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Automotive Burglar Alarm Monitoring System

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Introduction

Automobile in people's lives are increasingly becoming an integral part of, however, worried about the car user is the phenomenon of stolen vehicles was an upward trend year after year. This paper aims to design a convenient and reliable, powerful car alarm. When the vehicle encountered a dangerous situation, he immediately activated the alarm, at the same time to send the corresponding information to the designated mobile phone, informing owners anomalies. Mobile phone owners can monitor and control the situation inside the car, in order to effectively prevent the vehicle stolen. In addition, the increase in the car if an emergency button, the owner can not only encountered in the robbery or other dangerous situation, to call for help, they can help the police locate the car. Taking into account the time and cost issues, this article only for the detection of vibration information, vehicle information transmission and control of key research issues.

Vibration detection

Figure 1, when objects have the right of acceleration, due to inertia, the middle distance between baffle plate and the ensuing changes in capacitance, resulting in changes in capacitance value (also by changing the capacitor plate area to achieve changes in capacitance). After follow-up switched-capacitor, unity-gain amplification, such as the charge amplifier can be a series of processing information and the acceleration voltage signal proportional to the relationship. systems used in acceleration sensor MMA7260QT principle is based on the above.

Automotive Burglar Alarm Monitoring System

Traditional anti-theft alarm focuses on transient vibration, shock testing, although they could identify violence opened the door, but the police can easily result in miscarriage of justice (for example, led to the police near the abnormal sound). For the above problem, this paper has adopted the following three measures:

(1) increased the detection of movement to open the door, the door opened extract the acceleration information as the basis for one of the stolen vehicles.

(2) select the appropriate door was open violence characteristic time, rather than rely solely on the peak acceleration of cross-border basis as a stolen vehicle.

(3) increase the body angle measurement, trailers and vehicles to prevent theft and other means of transportation.

Vehicles and control of information transmission

Traditional technology and modern anti-theft alarm GSM digital mobile communication technology, can be achieved on the vehicle condition monitoring, scheduling, anti-theft alarm, anti-robbery alarm, remote control, tracking, positioning, mobile phone and other functions. SIEMENS system's module TC35i GSM Modem, so you can break through the space constraints, the vehicle information through the GSM network to all over the world. As the system needs the support of many functional modules, limited time and cost issues, the adoption of the following two points in this article only to verify the feasibility and practicality of the system:

(1) the current state of vehicles sent to the designated mobile phone, asked to identify sources of information stolen vehicle: door vibration, vehicle inclination anomaly, such as illegal access.

(2) mobile phone to send commands to the GSM Modem module, the request is only set to get the phone number of the control system that can distinguish between different command and the implementation of the control.

System Overview

System architecture diagram

As shown in Figure 2: The MC9S08QG8 single-chip as the core, supplemented by modules MMA7260QT acceleration, HOLUX GM-82 GPS module, TC35i GSM Modem Module module features real-time monitoring of motor vehicles. power part of the master to be used-vehicle battery power; once the main power is cut off, or switch to the built-in battery-powered, to enter the energy saving mode, the effective work of several months or more.

Automotive Burglar Alarm Monitoring System

System hardware

Single-chip microcomputer and its peripheral circuits MC9S08QG8

The model is a single-chip company Freescale main push of 8-bit MCU, which features several built-in car anti-theft alarm system with the requirements of exactly coincide, so use it for the core of the system.

The smallest single-chip system uses the company's Synhayato development board CT298. Substrate mainly by the following components: single-chip microcomputer (MC9S08QG8), USB-mini B type connector, power and reset switches, USB-COM converter (FT232R), BDM connector tools, input and output devices (button button LED lights, buzzer), MM-2860 with socket to connect an external expansion slot (for the pitch 1mm, 16-pin flat cable connector slot) and the test port.

MMA7260QT acceleration module and its peripheral circuits

Hyundai used the anti-theft system's impact on the body, vibration monitoring, early warning methods, devices commonly used for the magnetic-effect sensors. Magnetic effect as a result of acceleration sensor of its own problems, will make follow-up signal processing circuit and microcontroller interface circuit complexity, resulting in reduced reliability of alarm systems, high false alarm rate. In addition, a trailer or vehicle handling to deal with the most effective way is to tilt the body to monitor, and the magnetic-effect sensors can not measure the static acceleration of the body can not measure the tilt angle. Freescale designed MMA7260QT is the production of integrated single-chip three-axis acceleration sensor, it can be whole body vibration and the slight angle at the same time monitoring. Will be applied to automobile anti-theft system will not only expand the scope of the monitoring system, and simplifying the system, improved anti-theft alarm system reliability. MMA7260Q internal module structure is integrated in a single chip three independent of each other, measuring the direction of each vertical element of the sensitive measurement module is polysilicon surface micromachining process made of capacitive accelerometer; silicon surface by the elastic structural support from the following mass attached a plate capacitor, capacitance of the other fixed plate. When the acceleration caused by the relative positions of mass change, a change in capacitance value, and then after a capacitor voltage conversion and amplification circuit after the output filter circuit and the voltage signal proportional to acceleration.

TC35i GSM Modem Module

TC35i is a new generation of Siemens Introduces GSM communication module. Wireless Module TC35i compact size, installation design flexibility and easy integration and low power consumption. AT command set module interface, support for text and SMS PDU mode, the third Group II fax, and 2.4k, 4.8k, 9.6k non-transparent mode. TC35i modules mainly by the GSM baseband processor, GSM rf module, power supply module (ASIC), flash memory, ZIF connector, the antenna interface of six parts. TC35i as the core of GSM baseband processor to address the main terminal of voice, data signals, and cellular radio equipment covering all the analog and digital functions. No additional hardware in the premise, can support FR, HR, and EFR voice channel coding.

Other auxiliary circuits

In addition to the main function of the circuit, the system also includes a number of auxiliary circuits. They are mainly: 3.3V regulated power supply (CT-298 development board to provide the regulated power supply current is limited, can not afford the entire system of power supply), by TI's TLV2217-33 LDO and a number of capacitor structure, able to provide 500mA current; serial level conversion circuit (to connect easily with the TC35i communication), mainly from MAXIM's MAX3232 consists of providing TTL-level with the conversion of 232C level; LED indicator drive circuit as well as the button circuit.

System software

The overall system software design

System mainly includes four working condition: the state of parking, traffic, and stolen and robbed the state of the state. First, determine the status of single-chip parking and traffic state, which mainly depends on the achievement of key recognition technology. There are many types of identification keys, this article envisages the use of Radio Frequency identification technology (RFID, Radio Frequency Identification). Its fundamental principle is the use of RF non-contact way of two-way communication, so as to achieve the purpose of identification and exchange of data. RFID systems and radio frequency card reader can be completed between the contacts do not have to identify, through the operation of RFID card reader, enabling all types of objects or equipment (personnel, materials) in different states (mobile, stationary or harsh environment ) under the automatic identification and management. RFID cards can store 128 bytes of data, the former No. 4 bytes for the ID, the ID number is the only global, can be used as the owner identification signs, and the remaining bytes can be used to store information on a number of auxiliary check.

In the parking mode, the single chip will be followed by detecting the vibration information, angle information, car information, fire information, personnel information and whether it is normal, the system will integrate the above information to determine the status of vehicles. If the judge concluded that the stolen vehicle, the system model into the theft. First of all, the information will be sent to the owner, and then handed over control of the owner, the owner can find the position of the vehicle, the officers inside the vehicle information can also be used for sound and light to start the high-decibel alarm, shut down the engine, cut off oil and other operations. If the conclusion is that a normal vehicle, the system returned to the initial state of the cycle again. Moving mode, the system will continue to press inquiries, whether the help button, help button, once pressed, the vehicle will enter the model was robbed. First of all, the information will be sent to designated mobile phone number (for example, owners of a friend), and then handed over control of the control center (through the designated mobile phone number), the control center can also control the operation of the implementation of the above.

Automotive Burglar Alarm Monitoring System

Vibration, inclination information extraction and identification

We can see from the above, we need to extract information from the acceleration of the following three types of information: when picklock body vibration, the acceleration of the door open signal, changes in vehicle inclination. Their waveform as shown in Figure 3, under normal circumstances, the figure shown in the smooth zone, X, Y, Z three directions of acceleration will remain basically unchanged (but slightly disturbed). It was picklock, the acceleration value will be a reduction in the process of shock, vibration cycle is very short, only a dozen or so milliseconds. In the process of opening the door, the acceleration value will be a big change, and a longer duration, to achieve more than a hundred milliseconds.

Analysis we can see that the doors open picklock vibration and acceleration values at the time of changes in the speed and acceleration, and more suitable to indicate the difference; angle changes only with changes in the size of the acceleration values, but not with the speed of change has nothing to do can be directly used to express the current acceleration. Against the vibration caused by sound waves of false positives, this paper two ways: as a result of the frequency of sound wave vibration is much higher than the frequency of vibration picklock appropriate to reduce the ADC sampling frequency can be the majority of least squares, the system sampling frequency is 1000Hz; a number of adjacent margin of the weighted average score, which is equivalent to the role of low-pass filter, filter out sound waves can also be caused by vibration, system uses a weighted average of three. After the ADC sampling assumptions to quantify the value of

A = a (1) + ... + a (i-1) + a (i) + a (i +1) + ...

Weighted coefficient of M1, M2, M3, while the weighted average formula for dealing with

b (i) = [M1 * a (i-1) + M2 * a (i) + M3 * a (i +1)] / (M1 + M2 + M3)

Angle of detection for the adoption of the current value and a smooth acceleration of the acceleration value of state for worse, that set up the initial value of acceleration a (0), then a (i)-a (0) greater than the absolute value that the angle can change when exceeded, start alarm. Part of ADC is initialized as follows:

Automotive Burglar Alarm Monitoring System

Automotive Burglar Alarm Monitoring System

Vehicles and control of information transmission

Vehicles and control of information transmission is mainly through the company's Siemens module TC35i GSM Modem. TC35i Single-chip through the serial port on the AT commands to write to achieve the information transmission and reception purposes.

TC35i Single-chip transceiver control information in the main procedures are as follows:

Automotive Burglar Alarm Monitoring System

Automotive Burglar Alarm Monitoring System

Automotive Burglar Alarm Monitoring System

Note MC9S08QG8 Microcontroller Programmer

Unlike MC9S08QG8 single-chip single-chip microcomputer 51, in programming there are some noteworthy, especially given below:

1) SOPT1 register to write the question: SOPT1 is a one-time write registers, each can only be written once after reset. So every bit of its time write to, but not at many times to write. For example, the following statement

Automotive Burglar Alarm Monitoring System

Single-chip that is only the first valid instruction, and behind the statement is invalid. This has caused an external interrupt pin can be reset, watchdog timer can not be shut down. Should be written in the form of

Automotive Burglar Alarm Monitoring System

2)-chip start-up state of ICS Trim Register (ICSTRM) register must be set. This register is used to adjust the internal oscillator clock frequency, because the internal oscillator is made using semiconductor technology, different chips will be the oscillation frequency deviation, Trim register to adjust the bias on. Adjust the values at the factory in the chip on a fixed position, and can be directly used. However, according to BDM debugging settings will adjust the frequency (may be related to the initial power-on reset value), will result in minor changes in clock frequency, thereby BDM debug state after the reset and power-down of different clock frequencies, in the SCI communications caused by the baud rate are not allowed to g.


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