【正文】 ......................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 主控電路 ................................................................................................26 本科畢業(yè)設(shè)計(jì)（論文） III 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 ........................................................................................33 液晶顯示電路 ........................................................................................35 系統(tǒng)電源 .........................................................................................................37 芯片介紹 ................................................................................................37 電源電路 ................................................................................................38 報(bào)警電路 .........................................................................................................40 第四章 軟件流程 .............................................................................. 41 主程序流程圖 .................................................................................................41 主要中斷程序流程圖 .....................................................................................42 第 五 章 結(jié) 論 ...................................................................................... 44 致謝 .................................................................................................... 46 參考文獻(xiàn) .............................................................................................. 47 附錄 A： 英文資料 ......................................................................................................48 附錄 B： 英文資料翻譯 ..............................................................................................55 附錄 C： 原理圖 ..........................................................................................................62 附錄 D： Pcb 板圖 .......................................................................................................63 附錄 E： 元器件清單 ..................................................................................................64 本科畢業(yè)設(shè)計(jì)（論文） 1 第一章 緒 論 引言 質(zhì)量是測量領(lǐng)域中的一個(gè)重要參數(shù)，稱重技術(shù)自古以來就被人們所重視。 sampling circuit。 關(guān)鍵詞： 單 片機(jī)； 采樣電路 ； A/D 轉(zhuǎn)換器 ； 液晶顯示 本科畢業(yè)設(shè)計(jì)（論文） I 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 carr