Research on the application of wireless network technology in access control system

    1 Introduction

　　In recent years, due to the rapid development of wireless networks, the increase in speed and the decrease in prices, many users have begun to use wireless networks. Wireless networks have the characteristics of being able to move freely, access the Internet at any time and being easy to set up. Therefore, they are different from traditional wired connections. They are more convenient. The main wireless communication technologies at present are IEEE802.11, Bluetooth (Bluetoth) and Sensor Network (SensorNetwork). This article provides a wireless access control system WDCS (Wireless Door Control System) that combines wireless Bluetooth technology with IEEE802.11 and Ethernet to control the access control system using local area networks and the Internet respectively, so as to improve the convenience and security of the access control system, and is suitable for today's diverse environments and needs. This system uses two different systems, PDA (Personal Digital Assistant) and PC, as development platforms, and designs three different versions suitable for Bluetooth communication protocol, IEEE802.11 communication protocol and RS232 communication protocol. Combined with the access control system host with single chip as the theme, it develops into a multifunctional wireless terminal remote control access control system, thus achieving security and convenience.

　　2 System architecture and its functions

　　The wired aspect of WDCS is that the user uses a PDA to make a wireless remote control to control the door opening, and uses WindowsCE, a 32-bit real-time embedded operating system. In terms of wired remote control, a general personal computer is used to control the door opening, and the Windows XP operating system is used as the development platform. A computer is used as the central monitoring center. A monitoring gateway is used to communicate between the central monitoring center and the monitoring point subsystem. Its CPU is an EP7212 chip with an ARM7 architecture, and the Linux used in the general i386 platform is compiled into ARM Linux as its operating system. When the host receives the command issued by the terminal, it transmits the command to the monitoring point subsystem through the Bluetooth communication module. The monitoring point subsystem uses the 8051 chip as the system core, which is used to monitor the environmental voltage changes and transmit the detection information back to the monitoring gateway through the Bluetooth communication module. Then it is transmitted back to the central monitoring center.

　　2.1 WDCS Hardware Architecture

　　The hardware architecture of the system can be explained from three aspects: the first part is the WD-cs host, the second part is the WDCS server, and the third part is the WDCS client.

　　2.1.1 WDCS host hardware architecture

　　The hardware architecture of the WDCS host is mainly based on the 8051 single-chip microcomputer as the central controller. In addition, there are peripheral components such as a 4x4 keyboard, LCD display, EEPROM93C46 password memory, relays, etc., which serve as the I/O device and password setting of the WDCS host. When the user enters the user name and password from the 4x4 keyboard, the 8051 executes the instruction and verifies with the EEPROM93C46 whether the information entered by the user is correct, and then controls the action of opening or closing the door through the function of the relay, and transmits the information result to the LCD and the WDCS server.

　　AT89C51 is a low-voltage, high-performance CMOS 8-bit microcontroller produced by ATMEL Corporation of the United States. It has 4kB rewritable read-only program memory (FPEROM) and 128B random access data memory (I/O), compatible with the standard MCS51 product instruction system, 32 programmable I/O ports, 2 16-bit timers and counters, 6 interrupt sources, and programmable serial UART channels. Table 1 shows the connection of the WDCS host to each external port of 89C51. In the 4x4 keyboard, the principle is to use the fixed output of the column and the voltage value read in the row as the key value of the key. For example, when a key is triggered, the corresponding row and column will be turned on, and the fixed end of the column will output a low potential, and then the voltage value of the row will be read back. The voltage value of the row is low, indicating that the key is pressed. The decoding formula is key value = column × 4 + row. Table 2 shows the input pins and corresponding positions of the 4x4 keyboard. In EEPPROM93C46, the password is stored and can still be recorded after the power is off.

　　2.1.2 WDCS Server Hardware Architecture

　　The hardware equipment of WDCS server can be completed by using a general PC or Notebook. The operating system should be Windows version. It must have two hardware devices, Bhetootll and mEE802.11.

　　2.1.3 WDCS Client Hardware Architecture

　　The hardware requirements for the WDCS client (remote control) can be divided into two types, one is to use a PDA, and the other is a PC or Notebook. It can not only be used using a wired network, but also using wireless network communication technologies such as Bluetooth and local area networks as a connection. Therefore, one of the hardware devices such as Bluetooth Module and Wireless LAN Card is required.

　　2.2 Introduction to WDCS software architecture

　　The software architecture of WDCS will also be divided into three parts. The first part is the main architecture of WDCS host, the second part is the control architecture of WDCS server and WDCS host. The third part is the communication architecture of WDCS server and WDCS client. Assembly language is used as the development language for developing the main architecture of WDCS host. The flow chart is as follows.

　　Figure 1 Main program flow chart of WDCS host The basic structure of WDCS is divided into four steps. The first step is the basic system operation, including system environment and initial value setting. The second step is the timer interrupt. Responsible for sending or receiving information. The third step is to determine whether the input and output information is correct. The fourth step is responsible for the door opening action. [page]

　　In terms of input, the system provides a 4x4 keyboard as an input device, including 9 numeric keys, 2 arrow keys, and 3 function keys. Users can use these keys to select function forms. As well as input and modify user names and passwords, and control the relay to open and close the door, thereby achieving the purpose of access control. As shown in Figure 2, the WDCS host provides five function options: The main function of Keyboard is to allow users to enter passwords through the terminal keyboard or the local keyboard. First, use the arrow keys to select Keyboard and press the Enter key. Enter the UserName and Password. If the input is correct, the door will open and send the information back to the LCD display and the WDCS server. If the input is wrong, the system will ask you to re-enter. The CardReader function allows users to enter passwords through the card reader. First, use the arrow keys to select CardReader and press the Enter key. Enter the UserName and Card. If the input is correct, the access control will open. And send messages back to the LCD display and the WDCS server. If the input is wrong, the system will ask you to re-enter and swipe the card again. The SetUserP/W (Password) function is to modify the password used. First, use the arrow keys to select SetUserP/W and press Enter. Enter UserName. If it is correct, continue to enter NewUserP/W and re-enter NewUserP/W to confirm it. If the input is correct, the new password is successfully changed and the information is sent back to the LCD display and WDCS server. If the input is wrong, the system will ask you to re-enter UserName and SetNewUserP. The SetCardNo. function allows the user to set a new card number. First, use the arrow keys to select SetCardNo. and press Enter. Enter UserName. If it is correct, continue to enter NewCardNo. and confirm NewCardNo. once after swiping. If the swipe or swipe is wrong, the system will ask you to re-enter UserName and re-SetCardNo. Finally, the SetUserName function is to set the user's name. First, use the arrow keys to select SetUserName and press Enter. Enter UserName. If it is correct, continue to set NewUserName and re-enter NewUserName to confirm it. If the input is correct, NewUserName is successfully set and the information is sent back to the LCD display and WDCS server. If the input is incorrect, the system will ask you to re-enter UserName and SetNewUserName respectively.

　　Figure 2 Five functions provided by the WDCS host The second part is the control structure of the WDCS server and the WDCS host. First, start the WDCS host. Then the WDCS server starts the installed server version program. And start the RS232 port to connect to WDCS, you can issue commands and enter UserName and UserPassword. The WDCS host will return a successful login or error message to the WDCS server.

　　The third part is the communication architecture between the WDCS server and the WDCS client. Start the installed server program on the WDCS server. Start the R232 communication port and the Winsock server. Wait for the WDCS client to connect. The client must specify the server IP location or server name and server port number. Only then can it connect to the server and issue commands and enter UserName and UserPassword. The WDCS host will return successful login or error information to the WDCS server.

　　3. System integration and testing

　　The system integration and testing is divided into three steps. The first step is the connection between the WDCS server and the WDCS host, the second step is the connection between the WDCS client and the WDCS server, and the third step is to integrate and test the above two systems.

　　3.1 First Step

　　First, in order to test the effect of WDCS server and WDCS host, use a laptop as WDCS server and install WDCS server Windows version program, use the USB port on the laptop, and use R232 communication technology as the connection between the two devices. Because there is no COMEl on this laptop, a USB to R232 cable is used to convert the USB port into a 9PinCOM port and connect to the UARTPort of the WDCS host. When the two devices are ready, start the program on the WDCS server and open the communication port of the program.

　　3.2 Second Step

　　WDCS server and WDCS client To test the effect of this part: Use two laptops as WDCS server and WDCS PC client, and install the WDCS server Windows version program and the WDCS PC client Windows version program, and install Bluetooth Dongol and Wireless IEEE 802.1lb network card on the WDCS server. On the WDCS PC client, install the Wireless IEEE 802.1lb network card or network cable, and use two PDAs as WDCS clients to install the WDCS client Windows CE version program respectively, and start the Bluetooth module on one of them and install the Wireless IEEE 802.1lb network card on the other PDA. First, install Bluetooth Dongol, Wireless IEEE 802.1lb network card, WDCS server Windows version program on the WDCS server, and start Microsoft ActiveSynczTool, and at the same time open the access control system program on the WDCS server, set the Local Port, and start the access control system program. Open the WDCS client, and after one of the PDAs starts the Bluetooth module, it must synchronize the Bluetooth communication protocol with the WDCS server in the Microsoft ActiveSynczTool mode. Then, with other WDCS clients, open the access control system program and set the IP and Port to connect to the terminal WDCS server.

　　3.3 The third step

　　It is a system integration and testing system. This step mainly combines the network connection between the WDCS client and the WDCS server, and the system connection between the WDCS server and the WDCS host of the previous two systems. When the WDCS client and the service can be connected to the network, and the WDCS server can also control the WDCS host, the operation steps in the program are followed. First, the test user is controlled by the WD-cs server to achieve access control, function switching and change the user name and password. The steps are as follows: The user first determines whether to log in or use the change function. If you want to log in, you must determine how to log in. There are two ways, 1Key-board login and 2Insercard login.

　　4 Conclusion

　　The author's innovation: By designing a comprehensive wireless access control system, the 89C51 microprocessor is used as the access control host, and the handheld embedded system (PDA) is used as the development platform. Then, the wireless communication technology (Bluetooth, WEAN) and the characteristics of wireless network are combined to provide users with a visual and convenient interface for a variety of environments. Help users quickly master the operation method and meet the requirements of security and expandability. This system can also be used in different information appliance systems, providing a very flexible development model, which is different from the single-nature products on the market. In this system, we actually tested the application with the general electronic lock on the market, and issued a command to successfully open the electronic lock. And the electronic lock automatically executes the action of closing the door at the system set time (5s). Because the electronic lock is expensive and there is no actual transportation, this product was not purchased. For the future direction, the Bluetooth module can be transplanted to the single-chip microcomputer to achieve a small, beautiful and powerful product, which is in line with the characteristics of Bluetooth in personal wireless communication devices.

References:

[1]. RS232 datasheet http://www.dzsc.com/datasheet/RS232_585128.html.
[2]. EP7212 datasheet http://www.dzsc.com/datasheet/EP7212_300650.html.
[3]. AT89C51 datasheet http://www.dzsc.com/datasheet/AT89C51_810155.html.