【文章內(nèi)容簡(jiǎn)介】 了加快調(diào)試速度，用信號(hào)發(fā)生器產(chǎn)生的信號(hào)代替秒脈沖信號(hào)，然后在74LS245的使能控制端接3個(gè)開關(guān)，當(dāng)開關(guān)依次接低電平時(shí)，計(jì)數(shù)器應(yīng)以30送給計(jì)數(shù)器進(jìn)行倒計(jì)數(shù)。兩位數(shù)碼管應(yīng)有相應(yīng)顯示，否則查找原因。在仿真電路如圖 63所示：圖63 交通信號(hào)燈定時(shí)部分仿真電路
秒脈沖信號(hào)發(fā)生器的仿真電路如圖64所示。用示波器監(jiān)視秒脈沖發(fā)生器的輸出，調(diào)節(jié)電位器 RW，使輸出信號(hào)的周期為1s。圖64 秒脈沖信號(hào)發(fā)生器仿真電路示波器的輸出波形如圖65所示：圖65 示波器輸出波形圖由圖可知，該脈沖信號(hào)約為1s，符合設(shè)計(jì)要求。各單元電路均能正常工作后，再把各個(gè)單元電路互相連接起來(lái)，進(jìn)行系統(tǒng)總調(diào)。電路如圖66所示：
圖66 總電路總 結(jié)本系統(tǒng)由數(shù)字電路組成，整個(gè)系統(tǒng)主要由定時(shí)系統(tǒng)、狀態(tài)控制器，狀態(tài)顯示電路及秒脈沖發(fā)生器組成。定時(shí)系統(tǒng)用兩片CD4029構(gòu)成2位十進(jìn)制可預(yù)置減法計(jì)數(shù)器，時(shí)間顯示狀態(tài)由兩片中規(guī)模集成電路74LS47和兩個(gè)共陽(yáng)極LED七段數(shù)碼管進(jìn)行譯碼顯示，預(yù)置到減法計(jì)數(shù)器的時(shí)間常數(shù)通過(guò)三片8路雙向三態(tài)門74LS245來(lái)設(shè)定。狀態(tài)控制器以CD4029為核心。狀態(tài)顯示電路用發(fā)光二極管來(lái)模擬交通燈。秒脈沖發(fā)生器以NE555芯片為核心，設(shè)計(jì)產(chǎn)生周期為1s的秒沖。從而設(shè)計(jì)出主干道交替通行的交通燈控制系統(tǒng)。在設(shè)計(jì)一個(gè)較大的電路系統(tǒng)時(shí)，每一個(gè)環(huán)節(jié)都是很重要的，先要有一個(gè)較為合理的原理圖，然后才能對(duì)原理圖中的每一部分進(jìn)行仿真修改，這往往不是一蹴而就的，需要不斷地反復(fù)。先對(duì)單元電路進(jìn)行仿其分析，再對(duì)總體電路進(jìn)行仿真分析。仿真調(diào)試時(shí)，要把整個(gè)電路分成幾塊，每塊單獨(dú)調(diào)試，這樣才能減少故障率，提高調(diào)試的效率。
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From this causes traffic order worsened already serious influence modernization urban construction and national economy development. Studies vehicles39。 general rule, to alleviates the traffic jam according to the actual situation formulation corresponding general rule, raises the street intersection vehicles general efficiency to have the very vital practical significance. The streettraffic control lights are managing the transport network the most important element, but street various street intersections are also the vehicles general key are. Along with the electronic information technology39。s rapid development, its related hypothesized instrument technology in the data acquisition, the test automation and the instrument control domain obtains the widespread application, caused the test system and the survey control design method with realizes the technology to have the deep transformation. “the software was the instrument” already became the test and the measuring technique development important symbol. 2 Based on electronic information technology hypothesized instrument technological development and applied analysis Based on the electronic information technology39。s hypothesized instrument technology is one in new century science and technology core technologies, it contained the puter technology, the automatic control technology, the information technology, the electronic technology and so on to be various. The American Country Instrument Company in the mid1980s first proposed that based on puter technology39。s hypothesized instrument39。s concept, leads the hypothesized test technology the recent development time, afterward developed and has promoted based on many kinds of bus systems hypothesized. The hypothesized instrument broke through the tradition electronic instrumentation take the hardware as the main body pattern, in fact is one kind based on puter39。s automation measuring instrument system. The hypothesized instrument organically friendly blends the puter hardware source and the instrument hardware through the software into a unity, thus the puter formidable putation handling ability and the instrument hardware39。s survey, control unifies in together, reduced the instrument hardware39。s cost and the volume greatly, and realizes through the software to the data demonstration, the memory as well as the analysis processing.The hypothesized instrument is by the puter, the application software and the instrument hardware is posed. Unifies through the application procedure the generalpurpose calculator and the functional module hardware, the user may operate this puter through the friendly graphical interface, pletes to functions and so on test data gathering, analysis, judgment, demonstration and data processing. In the hypothesized instrument system39。s hardware is merely to solve the signal recuperation and the input output. Compares with the traditional electronic instrumentation, the hypothesized instrument has substituted for the part hardware by the software, realized the data read, data analysis processing, the data with the software to demonstrate that and so on traditional instruments only could use the function which the hardware realized. The hypothesized instrument operates this puter through the friendly graphical interface, looks like a traditional instrument which operates itself to have custommade to be the same. It by the transparent way the puter resources and the instrument hardware39。s survey, control unifies in together, realizes the data analysis processing, the expression through the software. By this way constitution39。s hypothesized instrument system materially is the puter instrument system, in a sense, “the software is the instrument”. The hypothesized instrument has the following some characteristics: (1) Instrument39。s function and the performance realize mostly use either plete plex control, analysis or processing by the software generation of hardware technology abilities and so on hardware software, emphasized “the software is the instrument” the new concept, in the hypothesized instrument, besides the necessary hardware, has solved the