论文总字数：32513字

摘 要

伴随着社会经济的发展、科技的进步、生活水平的改善，社会人口数量也越来越多；随之而来的就是住宅房、办公楼、工厂等建筑物的与日俱增。为了降低建筑的成本，便出现了林林总总的建筑材料，这也极大地增加了建筑物的易燃性。此外，各种各样的电子产品充斥着我们的日常生活，也给建筑物的易燃性带来极大的威胁。一旦火灾发生，若没有及时地采取施救措施，将带来无法估量的后果。为了避免火灾和减少火灾发生时造成的损失，准确的预防和实时的监测成为重中之重。如果能对火灾特征信号进行自动的实时监测，将可以预防火灾的发生。因此，一个火灾监控和自动报警系统的设计将很有意义。

本研究中，采用的核心控制器为单片微型计算机（单片机）。采用单片机来设计控制系统，它不同于可直接使用的PLC；使用前必须先搭建基本外围电路，构成单片机最小系统，以保证单片机可以正常运行。其次，就是根据所需的功能，开发各个功能模块电路，并编写各模块的程序。模块电路的接口用于和单片机最小系统进行衔接，从而构成价格低廉、稳定性好、监测准确的自动火灾报警系统。本系统设计中，开发设计的功能模块有主控模块、温度测量电路模块、烟雾检测电路模块、液晶显示电路模块、按键设置电路模块、声光报警电路模块。

以STC89C52单片机为控制器设计单片机主控电路；测温电路模块以温度传感器（DS18B20）为核心设计；以气体烟雾传感器（MQ-2）开发烟雾检测模块；这些模块同时工作，实时监测环境中火灾特征信号，并将数据发送至单片机处理。当检测环境中的温度值和烟雾浓度值超过程序预设值时，通过单片机驱动报警电路进行声光报警；以不同颜色的LED灯闪烁和不同频率的蜂鸣器鸣叫方式，区分不同的超限报警，报警声音可以提醒现场的人员做好疏散撤离和扑救火灾的准备。本系统具有稳定性好、结构简单、性价比高、智能化等特点，可以适用于绝大多数的火灾检测报警的场合，具有一定的实用性。

关键字：STC89C52 自动火灾报警 DS18B20 烟雾传感器MQ-2

Automatic Fire Alarm System Based on Single-chip Microcomputer

Abstract

Along with the development of social economy, the advancement of science and technology, and the improvement of living standards, the number of social population is increasing. The number of buildings such as residential houses, office buildings and factories is increasing. In order to reduce the cost of the building, there are a lot of building materials, which greatly increases the flammability of the building. In addition, a wide variety of electronic products are filled with our daily lives, and also pose a great threat to the flammability of buildings. In the event of a fire, failure to take timely action will have immeasurable consequences. In order to avoid fires and reduce the losses caused by fires, accurate prevention and real-time monitoring have become the top priority. If the fire characteristic signal can be automatically monitored in real time, it will prevent the occurrence of fire. Therefore, the design of a fire monitoring and automatic alarm system will make sense.

In this study, the core controller used was a single-chip microcomputer (microcontroller). The MCU is used to design the control system. It is different from the PLC that can be used directly. Before use, the basic peripheral circuit must be built to form the minimum system of the MCU to ensure that the MCU can operate normally. Secondly, according to the required functions, each function module circuit is developed, and the program of each module is written. The interface of the module circuit is used to interface with the minimum system of the single chip microcomputer, thereby forming an automatic fire alarm system with low price, good stability and accurate monitoring. In the design of the system, the functional modules developed and designed include a main control module, a temperature measurement circuit module, a smoke detection circuit module, a liquid crystal display circuit module, a button setting circuit module, and an audible and visual alarm circuit module.

The STC89C2 single-chip microcomputer is used as the controller to design the main control circuit of the single-chip microcomputer; the temperature measurement circuit module is designed with the temperature sensor (DS18B20) as the core; the smoke detection module is developed with the gas smoke sensor (MQ-2); these modules work at the same time to monitor the fire in the environment in real time. The characteristic signal is sent to the microcontroller for processing. When the temperature value and the smoke concentration value in the detection environment exceed the preset value of the program, the sound and light alarm is driven by the single-chip microcomputer to drive the alarm circuit; the different color LED light flashes and the buzzer sounding mode of different frequencies distinguish different over-limits. Alarms and alarm sounds can remind the on-site personnel to prepare for evacuation and fire fighting. The system has the characteristics of good stability, simple structure, high cost performance, and intelligence, and can be applied to most fire detection and alarm occasions, and has certain practicability.

Keywords: STC89C52 automatic fire alarm DS18B20 smoke sensor MQ-2

目录

摘要 I

Abstract II

第一章 绪论 1

1.1课题背景简介 1

1.2课题研究的目的与意义 2

1.3课题的主要研究内容 2

1.4研究的思路和手段 3

1.5本章小结 3

第二章 火灾报警系统总体方案设计 5

2.1系统的功能要求 5

2.2系统设计总架构 5

2.3主控模块 7

2.4烟雾检测模块 8

2.5温度测量模块 9

2.6液晶显示模块 9

2.7声光报警模块 10

2.8本章小结 10

第三章 软硬件选型 11

3.1 系统工作原理 11

3.2 软件选型 11

3.3 单片机选型 13

3.4 烟雾传感器的选择 15

3.5 A/D转换器的选择 17

3.6 温度传感器的选择 18

3.7 显示器件的选择 20

3.8 本章小结 23

第四章 系统硬件电路设计 24

4.1 主控电路设计 24

4.2 烟雾检测电路设计 25

4.3 温度测量电路设计 26

4.4 液晶显示电路设计 27

4.5 按键电路设计 28

4.6 声光报警电路设计 29

4.7 本章小结 30

第五章 系统软件设计 31

5.1 系统I/O口分配 31

5.2 主处理程序设计 31

5.3 传感器程序设计 33

5.4 本章小结 37

第六章 系统调试与成果汇报 38

6.1 系统仿真调试 38

6.2 仿真系统功能展示 40

6.3 注意事项 42

6.4 本章小结 43

第七章 总结与展望 44

参考文献 45

致谢 47

附录一 原理图和PCB图 48

附录二 程序源代码 50

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