毕业设计 - 智能压力变送器的研制 - 图文

毕业设计

题 目 智能压力变送器的研制 学 院 自动化与电气工程学院 专 业 流程工业及其自动化 班 级 学 生 学 号 指导教师

二〇一四年五月三十日

济南大学毕业设计

摘 要

随着工业应用对信号检测与处理的要求不断提高，新型智能仪表将在生产过程中占有越来越重要的地位。压力，作为工业生产过程中重要参数之一，实现对其精确的检测和控制是保证生产过程运行和设备安全必不可少的条件。高精度的压力测量和变送更是保证产品质量、提高效益的有力保障。因此，实现智能化的压力检测系统对工业过程具有非常重要的意义。

本设计主要是以ATC8951单片机为核心的信号测量、数据处理显示。是通过压力传感器将压力信号转换成电压信号，经过运算放大器进行放大，送至8位A/D转换器，从而将模拟信号转换为单片机能够处理的数字信号，再经单片机转换成LED显示器可以识别的信息，最后由LED数码管显示，并输出4-20mA的电流信号。在测量的过程中通过独立键盘进行设置测量的上下限，当输入的压力超出上下限时，蜂鸣器启动报警。

本设计的最终结果是，利用Proteus仿真软件进行模拟仿真，将软件下载至硬件上调试出需要显示的数据，当输入的模拟信号发生变化的时候，通过A/D转换，单片机数据处理后，LED数码管将显示不同的数值。

关键词：压力；ATC89C51；A/D转换，压力传感器；LED显示

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济南大学毕业设计

ABSTRACT

With the requirement of signal detection and processing in industrial application increasing, the new intelligent instrument will play an increasingly important position in the production process. Pressure, as one of the important industrial process parameters, to achieve accurate detection and control of their production process is the necessary condition to ensure the safety of operation and the equipment. Precise pressure measurement and transmission ensure product quality, enhance effective protection benefits. Therefore, intelligent pressure detection system has a very important significance in industrial processes.

The design is based on measurement and display of AT89C51 single-chip. This is the pressure sensors will convert the pressure into electrical signals. After using operational amplifier, the signal is amplified, and transferred to the 8-bit A/D converter. Then the analog signal is converted into digital signals which can be identified by single-chip and then converted by single-chip into the information which can be displayed on LED monitor, and finally display output. In the course of show, through the keyboard to input all kinds of data and commands into the computer, the single-chip will locate in a predetermined function step to display required values.

The end result of this design is that by downloading software to the hardware, it will get the data which is required to display by debugging. When the input analog signals change, the LED monitor will display different values through the A/D converting.

Key words: pressure; ATC89C51; A/D converter; pressure sensor; LED monitor;

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济南大学毕业设计

目 录

摘 要 ................................................................................................................................ I ABSTRACT ......................................................................................................................... II 1 前言 ................................................................................................................................... 1 1.1 相关背景和应用简介 ................................................................................................. 1 1.2 智能压力传感器的发展方向 ..................................................................................... 1 1.3 该设计研究的内容 ..................................................................................................... 2 2 系统总体设计 ................................................................................................................... 3 2.1 系统设计要求 ............................................................................................................. 3 2.2 总体设计方案 ............................................................................................................. 3 2.3 智能压力变送器原理组成图 ..................................................................................... 4 3 智能压力变送器的硬件设计 ........................................................................................... 5 3.1 压力传感器 ................................................................................................................. 5 3.1.1 压力传感器的选择 .............................................................................................. 5 3.1.2 压阻式压力传感器的工作原理 .......................................................................... 5 3.1.3 压阻式压力传感器的结构组成 .......................................................................... 7 3.2 电阻信号的测量桥路 ................................................................................................. 7 3.2.1 测量电路的工作原理 .......................................................................................... 7 3.3 信号放大电路 ........................................................................................................... 10 3.3.1 放大器的选择 .................................................................................................... 10 3.3.2 OP07双极性运算放大器 ................................................................................... 10 3.3.3 三运放差分放大电路 ........................................................................................ 11 3.4 A/D转换模块 ............................................................................................................ 11 3.4.1 ADC0809简介 .................................................................................................... 12 3.4.2 ADC0809与单片机连接 .................................................................................... 13 3.5 单片机 ....................................................................................................................... 14 3.5.1 AT89C51单片机简介 ......................................................................................... 14 3.5.2 单片机复位电路与自激振荡电路 .................................................................... 15 3.6 键盘接口输入 ........................................................................................................... 16 3.6.1键盘分类简介及选择 ......................................................................................... 16 3.6.2键盘抖动及消除 ................................................................................................. 17 3.7 LED显示接口电路 ................................................................................................. 18 3.7.1 LED数码管显示器............................................................................................. 18 3.7.2 LED数码管的静态显示与动态显示.............................................................. 19 3.7.3 LED数码管静态显示接口电路...................................................................... 20 3.8 D/A转换模拟输出及信号放大 .............................................................................. 21 3.8.1 DAC0832简介 ................................................................................................. 21 3.8.2 ISO EM系列直流信号隔离适配器简介 ........................................................ 22 3.8.3 D/A转换输出与放大电路 .............................................................................. 24 3.9 报警电路.................................................................................................................. 25 4 智能压力变送器软件设计 ............................................................................................. 26 4.1 A/D转换器软件设计 ................................................................................................ 26 4.2 单片机与键盘接口程序设计.................................................................................. 27

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济南大学毕业设计

4.3 LED数码管静态显示程序设计 ............................................................................. 28 4.4 D/A转换器程序设计 .............................................................................................. 29 4.5 智能压力变送器程序设计...................................................................................... 30 5 智能压力变送器PCB板设计 ........................................................................................ 31 结 论 ............................................................................................................................. 34 参考文献 ............................................................................................................................. 35 致 谢 ............................................................................................................................. 36 附 录 ............................................................................................................................. 37

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