【正文】 I 電子稱單片機(jī)控制系統(tǒng)的設(shè)計(jì) I 摘 要 該設(shè)計(jì)以 51系列單片機(jī) AT89S52 為控制核心，實(shí)現(xiàn)電子秤的基本控制功能。在設(shè)計(jì)系統(tǒng)時(shí)，為了更好地采用模塊化設(shè)計(jì)法，分步的設(shè)計(jì)各個(gè)單元功能模塊，系統(tǒng)的硬件部分可以分為最小系統(tǒng)、數(shù)據(jù)采集、人機(jī)交互界面和系統(tǒng)電源四大部分。最小系統(tǒng)部分主要包括 AT89S52 和擴(kuò)展的外部數(shù)據(jù)存儲(chǔ)器；數(shù)據(jù)采集部分由壓力傳感器、信號(hào)的前級(jí)處理和 A/D 轉(zhuǎn)換部分組成，包括運(yùn)算放大器 AD620 和A/D 轉(zhuǎn)換器 ICL7135；人機(jī)交互界面為鍵盤輸入和點(diǎn)陣式液晶顯示，主要使用ZLG7289 鍵盤控制 芯片和 OCM4x8C 顯示器，可以方便的輸入數(shù)據(jù)和直觀的顯示中文 。系統(tǒng)電源 以 LM317 和 LM337 為核心設(shè)計(jì)電路以提供系統(tǒng)正常工作電源。軟件部分應(yīng)用單片機(jī) C 語言進(jìn)行編程，實(shí)現(xiàn)了該設(shè)計(jì)的全部控制功能。該電子秤可以實(shí)現(xiàn)基本的稱重功能（稱重范圍為 0～ ，重量誤差不大于 177。 ） ,并發(fā)揮部分的顯示 購物清單的功能，可以設(shè)置日期和設(shè)定十種商品的單價(jià)， 還具有超量程和欠量程的報(bào)警功能。整個(gè)系統(tǒng)結(jié)構(gòu)簡(jiǎn)單，使用方便，功能齊全，精度高，具有一定的開發(fā)價(jià)值。 關(guān)鍵詞： 單片機(jī)； 采樣電路 ； A/D 轉(zhuǎn)換器 ； 液 晶顯示 II ABSTRACT The design is based on the microcontroller AT89S52 system as the core to carry out the basic control function of the electronics steelyard. While 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. Sampling circuit is prised of a 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, we 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 as 0～ , and the weigh error margin is no bigger than 177。 . 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, wellfound, convenient to use and has high accuracy and certain development value. Key words： microcontroller。 sampling circuit。 A/D converter。 LCD Manifestation III 目 錄 第一章 緒論 ........................................................................................... 1 引言 ...................................................................................................................1 選題背景與意義 ................................................................................................2 研究現(xiàn)狀 ...........................................................................................................2 影響因素 ..................................................................................................2 產(chǎn)品質(zhì)量 ...................................................................................................3 發(fā)展方向 ...................................................................................................3 電子秤的智能化 .......................................................................................3 本文的結(jié)構(gòu) .......................................................................................................4 第二章 系統(tǒng)方案的設(shè)計(jì) ........................................................................ 5 電子秤的設(shè)計(jì)要求 ...........................................................................................5 基本要求 ..................................................................................................5 發(fā)揮部分 ..................................................................................................5 創(chuàng)新部分 ..................................................................................................5 系統(tǒng)工作 原理及設(shè)計(jì)基本思路 .......................................................................5 系統(tǒng)工作 原理 ..........................................................................................5 系統(tǒng) 設(shè)計(jì)基本思路 ..................................................................................6 系統(tǒng)總體設(shè)計(jì)方案比較與論證 .......................................................................6 單片機(jī)的選型 ...................................................................................................8 數(shù)據(jù)采集部分的方案確定 ...............................................................................9 傳感器 ......................................................................................................9 前級(jí)放大器部分 ....................................................................................12 A/D 轉(zhuǎn)換器 .............................................................................................15 人機(jī)交互部分 .................................................................................................17 鍵盤輸入 ................................................................................................17 輸出顯示 ................................................................................................17 系統(tǒng)電源 .........................................................................................................18 具體實(shí)施方案簡(jiǎn)介 .........................................................................................20 第三章 系統(tǒng)硬件設(shè)計(jì) .......................................................................... 22 基于 AT89S52 的主控電路 ............................................................................22 芯片介紹 ................................................................................................22 IV 主控電路 ................................................................................................26 基于 ICL7135 的前端信號(hào)處理電路 ............................................................27 芯片介紹 ................................................................................................27 信號(hào)處理電路 ........................................................................................30 人機(jī)交互界面 .................................................................................................33 鍵盤控制電路 .......................................................................