【正文】 寄存器。 方案二 應(yīng)用 AVR， AVR是一種 高性能、低功耗的 高性能 微處理器 ，它采用哈佛結(jié)構(gòu)，廢除了復(fù)雜指令集計算機追求指令完備的做法；采用精簡指令集計算機，以字作為指令長度單位，將內(nèi)容豐富的操作數(shù)與操作碼安排在一字之中；取指周期短，又可預(yù)取指令，實現(xiàn)流水作業(yè)，可高速執(zhí)行指令。然而，高精密檢測的電子秤如果要達(dá)到這種分辨率，那么 ADC 的精度需要接近于 20 bit。目前，解決上述問題的最好方法是采用數(shù)字和算或數(shù)?；旌虾退恪Ｒ驗樾⌒蜕逃秒娮臃Q對適時性要求不高，運算也不太復(fù)雜，所以用 8位微處理器足可滿足要求。但就總體而言，我國電子衡器產(chǎn)品的數(shù)量和質(zhì)量與工業(yè)發(fā)達(dá)國家相比還有較大差距，其主要差距是技術(shù)與工藝不夠先進(jìn)、工藝裝備與測試儀表老化、開發(fā)能力不足、產(chǎn)品的品種規(guī)格較少、功能不全、穩(wěn)定性和可靠性較差 等。 60年代初期出現(xiàn)機電結(jié)合式電子衡器以來，經(jīng)過 40多年的不斷改進(jìn)與完善， 我國電子衡器從最初的機電結(jié)合型發(fā)展到現(xiàn)在的全電子型和數(shù)字智能型。基于電子秤的現(xiàn)狀，本項目擬研究一種用單片機控制的多功能電子秤設(shè)計方案。 目前，臺式電子秤在商業(yè)貿(mào)易中的使用已相當(dāng)普遍，但存在較大的局限性：體積大、成本高、需要工頻交流電源供應(yīng)、攜帶不便、應(yīng)用場所受到制約。 關(guān)鍵詞： 單片機 稱重傳感器 放大器 模數(shù)轉(zhuǎn)換 II The design of multifunctional electronic scale Abstract The development of the modern society has put forward higher request on weighing technology. The desktop electronic scales have been great application in mercial trade, but they have many shortings such as large volume, high cost, AC supply power and not cove nince to carry, so they are restricted to use. The usual portable scales are lever scales which are mostly used by residents, and spring balance which measure through pression or drawing of spring. They are being rejected for their big measuring errors. People have been expecting cheap portable electronic scales which can measure accurately and be carried conveniently for many years. The curriculum design of electronic scales in order to AT89S52 microcontroller to control the core, the use of fullbridge measuring principle, through the circuit output voltage and the standard weight of a linear relationship, the establishment of a specific mathematical model, the dimensionless voltage (V) changed the weight of Class ( g) bee a single original electronic scales. Measuring circuit in which the most significant ponent is the resistance strain sensor. Resistance strain gauge sensor is a sensor in the most widely used, this design uses a fullbridge measurement circuit, so that system to produce a smaller error, the output of the data more accurate. The amplifier circuit using AD620, whose role is to weak analog sensor output signals a certain multiple of the amplification in order to meet the A / D converter input signal level requirements. MAX187 A / D conversion is the role of the analog signals into digital signals, analogdigital conversion, digital signal and then transmitted to the display circuit and there, finally shown by the display circuit measurement results. Electronic Scale is a major by the power, weighing sensor, microcontroller, keyboard / switch 12864 LCD monitors and other parts. Its technical indictors include10kg maximal measuring range,10g division value, III precision, 5V work voltage. Its technical indictors refer to the indictors of the electri conic measuring tools of most popularity in the markets and of large output at home and board, so the instrument is strengthened the petitive power after putting on markets. Instrument III main functions are peeled, pricing, total, unit price setting, overload alarm, time display, etc. Key Words： SCM Weighing Sensor Amplifiers Analogdigital conversion IV 目 錄 第一章 前 言 ......................................................... 1 課題研究意義 ................................................. 1 國內(nèi)外研究情況 ............................................... 1 本設(shè)計的任務(wù)和主要內(nèi)容 ....................................... 2 第二章 方案論證 ...................................................... 3 單片機選擇 .................................................... 3 顯示部分 ..................................................... 3 數(shù)字時鐘 ..................................................... 4 放大部分 ...................................................... 4 A/D 轉(zhuǎn)換器選擇 ............................................... 5 壓力傳感器部分 ................................................ 5 第三章 總體方案 ...................................................... 7 工作原理 ..................................................... 7 系統(tǒng)各模塊的最終方案 .......................................... 7 第四章 硬件電路的設(shè)計 ............................................... 8 單片機控制電路的設(shè)計 .......................................... 8 Hl8傳感器的電路設(shè)計 ......................................... 9 信號放大電路的設(shè)計 .......................................... 13 信號 A/D 轉(zhuǎn)換器 .............................................. 16 DS1302 時鐘電路的設(shè)計 ........................................ 17 鍵盤和過量程報警電路設(shè)計 ..................................... 18 12864 液晶顯示電路的設(shè)計 ..................................... 19 電源電路設(shè)計 ................................................ 21 總體工作電路原理圖 .......................................... 21 第五章 軟件的設(shè)計 ................................................... 25 軟件所實現(xiàn)的功能 ............................................ 25 軟件主流程 .................................................. 25 數(shù)據(jù)采集子程序的設(shè)計 ........................................ 27 顯示子程序的設(shè)計 ............................................ 27 報警子程序的設(shè)計 ............................................ 28 V 軟件抗干擾設(shè)計 .............................................. 29 第六章 調(diào)試與分析 ................................................... 30 調(diào)試系統(tǒng)簡介 ................................................ 30 調(diào)試故障及原因分析 .......................................... 31 第七章 結(jié)論 ......................................................... 31 參考文獻(xiàn) ............................................................ 32 附錄 ................................................................ 33 致謝 ................................................. 錯誤 !未定義書簽。 電子秤主要由電源、稱重傳感器、單片機、鍵盤 /開關(guān)、 12864液晶顯示器等部分構(gòu)成。其中測量電 路中最主要的元器件就是電阻應(yīng)變式傳感器。目前，臺式電了秤在商業(yè)貿(mào)易中的使用已相當(dāng)普遍，但存在較大的局限性：體積大、成本高、需要工頻交流電源供應(yīng)、攜帶不便、應(yīng)用場所受到制約。但是在工業(yè)測量中還沒有讓人們期待的電子秤出現(xiàn)。電阻應(yīng)變式傳感器是 稱重 傳感器中應(yīng)用最多的一種，本設(shè)計采用全橋測量電路，使系統(tǒng)產(chǎn)生的誤差更小，輸出的數(shù)據(jù)更精確。主要技術(shù) 指標(biāo)為：稱量范圍 — 5kg；分度值 ；精度等級 m級；電源 5v。 1 第一章 前 言 課題研究意義 隨著經(jīng)濟的發(fā)展，出售商品品種的增加，需要稱量物品的設(shè)備也需要更新