毕业设计论文（定稿）蒋孟林 - 图文

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重庆邮电大学 毕业设计（论文）

设计（论文）题目： 基于单片机的气压传感器研制

学 院 名 称 ： 通信与信息工程学院 学 生 姓 名 ： 专 业 ： 班 级 ： 学 号 ： 指 导 教 师 ： 答辩组 负责人 ：

填表时间：2013年 6月 重庆邮电大学教务处制

蒋孟林 电子信息工程 0120902 08020222 郭晓金 漆晶

重庆邮电大学本科毕业设计（论文）

摘 要

人们对气压的认识也是人类科学研究的一大进步，人们从很久以前就在研究大气，并且有人认为有大气压值，直到马德堡半球实验，真正证明了大气压的存在。气压的应用也是比较早的，如著名的蒸汽火车头，就是人类应用气压的一个显著例子。气压计在现实生活中的使用并不是很明显，大部分人在一生中很少甚至没有接触过气压传感器，但是气压传感器在某些工作领域确实是不可或缺的重要器材，例如国防领域、工业领域、医疗领域以及气象学领域。

本设计介绍了一种基于单片机和气压传感芯片MPX4115A的数字式气压传感器的软、硬件实现方法。通过气压传感芯片MPX4115A获得被测环境中的气压值并输出相应的模拟电压值，此电压经过以LM331芯片为核心的V/F转换电路输出相应数字脉冲信号，输入到单片机的计数器。单片机在单位时间内获得该信号的脉冲数值,计算出脉冲信号的频率。根据电压与频率的线性关系计算出对应的实际气压值，最后通过液晶显示屏LCD1062显示出来，并进行了软硬件调试。

【关键词】单片机 气压传感芯片 液晶显示屏 V/F转换芯片

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重庆邮电大学本科毕业设计（论文）

ABSTRACT

Air pressure is a big step forward for the Human Sciences Research, human being have a long history of study air pressure. The Magdeburg hemispheres experimental proofed the existence of the air pressure. The application of air pressure is relatively early, such as the steam engine is a notable example of human being application of air pressure. Barometer use in real life is not very obvious, most of the people in their lives with little or no contact with barometer. Actually, barometer is an indispensable equipment in certain areas of work, such as the field of national defense, industrial fields，the medical field and the field of meteorology.

This design based on microcontroller STC89C52 and pressure sensor chip MPX4115A, and introduced how its software and hardware works. We can get analog output voltage which corresponds to the measured pressure, by pressure sensor chip MPX4115A. This voltage go through the V / F converter circuit unit which based on LM331, output digital pulse signal ,then input the digital pulse signal to the microcontroller STC89C52 counter. Microcontroller STC89C52 within a unit time obtains the signal pulse values and calculates the frequency of the pulse signal, Calculate the actual pressure value, according to the linear relationship between the voltage and frequency, then display it by LCD1062.

【Key words】Microcontroller Air pressure sensor chip LCD1602

V / F converter chip

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重庆邮电大学本科毕业设计（论文）

目 录

前 言............................................................................................................................ 1 第一章 系统总体方案的设计.................................................................................... 3 第一节 整体设计思想及系统原理........................................................................ 3 第二节 实现方案.................................................................................................... 3 第三节 元件选取.................................................................................................... 4 一、 单片机的选型.............................................................................................. 4 二、 气压传感器.................................................................................................. 5 三、 V/F转换芯片 .............................................................................................. 6 四、 显示器.......................................................................................................... 6 五、 三端稳压器.................................................................................................. 7 第四节 本章小结.................................................................................................... 7 第二章 硬件系统的设计与实现................................................................................ 8 第一节 单片机电路................................................................................................ 8 一、 单片机概述.................................................................................................. 8 二、 单片机片内结构、引脚及封装.................................................................. 8 三、 89C52单片机引脚功能 ............................................................................ 10 四、 单片机的复位电路.................................................................................... 12 五、 单片机的时钟电路.................................................................................... 12 六、 单片机电路图............................................................................................ 13 第二节 气压检测电路.......................................................................................... 14 一、 气压传感器MPX4115A的介绍 .............................................................. 14 二、 MPX4115的引脚及功能 .......................................................................... 14 三、 电压/频率转换器 ...................................................................................... 15 四、 气压检测部分电路图................................................................................ 15 第三节 液晶显示电路.......................................................................................... 16 一、 液晶显示屏介绍........................................................................................ 16 二、 LCD1602介绍........................................................................................... 17 三、 LCD1602的控制....................................................................................... 18 四、 LCD1602的电路图................................................................................... 19 第四节 电源电路.................................................................................................. 19

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重庆邮电大学本科毕业设计（论文）

一、 78L05的介绍 ............................................................................................ 19 二、 78L05的特点 ............................................................................................ 20 三、 78L05的引脚图 ........................................................................................ 20 四、 电源电路图................................................................................................ 21 第五节 总体电路.................................................................................................. 21 第六节 本章小结.................................................................................................. 22 第三章 软件系统的设计与实现.............................................................................. 23 第一节 软件系统设计的概述.............................................................................. 23 第二节 汇编语言和C语言开发单片机的优缺点比较 ..................................... 24 第三节 主要模块程序.......................................................................................... 25 一、 主程序........................................................................................................ 25 二、 主要子程序模块........................................................................................ 27 第四节 本章小结.................................................................................................. 30 第四章 系统的调试.................................................................................................... 31 第一节 硬件模块的测试...................................................................................... 31 一、 电源模块的测试........................................................................................ 31 二、 气压监测模块的测试................................................................................ 32 三、 单片机及LCD1602模块.......................................................................... 33 第二节 软件部分的测试...................................................................................... 34 第三节 本章小结.................................................................................................. 36 结 论.......................................................................................................................... 37 致 谢.......................................................................................................................... 38 参考文献...................................................................................................................... 39 附 录.......................................................................................................................... 40 一、英文原文...................................................................................................... 40 二、英文翻译...................................................................................................... 47 三、工程设计图纸.............................................................................................. 54 四、源程序：...................................................................................................... 55

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重庆邮电大学本科毕业设计（论文）

附 录

一、英文原文

Research and Development on Indoor 3G Wireless Network

Planning Platform

Peiliang CHAI

Hangzhou Normal University Hangzhou, China, 310017 chaipl@126.com

Liang ZHANG

Hangzhou Normal University Hangzhou, China, 310017 zhl@hznu.edu.cn Abstract—In this paper, the situation of 3G wireless technology developments and problems in indoor wireless network design are firstly introduced. The function requirements and architecture for the platform of 3G indoor wireless network design are discussed where the key technologies of the platform design and implementation are analyzed. Finally, this paper concludes the urgency of indoor plan and points out the prospect of the indoor wireless design software.

Keywords-Propagation Modeling; Indoor Wireless Planning; Digital Simulation; Visual Analysis

I. INTRODUCTION

With the development of 3G mobile communications, the coverage of indoor 3G wireless network is becoming more and more important. Recent statistics shows that the high-value customers 80% of working time is in the room. DoCoMo forecast that 20% of indoor coverage of 3G will bring 80% of benefits, and they believe that indoor and outdoor 3G wireless networking should be equal attention and carried out simultaneously at the initial construction. [1] In this context, indoor coverage system is even more important. [2, 3]

II. INDOOR WIRELESS COMMUNICATIONS

A. Problems

For the rapid increasing in mobile user number, the requirement of communication services density and coverage is increasing. Unfortunately, the high-rise buildings in the city have a strong shielding effect on wireless signal. So there are a great number of blind spots and communication crowds in large buildings. The current indoor wireless communication environment is very imperfect, embodied in the following areas:

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重庆邮电大学本科毕业设计（论文）

Coverage: Due to building its own shielding and absorption, resulting in greater transmission attenuation of radio signals, and formatting weak radio signal areas or even blind fields;

Capacity: In the buildings such as shopping malls, meeting centers, because the density of mobile phone use is too large, the Council Ministry of network capacity cannot meet user requirements, so wireless channel congestion occurs;

Quality: In the existence space of high-rise buildings, it easily leads to radio frequency interference. if the serving cells signal is instability, it will result in Ping-pong switching effect, and this will lead to communication interruptions. So it is difficult to guarantee communication quality in this situation. B. Solutions

To indoor users, indoor wireless network planning is a key means to improve the mobile communications quality inside building. It makes use of indoor wireless distribution system to uniformly distribute the wireless signal in every corner of the room. To make sure room area has a good coverage and service needs. The construction of indoor coverage system will improve the call quality and increase mobile phone uptake rates to ensure high-quality indoor mobile communications.

Meanwhile, indoor wireless distribution system can share the outdoor macro cell telephone traffic and expand the network capacity to increase the overall mobile network services. In general, the technical of indoor wireless single coverage can be divided into three types [3]:

1) Micro-cellular access mode

Take indoor micro-cellular systems as the signal source of indoor coverage system. This mode is used more in the city center, for it can be used to solve the coverage and capacity issues simultaneously. 2) Macro-cell access mode

Take outdoor macro-cell systems as the signal source of indoor coverage system. For low telephone traffic and interior blind coverage of small areas, it is used more in remote areas such as suburbs. 3) Repeater mode

When there is remaining capacity in the outdoor station, then we import the outdoor single into the blind spots of indoor through repeaters. C. The engineering design problems

Indoor coverage systems engineering[4, 5] is a complex task, requiring consideration of many factors, including: the signalsource, the field strength distribution, uplink signal to noise ratio, inter-modulation interference, downlink balance, transmission and distribution losses, installation and construction difficulty, cost and other factors, etc. Mainly in the following two aspects:

1) Difficulties on network system design

The design and calculation of network layout drawings and floor drawings is very complicated. The system design requires several software tools and several design staff working together. Especially, the floor layout design also needed structural information. Meanwhile, difficulty of the device statistics is likely to cause the device missing, statistical error of cable length, device waste and long period of design time [6].

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重庆邮电大学本科毕业设计（论文）

2) Difficulties on the analysis of the effect of the wireless signal coverage

Indoor wireless coverage will be affected by the size, shape, structure and layout of the building. These structures may change radio transmission path. Construction materials of different material, such as: wood, metal, glass and cement, will be a great influence of the electromagnetic wave propagation because of their dielectric properties differences. Therefore, the empirically estimated Indoor Wireless radio coverage effect is very difficult in the indoor complex scenes.

III. THE STATUS OF CURRENT RESEARCH

Indoor communications planning is early generated based on the experience. With the launching of 3G services and communications capacity demands increasing, accurate coverage prediction and capacity estimated will reduce comprehensive equipment costs and maintenance costs of operators. Thereby, it will enhance the overall effectiveness of wireless network services. In the respect of product development and applications of indoor wireless network planning, an early starts in foreign, and there has been a series of molded products now. But because of differences in propagation environment and large number of propagation model, there is no commercial standard and unanimously approved software at present.

The RF-uv[8] developed by iBwave is a business planning software to the layout of wireless engineering. This software focus on engineering applications, it can predict wireless signal coverage and supports multiple frequency bands. In addition, it provides comprehensive facilities database management functionality and powerful reporting output capabilities, and so on. Domestically, Shanghai Houli Electronic Technology Company developed Inwiz Indoor Wireless Designer is the first attempt in planning the layout of the indoor wireless. This software supports CDMA, GSM,

PHS, WLAN as well 3G mobile frequency bands. However, these tools cannot be used widely, their performance is limited by the types and scenes of their supported, Such as 3D visualization. Other indoor wireless layout planning software, such as AWE’s Proman[9, 10] is just an experimental and teaching product. AWE company take studying the propagation model as the main business.

IV. INDOOR 3G WIRELESS NETWORK PLANNING

PLATFORM

The wireless network planning software design in indoor and outdoor have significant differences. Indoor wireless network planning software requires a strong 3D model building capabilities to meet the indoor wireless propagation model simulation demand. Moreover, it needs the functions of connecting wireless networks devices, designing their layout and outputting statistical report . A. Functional Requirements

1) Building Structure Modeling (BSM)

Outdoor wireless network planning software can directly get the city's geographic

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重庆邮电大学本科毕业设计（论文）

information, and then simulate the spread of the wireless signal. However, the indoor network planning need BSM module because each building is different from others. Thus, the capabilities of BSM will directly affect the efficiency of indoor network planning software.

2) Radio Propagation Simulation (RPS)

According to the 3D model of the building, and antenna’s location and power, RPS module selects a certain propagation model to analyze and calculate the coverage of indoor wireless network and analyze the reasonableness of the current network coverage. 3) Network System Design (NSD)

Functions of NSD module include network topology of the devices connection, devices layout designing in floor flat, signal power distribution displaying. Its main features are:

? The selection and placement of devices, connections between devices, judgment

of the rationality of the connection between devices;

? Calculation of the signal transmission, attenuation and gain in devices and cables; ? Data synchronization of facility layout design in floor flat and 3D model; 4) System Performance Evaluation (SPE)

SPE is mainly to display 3D model of building, the signal coverage of all systems, equipment and layout. Then the designer can compare the signal coverage and capacity needs, consider whether the planed system meets the demand, or need further optimize. 5) Statistical Report (SP)

? Statistics the number of devices and calculate the length of cable, and so on. ? Print out statistical report and system planning drawings, and so on. 6) Database Management (DBM)

DBM module functions include construction materials database management and equipment database management. Construction Materials database mainly records electromagnetic wave propagation characteristics of different building materials for wireless signal propagation simulation to provide parameters. Device database mainly records of wireless network equipment power, frequency and connectivity features and provides parameters for the device connection, link signal calculation and icon display. B. Software Platform Architecture

According to the needs of the system function, the system can be divided into the function modules showing in TABLE I.

Architecture of the software platform is plug-in (components) architecture, that is, each functional module is in the form of component, the interaction between them through their service to be provided. Each component can provide one or more services. The components interact through the service, so as to constitute an organic whole. The relationship among different modules is show as Figure 1.

TABLE I. LOGICAL FUNCTION MODULES

Abbreviation BSM FLD NSD

Full Name

Building Structure Modeling Floor Layout Design Network System Design

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重庆邮电大学本科毕业设计（论文）

SPE DDM SDM MAT CAD V3D RPT PRT

System Performance Evaluation Device Database Management System Database Management Material Management CAD 3D View Report Print

InteractionFunctional ModuleDataUI InterfaceV3DRPTCAD SoftwarePRTFLDNSDDDMCADPropagation ModelSPEBSMMATSDMMaterialBuildingEquipmentSystemSignal

Figure1. Logical modules framework

V. KEY TECHNOLOGIES OF WIRELESS NETWORK

PLANNING SOFTWARE DESIGN

According to the needs of the system function, the key technologies to design the software are in BSM, NSD, SPE modules. A. Building Structure Modeling (BSM)

Constructing the 3D model of the buildings can be achieved in three different ways: ? Directly draw from scratch;

? Take the architectural image as a background and then draw; ? Read existing CAD file and transform it into 3D model.

From these three ways it can be seen easily that the third one is the most efficient. the key technologies of this method are as follows:

? Reading CAD architectural drawings;

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