Design of Wireless Intelligent Doorbell System Based on Wi-Fi

Today, with the continuous development of information, communication and intelligence, people's requirements for doorbells are more than simple reminders. The doorbell system has developed into a complete intelligent system with reminders, anti-theft and security. The management of the wireless intelligent system allows us to use the doorbell and its attached functions more easily and conveniently. The wireless intelligent system is based on the wireless network, and uses the computer, embedded system and communication network technology to combine the doorbell system with the terminal equipment such as computers. Compared with the ordinary doorbell system, the wireless intelligent system not only keeps the doorbell system a series of functions of the original doorbell, but also adds new functions such as remote control, and the wireless intelligent system is separated from the various cables, and has a strong Extensibility, this article only uses the doorbell system as an example. Under the right conditions, other home appliances can be incorporated into the wireless intelligent system to form a residential platform, which combines construction, network communication, information appliances, equipment automation, and integrates system, structure, service and management into one. A safe, convenient, and environmentally friendly living environment, which is what people often call SmartHome. The wireless network of wireless intelligent system can be roughly divided into two parts: data network and control network. This paper studies the control network related technology and establishes a wireless intelligent doorbell based on Wi-Fi technology.

First, Wi-Fi technology

1·Wi-Fi Overview

Wi-Fi full name WirelessFidelity, also known as 802.11b standard, its biggest advantage is that the transmission speed is higher, can reach 11Mbps, and its effective distance can reach 100m, fully meet the wireless doorbell data transmission.

2. Advantages of Wi-Fi technology

First, Wi-Fi has a wide coverage. In the applied technology, the effective radius can reach 100m. The coverage of some new switches is even more doubling.

Second, Wi-Fi is fast. Wi-Fi speeds vary depending on the standard used by the wireless network card. Among them, IEEE802·11b is up to 11Mbps (some manufacturers can reach 22Mbps when the device is equipped), IEEE802.11a is 54Mbps, and IEEE802.11g is also 54Mbps.

Third, Wi-Fi compatibility is good. Nowadays, wireless network cards of computers are connected devices based on Wi-Fi standards, and most of the new types of smart phones have Wi-Fi terminals.

Fourth, security and stability. Although Wi-Fi has some security flaws, in a smart wireless doorbell design, it is acceptable to set a series of keys. The stability of Wi-Fi is guaranteed in the wireless network, which can fully meet the design needs.

Second, Wi-Fi based wireless smart doorbell system

1. Overall design scheme The structure of the system (see Figure 1)

As can be seen from FIG. 1, the wireless smart doorbell system is mainly composed of a home gateway, a monitoring service terminal (including a computer terminal and a mobile terminal), and a monitoring site. The network is mainly divided into two parts, an indoor network and an outdoor network.

The indoor network consists of a wireless network that monitors the IEEE 802.11 standard between the field and the wireless route, and a wired or wireless connection between the home gateway and the computer terminal.

The outdoor part consists of an Internet network between a computer terminal and a remote control page (ie, a web page).

The working principle of the system: Firstly, the doorbell vibrates or makes a sound to remind the head of the household by pressing the doorbell button. The head of the household starts the monitoring service terminal, and sends an instruction to the determined IP address via the IEEE802.11b wireless network, that is, monitors the on-site power switch, and the monitoring site starts working. At the monitoring site, open input terminals such as cameras and microphones to collect live analog signals. The collected signal is sent to the video server, and the video server compresses and encodes the analog signal, and sends the data into the buffer, waiting for the connection request sent by the home gateway. When the home gateway invokes the connection request procedure, the video server reads out the audio and video data of the buffer, and starts the sending module at the same time. When transmitting, it is packaged by the RTP protocol 1. The video stream of the module read buffer is preferably a frame with a minimum unit. If the data is relatively long and the transmission is unstable in the network, the frame may be divided before being packaged, and then packaged. After the data is packaged according to the RTP protocol, it is transmitted to the home gateway through the UDP protocol 2 for transmission. The data continues to be wirelessly transmitted to the monitoring service terminal via the home gateway. After the monitoring service terminal receives the data, the data is decompressed and assembled according to the order and the flag of the data transmission to form a complete frame structure. By monitoring the corresponding video software in the service terminal, the data is MPEG-43 decoded, and the decoded data is video data; at the same time, the audio data is also operated correspondingly to obtain corresponding audio data. The software of the playback module is called by the monitoring service terminal to perform real-time playback, and the storage module is called for storage to achieve real-time monitoring.

2. Monitoring site design

Design Idea: The monitoring site consists of a common doorbell, camera, microphone and video server. The role of the ordinary doorbell is to remind the head of the household to monitor. The video server is the key to the entire monitoring site. It is mainly responsible for the encoding and compression of the analog signals collected by the camera and microphone, and the transmission of the network. It is also responsible for the control of the camera and microphone by the client. Its structure is shown in Figure 2:

The monitoring field wireless receiving device adopts ARMLinux embedded system.

The use of such a chip as a receiving device is because the Linux system has all the functions of full UNIX such as multitasking, virtual memory, rich program resources, loading executable files according to applications, executing program sharing, memory management, and TCP/IP network, while ARMLinux It is being transplanted or has been ported to more than 100 different types of machines, including personal computers, network computers and development tools, suitable as a network processor of the IEEE802.11b standard.

3. Home Gateway Settings

The home gateway is a relay transmission device for wireless networks, and can be composed of a wireless router and a supporting ARMLinux embedded system. The role of the ARMLinux embedded system is to set the IP address of the monitoring field wireless route, and receive the data of the monitoring site and transmit it to the wireless route. Wireless routing is a commonly used wireless transmission device through which all the IP addresses involved in the system are allocated and the received data is transmitted to the monitoring service terminal.

4. Monitoring service terminal settings

There are two types of monitoring terminals: mobile terminals and computer terminals.

(1) Mobile terminal settings: adjust the mobile Wi-Fi network card, set the IP, connect the wireless router, call the corresponding playback software, and monitor the monitoring site in real time. And can communicate interactively.

(2) Computer terminal settings are divided into two situations: indoor monitoring and outdoor monitoring.

Indoor monitoring: Adjust the computer Wi-Fi network card, set the wireless IP to the computer, receive the wireless routing and transmit data, and call the corresponding playing software to realize real-time monitoring of the monitoring site. And if the computer terminal is equipped with a microphone and a camera, it is also possible to perform two-way communication on the monitoring site.

Outdoor monitoring: Monitoring of the monitoring site can be implemented by setting a home gateway. The home gateway is a human-computer interaction web interface that allows users to monitor and monitor live information through the Internet and implement real-time monitoring.

5·Software design ideas

(1) Gateway setting, gateway flow chart shown in Figure 3:

The functions involved in gateway settings are as follows:

Main(); main function, gateway entry address

CenterGateWay; instantiated ClientManage and DeviceManage objects

getServerManage; returns the ServerManage object, used to listen to the client's control instructions

getDeviceManage; returns a DeviceManage object for supervising device information

(2) Monitoring site settings, monitoring site flow chart shown in Figure 4:

(3) Monitoring server settings

The main role of the Configure class: parse and extract the corresponding Socket connection parameters based on the information of the configuration file. The methods used in this class and their functions are as follows:

Configure(); This method is a constructor of the class, calling readConfigurePropertyFile()

getConfigure(); instantiated object of the Configure class

readConfigurePropertyFile(); read data from Configure, ProperTIes file

(4) Design of the server-side program DeviceManager class

The main function of the DeviceManager class is to extract the device information stored in the db4o database and convert it into an xml file for network transmission. At the same time, this class also has the function of adding and deleting device information. The methods used in this class and their functions are as follows:

DeviceManager(); constructor, call initDevice() method

initDevice(); initialize device information;

getDevicesManager(); instantiate DeviceManager for gateway class calls

getAllDevices(); get the device from the data port

DeviceObjeceToXML(); converts device object information into an XML file for device transfer

AddDevice(); add device to the database

DelDevice(); remove the specified device from the database

(5) Design of server-side program ServerManager class

The main role of the ServerManager class: Create a ServerSocket port listener according to the Socket connection parameter returned by the Configure class, and then send the device information to the client (mobile phone) for the client to initialize the UI according to the xml file information returned by the DeviceManager class to initialize the device information according to CenterGateWay. At the same time, it listens to the operation instructions sent by the client to perform corresponding device operations, and returns feedback information to the client. The methods used in this class and their functions are as follows:

ServerManager (); constructor, used to open a port to listen to the client's connection request

getServerManager(); instantiate class ServerManager

startMonitorClinet(); starts listening for client requests

Run(); this thread is used to implement the connection request

ClientThread is used to send device information to the client, and also calls analyzeAndExcuteCommand();

analyzeAndExcuteCommand(); is used to parse the control command sent by the client

6. Use of the software

(1) Software environment in which the system runs

For such embedded devices, the JAVA virtual machine CVM is required. This virtual machine can be compiled through the ARM-LINUX toolchain, or it can be used with off-the-shelf virtual machines. Jdk1·4·2 (version under LINUX), CVM source code, etc.

A detailed description of the CVM manual for this type of implementation. At the same time, the embedded device must load the peripheral driver.

(2) Hardware environment in which the software runs

Client: For the mobile phone platform, the mobile phone is required to support the JAVA platform operating environment, and the mobile phone has a Wi-Fi network card and related devices. For the computer platform, it is required to have an operating system of Microsoft WINDOWS2000 or higher, and install a Wi-Fi network card and its driving device.

Server: A processor with an InterXscalePxa270 chip or a higher version of it is required.

(3) Software installation

The client program loads the executable module of the mobile phone module into a mobile phone capable of supporting the JAVA platform. The computer needs to determine that the operating system supports the JAVA system and installs the JAVA virtual machine.

The installation of the gateway program is to burn the executable program of the embedded system module with the CVM to the Flash in the embedded system, and also burn the peripheral device driver to the 32M Flash.

(4) Operation of the software program

Reduce the client's operating time and space for our purpose in developing this system. The main steps of the operation are in the client terminal, and the implementation of the functions is all implemented in the gateway. The intended target is smooth transmission of video data and real-time simultaneous transmission. The steps are as follows:

1 Start all devices. 2 Connect to the network and automatically assign it to each system's independent URL through the router. 3 Manipulate the client software, open the camera and microphone of the doorbell system, and monitor. 4 If the operation is normal, you can monitor the live image of the scene in a synchronized and smooth manner. Otherwise, return the corresponding error message.

Third, the conclusion

This paper combines Wi-Fi standard and ARM chip to form a home wireless intelligent doorbell system with ARM chip as carrier and Wi-Fi standard as transmission standard. This system integrates doorbell, monitoring and alarm functions. Very strong practical performance, but also for the future home to establish a LAN to do a demonstration. In future applications, not only the doorbell system in the home, but all other smart home appliances can be incorporated into this wireless network, so it has good expansion performance. In addition, due to the practicability of the Wi-Fi standard and the stability of the ARM system, the system discussed in this paper can also be applied to public places and vehicles such as shopping malls, buses, etc., and become a development direction of public LAN and mobile LAN in the future.