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Infrared anti-theft alarm system based on WT588D voice chip voice IC

2018-04-26 09:36:09

This paper presents a design scheme of infrared anti-theft alarm system based on WT588D voice chip. WT588D voice chip is a powerful voice chip that can be repeatedly erased and written. With the help of embedded technology and infrared pyroelectric principle, it can play different alarm sounds to different degrees of illegal intrusion, so as to achieve the role of warning and anti-theft. The system has the characteristics of low cost, good sound quality and wide application range. With the continuous development of social economy, people's demand for anti-theft, robbery prevention and security equipment has increased greatly, and the requirements for its functions are becoming more and more demanding. People not only hope that it can achieve simple alarm, but also hope that the alarm sound is more humane and intelligent. In order to solve the above problems, the author uses single chip microcomputer control technology, combines STC single chip microcomputer, WT588D voice integrated chip and pyroelectric infrared detection equipment, and develops a new type of intelligent anti-theft alarm with voice function. The alarm can be a phased intelligent voice warning of illegal intrusion, when the illegal intrusion in the receiving voice warning still does not leave, the alarm will start the alarm signal. The following is a further description of the function, working principle, hardware and software design of the alarm.

Methods/Steps
1

WT588D speech chip WT588D speech chip is a powerful voice chip that can be repeatedly erased and written. The playback duration varies according to the external or built-in SPI-Flash memory. The SPI-Flash memory ranges from 2Mbit to 32Mbit. Support DAC/PWM two output modes, through the professional upper computer software, random combination of voice, can be inserted silent, silent insert does not occupy memory capacity. In the three-line serial port control mode, it can control voice playback, stop, loop playback and volume, or directly trigger any voice of 0~219 address bits. The three-line serial port control port expansion output can expand the output by 8 bits. PWM and DAC output mode, WM output can directly push 0.5W speaker, DAC output external power amplifier, good sound quality. (Figure 1 WT588D voice chip application block diagram)

2

The infrared anti-theft alarm system is mainly composed of the following three parts: infrared pyroelectric sensor Infrared pyroelectric sensor is mainly composed of two key components, one is the pyroelectric sensor, he can change the wavelength of 8-12um infrared signal sign, and the white light of nature has an inhibitory effect. Another device is the Fresnel lens, the Fresnel lens has two functions: one is used together, and the other is to distinguish the alarm into a number of bright areas and dark areas, so that the moving object entering the alarm area can produce a changing infrared signal on the pyroelectric sensor in the form of temperature change, so that the change number can be generated.

3

The single-chip microcomputer as the core of the processing system will capture the change signal generated by the pyroelectric sensor. If there is illegal intrusion, the single-chip microcomputer will respond immediately and control the WT588D voice chip to output the alarm voice response.

4

WT588D voice alarm system. This part is based on WT588D as the core, through the peripheral Flash chip, can store different length of voice signals. Through the three-wire serial port to receive single-chip instructions, play the voice signal of different address fields, the illegal intrusion is treated differently.

5

The hardware design of the system uses STC12C5616AD as the CPU, which is a new generation of 8051 MCU with high speed/low power consumption/strong anti-interference, and the instruction code is fully compatible with the traditional 8051, but the speed is 8-12 times faster. Internal integrated MAX810 special reset circuit, 4 PWM, 8 high-speed 10 bit A/D conversion, for motor control, strong interference occasions. 768 bytes of RAM are integrated on-chip and 16K bytes of user application space. The single chip microcomputer control technology is adopted, which plays a key role in the diversity of system functions and intelligence.

6

The single-chip microcomputer controls the WT588D voice chip to output the corresponding audio signal through the three-wire serial port control mode. The three-wire serial port control mode is composed of three communication lines, which are chip select CS, DATA DATA, clock CLK, and the time sequence is based on the standard SPI communication mode. Through the three-wire serial port can realize the voice chip command control, voice playback. The reset signal is pulled down by 5ms before sending the code, and then pulled up to wait for 17ms. The Reset level should always be high when working. The MCU control circuit in the figure above is shown below

7

In order to ensure the reliability of program operation, the system adds an external watchdog chip MAX813L, which continuously inverts the DOG's foot during the normal operation of the program to achieve the purpose of "feeding the DOG". Once the STC single chip program runs away, the MAX813L chip dog foot does not invert in time, and the MCU RST foot will be reset and the program restarted. The reliable operation of the program is guaranteed. When the infrared pyroelectric sensor detects illegal intrusion, it will inform the microcontroller by interrupt through INT1 of Header2, and the microcontroller will control WT588D to play the corresponding warning sound through analysis and processing.

8

The information illegally crawled from experience

Matters needing attention
1

The playback duration varies according to the external SPI-Flash memory. The SPI-Flash memory ranges from 2Mbit to 32Mbit

2

Supports both DAC/PWM output modes

3

Working voltage DC2.8V ~ 5.5V

4

The resting current is less than 10uA

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