【正文】 起，松開按鍵錄音停止。音頻放大電路中采用的芯片為LM386。LM386的封裝形式有塑封8引線雙列直插式和貼片式?！?”、“－”輸出端可以很好地抵消共模信號，有效抑制共模噪聲。此電容可以有隔直（隔斷直流電壓）和耦合（耦合音頻的交流信號）。自動排氣電路主要包括5V繼電器和排氣扇。三極管是處于飽和導(dǎo)通還是處于截止斷開，則由其基極B控制。4．系統(tǒng)軟件設(shè)計 。根據(jù)整體軟件流程圖用C語言編寫程序。 void delay1(uint z) //延時子程序 1ms{ uint x,y。y0。 yuyin=0。jidianqi=0。為了便于集中管理建議新建一個文件夾（上面第二個圖標(biāo)）。然后保存這個文件filesave彈出框save as 填寫你要保存的文件名。右邊 target 1 右鍵彈出框，找到output，再找到creat hex fi:前面復(fù)選框選中 OK。它不僅具有其它EDA工具軟件的仿真功能，還能仿真單片機及外圍器件，它是目前最好的仿真單片機及外圍器件的工具。在編譯方面，它也支持IAR、Keil和MPLAB等多種編譯器。(2) 在元器件庫中選擇需要的元器件，再擺放好元器件，設(shè)定好參數(shù)，最后連接電路圖。 硬件制作在Proteus軟件中仿真無誤后就可以進行安裝、焊接元器件。根據(jù)本設(shè)計的實際情況，就要先焊電阻、插槽、晶振、瓷片電容、電解電容，最后焊接煙霧傳感器和喇叭。(3)檢測P 3口或P2 口的空閑電壓是否有5V電壓，如果沒有，說明單片機系統(tǒng)沒有工作。如果有，則表示振蕩電路正常。 濃度（%）電壓（V）01020304050607080901000從該表中可以看出，電壓值與煙霧濃度之間是非線性關(guān)系，為了實時顯示氣體濃度，需要對其進行線性化處理，使顯示的煙霧濃度與實際誤差在177。因此，本論文中的可燃性報警器滿足檢測要求。結(jié)束語設(shè)計的煙霧超標(biāo)報警自動排氣電路，選用MQ2煙霧傳感器，AT89S51單片機、語音芯片ISD1820PY等器件，實現(xiàn)了煙霧檢測、語音報警、自動排氣等功能。 the central or the top level provides the lower units with a model of the relationship between its action and the response of the system.It is evident that a powerful machine is required at this stage so that all the required functions can be implemented. The availability of the new generation of microchips makes this architecture a feasible solution.A single chip microputer was chosen over discrete digital and analogue devices to interface to the field devices and to the central microputer. This is the main reason that previously this approach was not feasible.In selecting the microputer for the local stations, the criterion was the requirement for a chip which contains the most integration of the analogue and digital ports required for the interface and the utilization of CMOS technology owing to remoteness of the local stations. The choice was the Motorola 68HC11A4, for the following reasons:(a) It is CMOS technology。 this satisfied all our memory and 1/0 requirements at the local station side.4 System implementationThe local station: Fig. 3 is the block diagram of the circuit used to utilize the MC68HCllA4 as a remote fire detecting circuit while Fig. 4 illustrates the same circuit in an expanded form. It can be seen that the single microcontroller can be used to monitor more than one detector, thus reducing system cost. Closed loop connectionsThe loop power supply, which is usually between 28 and 26 V, is further regulated by a 5 V 100 mA monolithic low power voltage regulator to supply power to the microcontroller. The onboard oscillator, coupled with an external crystal of MHz, supplies the microcontroller with its timing signal which is divided internally by four to yield a processor frequency of kHz, which is an even multiple of the RS 232 [7] baud rate generator. In this Section the term ‘supervised input or output’ will be used to mean that the function in question is monitored for open and shortcircuit conditions in addition to its other normal functions. More information can be found in Reference 9.5 Main loop Main loop flow chart6 ConclusionThis paper describes the development of a large scale fire detection and alarm system using multisingle chip 。 this facilitates serial munication.(e) It has an a/d converter on board。致謝致謝人： 參考文獻[1][J].電子制作,2007,154(1):1212.[2][J].電子制作,2006,149(8):6263. [3][J].家庭電子,2004,156（2）:1920[4]趙婷. 美國煙霧報警器的統(tǒng)計報告[J].消防科學(xué)與技術(shù),2010, 151(3):183184[5][M].北京:北京航空航天大學(xué)出版社,2004.[6]李永生,[J].儀表技術(shù)傳感器,2002,148(3): 19.[7][J].儀器儀表用戶,2006,13(5): 12.[8][J].電腦開發(fā)與應(yīng)用,2007,20(11):6062. [9][M].西安:西安電子科技大學(xué)出版社，2009.[10][M].北京:高等教育出版社,[11]華成英,[M].北京:高等教育出版社,[12] Wang Xi huai，Xiao Jianmei，Bao Minzhong. Multisensor Fire Detection Algorithm for Ship Fire Alarm System Using Neural Fuzzy Network[J]. Signal Processing Proceedings. 2000，16(11):16021605.[13] James A. Milke. Monitoring Multiple Aspects of Fire Signatures for Discriminating Fire Detection[J] .Fire Technology, 1999,35 (3)：2526 .[14] Tomkewitsch R. Fire detection systems with distributed Intelligence the puls polling system[J] .Fire Safety Journal, 1993,96 (6) :225231 .附錄A 英文文獻原文Multiple singlechip microputer approach to fire detection and monitoring system . AIKhalili, MSc, PhDD. AIKhalili, MSc, PhD. Khassem, MScIndexing term : Hazards, Design, Plant condition monitoringAbstract: A plete system for fire detection and alarm monitoring has been proposed for plex plants. The system uses multiple single chip architecture attached to a party line. The control algorithm is based on a twolevel hierarchy of decision making, thus the plexity is distributed. A plete circuit diagram is given for the local and the central station with requirements for the software structure. The design is kept in general form such that it can be adapted to a multitude of plant configurations. It is particularly shown how new developments in technology, especially CMOS single chip devices, are incorporated in the system design to reduce the plexity of the overall hardware, . by deposing the system such that lower levels of hierarchy are able to have some autonomy in decision making, and thus a more plex decision is solved in a simple distributed method.1 IntroductionRegulatory requirements for most high risk plants and buildings mandate the installation of fire detection and warning systems for all sensitive areas of the plant or the building. Most fire codes state the requirement for monitoring and control specifically related to a type of a plant or building such as chemical plants, petroleum, nuclear plants, residential highrises etc. A general conclusion of these codes can be specified as the following requirements :(a) The source of all detector signals should be exactly identifiable by the central station(b) An extra path of munication between the central station and all local controllers(c) Direct means of control of alarm and central equipment by the central station(d) Means