USB（Universal Serial Bus）是一种新型的通用串行总线，它是快速的、双向的、同步的、可以热插拨的、动态连接且价格低廉的串行接口。正是基于这一特点，现在很多的计算机外设都有USB接口。本文正是利用这一新型USB接口来设计上位机与下位机系统之间的通信。利用新型的一线式数字温度传感器测量温度，并通过USB接口和计算机端应用软件进行通信。

本文首先介绍了本系统相关的背景知识以及USB的通信协议，进而介绍温度控制的基本意义，提出利用USB设备芯片CH372、一线式数字温度传感器DS18B20和单片机AT89C51来开发基于USB温度控制系统。采集的温度数据通过USB接口上传到上位PC机上，并利用应用软件对其进行处理。上位机应用软件用C ++ builder 编写，其运用CH372接口芯片的动态链接库建立起上位机和下位机之间的通信机制。上位机将采集到的温度数据在PC机上显示出来，并且显示实时温度采集图像。

此外，应用软件可以对下位机进行温度极限设置等简单控制功能，当采集到的温度超过某一设定极限温度，则对系统进行报警。另外下位机还为今后的扩展保留一定的资源。

引言···························································································· 1

1  背景知识················································································ 1

2  系统概述················································································ 2

2.1 系统的特性································································································ 2

2.2 系统的功能······························································································· 2

2.3 系统开发平台····························································································· 2

3  系统总体设计·········································································· 3

3.1 系统整体方框图·························································································· 3

3.2 系统方案比较····························································································· 3

3.2.1系统两种可行方案···················································································· 3

3.2.2方案最终选择·························································································· 4

4  系统硬件设计·········································································· 5

4.1 中央处理器----AT89C51·············································································· 5

4.2 温度传感器DS18B20···················································································· 8

4.3 温度采集模块电路设计·············································································· 13

4.4 系统接口模块电路设计·············································································· 15

4.4.1 USB简介······························································································· 15

4.4.2 USB芯片选择························································································· 16

4.4.3 USB设备端接口设计··············································································· 18

4.5 系统硬件整体实现····················································································· 20

5  系统软件设计········································································ 20

5.1 软件设计工具··························································································· 20

5.2 系统软件设计··························································································· 21

5.2.1下位机的软件设计·················································································· 21

5.2.2上位机的软件设计·················································································· 24

6  系统调试··············································································· 25

6.1 硬件调试·································································································· 25

6.2 软件调试·································································································· 26

6.2.1 下位机的软件调试·················································································· 26

6.2.2 上位机的软件调试·················································································· 27

6.2.3 上位机和下位机联机调试········································································ 28

6.3 系统性能指标··························································································· 29

7  系统的简单操作说明······························································ 29

8  总结······················································································ 29

谢辞··························································································· 31

参考文献···················································································· 32

附录··························································································· 33