I摘 要本文论述了一种基于单片机的多功能参数检测系统的设计与实现过程。系统采用了单片机 STC89C52 为主控芯片，设计了电流电压转换电路，能够将现场的温度、压力、流量、液位等物理量所对应的 4-20mA 电流信号转换成 1-5V 的直流电压信号，并提供给 A/D 转换电路。根据系统测量的模拟量较多的特点，使用 ADC0809 作为 A/D转换芯片。使用 LCD1602 作为显示器件，能够实时显示采集的温度、压力、流量、液位等物理量。同时，系统还设计了参数设置与报警提示等功能电路。论文共分三部分介绍了基于单片机的多功能参数检测系统设计过程。第一部分，主要介绍了系统的方案设计，明确了系统的功能要求，给出了系统方案框图，并对部分元器件的选择、软硬件开发环境进行了介绍；第二部分，主要介绍了硬件电路的设计过程，包括主要器件的介绍、与单片机接口电路设计思路叙述；第三部分，对软件部分的设计思路做了介绍，并分别数据采集、显示、按键处理等各功能部分设计过程进行了叙述。关键词：单片机；电流电压转换； A/D 转换；LCD1602；声光报警IIAbstractThis paper discusses a kind of multi-functional parameter detection system based on single chip microcomputer.This design use the single chip microcomputer as the controller STC89C52 chip,using current voltage conversion circuit can change the scene of the physical quantities,such as temperature,pressure,flow,level of 4-20 mA current signal into 1-5 V voltage signal,and provide for A/D conversion circuit.According to the characteristics of the measurement system that there are much more analog quantities,ADC0809 is used as A/D conversion chip,using LCD1602 as a display device,can collect real-time display of temperature,pressure,flow and liquid level.At the same time,the system also designed the circuit for parameter setting and sound and light alarming function.This paper is divided into three part introduces multi-functional parameter detection system based on single chip microcomputer.The first part,mainly introduced the system design,the functional requirements of system,the system block diagram is given,and the selection of some components,hardware and software development environments are introduced;The second part,mainly introduces the design process of hardware circuit,including the main device,single chip microcomputer interface circuit design ideas of narrative;The third part,the design idea of the software part is presented,and various functions such as data acquisition,display and buttons processing are discusses.Key words: Single chip microcomputer; Current voltage conversion; A/D conversion; LCD1602;Sound and light alarmIII目 录绪 论.11 方案设计.21.1 总体框架的设计.21.2 单片机开发环境的选择.31.2.1 电路图绘制软件.31.2.2 Keil_C 软件.42 硬件电路设计.62.1 传感器的选型.62.2 单片机最小系统设计.62.2.1 单片机的选型.62.2.2 时钟电路与复位电路.82.2.3 单片机使用注意事项.102.3 电流电压转换电路设计.112.4 模拟量采集电路设计.132.4.1 ADC0809 概述.132.4.2 ADC0809 与单片机接口电路.152.5 显示电路设计.162.5.1 LCD1602 引脚结构.162.5.2 LCD1602 主要技术参数及特性.162.5.3 LCD1602 与单片机的接口电路.172.6 按键接口电路设计.172.7 报警电路设计.182.8 串行口功能设计.192.8.1 RS-232 串行接口.192.8.2 MAX232 简介.203 软件部分设计.