目录
摘要 III
Abstract IV
第一章      绪       论 1
1.1  称重技术和衡器的发展 1
1.2  电子秤的发展现状和发展趋势 2
1.3  项目研究意义 4
第二章  电子秤的硬件构成 6
2.1   电子秤的构成 6
2.2   称重传感器 6
2.2.1   称重传感器选用时需考虑的问题 7
2.2.2   称重传感器的基本结构 9
2.3  应变式传感器 11
2.3.1   弹性元件 11
2.3.2   应变胶 12
2.3.3   应变片 13
2.3.4   应变式称重传感器的各种补偿 14
2.4  单片机系统 16
2.5  电路设计 18
2.5.1   称重传感器的供桥电源 18
2.5.2   电子秤的调零电路 20
2.5.3   电子秤的数据采集、处理部分 20
2.5.4   键盘/开关输入电路 25
2.5.5   LCD显示器 26
2.5.6   打印部分 28
2.5.7   掉电保护和检测电路、报警电路 29
第三章  仪器软件设计 31
3.1 仪器主程序 31
3.2 中断服务程序 32
第四章   仪器的误差及误差分配 33
4.1 仪器的误差来源 33
4.1.1 称重传感器的误差 33
4.1.2  电子设备的误差 33
4.1.3 机械承重系统的误差 34
4.2  仪器误差分配 35
4.3  仪器误差的计算方法 35
结论 37
参考文献 38
致谢 39
附录 40
基于单片机的智能数字电子秤设计
摘要
    现代社会的发展，对称重技术提出了更高的要求。目前，台式电子秤在商业贸易中的使用已相当普遍，但存在较大的局限性：体积大、成本高、需要工频交流电源供应、携带不便、应用场所受到制约。现有的便携秤为杆秤或弹簧压缩、拉伸变形来实现计量的弹簧秤，居民用户使用的是国家已经明令淘汰的杆秤。多年来，人们一直期待测量准确、携带方便、价格低廉的智能电子秤投放市场。
本文设计了一种智能电子秤，论述了仪器的工作原理，介绍了仪器的误差来源于误差分配，给出了仪器电路设计与软件流程。
智能电子秤主要由电源、称重传感器、A/D转换器、单片机、键盘/开关、LCD显示器等部分组成。主要技术指标为：称量范围0～15kg；分度值为0.005kg；精度等级Ⅲ级。仪器主要功能有自检、去皮、计价、单价设定、过载报警等。仪器若不进行称量操作，5分钟后自动进入休眠模式，降低电源消耗。
智能电子秤体积小、计量准确、携带方便、操作简单、称量速度快，并集质量称量功能与价格计算功能于一体，能够满足商业贸易和居民家庭的使用需求，具有广阔的应用前景。
关键词：智能电子秤， 称重传感器， A/D转换器， 8051单片机， 误差分析, 软件设计
A design of the intelligence electronic scales of micro-controller
Abstract
The development of the modern society has put forward higher request on weighing technology. Currently, the desk-top electronic scales have been great application in commercial trade, but they have many shortcomings such as large volume, high cost, not inconvenience to carry and AC supply power, so they are restricted to use. The usual portable scales are lever scales which are mostly used by residents and spring balance which measure through compression or drawing of spring. They are being rejected for their big measuring errors. People have been expecting cheap Intelligence electronic scales which can measure accurately and be carried conveniently for many years.
This text designs a kind of intelligence electronic scales. It discusses the instrumental working principle, and introduces its error sources and how to distribute the error. Give instrument electric circuit design and software process.
Intelligence electronic scales consist of power, and weighs to spread the machine, A/D conversion, keyboard/switch, list slice, LCD etc. Its technical indictors include : Measuring range from 0 to15 kg; Cent degree is 0.005 kg; Ⅲprecision. The instrument possesses many intelligence functions, such as shelling, overload alarm, unit price enactment, accumulation computation, self-calibrating and so on. For lowering power supply to consume, it can get into “sleep” automatically if the instrument is not measuring for 5 minutes.
The intelligence electronic scales can measure mass rapidly and accurately and communicate value. Furthermore, it is small, simply structured, easy to operate and convenient to carry. The instrument is able to meet the needs of commercial trade and residents, so its application has a bright future.
Keyword: Intelligence electronic scales， Weigh to spread a feeling machine，A/D conversion，  micro-controller 8051，  Error margin analysis，  Software design