1 Introduction
Currently used in all kinds of anti-theft security alarm system are basic ultrasound. Active Infrared transmission / receive and microwave technology, but the high cost of the alarm, and the error rate is high, hidden poor. And the design here is a passive infrared alarm system, the sensor is used in the United States -- piezoelectric infrared sensor Satellite 8. This pyroelectric infrared sensor to detect the human form of non-contact infrared radiation, and convert it into a voltage signal. Meanwhile, it has also identified other biological and non-biological movement. Piezoelectric infrared sensor can be used to burglar alarm device could also be used in automatic control, proximity switches, telemetry and other fields. It is used to produce an anti-theft alarm system with the current marketing many of burglar alarm equipment, it will have the following characteristics : no infrared or other sources of electromagnetic concealed, and can be installed mobile high sensitivity, control, more alert targets for monitoring, reporting rate is a low voice alarm circuit and set up a digital display circuit. report as a clear, innovative way.
2．Principle system
Structure shown in Figure 1, can be seen from the main system of foreign acquisition amplifier module. MCU control module, the Voice Alarm module and digital display module. The main function of each module : Data Acquisition Module piezoelectric infrared sensors to collect the data to enlarge MCU;MCU data will be based on input data signal into the judgment of the situation on the spot. have a voice chip and the address signals and voice signals LED digital display under MCU chip output signals to the address, will be preserved in the voice signal output which addresses the same time, LED shows with the corresponding figures of speech signal information.
3 hardware circuit
Design is a passive-based multi-channel piezoelectric infrared detection of intelligent alarm device. System hardware consists of three parts : the first part is the infrared sensor data acquisition, and data for amplification; The second part of the MCU to take control; The third component is a voice alarm and digital display, Each chip addresses the voice of the voice, digital clock and data management static show Output is provided by the MCU. By optical passive infrared alarm system, piezoelectric infrared sensors, signal filtering and amplification. Alarm signal processing circuit, and several other components. Fresnel lens optical system is, piezoelectric infrared sensor design is the core of the alarm device. It could combine the infrared signals are converted to electric signals in the human body for some signal processing; sensor signal processing is the key to amplify weak signals, filtering, delay, To lay the foundation for the realization of the police function.
3. 1 infrared sensors more amplification circuit
3. 1.1 Multi-more than one way infrared detection circuit functions of the thermal infrared detection Post infrared sensor to achieve the P2288 [1]. The use of multiple probes, in a different location, mutual coordination, multi-channel detection, we can eliminate blind spots and the expansion of the scope of monitoring. Detection and Alarm design is a three-way home.
3. 1. 2 amplification by VT9013 comparison amplifier to achieve the amplification levels and CA3140 components, Because pyroelectric infrared sensor output voltage detect very weak signals (usually only EF%), it is a signal change, Meanwhile Fresnel lens and the role of the output signal voltage pulses (voltage measured by the frequency of mobile speed degrees, usually 0-4. 1~10Hz%), In comparison circuit is achieved by the CA3140 [2]. First class triode amplification total emitter then, about 100 times the voltage amplification; The second level will be operational amplifier output voltage of the transistor collector amplified further enlarged 100 times, and about 70 dB of gain time, in the second stage amplifier 6 feet CA3140 a 10V output voltage signal But even in the infrared sensor when no infrared sensors, The second paragraph 6 feet CA3140 amplifier output voltage around a tem. What we need is a stable and the number of voltage, that is not in the infrared sensor when piezoelectric infrared sensor output to zero. feeling when measuring the output of a receiver. So should further into second-class amplifier output voltage from the voltage comparator amplifier composed CA3140 comparison Amplification, after more uncertain after the analog signal into a digital signal stability. RP potentiometer adjustments in static, the comparator output is exported Low Level 6 feet; When the sensor signal input comparator 3 feet, 6 feet immediately output switching, but now is the voltage of 12V. Through this opt coupler into 5V voltage, the voltage will be converted into a voltage comparator through digital,
3.2 SCM can provide data signals.
Infrared sensors more amplification circuit shown in figure 2. 3. 2 to take control of part by the MCU to take control of the AT89C51 to achieve [3 - 4]. Three-way piezoelectric infrared sensor to the human body more magnified, Access to their respective voltage signal to the data input port MCU, after SCM, Output control the voice chip output in the address so that the audible alarm; In addition, it will have to control the clock. of the shift register control, LED display. To achieve this function, the need to address the distribution and transmission of data using SCM. Therefore, the voltage sensor signals were three access P10, P11, P12 three subscribers. P1 regard as a data input port. Voice Chip ISD2560 because the addresses were 10, why P0 and P20. P21 mouth as a voice chip address lines, the control voice chip. To achieve the transfer of digital control, P26 I regard as a serial terminal access shift register data show divides the imported, P27 as a serial shift register divides the clock showed clock access port.
3. 2.1 One voice audible voice audible alarm function primarily by the Voice Chip ISD2560 and subsidiary -- resistance, capacitance and loudspeakers to achieve the voice chip in the address mode this chip to be the longest 60 seconds of the recording, which can be divided into internal 600, or may choose to address Playback Music. The biggest feature is that it E2 PROM chip capacity of 480K, the Music Playback time, anti houses. sound quality, is easy to apply. Voice Chip ISD2560 in subparagraph recording time to address A0-A9 Assignment. set the start address of the beginning of this address, as recorded at the end of the internal chip automatically inserted in the position of the end of the end of the decade (So Edom); MCU chip to choose and a tape to tape at the beginning of a tape those addresses. So Edom encountered signs automatically stop tape, and can accurately reported the accident occurred.
3. 2. 2 digital display circuit is shown by the 8-bit serial digital input/output parallel shift register to control divides The static digital control system[5]shows. LED cathode connection and total system control circuit shown in figure 3.
4 Software Design
Translation software design input in light of the above four elements in the circuit, request a signal at different positions, different voices made shows the corresponding data. As it is a three-way detection, the need for a sensor array to record the signal, if the signal path is. This road is the corresponding array of numerical approach this way, and zero otherwise. First of all, we approach this test also array assignment, and then make a judgment on the array. According to the array values for each position to judge which is also a road or several sensors signal. Then, the function call audible and display circuit, the circuit functions can be achieved. Audible voice as a function of the circuit is a voice chip, in the recording, each voice has a clear path to the address, So audible when the procedure only needs to be audible sounds that way on the address. Digital display can be seen from the circuit, is a serial digital, and digital control is the total cathode then, serial show. Software Process As shown in figure 4.
4.1 Serial 1 shows the transfer function
74 ls164 basic operating principle is : 74 ls164 the rising edge of each clock into one of the pulse sequence will be put out of high first. 8 bytes necessary for a pulse. As Lane in the process to achieve this. C language, operating relatively simple words : ACCB=ACCB〈 1 to the left is a Conceal, After eight bytes of data transmission cycle Conceal had to be moved back. For (i = 0 I. "4; I) {Dips laser [Alarm]; ) which Alarm[ i] is transmitted to the array. Lane, the main program through its initial report under each different way to install.
4. 2 three-way detection Then in a three-way input SCM P1. 0, P1. 1, P1. 2 3 I, Lane Interface procedures in the monitoring of every level corresponding changes to judge whether the report should be implemented. Lane definition of a process array, which is used to record the level of each / signs, if it is just a simple home and home 0 1 So when errors of judgment. For example, the way -- and have chosen for peaceful change, then this kind of procedure should be judged:
if (Alarm[ 1]) do ()
if (Alarm[ 2]) do ();
Due to the need to monitor more road and procedures in place will give them each a corresponding array of numerical Road. They will also increase and that the situation there is a judgment multiple different combinations on the road while it is easier to know what a signal. The following procedures:
For ( i = 4; i > = 1; i - - )Alarm[ i ] = 0; / / Array is first home
While (1)
{k = P1; / / Reading into the P1 level
For (i = 1, Temp = 0x01; i < 4; i + +)
{if ( ( k&Temp ) = = Temp ) Alarm [ i ] = 0; / / Low-level effective
Else Alarm[ i ] = i;
Temp < < = 1; } }
Hardware Lane in a Opt coupler signal is coming from, when a warning signal. Interface by switching into the corresponding low level, and has procedures for the low level should make judgments, the words : if ( ( k&Temp) = = Temp)Alarm[ i ] = 0;Interface to judge whether the receiver is, the value of P1 and 0x01 phase, and then home spaces corresponding array spaces. This will position them to the corresponding array and the corresponding ones in and, quite clear numerical combinations, Lane, as long as the process can determine which combination of value to know what action the police should enforce road. The action here is that the voice prompt and Digital Display
To the table in the decoding process can be carried out to correct a wrong code. Table 4 represents the last four state code calibration errors, and then could not carry out correction. Hamming code of this algorithm is because of a number of mistakes in the code into the code for a number of Hamming code mistake Therefore, each data byte count can be increased to increase the unexpected interference of the correction algorithm, and Error-correcting code can continuously increase the median. But this would ham codes with different spaces in different byte. Thus, Hamming codes emerged with a possibility of increasing the number of errors. Thus, the system of random thermal noise caused by the relative decline in the ability of correction. This is the original and specific communication channel bit error rate related. Channel original high bit error rate, the higher the frequency of random interference can be reduced to a size. so as to enhance the ability of error-correcting algorithm for random; low bit error rate of the original, its relatively low frequency of random disturbances can increase the size of a, so as to enhance the ability of error-correcting algorithm of unexpected interference.
4．3 Voice Alarm
Which first established the need to voice alarm. The report is required by a specific ones seeking to complete the array, and will be stored in variables TEMP : for (i = 1, 0 TEMP = i "= 3; i) (if (i] Alarm[! = 0) TEMP =Alarm ] / / 2. 3, 3, 4, 5, A/CONF.183/4 TEMP passed judgment on the value of the police should be able to know the exact details. Use is done (address) Function voice broadcast functions It is used to address the parameters given voice chip broadcast addresses, said in the address recorded on record should be better
4 low cost,
With a piezoelectric infrared sensor monitoring alarm system is simple, low cost, A point-to-multipoint control can be achieved, the report accurate. After several tests, the system is in stable condition. In the family safety, energy-saving switch, and high-voltage X-rays, gamma rays, industrial nondestructive testing applications have many occasions.
References :
[1] and Xiao Jinghao, Zhao said. Piezoelectric infrared and ultrasonic remote control circuit [M]. Beijing : Posts And Telecommunications News Press, 1998.
[2] Tsinghua University faculty Electronics, Shi Yan owners. [M] digital electronic technology infrastructure. Beijing : Higher Education Press, 1998.
[3] You have. Zhao Zhiying, when Mr Liang. microcom principle, application and testing [M]. Shanghai : Fudan University Press, 2000.
[4] SUN Zhan, who takes Zhang. Zhang as such. MCS-51 SCM principles and should use [M]. Beijing : Tsinghua University Press, 2002. [5] Qingyuan computer studios. Protel 99 Z] diagram and PCB design. 1 998.
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