论文总字数：25304字

摘 要

随着现代信息科学技术的迅猛发展，健康舒适的生活成为人们提升幸福感的迫切需要。生活质量要求的提高也包括对空气质量要求的提高，同时对空气质量检测系统的需求也增大了。目前大部分的幼儿园都没有配备实时的空气质量检测系统，免疫系统尚未完全建成的幼儿更容易收到空气污染物的危害。所以设计一个可以在幼儿园实时监测空气质量的系统意义重大。

本毕业设计是制作幼儿园空气质量实时监测系统，分为数据采集端和上位机端。本论文涉及到的主要是数据采集端的设计。该系统的设计以STM32F103C8T6为核心。气体传感器SGP30采集空气中污染物含量的信号，单片机通过IIC串口读取数据（包括校验位）后进行简单处理（舍弃校验位）。因为要求的设计的有线传输距离为100米，所以采用RS485传输协议。而此时单片机输出的信号为TTL电平，无法在RS485传输线中直接传输。因此在单片机的下位加入TTL转RS485模块使信号可以正常输出。同理，RS485传输也无法直接接入电脑，所以在传输进上位机前用RS485转USB模块转化电平逻辑。最后上位机再根据设计的要求对数据进行处理。

毕业设计通过了毕业软硬件验收，且可以达到设计要求。

关键词: STM32F103C8T6 空气质量监测 实时 SGP30 RS485

Kindergarten Air Quality Detection System

Abstract

With the rapid development of modern information science and technology, healthy and comfortable life has become an urgent need for people to improve their happiness. The improvement of quality of life also includes the improvement of air quality, and at the same time, the demand of air quality detection system also increases. At present, most kindergartens are not equipped with real-time air quality detection system, and children with incomplete immune system are more vulnerable to air pollutants. Therefore, it is of great significance to design a system that can monitor air quality in kindergarten in real time.

This graduation project is to make a kindergarten air quality real-time monitoring system, divided into data acquisition terminal and upper computer terminal. This paper deals with the design of data acquisition terminal. The design of this system is based on STM32F103C8T6. Gas sensor SGP30 collects the signal of pollutant content in the air, and the single-chip microcomputer reads the data (including the check bit) through the IIC serial port for simple processing (abandoning the check bit). Because the required design of the wire transmission distance is 100 meters, so the use of RS485 transmission protocol. At this time, the output signal of SCM is TTL level, which cannot be directly transmitted in RS485 transmission line. Therefore, TTL to RS485 module is added in the lower bit of SCM to make the signal output normal. Similarly, RS485 transmission cannot be directly connected to the computer, so RS485 to USB module is used to convert level logic before transmission to the host computer. Finally, the host computer processes the data according to the design requirements.

This graduation design has passed the hardware acceptance, and it can meet the design requirements.

Key words: STM32F103C8T6;real-time air quality monitoring;SGP30;RS485

目录

摘要 I

ABSTRACT II

目录 III

第一章绪论 1

1.1研究的目的和意义 1

1.2国内外研究现状 3

1.3研究内容 4

第二章系统方案 5

2.1 总体设计思路 5

2.2 系统硬件模块选择 6

2.2.1 气体传感器 6

2.2.2 单片机芯片 9

2.2.3 有线传输 13

第三章 硬件电路设计 16

3.1 单片机系统 16

3.2有线传输电路 19

3.3气体传感器电路 21

3.4电源电路 22

3.5硬件完整原理图 22

第四章 现场数据采集及处理软件设计 24

4.1 Keil u Vision5 24

4.2 数据采集程序思路 24

4.3 编程实现 25

第五章 软硬件联调结果及分析 29

5.1 烧录程序 29

5.2硬件调试 29

5.3 软件调试 30

5.4 整体联调 36

5.4.1 数据传输（USB） 36

5.4.2 数据传输（有线） 38

5.5 结果及其分析 39

总结与展望 41

参考文献 43

致谢 45

附录一 硬件整体原理图 46

附录二 PCB图 47

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