【正文】 this eliminates an external A/D.(d) It has 4K of ROM, 256 bytes of RAM, 512 bytes of EERROM with 40 1/0 lines and a 16 bit timer。 smoke detectors are used for sleeping areas, infrared or ultraviolet radiation are used when flammable liquids are being hand電機(jī), heat detectors are used for fire suppression or extinguishing systems. In general, life and property protection have different approaches.Alarm devices, apart from the usual audible or visible alarms, may incorporate solid state sound reproduction and emergency voice munication or printers that record time, date, location and other information required by the standard code of practice for fire protection for plex plants. Heaviside [4] has an excellent review of all types of detectors and extinguisher systems. Control philosophy and division of labourOur control philosophy is implemented hierarchically. Three levels of system hierarchy are implemented, with two levels of decision making. There is no munication between equipment on the same level. Interaction between levels occurs by upwards transfer of information regarding the status of the subsystems and downwards transfer of mands. This is shown in Fig. 1 where at level 1 is the central station microputer and is the ultimate decision maker (when not in manual mode). At level 2 are the local controllers, which reside in the local stations. At level 3 are the actual detectors and actuators. A manual mode of operation is provided at all levels.Information regarding the status of all detectors is transmitted on a per area basis to the local controllers. Their information is condensed and transmitted upward to the central microputer. Transfer of status is always unidirectional and upwards. Transfer of mands is always unidirectional and downwards, with expansion at the local control level. This approach preserves the strict rules of the hierarchy for exact monitoring detection and alarm systems associated with high risk plants. Control philosophyIEE PROCEEDINGS,Pt,G,FEBRUARY 1988The classification of the two layers of controls is based upon layers of decision making, with respect to the facts that(a) When the decision time es, the making and implementation of a decision cannot be postponed(b) The decisions have uncertainty(c) It will isolate local decisions (. locally we might have an alarm although there may be a fault with the system)3 General hardwareI :Fig. 2 depicts our design in the simplest of forms. The system uses an open party line approach with four conductor cables going in a loop shared by all the remote devices and the control panel. This approach is simple in concept and is economically feasible. However, one major disadvantage is the dependency on a single cable for power and signaling. In cases where reliability is of extreme importance, two or even three cables taking different routes throughout the system may be connected in parallel. Fig. 3 gives the driver circuitry required to derive an expandable bus. This design takes advantage of recent advances in the single chip microputer technology to reduce the interface between the central station and the local stations. System schematic open line connection Block diagram of remote stationIEE PROCEEDINGS,VOL,135,Pt,G,No,1,FEBRU ARY 19883. 1 Central control taskA central unit provides a centralized point to monitor and control the system activities. Remote station circuit diagramIn the system to be described the central control unit serves a fivefold purpose.(i) It receives information from the local stations and operates the alarms and other output devices.(ii) It notifies the operator in case of system malfunction.(iii) It provides an overall system control manual and automatic.(iv) It provides a system test point of local stations and itself.(v) It provides a central point for observation, learning and adaptation. Local stationsThe local stations can take local decisions regarding recognition of a risk situation, and act independently on local affairs. In this technique we depend on ‘loadtype coordination’, . the lower level units recognize the existence of other decision units on the same level。焊接時(shí)，所有外圍元件盡可能靠近LM386；地線盡可能粗一些；輸入音頻信號通路盡可能平行走線，輸出亦如此。5%之 內(nèi)。因?yàn)榧矣妹簹庵兄饕煞譃榧淄?，所以本?shí)驗(yàn)在煙霧標(biāo)定時(shí)，選用甲烷煙霧。檢測是否有振蕩波產(chǎn)生。目的是確保使用了片內(nèi)存儲(chǔ)器。焊接一般遵循先低后高，一個(gè)方向的原則。(5) 檢查錯(cuò)誤直至達(dá)到要求。） 整體電路仿真圖Proteus仿真步驟：(1) 創(chuàng)建文件并命名“”。是目前世界上唯一將電路仿真軟件、PCB設(shè)計(jì)軟件和虛擬模型仿真軟件三合一的設(shè)計(jì)平臺(tái)，其處理器模型支持805HC11 PIC10/12/16/18/24/30/DsPIC3AVR、ARM、8086和MSP430等，2010年又增加了Cortex和DSP系列處理器，并持續(xù)增加其他系列處理器模型。 Progisp程序下載界面 Proteus仿真 Proteus軟件是英國Labcenter Electronics公司出版的EDA工具軟件。生成HEX文件。新建文件filenew將彈出一個(gè)文本框，輸入程序。新建工程projectnew project將彈出 creat new project框，寫入工程名稱。} else {yuyin=0。 jidianqi=0。x) for(y=110。 sbit jidianqi=P1^2。當(dāng)檢測到煙霧時(shí)，煙霧傳感器會(huì)將信號傳輸?shù)絾纹瑱C(jī)，單片機(jī)再控制語音報(bào)警電路和自動(dòng)排氣電路工作。當(dāng)三極管T2飽和導(dǎo)通時(shí)，繼電器中有電流通過，此時(shí)是二極管D2相當(dāng)于開路，對電路無影響；當(dāng)三極管在轉(zhuǎn)換到截止?fàn)顟B(tài)的瞬間，由于繼電器中含有電感元件，那么必然會(huì)在此刻產(chǎn)生極大的電流，如果不加二極管D2，電路可能會(huì)因電流過大而損壞，而加上二極管后，電流改變流向，通過二極管D2和繼電器中的電感組成的回路完成放電過程，不會(huì)損壞電路。當(dāng)三極管處于截止?fàn)顟B(tài)時(shí)，繼電器中無電流通過，故而繼電器開關(guān)無法動(dòng)作，導(dǎo)致電機(jī)回路開路，無電流通過，電機(jī)不工作。 自動(dòng)排氣電路的設(shè)計(jì)。在芯片上電、掉電時(shí)產(chǎn)生的噪聲就是由該偏置電壓的瞬間跳變所致，減少輸出耦合電容可以有效地降低噪聲。采用雙音頻輸入/輸出。輸入端以地位參考，同時(shí)輸出端被自動(dòng)偏置到電源電壓的一半，在5V電源電壓下，它的靜態(tài)功耗為24mW，使得LM386特別適用于電池供電的場合。 音頻放大電路音頻放大電路主要有音頻放大芯片和相關(guān)元器件構(gòu)成。、SS3分別是錄音鍵、邊沿觸發(fā)放音、電平觸發(fā)放音。SP+和SP之間通過內(nèi)部的50KΩ的電阻連接，不放音時(shí)為懸空狀態(tài)。當(dāng)以差分形式連接話筒時(shí)，可減小噪聲，提高共模抑制比。片內(nèi)自動(dòng)增益控制電路(AGC)控制前置放大器的增益。錄音指示(/RECLED)：當(dāng)芯片處于錄音狀態(tài)時(shí)，此端為低電平，可驅(qū)動(dòng)LED發(fā)光。放音一直持續(xù)到EOM標(biāo)志，放音結(jié)束后芯片自動(dòng)進(jìn)入節(jié)電狀態(tài)。整個(gè)錄音期間，REC要一直保持為高電平。電源端的去耦電容回路應(yīng)該盡量靠近芯片，從而有效的減少電源中的各種干擾。其中語音芯片ISD1820PY是美國ISD公司于2001年最新推出一種可錄放一段8～20秒的語音的芯片，它的基本結(jié)構(gòu)與ISD111420完全相同，采用CMOS技術(shù)，內(nèi)含振蕩器，話筒前置放大，自動(dòng)增益控制，防混淆濾波器，揚(yáng)聲器驅(qū)動(dòng)及FLASH陣列。 語音報(bào)警電路的設(shè)計(jì)。當(dāng)傳感器輸出的信號經(jīng)過前置放大電路對其進(jìn)行的放大、濾波、電平調(diào)整后，輸出的信號才能滿足單片機(jī)對輸入信號的要求。 煙霧傳感器電路。（當(dāng)輸出為低電平時(shí)信號燈亮，可直接單片機(jī)）(4)模擬量輸出0~5V電壓，濃度越高電壓值越高。若氣濃度發(fā)生變化，其阻值也將隨之變化。該傳感器常用于家庭和工廠的氣體泄漏裝置，適宜于煙霧、液化氣、丁烷、丙烷、甲烷、酒精、氫氣等的探測。當(dāng)遇到空氣中可燃?xì)怏w時(shí)，由于可燃?xì)怏w能夠提供給電子，可燃?xì)怏w中就會(huì)有正離子吸附在金屬氧化物半導(dǎo)體表面，氧負(fù)離子放出電子使可燃?xì)怏w以正離子的吸附也要放出電子，電阻值下降就是因?yàn)榘雽?dǎo)體電子密度增加。它主要包括半導(dǎo)體氣敏傳感器、接觸燃燒式氣敏傳感器和電化學(xué)氣敏傳感器等，其中用的最多的是半導(dǎo)體氣敏傳感器。 煙霧檢測電路的設(shè)計(jì)煙霧傳感器的主要分為離子式煙霧傳感器、光電式煙