基于单片机的智能车载酒精检测及控制系统设计文档.doc

基于单片机的智能车载酒精检测及控制系统设计
摘 要：本文介绍了一种基于单片机低功耗酒精检测控制器，该控制器采用酒精传感器、压力传感器、语音报警、电子锁等与汽车组成车载酒精检测及安全控制系统。该系统可以分为两部分：一个为可手持的检测部分，另一个为控制部分，安装在车内，从而实现智能车载酒精检测及安全控制。由于该系统具有高灵敏度和低功耗的功能，因此具有较高的实用价值。
关键词：酒精探测器；压力传感器；语音报警；车载
一 引言
近年来，酒后驾车造成的交通事故时常发生，给驾驶员自身和他人造成了巨大的损失，因此，对酒后驾车的检测和管理成为必不可少的环节。但利用普通的监测和管理成为必不可少的环节但利用普通的监测方式，主要是驾驶员的自觉和交警的抽查，一方面，花了很大的精力但是效率极低；另一方面，酒后驾车引起的交通事故仍居高不下。尽管国家在去年5月实施了行的酒后驾车的处罚条例，但是酒驾事故仍时有发生。
为此，笔者研究了具有智能化酒精检测及语音报警的电路系统，有效地实现了简单电路。简单地说，就是当驾驶员呼出气体中的酒精浓度达到设定的酒精浓度，就会语音提示，并强制切断汽车电源总线，令其无法启动汽车。此设计在综合社会现象和前人设计的基础上，经过与同学、指导老师的仔细商讨，在原有设计的基础上注入我们的设计思想，融合我们的设计方法，基本上能实现令我们满意的硬件电路。这样最大限度地限制和减少酒后驾车的现象，尽可能降低交警的工作量，同时提高交警的工作效率。
二 系统结构及总体方案设计
该控制系统主要以单片机为核心，配以检测电路、控制电路、显示电路、语音电路组成，并采用强制驾驶员呼气的方法，以判断驾驶员是否饮酒。具体工作流程为：首先压力传感器进行压力检测，若驾驶员就坐，压力传感器检测到信号，启动系统并激活语音模块，通过语音提示进行酒精检测，此时驾驶员可进行酒精检测。为防止驾驶员逃避检测，设置一个话筒，当呼气确认后，酒精传感器开始作为呼气判断装置。对探测的气体进行检测，并把检测到的信号进行放大和滤波，滤波之后的信号送入A/D转换器进行数字转换，由单片机对此数字信号进行处理判断，并把处理的酒精数据送至LCD1602进行酒精浓度显示，同时把处理判断后的信号通过发射模块发送至接收控制继电器不起作用，语音模块。若酒精含量正常，提示汽车可以启动；反之，超标指示灯亮起，控制继

电器起作用，汽车制动，语音提示汽车不可以启动，使汽车无法行驶。若驾驶员无视进行酒精检测的提醒，强制进行点火启动，则汽车立即处于制动状态，汽车无法启动。从而实现控制酒后驾车的功能。
三 硬件设计
根据系统结构及总体方案的设计，可以把硬件电路的设计分为手持模块和车载安全控制模块，具体设计如下。
3.1 手持模块电路设计
3.1.1 酒精检测模块
本模块采用TGS2620气敏酒精传感器并配以滤波电路放大电路以及A/D数字转换电路。该传感器 由集成的加热器以及在氧化铝基板上形成的金属氧化物半导体构成。当可检知的气体存在时，空气中该气体的浓度越高，传感器的电导率就越高，使用简单的电路就可以将这种电导率的变化变换为与气体浓度对应的输出信号，同时具有寿命长、功耗低、灵敏度高及后期电路简单等优点。一旦检测到酒精，其输出与浓度对应的电压信号，此信号经过滤波、放大后送至12位A/D转换芯片TLC22543CN进行数字化转换，并把数字量送到单片机进行计算并阀值判断，检测驾驶员呼出气体中酒精含量是否超标。

3.1.2 呼气判断模块
此模块采用送话器咪头9767，用来判断驾驶员是否呼气。当驾驶员呼气时，送话器咪头产生一个脉冲信号送至单片机，单片机判断几十元呼气，再检测酒精探头送来的信号；若驾驶员不呼气，则送话器咪头不产生脉冲信号，此时不检测酒精探头送来的信号。
3.1.3 单片机模块
选用51系列的89C51单片机作为处理器，用来接收呼气判断信号并接收气体中的酒精含量数据，同时送至LCD进行显示，并生成相应的信息码发送给发射设备。89C51是一种带4K字节闪烁可编程可擦除只读存储器的低电压、高性能CMOS8位微处理器。
3.1.4 发射模块
采用PT2262芯片，该芯片为编码芯片，其第17脚输出经调制的串行数据信号，当17脚为高电平期间315MHz的高频发射电路起振并发射等幅高频信号，当17脚为低电平期间315MHz的高频发射电路停止振荡，所以高频发射电路完全受控于PT2262的17脚输出的数字信号，从而对高频电路完成幅度键控（ZSK调制）相当于调制度为100%的调幅。当检测到酒精含量超标时，发射超标码；反之，发射不超标码。

3.1.5 液晶显示模块
本模块采用LCD1602进行酒精含量的显示，1602字符型液晶是一种专门用来显示字母、数字、符号等的点阵型液晶模块，它由若干个5X7或者5X11等点阵字符位组成，每个点阵字符位都可以显示一个字符，每行16个字符型液晶。
3.2 车载安全控制模块
3.2.1 接收设备模块
采用PT2272芯片，该芯片是一款用以解码的芯片。编码芯片PT2262发出的编码信号由地址码、数据码、同步码组成一个完整的码字，解码芯片PT2272接收到信号后，其地址码经过两次比较核对后，VT脚才输出高电平。与此同时，相应的数据脚也输出高电平，该模块用来接收发射模块的信号。
3.2.2 单片机
采用89C51，与发射的单片机一样，收到接收设备送来的码，根据不同码进行不同的操作。其控制工作指示灯、继电器和语音模块。
3.2.3 继电器控制模块
继电器受51单片机的控制，相当于开关，控制制动装置开闭、车灯的亮灭和喇叭的响与不响。
3.2.4 语音模块
采用ISD4004芯片，该芯片采用CMOS技术，内含振荡器、防混淆滤波器、平滑滤波器、音频放大器、自动静躁及高密度多电平闪烁存贮陈列。芯片设计是基于所有操作命令可通过串行通信接口送入。芯片采用多电平直接模拟量存储技术，每个采样值直接存贮在片内闪烁存贮器中，因此能够非常真实、自然地再现语音、音乐、音调和效果声，避免了一般固体录音电路音量化和压缩造成的量化噪声和“金属声”。采样频率可选4.0、5.3、6.4、8.0kHz，频率越低，录放时间越长，而音质则有所下降，片内信息存于闪烁存贮器中，可在断电情况下保存100（典型值），反复录音10万次。采用ISD4004语音芯片作为语音模块核心部分，当压力传感模块感应有人时，发出酒精检测提示音；当酒精含量超标时，发出禁止行车警告音；当酒精含量未超标时，发出允许行车提示音。

四 软件设计
软件部分根据总体方案设计，可划分为手持模块和车载安全控制模块两个部分，各模块均采用模块化编程。
五 结束语
本文介绍了车载酒精检测的新思路，讨论了新型酒精检测及其控制系统的设计与实现。鉴于设计者的能力和水平及电子产品的开发不断进行，针对此系统的优化和扩展还有比较复杂的问题需要进一步的探讨和研究。
参考文献
[1] 华成英.信号运算符和过滤器.模拟电子技术基本教程，2006:257-268.
[2] 曾兴雯，刘乃安，陈健.频率调制和解调.高频电路原理与分析，2006：232-267.
[3] 邱关源，罗先觉.对含理想运放的扩音器的分析.电路，2009：120-123.
[4] 张先庭，向瑛，王忠，周传璘.单片机原理、接口与C51应用程序设计，2011：189-206.
[5] 白中英.数字系统的基本模型.数字逻辑与数字系统，2008：157-162.
[6] 阎石.模拟数字转换.数字电子技术基础，2007:506-545.
[7] 高西全，丁玉梅.模拟信号的数字化处理.数字信号处理，2011:21-29.
Based on single chip microcomputer intelligent vehicle alcohol detection and control system design
Abstract: this paper introduces a kind of controller based on single-chip low-power alcohol detection, the controller adopts the alcohol sensor, pressure sensor, voice alarm, electronic lock and auto vehicle alcohol detection and safety control system. The system can be divided into two parts: one for handheld detection part, another for the control part, installed in the car, so as to realize intelligent vehicle alcohol detection and safety control. Due to the function of the system has high sensitivity and low power consumption, thus has high practical value.

Key words: alcohol detector; Pressure sensor; Voice alarm; An on-board
1.Introduction
In recent years, traffic accidents caused by drunk driving frequently occurred, caused huge losses to drivers themselves and others, as a result, the detection and management of drunken driving to become indispensable link. But using ordinary monitoring and management become essential link. But using the ordinary monitoring mode, mainly is the driver's consciousness and the traffic police spot checks, on the one hand, spend a lot of energy but the efficiency is extremely low; On the other hand, drunk driving cause traffic accident remains high. Although the national in May last year implemented a lines of drunk driving penalties, but the drunk driving accidents still happen.
To this end, the author studies the intelligent alcohol detection and voice alarm circuit system, effectively implements a simple circuit. , in a nutshell, is when the alcohol concentration to set in the driver's breath gas concentration of alcohol, can voice prompt, and force to cut off the car power bus, make its can't start the car. This design on the basis of the general social phenomenon and the previous design, with classmates, guidance of the teacher's careful discussion, on the basis of the original design into our design ideas, design method of integration we basically hardware circuit can realize to our satisfaction. Such maximum limit and reduce the phenomenon of drunk driving, as far as possible to reduce the traffic police work, improve the work efficiency of the traffic police at the same time.
2.The system structure and the overall scheme design
The control system mainly by single chip microcomputer as the core, the detection circuit, control circuit, display circuit, voice circuit, and adopts the method of forced the driver out, to determine whether drivers to drink. Specific work process is: the first pressure sensor is used to detect the pressure, if the driver sat, pressure sensor detects the signal, startup system and activate the voice module, through the voice prompt alcohol detection, driver's alcohol detection can be performed at this time. In order to prevent the pilot to escape detection, set up a microphone, exhale when confirmed, alcohol sensor began to exhale as judging device. To test the detection of gas, and the detected signal is amplified and filter, filter after into the A/D converter to convert the digital signal, the digital signal by single-chip microcomputer for processing, and processing of data sent to the LCD1602 alcohol alcohol concentration showed that at the same time, the treatment after the judgment signal by emitting module sending and receiving control relay doesn't work, the voice module. If alcohol is normal, prompt car can be started; On the other hand, the excessive light is lit up, control relay, automobile brake, voice prompt car can't start, is unable to drive the car. If the driver to ignore for the detection of alcohol to remind, to enforce the ignition starts, the car immediately in the braking state, the car won't start. So as to realize the function of control driving under the influence of alcohol.

3. Hardware design
Based on the system structure and the overall scheme design, can be divided into hand-held module and the hardware circuit design of on-board security control module, design details are as follows.
3.1 holding a module circuit design
3.1.1 alcohol detection module
This module USES TGS2620 alcohol gas sensitive sensor and filter circuit, amplifying circuit and A/D digital conversion circuit. Integration of the sensor by the heater and the alumina of metal oxide semiconductor is formed on the substrate. When there is gas detector, the higher the concentration of the gases in the air, the higher the conductivity sensor, using a simple circuit can change with the conductivity of the gas concentration of the corresponding output signal, and has long service life, low power consumption, high sensitivity and late simple circuit etc. Concentration of alcohol once detected, the output and the corresponding voltage signal, the signal after filtering and amplification to 12 bits A/D conversion chip TLC22543CN to digital conversion, and the digital quantity to single chip microcomputer to calculate and threshold judgment, whether the detection of alcohol content in the driver's breath gas exceeds bid.

3.1.2 expiratory judgment module
This module USES the microphone microphones, 9767, which is used to determine whether the driver out. When the driver exhale, microphone microphones to generate a pulse signal sent to the single-chip microcomputer, exhale, MCU to judge a few yuan to detect alcohol from probe signal; If the driver fails to exhale, the microphone microphones do not produce the pulse signal, while the signal from alcohol detection probe.
3.1.3 MCU module
Choose 51 series of 89 c51 single chip as the processor, used to receive a breath alcohol in judge signal and receives gas content data, at the same time sent to the LCD display, and generate the corresponding information code sent to the transmitting equipment. With a 4 k byte flash is 89 c51 is programmable to erase the read only memory (ROM) of low voltage, high performance CMOS8 bit microprocessor.
3.1.4 launch module
USES PT2262 chip, this chip for encoding chip, its 17 feet by the modulation of the serial data output signal, when 17 feet for high level during the high frequency of 315 MHZ transmission circuit of high frequency signals, such as vibration and launch when 17 feet for low level during the high frequency of 315 MHZ transmission circuit to stop oscillation, so high frequency circuit is completely controlled by the launch of PT2262 17 feet output digital signals, thus for high frequency circuit to complete the amplitude keying (ZSK modulation) equal to 100% of the modulation of amplitude modulation. When detected, over the legal alcohol limit, emission standard code; On the other hand, the launch is not overweight.

3.1.5 liquid crystal display module
This module adopts the LCD1602 to alcohol, according to a 1602 character LCD is a kind of special used to display the letters, Numbers, symbols, such as the point of formation of LCD module, it consists of a number of 5 x7 or x11 dot matrix characters such as composition, each dot matrix characters can display a character, line 16 character LCD.
3.2 vehicle safety control module
3.2.1 receiving device module
Using PT2272 chip, the chip is a to decoding chip. Encoding chip PT2262 encoding signals by the address code, data, synchronization code to form a complete code word, after decoding chip PT2272 receives the signal, its address code after two comparison, after checking VT feet to output high level. At the same time, the corresponding data foot also output high level, the module is used to receive signals launch module.
3.2.2 microcontroller
Using 89 c51, the launch of the single chip microcomputer, and receive from receiving equipment code, according to the different code for different operation. Its control work lights, relays and voice module.
3.2.3 relay control module
Relay controlled by 51 single chip microcomputer, is equal to the switch, brake control opening and closing, destroy the light of lights and horn ring and not ring.
3.2.4 voice module
The ISD4004 chip, the chip USES the CMOS technology, embedded oscillator, prevent blur filter, smoothing filter, audio amplifier, since the action mania and high-density multilevel flash storage display. Chip design is based on all commands into through serial communication interface. Chip adopts multilevel direct analog storage technology, each sampling value directly storage in glint on chip memory and therefore able to reproduce the very real, natural voice, music, tone and sound effect, avoids the general solid quantitative and compressed sound recording circuit caused by the quantization noise and "metal". Sampling frequency optional 4.0, 5.3, 6.4, 8.0 kHz, the lower the frequency, the longer the playback time, and the sound quality is declined, glint on chip information stored in memory and may be retained in the case of power cuts 100 (typical), the tape 100000 times over and over again. The ISD4004 voice chip as the core voice module, when the pressure sensor module induction someone sends an alcohol test sound; When alcohol content exceeds bid, a ban on driving warning sound; When alcohol content was not overweight, driving prompt to allow.

4. The software design
Software part according to the overall scheme design, handheld module and vehicle safety control module can be divided into two parts, each module adopts modular programming.
5. Conclusion
On-board alcohol detection are introduced in this new way of thinking, discusses the new alcohol detection and control system design and implementation. In view of the designer's ability and level and the development of electronic products, for the system optimization and extension and a more complex problems need further discussion and research.
Reference
[1]Hua cheng ying. signal operator and filters. Analog electronic technology basic course, 2006:257-268.
[2] Xing-wen zeng, nai-an liu, Chen jian. Frequency modulation and demodulation. High-frequency circuit principle and the analysis, 2006:232-267.
[3] Qiu Guanyuan xian-jue luo. To contain the analysis of the ideal operational amplifier. Circuit, 2009:120-123.

[4] Zhang Xianting to ying, worsley, Chou Lin. With C51 single-chip microcomputer principle and interface application design, 2011:189-206.
[5] Zhong-ying bai. The basic model of digital system. Digital logic and digital system, 2008:157-162.
[6] Yan Shi. Analog to digital conversion. Digital electronic technology base, 2007:506-545.
[7] Gao Xiquan, yu-mei ding. Analog signal digital processing. Digital signal processing, 2011:21-29.

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