数字流量计

摘    要
目前人类已经步入数字时代，本文设计的数字式流量计由霍尔传感器、放大器、门控电路、计数器、单片机CPU处理器和液晶（LCD）显示系统组成。霍尔传感器是采用霍尔效应做成的磁性传感器。具有稳定性好，受漂移电压的影响较小，线性好等特点。78E58B单片机具有自带程序存储器，不需要扩展外部存储器的优点。液晶显示器（LCD）是一种显示清晰、高可靠、高寿命、低功耗、低价格工作电压的显示器件，广泛应用于计算器、万用表、各种便携式仪器和低功耗应用系统中。
本文采用单片机技术来设计数字式流量计。首先，利用霍尔传感器检测涡轮的转动频率，放大器将霍尔传感器输出的比较弱的表示转动频率的脉冲信号放大，门控电路用于控制检测周期，然后通过计数器计数将脉冲数目输入给CPU——78E58B单片计算机，用78E58B单片机计算出检测信号的转动频率值，采用查表方式，每一转动频率值对应流量值，最后，液晶（LCD）显示器将测量过程中输入和需要输出的控制信息以及测量结果通过液晶显示器显示出来。用单片机技术和数字电路设计的数字式流量计克服了传统机械表头式流量计的一些弊端。
本文介绍了数字式流量计的系统总体结构、系统的硬件电路设计和系统的软件设计。数字式流量计广泛应用在工业生产特别是在化工和能源等领域对液体、气体等流体的流量进行计量。

                                                           

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关键词：数字式流量计 、流量、单片机
Abstract
Current mankind have already followed the arithmetic figure ages,this text the arithmetic figure type that design the floweter spread to hall,englarger,single slice the machine CPU the processor to show the system with LCD to constitute.
The hall spreads to adopt the made-up magnetism of hall effect dpread to hall sensor.The stability that have the influence is good,and suffer the drift electric voltage small,and characteristics of line is good.78E58B is only a slice advantage for machine tool having from taking the procedure rom,not needing expanding the exterior rom.It’s clear that liquid crystal display(LCD) is a kind of manifestation,high dependable,the high life span,low cost,low price work the electric voltage’s display piece,extensive application is in the calculator every kind of instrument with the system inside of low cost application.
We use single-chip computer technology to design digital flowmeter. Firstly，use hall sensor to sense running frequency of turbine flowmeter. Secondly， use amplifier to amplify the weak frequency signal(analog signal) outputted by sensor,  gating circuit is used to control measurement cycle. Then, use counter to translate the analog frequency signal into digital signal which can be processed by computer, and input to 78E58B single-chip computer. Use 78E58B singlechip computer comput frequency value, and find corresponding flow value of each frequency value through table. Lastly, LCD display system display the control and  measurement information.

The  system  framework, hardware circuit design and software design  of  digital flowmeter are  presented in the paper. The extensive application of flowmeter of arithmetic  figure type produces in the industries to especially wait the realm with energy at the chemical engineering to liquid, air……etc. the fluid dischange processds to calculate.
                                                           

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Keywords: Digital flowmeter、 Flow、 Singlechip computer [资料来源：http://www.THINK58.com]

目   录
绪   论 6
第一章  系统总体设计 7
1-1  应用开发过程 7
1-1-1 总体论证 7
1-1-2 系统设计 8
1-1-3 硬件及软件开发及联机调试 8
1-2  系统设计 9
1-2-1 系统原理 9
1-2-2 系统结构 9
第二章  系统硬件电路设计 11
2-1  放大部分 11
2-1-1 霍尔传感器 11
2-1-2 放大电路设计 14
2-1-3 整形电路设计 16
2-2  计数部分 19
2-2-1 门控电路设计 19
2-2-2 计数器设计 19
2-3  主控部分(CPU选用) 20
2-3-1 复位电路 23
2-3-2 振荡电路 23
2-3-3 系统电源稳压滤波电路 24
2-4  液晶显示器（LCD） 25
第三章  系统软件设计 27
3-1  系统软件设计概述 27
3-2  几个关键的软件模块设计 29
3-2-1 软件定时器中断服务模块 29
3-2-2 流量数据处理及转换模块 30 [来源：http://www.think58.com]
第四章  结束语 31
致   谢 32
参考文献 33
附录A：源代码 34
附录B：系统原理图 67 [资料来源：http://www.THINK58.com]

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