论文总字数：14909字

摘 要

改革开放以来，随着经济的飞速发展，汽车走进了千家万户，成为了许多行业必不可少的工具，在拉近了地域之间距离的同时，交通事故的发生也酿成了许多悲剧，据有关部门的不完全统计，大约60%的交通事故都是由酒后驾驶造成的，醉酒驾车已严重威胁到人们出行安全。本课题以社会普遍关注的酒驾问题为背景，提出了一款兼具浓度检测及报警功能的车载酒精含量检测系统。

本系统在硬件设计上，以STC89C52单片机作为控制核心，以MQ-3气体传感器作为空气采集模块，它能随着外部气体的浓度或不同而改变敏感膜的电阻。通过电路设计将电阻变化转变成电压的变化，并通过A/D转换芯片采集电压信息，通过模数转换器进行数据转换和处理，最后经由LCD显示模块显示被测酒精浓度值，这样有利于用户更直观的看到显示数值。同时，系统中还构筑了报警电路，一旦车内的酒精含量超过设置的极限值，系统就会发出报警，提醒驾驶员请勿继续驾车。在软件设计上，则采用了主程序调用子程序的方式编写，先编写各控制部分的子程序，最后再编写主程序，这样的编写方式更有利于后期纠错。在编写时，需要先弄清各个部分的工作流程，比如，单片机对气体传感器检测模块和A/D转换模块反馈结果的处理方式，显示模块需要了解LCD液晶显示的工作方式，根据工作方式了解单片机控制LCD显示的流程并进行编程，之后，还需考虑按键部分，先对按键进行消抖，然后用按键的动作对数值进行设置。

在软硬件设计完成后，还需对硬件和软件进行联合调试。经反复调试后得出，本系统可以有效检测出空气中的酒精含量，偏差在可以接受的范围内，非常适用于饮酒量自测，可以广泛应用于日常生活中。

关键词：MQ-3传感器；酒精含量检测；STC89C52；A/D转换

Design and implementation of vehicle borne alcohol content detection system

Abstract

From factories and enterprises to households, the detection and monitoring of alcohol leakage and the monitoring of drunk driving are very important and essential for the personal and property safety of residents. With the increasing number of cars in the world, the frequency of traffic accidents is also increasing. According to the survey of relevant departments, about 60% of traffic accidents are caused by drunk driving, which has seriously threatened people's safe travel. In this paper, a vehicle alcohol content detection system with the function of concentration detection and over limit alarm is designed based on the problem of alcohol driving which is generally concerned by the society. In addition, the alcohol tester can also be used in food processing, wine making and other fields that need to monitor the alcohol concentration in the air.

In the hardware design of the system, single chip microcomputer is used as the control core, and MQ-3 semiconductor is used as the gas acquisition module. It can change the resistance of the sensitive film with the concentration or difference of the external gas. Through the circuit design, the resistance change is transformed into the voltage change, and the voltage information is collected through the A/D conversion chip, the data is converted and processed through the analog-to-digital converter, and finally the measured alcohol concentration value is displayed through the display module, so that the user can see the displayed value more intuitively. In the software design, the main program is used to call the subroutine. The subroutine of each control part is written first, and then the main program is written, which is more conducive to later error correction. When compiling, it is necessary to first understand the workflow of each part, for example, the single-chip microcomputer's processing method for the feedback results of the gas sensor detection module and A/D conversion module, the display module needs to understand the display's working mode, understand the single-chip microcomputer's control display process and program according to the working mode, and then, it is necessary to consider the key.

The experimental results show that the system can effectively detect the alcohol content in the gas, with the advantages of low power consumption, small volume and sensitive response. Its concentration measurement range is 0.107 ~ 0.186mg/l, and the error is about 0.003mg/l. It is very suitable for the self-test of alcohol consumption, and can be widely used in daily life.

Keywords: MQ-3 sensor; Alcohol content testing; STC89C52; A/D conversion

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 研究的目的和意义 1

1.2 酒精含量检测仪背景 1

1.3 酒精含量检测仪研究现状及发展 1

1.4 课题研究内容 2

1.5 本章小结 2

第二章 系统总体设计方案 3

2.1 控制方案分析 3

2.2 总体方案设计 3

2.3 本章小结 3

第三章 系统硬件设计 4

3.1 主控制器 4

3.2 单片机最小系统 5

3.3 气体传感器 5

3.3.1 酒精传感器分类 5

3.3.2 MQ-3传感器 6

3.4 模数（A/D）转换单元 6

3.5 独立按键模块 7

3.6 报警电路设计 8

3.7 LCD显示模块 8

3.7.1 LCD1602液晶的概述 8

3.7.2 LCD1602液晶工作原理 9

3.8 本章小结 10

第四章 系统软件设计 11

4.1 系统的主函数设计 11

4.2 A/D转换函数的设计 12

4.3 显示子函数设计 13

4.4 本章小结 13

第五章 系统测试 15

5.1 硬件调试 15

5.2 软件调试 15

5.3 整体功能调试 15

5.4 问题及解决方案 16

5.5 调试结果 16

5.6 本章小结 17

第六章 结论 18

致 谢 19

参考文献 20

绪论

研究的目的和意义

根据我国公安部交通管理局所公布的最新数据显示，全国机动车保有量已达3.4亿辆，截至2019年6月，仅私家车数量就达到1.98亿，同时，机动车驾驶人数量已达4亿人，而且这些数字仍旧在逐年增涨，目前我国机动车、驾驶人总量及增量均居世界第一。

汽车给人们的生活带来了许多便利，但随之而来的交通事故却也在威胁着人们的安全，中国的酒桌文化由来已久，这也就造成聚会、谈生意等场合无酒不欢。据WHO对各国交通事故的调查统计，大约50%~60%的交通事故和酒后驾车有关。据悉，酒精在人体血液中达到一定浓度（80mg/100ml）时，驾车引起交通事故的概率是未饮酒的3倍，原因是酒精会麻痹人的脑神经，造成大脑反应迟钝，控制能力降低，应对突发情况的能力几乎为零。而有些饮酒很少的驾驶者往往存在侥幸心理，认为自己喝的少便不会出事，但即便如此事故的发生率也是成倍增长，酒后驾驶已成为诱发交通事故的头号杀手。

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