基于单片机的超声波液位测量系统的设计

论文编号:JD635  附任务书,答辩PPT,原理图,论文字数:14810,页数:39

摘 要

根据声波在空气中传播反射原理, 以超声波换能器为接口部件, 应用单片机技术对超声波在空气中的传播时间进行测量, 从而设计了一套超声波液位检测系统。从而实现无接触式测距。系统硬件由系统由AT89C4051 单片机、超声波发射电路、超声波接收放大电路、环境温度采集电路及显示电路组成。并对其检测原理、方法以及系统软件结构作了详细介绍, 在超声波测距中进行温度补偿和对时间计算的误差修正, 讨论了提高测距精度的方法, 并提出了干扰噪声的处理方法。对产生测量误差的原因进行了分析, 并提出了解决的途径和方法。

关键词:超声波测距; 声速; 单片机；液位；温度补偿

Meter Based on Ultrasonic to Measure
the Liquid-level

Abstract
According to an up in the air dissemination  glint principle, with a wave changes the ability machine for connect a people's parts, apply a machine technique to carry on the diagraph to an up in the air dissemination time, thus designed an examination system. Thus carry out to have no contact the type measures to be apart from the system hardware is been shot the electric circuit, a wave by a machine of AT89C4051, a wave by the system to receive to enlarge the electric circuit, the environment temperature to collect the electric circuit and the manifestation electric circuits to constitute the Combine the as the to the it's the examined the principle, the method the and the system the  software the structures the to the make the detailed introduction, the carry the on the temperature the repair the and the compute to the time the in the a wave the measuring the to the be apart the from the of the error margin revise, the discuss the exaltation to the measure the method of the be apart the from the accuracy, and put forward the processing method of the interference noise voice. Measured the reason of the error margin to carry on the analysis to the creation, and the path and the method that definitely put forward the understanding.

Key words: ultrasonic ranging; velocity of sound; microprocessor；Liquid-level; temperature compensate

目  录

摘要…………………………………………………………………………………Ⅰ
Abstract……………………………………………………………………………Ⅱ
绪论……………………………………………………………………………………1
第1章 超声波液位测量仪的硬件设计………………………………………………3
     1.1 超声波液位测量仪的总体设计…………………………………………3
        1.1.1  超声波测距原理 ………………………………………………3
        1.1.2  超声波液位测量仪硬件的结构…………………………………4
1.2 单片机与各部分电路的接口…………………………………………5
     1.3 超声波发射及驱动电路……………………………………………………6
1.4 超声波接收和过零检验电路 …………………………………………6
1.5 温度采集和V/F转换电路………………………………………………7
 1.5.1 信号采集电路…………………………………………………………7
1.5.2 放大电路与线性调整电路……………………………………………9
1.5.3  V/F转换电路   …………………………………………………… 9
1.5.4  PT100分度表 …………………………………………………………11
     1.6 显示电路及键盘输入…………………………………………………………11

1.7 直流供电电路的设计………………………………………………………13
第2章  PC机与单片机之间的通信………………………………………………………14
     2.1 PC机与单片机通信系统总框架……………………………………………14
     2.2 串口通信网络硬件构成…………………………………………………15
         2.2.1 RS-485通信总线简介…………………………………………………15
         2.2.2 通信接口设计方案……………………………………………………16
         2.2.3 串口的通信协议 ………………………………………………………17
第3章  误差分析…………………………………………………………………………20
     3.1  超声波回波声强的影响………………………………………………………20
  3.2   超声波波束入射角的影响………………………………………………20
  3.3   超声波传播速度的影响 ……………………………………………………21
     3.4   提高测试精度的措施…………………………………………………………22
     3.5   数据误差 ……………………………………………………………………23
     3.6   抗干扰…………………………………………………………………………23
第4章  超声波液位测量仪的软件设计 …………………………………………………24
     4.1  主程序模块 …………………………………………………………………24
     4.2  串行口中断程序模块 ………………………………………………………25
结论 ………………………………………………………………………………………26
致谢……………………………………………………………………………………27
参考文献 …………………………………………………………………………………28
附录（一）………………………………………………………………………………29
附录（二）………………………………………………………………………………37
附录（三）………………………………………………………………………………39

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