In - vehicle Alcohol Detection Based on MCU and Design and Implementation of Safety Control System

Chong Fang Fu, Liu Chan Wan, Xin Gang Xu, Yin Liang Zhou, Gang Gang Li

Information Engineering, Nanchang Hangkong University, Jiangxi, NanChang, China

fcfnc2006@126.com, 1172662844@qq.com, 772914916@qq.com, 272238861@qq.com, 1272371204@qq.com

Keywords: Alcohol detector; Pressure sensor; Voice alarm; Expiration judgment; Vehicle;

Abstract.This article describes an alcohol detection based on MCU low-power controller, the

controller uses alcohol sensors, pressure sensors, voice alerts, such as vehicle alcohol detection and

safety control system, the system can be divided into two parts, one part detection may be handheld,

another for controlled part, installed in the car, so as to realize intelligent vehicle alcohol detection

and safety control. Because the system has high sensitivity and low power features, it has a high

practical value.

1. Primed words

In recent years, the frequent traffic accidents caused by drunk driving, causing huge losses to the

ourselves and others, so, the monitoring and management of drunk driving became an essential part,

but by common monitoring methods, mainly the consciousness of drivers and traffic police's

sampling. On one hand, spent a great deal of effort is very inefficient ; on the other hand, the traffic

accident caused by drunk driving are still high. While national in May last year of implementation

of the new drink - driving penalties, but alcohol driving accidents have also occurred frequently.

To this end, we have studied the circuit with alcohol detection and intelligent voice alarm system,

effective for simple circuit. Simply put, that is, when the alcohol concentration in drivers exhaled

gas up alcohol, voice prompting and forcing power car bus, so that Make it unable to start the car.

This integrated design based on the design of social phenomena and the predecessor, after a

discussion with the students and instructor carefully, on the basis of the original design into our

design ideas,fusion we design method, realizing that we are satisfied with the hardware circuit,

which maximum limit and reduce drunk driving, minimize the amount of traffic police, while

improving the efficiency of the police.

2. The system structure and the overall scheme design

The system mainly consists of MCU as the core, combined with detection circuit, control circuit,

display circuit ,voice circuit,and introduces a mandatory driver's breath method to determine if the

driver is alcohol. Specific workflow to : first of all, pressure sensors for pressure testing, if the

driver sat, pressure sensor signal is detected, start the system and enable voice prompts voice

module to detect alcohol, drivers for alcohol testing at this time, to prevent driver escape detection,

setting up a microphone as breath judging device. When breath upon confirmation, the start signal

detection of gases to be detected. And to zoom in and detect signal filtering , After filtering the

signal into A/D converter for digital conversion , by MCU on this digital signal for processing

judgment , and to process of alcohol data sent to LCD1602 for alcohol concentration display. At the

2012 2nd International Conference on Future Computers in Education Lecture Notes in Information Technology, Vols.23-24

978-1-61275-014-9/10/$25.00 2012 IERI ICFCE2012

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same time after judge handling the signal sent over transmitter to the receiver. If alcohol content

normal , the MCU control following electrical that does not work , voice prompted car can start ;

Instead , exceeded indicates lamp light up , controlling following electrical work,it makes car

cannot work . If drivers ignores the reminder for alcohol testing and forces start ignition, the car

immediately in a state of brake, wheel could not be started. To achieve the control function of drunk

driving.System structure chart as shown in Figure 1.

Fig 1 general principle diagram

3. Hardware design

According to the system structure and the design of the overall scheme, hardware circuit design can

be divided into a hand-held module and vehicle safety control module, the detailed design are

3.1 Handheld module circuit design

3.1.1 Alcohol detection module

This module uses the TGS2620 gas sensitive alcohol sensor, and is matched with the filter circuit,

amplifying circuit and A / D digital conversion circuit. The sensor consists of an integrated heater as

well as in the alumina substrate shape.

A metal oxide semiconductor.When the inspection of gas, the gas concentration in the air is

higher, the higher the conductivity sensor. Using a simple circuit can be transformed into the

changes of electrical conductivity and gas concentration corresponding to the output signal, and has

a long life, low power consumption, high sensitivity and simple circuit and other advantages of the

late. Upon detection of the alcohol concentration, Output voltage signals corresponding to the

concentration of alcohol,the signals are filtered, amplified and sent to the 12 bit A/D conversion

chip TLC2543CN to digital conversion, And the digital content to MCU to calculate and threshold

judgment, detect exhaled breath alcohol content whether drivers exceed the standard.

3.1.2 Expiration judgment module

This module uses the microphone 9767, used to judge whether the driver expiratory, expiratory

when the driver, microphone generates a pulse signal is sent to the single MCU, micro controller

judgment driver breath, then to detect alcohol probe the signal sent, if the driver is not positive,then

the microphone no pulse signal, then probe signal from the detection of alcohol.

3.1.3 MCU module

Selection of 89C51 51 Series MCU as the processor, used to detect expiratory judging signal and

detecting gas in the alcohol content is sent to the display LCD, and generates the corresponding

information code is sent to the transmitting device. 89C51 is a4K flash programmable and erasable

read only memory of the low voltage, high performance CMOS8microprocessor.

3.1.4 Transmitter module

Using PT2262 chip, the chip for coding chip, its seventeenth foot output modulated serial data

signal, when the 17 feet high315MHz during high frequency transmitting circuit vibration and

launch the equiangularity high frequency signal,When the 17pin low during 315MHz high

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frequency transmitting circuit oscillation stopped, so the high frequency transmitting circuit

completely controlled in PT2262 17 pin output digital signal,The high frequency circuit amplitude

shift keying (ASK modulation) corresponds to the modulation of 100% AM, when detecting the

alcohol content exceed the standard, emission exceed the standard code, conversely, do not exceed

the standard code transmission.

3.1.5 Liquid crystal display module

This module uses the LCD1602 alcohol content of 1602 character LCD display, it is a kind of

special used to display letters, numbers, symbols and other LCD module which is provided with a

plurality of 5X7or 5X11dot matrix character components, Dot matrix character, each bit can display

a character,16 characters per line of LCD module.

2.2 Vehicle safety control module

2.2.1 The receiving device module

Using PT2272 chips, the PT2272 is a used to decode chip,and the PT2262 is used to encode

code,including address code, data code, synchronization code . after the decoding chip PT2272

receive the signal, the address code has to be checked by two time.if correct, VT foot to output

high level, and At the same time the corresponding data feet high level output.the module is used

for receiving and transmitting module signal.

2.2.2 MCU module

Using 89C51, it is the same as the emission MCU, according to the different codes for different

operations. Its control a working indicating lamp, relay, the voice module.

2.2.3 Relay control module

By 51 MCU control,It likes a the equivalent switch, Controlling of braking device for opening and

closing, lamp lights and horns to ring or not.

2.2.4 The voice module

Using ISD4004 chip,the chip adopts the CMOS technology,including the oscillator,antialiasing

filter,smoothing filter,an audio amplifier,automatic squelch and high-density multi-level flash

memory display.Chip design is based on the method that all operations must be controlled by the

micro controller,and operation commands through the serial communication interface . using

multilevel direct analog storage technology,each sampled value stored in on-chip flash memory

directly,thus can be very real,natural reproduction of voice,music,tone and sound effects,to avoid a

general solid recording circuit due to quantization and compression caused by quantization noise

and"metallic sound".Sampling frequency can be 4,5.3,6.4,8.0 kHz,and the lower the frequency,the

longer the sound recording.Inside information stored in the flash memory ,in case of a power

failure,can be preserved for 100 years(typical),and record 100000 times.Using ISD4004 voice chip

as the core part of the voice module,when the pressure sensing module senses that there are

people,the module will make alcohol test tone to them.when the alcohol content exceed the

standard,the module make a Prohibited warning tone;if not exceed the standard,he module make a

permission tone.

4. Software design

The software part according to the overall plan design, can be divided into two parts ---handheld

module and vehicle safety control module, each module uses the modular programming. the main

program flow diagram of hand held module is shown in Figure 2,to achieve insufflation judgment,

alcohol testing, to judge whether exceed the standard, LCD alcohol concentration, and to Generate

the information code and the message code is sent to the vehicle safety control module function.

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Fig 2 hand-held module flow chart of main program Fig 3 flow chart of vehicle safety control module

As shown in Figure 3 , the vehicle safety control module is part of the main program flow chart.

Its function is the realization of receiving information.when receiving the information code and

exceed the standard codes are the same, it execute exceed the standard operation, namely speech

module sends out" do not drive" warning and control the relay to turn on the brake device,

Conversely, speech module sends"drive" the reminder and a control relay does not play role.

5. Conclusion

This article introduces the vehicle alcohol detection, discusses new alcohol detection and control

system design and implementation. In view of the designer's ability and level and electronic product

development continued to develop in this system, there are many disadvantages, only in the

laboratory test stage, many standards are not mature, but also for the extension and optimization of

the system and the complex problem, need further study.

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