积分式数字电压表设计

摘要

在集总参数电路中，考虑到操作的安全性、方便性、准确性等因素，测量的主要参量是电压，电子电路的许多特性，如频率特性、调制度、非线性失真系数等都可以视为电压的派生量，各种电路的工作状态，如谐振、平衡、饱和、截止及动态范围等，通常都用电压的形式来反映。电子设备的各种控制、反馈信号也主要表现为电压量。因此电压测量是电子测量的最基本内容之一。本系统是利用AT89C51单片机的一种电压测量电路,该系统除了采用ICL7135高精度、双积分A/D转换电路外，还增设了超限报警电路。正文着重给出了软硬件系统的各部分电路，介绍了双积分电路的原理，AT89C51的特点，ICL7135的功能和应用。

关键词：数字电压表AT89C51 ICL7135双积分A/D转换器

Abstract

In the lumped parameter circuit, taking into account the safety of operation, convenience, accuracy and other factors, the main parameters measured are voltage, many of the features of electronic circuits, such as frequency, modulation, nonlinear distortion factor and so can voltage is derived as the amount of the working status of various circuits, such as resonance, balance, saturation, cut-off and dynamic range, etc., are usually used to reflect the form of voltage. A variety of electronic equipment control, the feedback voltage signal can also be reflected as the amount. Therefore, the voltage measurement is one of the most basic electronic measurement. This system is the use of a voltage measurement AT89C51 microcontroller circuit,In addition to using the system ICL7135 precision, double integral A / D converter circuit, but also added a limit alarm circuit. Text focuses on the various hardware and software system is given part of the circuit, introducing the principle of the double integrator, AT89C51 features, ICL7135 features and applications.

Keywords:Single Chip Micyoco Voltage detection Analog Digital Conversion

前言1

1总体方案论证与选择1

2硬件设计3

2.1输入电路3

2.2 A/D转换电路4

2.2.1双积A/D转换器的工作原理4

2.2.2 7135的应用5

2.2.3 AT89C51单片机6

2.2.4 7135数字部分6

2.2.4.1主要介绍引脚的使用7

2.2.4.2性能8

2.2.4.3数据输出方式8

2.2.4.4与单片机系统的串行连接9

2.2.4.4.1输入衰减器和放大器增益控制10

2.2.4.4.2电路参数计算11

2.3单片机部分12

2.4液晶显示部分12

3系统的软件设计13

3.1时钟频率的确定13

3.2监控程序设计13

3.3主程序流程图15

3.4开机自检流程图16

3.5 ROM自检流程图17

3.6显示子程序流程图18

3.7A/D中断服务流程图19

4结束语20

附录1：主程序21

附录2：ROM自检23

附录3：RAM自检25

附录4：输入通道自检26

附录5：LED显示自检（显示4位“0“和4位数字“8”）28

附录6：显示子程序30

附录7：A/D中断32

附录8：数字电压表设计图35

参考文献36