RFID (RADIO FREQUENCY IDENTIFICTION) is a wireless RF identification is a short distance wireless communication technology. The biggest difference is that the RFID is the passive working mode compared to other short-range wireless communication technology WLAN, Bluetooth, infrared, ZigBee, UWb. RFID technology adopts large-scale integrated circuit computing, electronic identification, computer communication and other technologies, the RFID tags such as electronic recognition, computer communication are used to exchange non-contact identification and data information exchange of carriers, and their convenient and fast, recognition speed. Fast, large data capacity, long service life, functional changes in label data, therefore with better security, dynamic real-time communication, etc., is widely used in home, hotel, company and other access control systems.
ASR (Automatic Speech Recognition), that is, voice recognition technology, its goal is to convert vocabulary in human speech to computer readable input data. The problem to be solved by ASR technology is to let the computer can "understand" human voice, extract the text information contained in the voice. ASR technology plays an important role in the smart computer system "can listen to", which is equivalent to installing "Ears" to the computer system to make it, "can listen", so that the information age uses "speech" this The most natural, and most convenient means for human-machine communication and interaction. The RFID technology and ASR technology can be used to access control systems to make access control systems safer, humanized and intelligent.
Overall structure design
Figure 1 is a block diagram of a hardware configuration of the system. The system uses the Lingyang SPCE061A microcontroller as the core device, combined with RFIT technology and speech recognition technology to realize system dual safety, and use LCD 12864 to display user credit information. The access control system also communicates with the host computer via the serial port.
The user first swipes the card, and the microcontroller compares the acquired card number with the card number in the own RAM. If the card number is the same, speech recognition is performed. If the user's voice characteristic model is consistent with the system existing voice feature model, the system opens the electronic lock. When you swipe, the microcontroller communicates with the RS232 serial protocol with the host computer, so that the upper function can obtain user data and credit information, and can be added, delete the user.
RF identification technology uses RF reader modules and non-contact ID cards, which avoids the friction of the card reader when the magnetic card swip can greatly increase the service life of the hardware. Lingyang SPCE061A microcontroller contains voice function, which can complete the task such as voice recording, voice playback, voice sampling, and speech recognition. At the same time, Lingyang SPCE061A monolithic voice recognition is low, and after compensating the card loss, the criminals use the card to open the door to enter the door.
12864 LCD user card number, credit card time, credit number, and display the card number error.
System overall hardware structure block diagram
2. Main hardware circuit design
This design main hardware circuit includes a radio frequency card reader circuit and an electronic lock drive circuit.
2.1 RF card reader circuit principle and composition
When the radio card reader is transmitted with the card, the signal emitted by the card reader consists of two parts: a portion of the carrier signal (125kHz) that is received by the card, generates an instantaneous power with the card itself. Supply the card chip work; another part is instructions and data signals, and control the read, storage of the card's chip completion data, and return the signal to the card reader.
2 is a circuit diagram of a radio frequency card reader. The RF card reader circuit consists of a signal count module, a cross-division module, a coil, a filter module, an enlarged module, and a plastic module. The 125kHz sinusoidal signal generated by the cross-module and the count module provides a carrier through the coil as a radio frequency card. After the induction of the RF card is induced, the carrier and the data signal enters the filter module together. After the carrier and data signals are filtered, the carrier is filtered out, only the signal remains. The signal outputs a valid signal after passing the amplified and plastic module.
Figure 2 RF card reader circuit diagram
2.2 Electronic lock drive module circuit composition and principle
3 is a circuit diagram of an electronic lock drive module. The module circuit consists of optocoupler, NPN triode, and Dulinton triode. When the microcontroller IO end is high, the optical coupling is turned on; the NPN triode of Q1 is turned on; since the emitter of Q1 is connected to the base of the Dormon tube Q2, the Dundon Tube is turned on, thereby driving the electronic lock.
Figure 3 Electronic lock drive module circuit diagram
3. Implementation of speech recognition
Lingyang single-chip voice recognition is only divided into "training" "identification" and two phases. In the training phase, the microcontroller analyzes the collected speech samples, extracts speech feature information, and establishs a feature model. In the identification phase, the microcontroller is equally analyzed by the collected speech sample, extracts the feature information of the voice, and then compares this information with the existing feature model. If the two reach a certain match, the voice is entered. Be identified. In order to avoid the shortcomings of the single-chip "training", the speech recognition function of this design has joined the process of writing the speech sample model to flash, "training" on the basis of the above-mentioned principles. That is, you can repeat the voice.
4 is a flowchart of speech recognition, and the program first judges whether there is a voice template in the FlashRom, and if there is a voice recognition. If there is no voice sample template in FlashROM, "training" starting to perform the sample is in the "training", "Training" will store the obtained speech sample template into FlashRom, and then start speech recognition.
Figure 4 Speech diagram of speech recognition
4. Upon realization
There are now many programming languages available to write hosts, VB, C ++, such as C #, Java, graphical language, and more.
Considering that the C # language contains the following advantages:
(1) C # language Similar to C language, if there is a C language basis, then C # programming is much easier.
(2) C # language contains many ready-made controls to be called directly, reducing the cycle of software development.
(3) The upper machine interface is the same as the interface that appears in the Windows operating system, and the user is more convenient and fast.
Therefore, the host computer of the system is written in C # language in the VisualStudio programming environment.
Figure 5 is a top machine software tree structure diagram, the host computer is communicated with the lower computer, the user's card number, the credit time, the user interface data, and stores this information into the database. The upper computer can also add / delete the card number to control the number of users of the access control system.
Figure 5 Loconiograph Software tree structure
5. Summary
This article describes the implementation of the smart access control system with the Lingyang SPCE061A microcontroller as the core, combined with RF card card reader module, speech recognition module, LCD12864 display module and host machine. The specific advantages are as follows:
On the one hand, the access control system uses the RFID RFIT, that is, to swipe the card by a non-contact ID card. Avoid the friction of the card reader while the normal magnetic card swiping is avoided, and the hardware life is increased.
On the other hand, this design also applies speech recognition. Only a particular person can enter the access control system, improve the security of the access control system, and avoid the disadvantage of the unmeneous molecular profit card into the access control when the card is lost. From the experimental results, the system has basically realized the function of the expected set, which is more stable and has good effect.
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