北方工业大学 毕业设计（论文）
基于单片机的便携式酒精浓度测试仪设计
姓 名： 张 长 亮____ 班 级： 电09A—1___ 学 号： 09101040102__ 指导教师： 武 梦 龙____ 日 期： 2013.6.14___
毕业设计（论文）
基于单片机的便携式酒精浓度测试仪设计
摘要
本设计实现了对不同浓度酒精的检测、显示和报警，通过适当改进可安装于汽车上用于防止酒驾的智能闭锁系统。本文用AT89C51单片机与MQ-3型气体传感器实现了对酒精浓度的测量，并对测量数据进行显示，同时利用液晶显示浓度的高低，在浓度超过设定的阀值时蜂鸣器发出报警。
此次设计主要研究了（1）硬件方面：MQ-3气体传感器技术参数的检测和将它接入到酒精浓度检测模块中；将采集到的模拟电压信号通过A/D转换，得到数字电压信号；用于显示浓度的显示模块。输入模块可改变阀值，报警模块可在超过阀值时发出报警，同时继电器模块启动，以方便改进，用于防止酒驾。（2）软件方面：主要研究了电压到浓度的线性转换和最终浓度值的显示。（3）对设计的传感器进行了标定。传感器对酒精气体反应灵敏，能在有效范围内测量它的浓度值。并且在检测低浓度酒精时误差较小，当浓度较高的时候误差相对较大，但也满足设计的需求。
这次设计的优点在于对不同的区间浓度和电压转换关系做线性化处理，简化了硬件电路的设计。设计的传感器可以检测不同浓度的酒精气体，改进之后，将继电器模块与汽车电路相连，驾驶员经酒精检测后方可启动车辆，若超标，则继电器模块切断引擎电路，无法启动车辆。从而杜绝酒后驾车。 关键词：酒精浓度检测，单片机控制，A/D转换
I
毕业设计（论文）
Portable Alcohol Tester Is Designed Based On MCU
Abstract
This design has realized the detection of different concentration of alcohol, display and alarm, by appropriate improvements can be mounted on the vehicle to prevent drunk driving intelligent locking system. Different concentrations of alcohol solution are detected and showed in the design by AT89C51 and MQ - 3 type gas sensor, and the measured data show that using LCD display concentration at the same time, the concentration exceeds the threshold of the set alarm buzzer.
This design is mainly studied: (1) hardware: MQ - 3 gas sensor technology parameters detection and it access to the alcohol concentration detection module; Will gather to analog voltage signal through A/D conversion, digital voltage signal; Used to display the concentration of the module. Can change the threshold input module, alarm module can send alarm over the threshold, relay module starts at the same time, to facilitate improvements, to prevent drunk driving. (2) software: mainly studies the linear transformation and voltage to the concentration of the final density of the display. (3) on the design of the sensor calibration. Sensitive response to alcohol gas sensor, it can be measured within the effective range of density. And in detecting low concentration alcohol when the error is small, when the concentration is higher when error is relatively large, but also meet the design requirements.
The advantages of this design lies in the relationship between concentration and voltage conversion to different interval do linearization processing, to simplify
II
毕业设计（论文）
the design of hardware circuit. Design of the sensor can detect the different concentrations of alcohol gas, after improvement, relay module connected to the car circuit, the driver by the alcohol detection rear can start the vehicle, if excessive, the relay circuit module to cut off the engine, vehicle cannot be started. To prevent drunk driving.
Key Words：Detect concentrations of alcohol, Control by MCU, A/D conversion
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毕业设计（论文）
目录
摘要 .............................................................................................................. I Abstract ....................................................................................................... II 目录 ........................................................................................................... IV 1 绪论 ......................................................................................................... 1 1.1 课题背景 .................................................................................................... 1 1.1.1 课题研究的目的 ............................................................................... 1 1.1.2 课题研究的意义 ............................................................................... 1 1.2 相关产品的发展概况 ................................................................................ 2 1.2.1 国外研究现状 ................................................................................... 2 1.2.2 国内研究现状 ................................................................................... 4 1.3 研究内容 .................................................................................................... 6 2 总体方案设计 ......................................................................................... 8 2.1 设计思路 .................................................................................................... 8 2.2 系统方案设计 ............................................................................................ 8
IV