)碼管。它具有功能多 ,功耗小、直觀準(zhǔn)確 ,可顯示時(shí)間、限速報(bào)警系統(tǒng)、打印、瞬間轉(zhuǎn)速等優(yōu)點(diǎn)。 由于單片機(jī)具有體積小、控制功能強(qiáng)等特點(diǎn) ,故它在控制方面得到了廣泛的應(yīng)用。 關(guān)于轉(zhuǎn)速表的設(shè)計(jì)已經(jīng)有很多可供參考 ,但大部分都是由機(jī)械式或模擬數(shù)字電路來實(shí)現(xiàn)的。本課程主要針對(duì)目前我國早期應(yīng)用比較廣泛的“ MCS51”單片機(jī)進(jìn)行系統(tǒng)的講解和分析。 就目前 而言，單片機(jī)的發(fā)展勢頭依然不減，各種型號(hào)和功能更強(qiáng)的單片機(jī)和超級(jí)接口芯片不斷出現(xiàn)，進(jìn)一步向高層次發(fā)展的重要標(biāo)志就是構(gòu)成多機(jī)系統(tǒng)和分布式網(wǎng)絡(luò)。機(jī)電一體化產(chǎn)品所需要的是嵌入式微機(jī)，而單片機(jī)具有體積小、集成度高、功能強(qiáng)等特點(diǎn)，適于嵌入式應(yīng)用。 機(jī)電一體化是當(dāng)今制造技術(shù)和產(chǎn)品發(fā)展的主要傾向，也是我國機(jī)電工業(yè)發(fā)展的必由之路。單片機(jī)是計(jì)算機(jī)家族的一個(gè)重要分支，它具有體積小、價(jià)格低、面向控制的特點(diǎn)，適用于各種工業(yè)控制、儀器儀表裝置，在人類生產(chǎn)和生活的各個(gè)領(lǐng)域都有極為廣泛的應(yīng)用。 單片機(jī)課程是已們實(shí)踐性很強(qiáng)的專業(yè)技術(shù)課程，初學(xué)者只有通過大量的編程、實(shí)驗(yàn)、調(diào)試、設(shè)計(jì)制作等一系列的實(shí)踐 環(huán)節(jié)的訓(xùn)練，才能真正理解單片機(jī)軟件及硬件設(shè)計(jì)和調(diào)試技巧，才能靈活的運(yùn)用單片機(jī)的各條指令系統(tǒng)和各種開發(fā)調(diào)試工具，設(shè)計(jì)出高效、可靠、低功耗、體積更小的單片機(jī)應(yīng)用系統(tǒng)，充分體現(xiàn)單片機(jī)的嵌入式應(yīng)用特色。經(jīng)實(shí)際使用證明，該里程表完全可以取代傳統(tǒng)的以軟軸驅(qū)動(dòng)的車速里程表。再利用霍爾傳感器傳輸信號(hào)。取用了各種補(bǔ)償和保護(hù)措施的霍爾器件的工作溫度范圍寬可達(dá)－ 55℃～ 150℃。 霍爾傳感器具有許多優(yōu)點(diǎn)，它們的結(jié)構(gòu)牢固，體積小，重量輕，壽命長，安裝方便，功耗小，頻率高（可達(dá) 1MHZ），耐震動(dòng)，不怕灰塵、油污、水汽及鹽霧等的污染或腐蝕。它具有 4 字節(jié)頁寫方式和 10 萬次使用周期，數(shù)據(jù)可保存 100 年。Ｋ 1 為小計(jì)里程清零鍵，Ｒ４用于調(diào)節(jié)液晶顯示器的視角對(duì)比度。 LCM1010 為十位八段式帶背光液晶顯示模塊，采用三線串行接口，它具有功耗低和編程方便的特點(diǎn)。你可以把速度調(diào)整到最高，也可以調(diào)整到一個(gè)固定值，比如 300 邁 . 依據(jù)車型不同，速度有所不同，可以通過調(diào)整儀器上速度旋鈕改變速度。使用安全，放心。 操作簡單，使用方便。 可靠性好。 這種小巧的儀器有著比其它同類產(chǎn)品明顯的優(yōu)點(diǎn)： 電路設(shè)計(jì)精湛，嚴(yán)密。司 機(jī)又需要增加里程數(shù)時(shí)，用這種跑表器就可以很輕松地實(shí)現(xiàn)。凡此種種，使得基于非接觸式轉(zhuǎn)速傳感器的電子式轉(zhuǎn)速里程表得以迅速發(fā)展。s resources. The monolithic integrated circuit and the ratemeter are inseparable. 9 轉(zhuǎn)速表與單片機(jī) 傳統(tǒng)的轉(zhuǎn)速表的功能有兩個(gè)，一是用指針指示汽車行駛的瞬時(shí)車 速，二是用機(jī)械計(jì)數(shù)器記錄汽車行駛的累計(jì)里程。s 16 registers. When system initialization, may cause T0 and the T1 timer work through the establishment at the pattern 1 way. The T1 timer mainly uses in forming 1 second timing signal, with thought that the survey course provides the time condition. This article introduced one kind based on the monolithic integrated circuit AT89C2051 speed odometer39。s 6 mouth line. Because this monolithic integrated circuit and 89C51 patible, therefore is more convenient in the hardware circuit design and the software programming aspect. Considered AT89C2051 itself inherent characteristic, when design must pay attention to the following several points: First, its program memory space is 2kB, therefore all skipping and the branch branch instruction must limit in this scope. Next, it does not have the MOVX instruction, ., it does not support the exterior memory operation, when this point design certainly must consider. In addition, AT89C2051 oneself also has some 8 other characteristics, for example may use the order to cause its work at the low power loss pattern and so on. The monolithic integrated circuit surveys input squarewave signal using the T0 timer and the INT0 pin the cycle, but uses the external interrupt 0 to control timer T0 whether to start fixed time. When timer T0 operating control position replacement, no matter the pin is what value, the timer does not work. When after timer T0 operating control position setting, can according to the pin condition decide whether the timer does work. When the pin presents the high level, timer T0 starts fixed time。s signal processing core. AT89C2051 contains 2kB to dodge saves, 128B RAM, 15 I/O mouth line, 2 16 fixed time counters, 5 vector secondlevel interrupt structure and 1 fullduplex39。s speed change module and the demonstration data transfer the BCD code module to use the fast algorithm. Moreover, but should also guarantee other submodule in programming time versatility and highly effective as far as possible. This design39。s choice situations. For the convenience putation must demonstrate data value Duan Ma, may transform again it the pression the BCD code, then in the data value which is going to demonstrate through the table lookup each pression BCD code transforms 8 sections of codes to deliver the demonstration buffer, finally passes through the serial port to deliver to the liquid crystal display module demonstrated measured speed or course. When design, should the overall evaluation measure the fast precision and the system reaction time. This design with measuring impulse frequency putation speed, thus has high measures the fast precision. For guarantee system39。s signal impulse