Design of anti-theft monitor based on GSM module

    With the rapid development of mobile communication technology, the application field of computer remote control technology has become more and more extensive, and the research value of theory and practice has also increased day by day. GSM public network is widely used in remote control technology because of its high coverage rate. The anti-theft monitor designed in this paper makes full use of the short message value-added service and wireless communication service of GSM public network to realize the functions of remote monitoring, alarm information sending and receiving, and on-site alarm. It adopts active anti-theft mode to enable users to get rid of the passive anti-theft that cannot be seen or heard. It is not restricted by geographical location and has the characteristics of networking and intelligence.

1 System composition and working principle
    The system is mainly composed of storage unit, GSM unit, actuator, anti-theft sensor, and single-chip control mechanism. The mobile communication module in the system adopts SIM508 of SIMCOM Company of the United States, and the single-chip microcomputer adopts MSP430 series single-chip microcomputer. The mobile communication module is connected via the RS 232 serial port of the single-chip microcomputer, and the GSM07.05 of the European Telecommunications Standards Institute ETSI is used as the short message coding standard. This paper adopts MSP430F series single-chip microcomputer for system design, making full use of its ultra-low power consumption and communicating with the mobile communication module through its standard full-duplex serial port.
    MSP430 single-chip microcomputer is the control center of the anti-theft alarm, integrating the mobile communication module, the alarm information collection module and the alarm module. The anti-theft sensor collects the alarm signal at the front end and sends it to the MSP 430 single-chip microcomputer. After the single-chip microcomputer judges and processes it, the control command is sent to the mobile communication module. The mobile communication module sends the matching alarm short message to the user's mobile terminal through the GSM network according to the command content to realize the alarm. When the user receives the alarm SMS, he can reply the corresponding anti-theft command to the alarm system through a short message. The alarm system activates the actuator of the control system according to the content of the short message to implement the corresponding anti-theft measures. The core part of completing the design of the mobile alarm system is the development of AT commands based on the GSM public network system and the communication between the mobile communication module and the single-chip microcomputer control module. The overall design block diagram of the alarm system is shown in Figure 1.

    The design of the anti-theft alarm system makes up for the shortcomings and deficiencies of the traditional alarm system, such as the noise of the alarm ring, the small alarm range, the geographical restrictions, and the low effectiveness of the alarm, and provides an effective means for the development and utilization of value-added services and wireless communication services of mobile communication systems.

2 Hardware Design
    The system uses the MSP430 microcontroller as the core control module. The 16-bit high-performance MSP430 series microcontroller launched by Texas Instruments of the United States has high cost performance, outstanding low power supply voltage, fast running speed, and rich on-chip peripheral modules, which can meet the functional requirements of system design. The
    hardware circuit of the system is mainly composed of the MSP43 microcontroller control module, alarm module, alarm information collection module, communication module, information storage module and control actuator. The alarm collection module is composed of a pyroelectric infrared sensor and a Fresnel lens. The communication module uses the SIM508 of SIMCOM of the United States. The microcontroller uses the MSP430 series microcontroller, which is connected to the communication module through the RS 232 serial port. The principle block diagram of the system main control module is shown in Figure 2.

[page]

3 Software Design
    After the system is initialized, the control system will identify the mobile phone user by sending a confirmation text message. If the arming signal is invalid, the control system will not detect its status. Once the control system detects an alarm signal, it will immediately send an alarm text message to the user's mobile phone, and at the same time send a local alarm signal lasting 10 seconds. When the user's mobile phone sends a pre-set feedback text message to the system, the control system will give a corresponding reply based on the judgment result to realize the interactive operation between the alarm system and the mobile phone user. The software flow chart is shown in Figure 3.

4 Conclusion
    This paper focuses on the design of a remote anti-theft alarm based on the GSM public network. It uses the MSP430 single-chip microcomputer system as the main control module, relies on the GSM public network wireless communication, and realizes the communication between the user and the system by sending short messages, so as to remotely monitor valuable items in real time.
    With the rapid development of science and technology and the continuous improvement of people's living standards, the application of mobile communication technology in remote industrial control systems, remote robot systems, warehouses, cars, homes and other environments is becoming more and more frequent, and the theoretical and practical value is gradually highlighted. The anti-theft alarm based on the GSM public network control can not only realize the function of remote anti-theft alarm, but also ensure the communication effect. The communication distance is not limited by the region, which improves the reliability of the alarm system and enables users to realize remote real-time monitoring of valuable items.