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1、Research on Application of Intelligent Fire Alarm System in 　　Abstract： This paper introduces the automatic fire alarm system using sensor， and describes the composition of hardware system and the principle of automatic fire alarm controller， introduces the application of C8051 mi

2、crocontroller， sensor and signal conditioning circuit， sound and light alarm control circuit， stepping motor drive control circuit， network interface circuit and power circuit； finally， software of automatic fire alarm system is given， the software includes two parts of the embedded program running

3、on the microcontroller and running in the host computers serial communication program. After debugging， fire localization accuracy and false alarm rate are up to the requirements of warehouse management. 　　Keywords： Automatic fire alarm system； MCU； UV sensor； infrared sensor 　　0 Introductions

4、 　　Automatic fire alarm system is control system with alarm and fire. In order to discover the hidden danger of fire and put out the fire， fire protection， power system places a variety of commercial and industrial buildings and modern intelligent buildings has the automatic fire alarm system. With

5、 the development of economy in China， many modern buildings put forward higher demand for fire alarm and automatic fire extinguishing system. Large hotels， hotels， shopping malls， libraries， museums， archives and office buildings， automatic fire extinguishing system has become an essential safety de

6、vice. 　　Set the function to improve fire safety， to protect peoples lives and property safety， it is very important [1]. Fire alarm system for fire detection and give warning sound signal， the cloth on the site of the detector， transmission lines and placed in the control room. Various physical par

7、ameters of field detector feel substance when burning， the judgment result or analog values through the field bus back to the controller， controller for further processing after the alarm signal is given， the running state information is also obtained from monitoring module of fire fighting equipmen

8、t. 　　1 The hardware composition and control principle of intelligent fire alarm system 　　1.1 The overall block diagram of the system hardware 　　The electrical part of this system is mainly composed of detection unit， the central control unit， motor driving unit and communication module is compose

9、d of four parts. The overall block diagram is as shown in Figure 1. 　　The detection unit is mainly composed of fire detection sensor. In order to improve the system reliability， reduce false positives and false negatives， this system uses two kinds of different sensors， can also signal a fire accor

10、ding to the situation. 　　The central control unit takes C5l microcontroller as the core， receiving and processing for fire alarm signal， the output alarm signal， driving motor signal， providing regional water supply solenoid valve action signal. 　　Motor drive unit for a motor drive circuit， the S

11、CM sends out control signal to control the motor rotating positioning. 　　Communication module makes the system with remote control and self checking function， the receiving module receives the remote control signal to judge signal to realize the corresponding self-test function. 　　1.2 The design o

12、f detector in the system 　　1） Ultraviolet detection. This system is used in flame UV sensor / flame sensor （ Hamamatsu R2868）， that made by Japanese production， called the fire finder. Produce instant can accurately found on Mars， and high transmission corona phenomena of non visible light can be c

13、ompletely removed. HamamatsuR2868 is the use of ultraviolet TRON to find Mars source through the photoelectric effect and the metal gas multiplication effect， it has a very small volume and wide angle sensitive （directivity）， and can quickly and accurately find the weak ultraviolet light is emitted

14、from the flame （capable of detecting SM or find a cigarette spot size at a distance of the flame.）. It looks as shown in figure 2. 　　Sensor signal conditioning circuit of Hamamatsu R2868 UV flame is as shown in figure 4. 　　2） Infrared sensor. In nature， any more than the absolute temperature （273

15、degrees） when the objects will have infrared spectra， objects at different temperatures， the wavelength of the infrared energy release is not the same， so the infrared wavelength and temperature is related to the. This system uses the unit of pyroelectric infrared sensor， the working wavelength of 4

16、.35-0.15 to 4.35+0.15um it. Infrared sensor input amplifier circuit is through the two stage low pass filter circuit， as shown in figure 5. 　　3） Signal isolation circuit. All signal of microcomputer output through TLP521-4 to control three motors. When the output of MCU control pin is low， the ligh

17、t emitting diode conduction light-emitting， so that the three level pipe， the drive control signal is low. When the MCU control pin outputs high level， the light emitting diode cutoff， three tubes are first off， driving control signal is pulled into high level drive circuit. The internal structure a

18、nd the system of TLP521-4 photoelectric isolation circuit are shown in figure 6. 　　4） Fire alarm module 　　Fire alarm system module uses the alarm mode of double insurance. When the fire occurs， on the one hand at the scene of the fire through the loudspeaker alarm sound， at the same time， then th

19、e MCU pin output to the relay control circuit， can control the alarm device for engine control room. SCM through two pins the same output signal in order to double insurance， the alarm system is more reliable. The circuit principle is as shown in figure 7. 　　2 The software structure diagram 　　The

20、overall structure drawing software is as shown in figure 8. The system is a signal detected by the detector to detect various. The system has used three detectors： photosensitive sensor （light activated triode）， UV sensor， infrared sensor. By collecting the data of the three sensors， with each other

21、 the three motors respectively after the treatment to control the rotation to be able to rotate and accurate positioning of the probe in order to achieve the accurate judgment. 　　3 Serial communication modules 　　Serial communication module achieves three main functions： 1， observe the operation of

22、 the state； 2， it can through the PC to change the system parameters to change the running state of system； 3， to realize the artificial simulation of detecting motor function. The machine can be realized by MCU. Initial state of serial port is set to receiving， when receiving host computers command

23、 word， to distinguish between three different values to achieve three different functions. Serial main program flow is shown in figure 9. Port interrupt program flow is shown in figure 10. 　　The serial communication program in PC machine： First， create a dialog box to create communication through V

24、C6.0++， in the dialog box controls， the controls from the toolbox to pull the dialog box. At this time， only need to be concerned with the control of Windows communication API function driver interface. In other words， only need to set and monitor the MSComm controls properties and events. 　　4 Conc

25、lusions 　　The system adopts two different sensors： flame UV sensor and element pyroelectric infrared sensor， to judge the fire at the same time， the sensor probe horizontal rotation and vertical rotation is controlled by a stepping motor. Two sensors is converted to electric signal through horizont

26、al and vertical scanning light signal， by the amplifier circuit is transmitted to the controller of the system： C8051R edge 5 microcontrollers， microcontroller through the comprehensive judgement to decide final judgment fire alarm. The MCU system is mainly used in factories and other large construc

27、tion， realize the communication between MCU and PC， in order to achieve the wireless remote control function of the system， which brings great convenience for the repair or testing. 　　Reference 　　[1] Li Wenbin， Tang Xiaolan. The design of automatic fire alarm system in intelligent buildings[J]. el

28、ectrical design， 2002，12：12-14. 　　[2] Lv Junfang sensor interface and detecting instrument circuit[M]. 1994， Beihang University press. 　　[3] Wang shenjue， Luo Jian.C language program design[M]. Beijing： Chinese Railway Publishing House， 2003 　　[4] Wang Ying， Liu Shunzhou. The principle of the reliability of alarm [J].Fire control technology， 2001， l：12-16.