摘要该设计以 51系列单片机 AT89S52 为控制核心,实现电子秤的基本控制功能。在设计系统时,为了更好地采用模块化设计法,分步的设计各个单元功能模块, 系统的硬件部分可以分为最小系统、数据采集、人机交互界面和系统电源四大部分。最小系统部分主要包括 AT89S52 和扩展的外部数据存储器;数据采集部分由压力传感器、信号的前级处理和 A/D 转换部分组成,包括运算放大器 AD620 和 A/D 转换器 ICL7135 ;人机交互界面为键盘输入和点阵式液晶显示,主要使用 ZLG7289 键盘控制芯片和 OCM4x8C 显示器,可以方便的输入数据和直观的显示中文。系统电源以 LM317 和LM337 为核心设计电路以提供系统正常工作电源。软件部分应用单片机 C语言进行编程,实现了该设计的全部控制功能。该电子秤可以实现基本的称重功能(称重范围为 0~ ,重量误差不大于± ), 并发挥部分的显示购物清单的功能,可以设置日期和设定十种商品的单价, 还具有超量程和欠量程的报警功能。整个系统结构简单,使用方便,功能齐全,精度高,具有一定的开发价值。关键词: 单片机;采样电路; A/D 转换器;液晶显示 ABSTRACT The design is based on the microcontroller AT89S52 system as the core to carry out the basic control function of the electronics steelyard. W hile designing the system, I adopt the mold piece method to divide the hardware of the system into four parts: the minimum system, sampling circuit, I/O interface and the system power supply. The minimum system mainly includes the AT89S52 and the expanded exterior data memory. S ampling circuit prised ofa pressure sensor, a differential measuring amplifier AD620 and a A/D converter ICL7135. With the usage of ZLG7289 keyboard control chip and OCM4*8C display, plete the function of the key board input and the LCD manifestation. The power supply system selects the LM317 and LM337 to design the electric circuit to provide the needed power supply. The software part applies a machine C language to carry out all control function. The electronic steelyard can weigh the scope as0~ Kgs, and the we igh error margin isno bigger than ± . It also has many other functions, such as displaying the shopping detailed list, setting the date and ten kinds of unit prices of merchandise and overweighing alarm. The whole system is simple, well-found, convenient to use and has high accuracy and certain development value. Key words : microcontroller ; sampling circuit; A/D converter; LCD Manifestation 目录第一章绪论............................................................................................... 1 ...............
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