This paper mainly studies and designs indoor security. Based on OpenWrt open source software and based on existing hardware, the intelligent home indoor security system based on OpenWrt is designed.
1. Overall designThe overall structure of the design is divided into two parts, the hardware design part and the software design part. The overall function is realized by a combination of hardware and software. Modular design is adopted in hardware design, which mainly includes five modules: remote monitoring module, wireless communication module, video acquisition module, single-chip control module and Sensor data acquisition module. The software design is based on the OpenWrt open source embedded Linux system. The OpenWrt open source system contains more than 3,000 software packages that users can choose freely. They can write their own packages to build their own applications according to their own needs. Maximize your own embedded devices. The overall design block diagram of the system is shown below:
The remote monitoring module refers to the mobile terminal and the computer. The user can obtain the indoor monitoring screen and environmental parameters in real time through any mobile phone or computer in any place with network connection. When an abnormality occurs through the obtained SMS alarm information, the video and client can be viewed in real time. Data, enabling users to respond in a timely manner.
2.2 wireless communication moduleThe wireless communication module is the core of this design. Its main chip is Ralink's RT5353 chip. It has a high-performance, highly integrated central micro-processor with a frequency of 350MHz, which fully meets the needs of embedded operating systems. It supports
In the IEEE 802.11 standard Wi-Fi network, the 20/40M band allows data transmission efficiency of up to 150 Mbps, which makes it more widely available and has higher data throughput. In addition, he provides multiple Ethernet interfaces to connect to external networks and multiple internal network devices. It also provides a USB host interface and two universal asynchronous transceivers 31, which makes it very convenient for external devices. Expansion.
2.3 video monitoring moduleIn order to ensure the clarity of indoor video image information, so that users can receive images in real time, this design uses a USB camera as a video image acquisition tool. It does not require signal conversion to directly transmit digital signals of image information. The client (PC/cell phone) only needs USB interface or wireless transmission to directly receive image and video signals, and USB to 31 converts faster. The USB camera market is widely used and cost-effective, and is easy to use. Comprehensive consideration of the use of Tianmin.com UVC-T24 driveless camera, 640x480 pixels, USB2.0 interface, effectively improve the image transmission speed, high frame rate video display, smooth and uninterrupted picture, in the dark environment can ensure the clarity of the picture. The schematic of the digital camera is shown below:
The control module is a combination of STC89C52 single-chip microcomputer and GSM communication module. The GSM module is controlled by a single-chip microcomputer to realize the function of remote information communication alarm.
This design selects the TC35 series of the new generation wireless communication GSM module launched by Siemens . It can safely and reliably realize the data, voice and short message transmission in the system scheme and can guarantee the transmission rate requirement. The module's working voltage is 3.3-5.5V, it can work in 900MHz and 1800MHz frequency bands. The module has AT command set 1. This module integrates RF 3 circuit and baseband to provide fast and reliable data, voice and short message. , secure transmission. The single-chip microcomputer and the GSM module adopt an asynchronous serial communication interface, and the communication speed can be set according to actual needs. The connection diagram of the control module is shown in Figure 3.
2.5 sensor data acquisition module The design of the sensor acquisition module combines the methods of ZigBee technology and sensor technology. The infrared sensor, gas sensor and temperature sensor are used to collect indoor access control, smoke, temperature and other information, and the collected information is uploaded to the upper computer by the wireless communication module. The technology is the key to this design. Since the design belongs to the indoor security environment, the scope of monitoring is relatively small, and each node does not need to communicate with each other, so a star network is selected. The coordinator is connected to the wireless communication module through the RS232 serial port. Each node uses the RFD connection sensor and is powered by the battery. It can be placed anywhere in the room according to actual needs. The data collected by all nodes will be sent to the coordinator, the host computer ( The PC/mobile terminal) client can receive real-time data of the sensor through the wireless communication module.
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