摘要：随着社会的进步，生产技术和生产工艺的发展，人们对液位检测的要求越来越高。这是由于电子技术、微电子技术和微机控制系统的广泛应用，单片机控制系统以其控制精度高，性能稳定可靠，设置操作方便，造价低等诸多特点，被应用到液位系统的控制中来。

   本文概述了通过极板间由于介质不同，介电常数发生变化而导致其电容值发生变化的基本原理，从而设计的一款电容式液位计。对于系统的一些主要参数进行了讨论，并且在介绍液位检测功能的基础上，提出了系统的总体构成。通过多种测量电路设计方案比较，得出了最佳设计方案。

本文介绍了以电容式液位传感器、A/D转换芯片TLC2543、液晶显示器LCD12864和AT89S52单片机为主要控制元件的液位检测的设计方法。本文从液位检测、A/D转换、液晶显示、超限报警等方面详细介绍了硬件电路，并且对组成各系统电路的芯片及其工作原理进行了介绍。然后详细介绍了A/D转换程序、液晶显示程序、按键程序、超限报警程序等，并用流程图进行了说明。

通过硬件和软件的联合调试，实现了对一定范围内的液位的测量，实现了液位动态显示的结果，并实现了上下限报警，任务书上所要求的内容均已经完成。

关键词：单片机；液位传感器；液位检测；A/D转换；超限报警

Water level sensor circuit and display intelligent detection

Abstract: With the development of society and the development of production technology and production technology, people's requirements for liquid level detection are getting higher and higher. This is due to the wide application of electronic technology, microelectronic technology and microcomputer control system. Single chip microcomputer control system has been applied to the control of liquid level system with its high control precision, stable and reliable performance, convenient operation and low cost.

In this paper, the basic principle of the change of the capacitance value caused by the change of dielectric constant between the polar plates and the dielectric constant is summarized, and a capacitive level meter is designed. The main parameters of the system are discussed, and on the basis of introducing the function of liquid level detection, the overall structure of the system is put forward. Through the comparison of various measuring circuit design schemes, the best design scheme is obtained.

This paper introduces the design method of liquid level detection with capacitive level sensor, A/D conversion chip TLC2543, liquid crystal display LCD12864 and AT89S52 single chip microcomputer as the main control elements. In this paper, the hardware circuit is introduced in detail from the aspects of liquid level detection, A/D conversion, liquid crystal display and overlimit alarm, and the chip and its working principle are introduced. Then, the A/D conversion program, LCD display program, key program and overrun alarm program are introduced in detail.

Through joint debugging of hardware and software, the measurement of liquid level in a certain range has been realized, the result of dynamic display of liquid level is realized, and the alarm of upper and lower limits is realized. All the contents required in the task book have been completed.

Keywords: single chip microcomputer; liquid level sensor; liquid level detection; A/D conversion; out of limit alarm.

目录

摘要 i

Abstract ii

1 绪论 1

1.1 本课题研究意义 1

1.1.1 课题背景 1

1.1.2 国内外研究现状与水平 1

1.1.3 行业发展趋势 4

1.2 本课题方案讨论 5

1.2.1 传感器选择的讨论 5

1.2.2 测量电路方案讨论 7

1.3 本课题主要研究工作及内容安排 8

2 电容式传感器的设计 9

2.1 传感器的组成及原理 9

2.1.1 电容器特性 9