In recent years, there have been more and more car theft cases, which have brought huge economic losses to people. Various car anti-theft devices appeared on the market. The car anti-theft system uses the STM32F103R6T6 (hereinafter referred to as STM32F103) single-chip microcomputer produced by ST Company as a controller, which has powerful functions and good real-time performance.
1 System structure and function
The car remote anti-theft system is designed based on modern wireless communication technology. It can send the status information of the car directly to the owner's mobile phone without distance constraints, and conduct one-to-one anti-theft alarm. The structure of the car remote anti-theft system is shown in Figure 1.
The information collection module of the automobile anti-theft system includes a human body induction sensor, a vibration sensor, etc., which is used to collect car alarm information. The sensor will collect the alarm information and send it to the microprocessor for processing. The microprocessor starts to execute the alarm procedure. First, send a text message to the owner's mobile phone; then, the alarm will give a voice warning according to different alarm conditions. For example, if someone enters the car, the alarm will send out a voice alert "You have entered the car, please leave".
Owners can send instructions at any time to check the status of the car.
When the anti-theft device is armed, the system controls the rearview mirror to fold; when disarming, it controls the rearview mirror to unfold.
The liquid crystal display part is used to display the angle value set by the owner.
The wireless remote control is used to arm and disarm.
2 System hardware design
2.1 The minimum system of single chip microcomputer
The STM32F103 minimum system is shown in Figure 2, which is composed of STM32F103 single-chip microcomputer, crystal oscillator circuit, JTAG interface and reset circuit. STM32F103 enhanced MCU is based on high-performance ARM Cortex-M3 (32-bit RISC core), built-in 32 KB Flash and 10 KB SRAM, 64 enhanced I / O ports, 2 USARTs. STM32F103 uses 64-pin LQFP package, supply voltage It is 2.0 ~ 3.6 V, the power saving mode guarantees the requirement of low power consumption and high cost performance. The single chip microcomputer adopts 32.768kHz and 8 MHz external crystal oscillator to provide accurate clock source and working clock respectively; the reset circuit is designed to combine key reset and power-on automatic reset. The application of the STM32F103 chip improves the execution efficiency of the entire system, enhances system stability, and reduces power consumption and production costs.
2.2 Information collection module
The information collection module mainly includes a human body induction sensor, a vibration sensor and a rearview mirror angle collection circuit. The human body sensor mainly detects whether a car thief enters the car for theft, and the data output terminal is connected to the single-chip PC10 pin. When the car is hit, smashed, shaken or pulled, the vibration sensor detects the relevant information and sends it to the single-chip PB0 pin for processing.
In the car anti-theft system, the PC4 and PC5 pins of the STM32F103 receive the input data of the left and right angle sensors, respectively, and the A / D conversion function of the PCA and PC5 pins converts the analog voltage into a digital value and displays it on the LCD1602. .
2.3 GSM module
The GSM module selects Huawei's EM310. EM310 GSM supports a serial interface, communicates serially with the outside world through a UART interface, connects to the RXD0 and TXD0 pins of the STM32F103 microcontroller, and is controlled by AT commands. UART supports programmable data width, programmable data stop bit, programmable parity check or no check. It supports a maximum baud rate of 115.2 kb / s and a minimum baud rate of 300 b / s. By default, it supports a rate of 9 600 b / s, and supports baud rate power-down storage. The GSM module has a standard SIM card interface, and the GSM module connection circuit diagram is shown in Figure 3.
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