【正文】 part mainly realizes the demonstration of the diodes and the control of keyboard ,the part of data’s acquisition is consists of the simulator of weighing meter , signal level processing (amplifier INA121) and the fraction of the double integral A/D conversion . Because of the high request in precision of the electric circuit of the weighing meter design and the ability of antipower frequency disturbance, the selection of the high precision appliance such as the amplifier INA121 and double integral A/D switch MC14433. The guiding ideology is using infrared luminescence tubes launch infrared, infrared receiving tube receiving this infrared, and put the amplification, rectifier form low level signals. When someone or something blocking infrared, receiving tube without receiving infrared signal, amplifier output high level, at the same time will the level signal into SCM control counted, and making digital tube display Numbers. So get to statistics, the number of people or things. Key words ： double integral A/D transformation, measuring appliance enlargement， Scm, Automatic counting , Digital tube I 目 錄 緒論 ................................................................................................................................. I 1 課題的研究意義和目的 ............................................................................................ 1 自動(dòng)稱重和計(jì)數(shù)的現(xiàn)狀及前景 ............................................................................. 1 課題研究?jī)?nèi)容 ......................................................................................................... 2 2 基于單片機(jī)構(gòu)成的產(chǎn)品自動(dòng)計(jì)數(shù)器 的設(shè)計(jì) ............................................................ 2 方案論證 ................................................................................................................. 2 系統(tǒng)總體框圖和原理 ............................................................................................. 3 系統(tǒng)單元電路設(shè)計(jì) ................................................................................................. 3 電源供電電路 ...................................................................................................... 3 橋式整流電路 ...................................................................................................... 4 濾波電路分析 ...................................................................................................... 5 穩(wěn)壓電路 .............................................................................................................. 6 紅外線檢測(cè)部分 .................................................................................................. 6 數(shù)碼管顯示部分 .................................................................................................. 6 LED 數(shù)碼管的特點(diǎn) ................................................................................................ 7 數(shù)碼管動(dòng)態(tài)掃描 ..................................................................................................... 8 數(shù)碼管驅(qū)動(dòng)部分 ..................................................................................................... 8 單片機(jī)計(jì)數(shù)及控制部分 ......................................................................................... 9 復(fù)位電路 ............................................................................................................... 12 上電復(fù)位 ............................................................................................................. 12 看門狗復(fù)位 ......................................................................................................... 13 3 自動(dòng)稱重系統(tǒng)的設(shè)計(jì) .............................................................................................. 14 硬件的選擇 ........................................................................................................... 14 轉(zhuǎn)換電路芯片選擇 ............................................................................................ 14 主控芯片選擇 .................................................................................................... 16 儀表放大器選擇 ................................................................................................ 17 電源選擇 ............................................................................................................ 18 顯示模塊選擇 .................................................................................................... 19 電路總體原理框圖設(shè)計(jì) ....................................................................................... 19 主芯片引腳應(yīng)用 ................................................................................................... 20 控制模塊與轉(zhuǎn)換模塊的連接 ............................................................................... 23 前級(jí)放大模塊 INA121......................................................................................... 24 自動(dòng)稱重模塊 ....................................................................................................... 25 II 顯示模塊與控制模塊的連接 ............................................................................... 25 系統(tǒng)測(cè)試 ............................................................................................................... 27 硬件抗干擾的設(shè)計(jì) ............................................................................................ 27 電源的干擾以及抑制措施 ................................................................................ 27 空間干擾的防御措施 ........................................................................................ 27 軟件系統(tǒng)的設(shè)計(jì) ................................................................................................... 27 4 結(jié)束語(yǔ) ...................................................................................................................... 33 參考文獻(xiàn) ...................................................................................................................... 35 附錄 .............................................................................................................................. 39 附錄 Ⅰ 自動(dòng)稱重器設(shè)計(jì) ..........................