基于STC单片机的电子称重系统设计

论文编号:ZD1107    论文字数:17943,页数:48

摘  要

 本次毕业设计是基于STC单片机电子称重系统的设计和制作。电子秤是一种常用的测量器具，与普通器具相比，数字电子秤具有称重速度快、读数直观、性能稳定、测量准确等优点。本文提出的电子称重系统采用低功耗，低成本的控制芯片STC 12系列自带A/D转换的单片机，设计一种体积小，低功耗、称量准确、使用方便、多功能显示、能够与微机进行串行通讯的低成本电子秤。    本次毕业设计所设计的电子称重系统通过电阻应变式称重传感器将被测物体的重量转换成毫伏级的模拟电压信号。较小的电压信号通过仪表放大器进行准确、线性的放大，以满足模/数转换器对输入信号电平的要求。放大后的模拟电压信号经过模/数转换电路将模拟量转变成数字量，然后由单片机控制系统经过数据转换处理之后把数字信号存入寄存器。通过键盘功能键可以将数字信号送入显示电路，由4位LED七段数码管来显示出测量结果，也可以通过切换功能键输入数字单价、得到总价格的数字显示，而且还可以将测量结果上传至微机实现串口通讯的功能。

关键词： 单片机；电子称重系统；称重传感器
 

Abstract

 This graduation project is the design and production of electronic weighing system which is based on the STC single-chip microcomputer. Electronic scale is a commonly used measurement instruments. Compared with ordinary equipment, digital electronic scale has such characteristics as rapid weighing, intuitive readings, stable performance, accurate measuring.
 In this paper, the electronic weighing system uses low power, low-cost controller chips STC 12 Series comes with A/D converter single-chip microcomputer to design a small size, low power, accurate weighing, easy to use, low-cost electronic scale with multi-function display and it has the ability of serial communication with PC.
 The electronic weighing system designed in this graduation project uses resistance strain gauge load cell to convert the weight of detected objects to millivolt level analog voltage signal. The small voltage signal is amplified accurately and linearly through the instrumentation amplifier to to meet the A / D converter input signal level required. The amplified analog voltage signal through A / D conversion circuit convert to digital, the single-chip microcomputer control system then processed through the data conversion before The digital signal stored into the register. Through the keyboard function keys,it can transport digital signals into the display circuit and the measurement results can be displayed by the four seven-segment LED digital tube. It can also switch the function key to input the numbers keys as the unit price,or figure out the total prices and displayed . Moreover,it has the function of serial communication ,and the measurement results can be uploaded to PC.

 
Keywords： Single-chip microcomputer；Electronic weighing system；Load cell

目 录

摘  要 I
Abstract II
目 录 III
1  绪  论 1
2  总体方案设计 3
2.1  设计制作要求 3
2.2  设计思想 3
2.3  系统总体结构 4
2.4  主控芯片介绍 6
3  系统硬件设计 7
3.1  系统硬件模块框架图 7
3.2  测量模块 7
3.2.1  称重传感器 7
3.1.2  仪表放大器 9
3.2  单片机系统 11
3.2.1  A/D转换器 11
3.2.2  单片机控制模块 13
3.2.3  EEPROM 15
3.3  人机对话模块 15
3.3.1  多功能LED显示模块 15
3.3.2  键盘输入模块 17
3.4  串口通讯模块 17
3.4.1  MAX232芯片 17
3.4.2  9针串口 19
3.4.3  通信连接电路 19
3.5  复位电路和时钟电路 20
4  系统软件设计 22
4.1  监控程序设计 22
4.2  功能处理程序设计 24
4.2.1  质量的数字显示功能程序设计 24
4.2.2  去皮功能程序设计 26
4.2.3  数字参数设置的输入显示功能程序设计 27
4.2.4  计算总价数字显示的功能程序设计 28
4.2.5  上传通讯功能程序设计 30
5  系统的调试 32
5.1  系统开发平台 32
5.1.1  Keil C软件集成开发环境 32
5.1.2  Proteus ISIS软件 34
5.2  设计制作的系统 36
5.2  系统调试 37
5.2.1  软件仿真调试过程 37
5.2.2  硬件调试过程 38
5.2.3  系统的改进方向 39
5.2.4  调试总结 40
6  总  结 41
致 谢 42
参考文献 43
附 录 44