摘 要
本设计实现了对不同浓度酒精的检测和显示，通过适当改进可以用于检测酒后驾车。本文用STC12C5A16AD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。
本设计主要研究了（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单片机控制经A/D转换，得到数字电压信号；用于显示浓度的数码管显示模块。（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数码管显示。（3）对设计的传感器进行了标定。设计的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，最大误差为8.2%满足设计要求。
本设计的特色在于标准的确定。对于流动空气，样品的稳定性和水蒸气的影响，提出了解决方案和验证方法。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，改进之后对解决酒后驾车事故和特殊场合酒精检测都可以使用。 关键词：气体传感器;模数转换;单片机
Abstract
Different concentrations of alcohol solution are detected and showed in the design. The design can be used to the detection of drunk driving through improvement. In this thesis, the concentration of alcohol can be measured and displayed by using the gas sensor based on STC12C5A16AD MCU and MQ-3.
In the thesis Major researches are three points. (1) In the hardware, detecting the technology parameters MQ-3 gas sensor, and connecting it to a testing part of the alcohol gas concentration; Analog voltage signal amplification to drive light-emitting diode light to alarm; conversing the voltage signal through the A/D conversion at the control of the single-chip, obtaining the digital voltage signal; displaying the concentration in the digital tube display module.(2)In the Software, linear conversion between the concentration of the alcohol and the voltage and the digital display of the final concentration value.(3) The designed sensor is calibrated. The design of gas sensor is responsive to the alcohol, can measure concentration in the effective range of its concentration. And in the low concentration of alcohol in the test the error is small with the maximum error 8.2%, meeting requirements of the design.
The characteristics of the thesis are to determine the standard. The solutions and verification methods are proposed about the flow of air samples, the sample stability and water vapor. The conversion between voltage and concentration in different range is treated as linear relationship. The design of sensor can detect different the alcohol gas with different concentration. It plays an important role to solve the drunk-driving accidents and alcohol testing for special occasions after improvement.
Key Words: Gas sensor; A/D conversion; Single-chip Microcomputer
毕业设计用纸
目录
第一章 引言 ............................................................ 1
1.1 设计背景 ....................................................... 1 1.2 设计酒精浓度探测仪的意义 ....................................... 1 1.3 本文主要研究工作 ............................................... 1 第二章 元器件和开发工具介绍 ............................................ 3
2.1 ADC0809 ........................................................ 3
2.1.1主要特性 .................................................. 3 2.1.2内部结构 .................................................. 3 2.1.3外部特性（引脚功能） ...................................... 4 2.2 STC12C5A16AD ................................................... 4 2.3 Protel软件介绍 ............................................... 5 2.4 KEIL介绍 ..................................................... 6 2.5 ProtuesISIS介绍 .............................................. 6 第三章 硬件电路设计 .................................................... 8
3.1 设计框图 ...................................................... 8 3.2 乙醇信号检测及调理电路 ........................................ 8 3.3 单片机电路 .................................................. 11 3.4 显示电路 ..................................................... 12 3.5 阈值存储 ..................................................... 13 第四章 软件设计 ....................................................... 14 第五章 调试 ........................................................... 17 参考文献 .............................................................. 20 致谢 .................................................................. 21 附录A元器件清单 ...................................................... 22 附录B 实物图 ......................................................... 23 附录C 程序 ........................................................... 24
第0页 共 28 页