【正文】 東北大學(xué)秦皇島分校畢業(yè)設(shè)計（論文） 第 II 頁 Said design based on 51 singlechip doubleprecision electronic Author： Jin Shan Tutor： Qi Shiqing Abstract With the rapid development and application of digital technology, electronic weighing technology has been developed and applied extensively .And a variety of intelligent digital electronic weighing is emerging progressively, but in small and middle market, the mercial electronics, which is an important part of the electronic weighing, is still limited to the simple electronics said such as steelyard, platform scales and simple electronics. All these are known as the main mercial electronic scales, but the existence of accuracy, easily damage, and difficult to repair defects also affect itself. Especially during weighing some minor objects such as tea, medicinal herbs, mistakes is easy to appearance through measuring. This paper, the design of the doubleprecision electronic using microcontroller AT89S52 as the core, achieve the simulation capabilities of electronic design by using Proteus Software and KEIL software. Now dividing this paper into five main modules: how to collect the weight of the object with this doubleprecision electronic said module, how to deal with the data through singlechip machine, how to control keyboard module, the display module and how to drive software module. Fristly, use different pressure sensor to acquire pressure parameters. Secondly the signal processor and A / D conversion work out the data, finally given to the MCU. Thridly according to the data above the MCU will automatically select whether the 12 precision values or 8 precision value puting processor. Ultimately the input through the keyboard will be showed on the LCD12864 realtime display. The entire electronic system can intelligently acplish doubleprecision measurement automatically, automatic alarm, visual display, at the same time, it’s easy to operate, accurate measurement, low cost, stability and high reliability. Based on the introduction above ,it can be used in different applications occasions, and it can adapt to the needs of small and mediumsized market. Key Words: Doubleprecision electronic, AT89S52, Load sensor, A/D converter, LCD display 東北大學(xué)秦皇島分校畢業(yè)設(shè)計（論文） 第 1 頁 目 錄 1 緒論 ..................................................................................................................................... 3 課題研究背景 .............................................................................................................. 3 電子衡器的研究現(xiàn)狀 .................................................................................................. 4 國內(nèi)外發(fā)展情況 ................................................................................................. 4 電子稱的發(fā)展方向 ............................................................................................. 5 課題的研究意義 .......................................................................................................... 5 本文的設(shè)計思路 .......................................................................................................... 5 2 系統(tǒng)方案論證與硬件選型 ................................................................................................. 8 系統(tǒng)總體設(shè)計方案的比較與論證 .............................................................................. 8 硬件方案設(shè)計與論證 ................................................................................................ 10 CPU的選擇方案 .............................................................................................. 10 傳感器的選擇 ................................................................................................... 11 放大電路的選擇方案 ....................................................................................... 13 A/D 轉(zhuǎn)換器的選擇 ........................................................................................... 15 鍵盤處理部分方案的論證 ........................................................................................ 18 顯示器部分的選擇 .................................................................................................... 20 超量程報警部分的選擇 ............................................................................................ 20 3 硬件電路設(shè)計 ................................................................................................................... 21 AT89S52 單片機介紹 ............................................................................................... 21 AT89S52 單片機綜述 ....................................................................................... 21 AT89S52 的最小系統(tǒng)電路構(gòu)成 ....................................................................... 22 A/D 轉(zhuǎn)換器與 AT89S52 單片機接口電路 ............................................................... 23 顯示電路與 AT89S52 單片機的接口電路 ............................................................... 26 12864 點陣型 LCD 簡介 .................................................................................. 26 東北大學(xué)秦皇島分校畢業(yè)設(shè)計（論文） 第 2 頁 點陣 LCD 的顯示原理 ..................................................................................... 27 12864LCD 指令系統(tǒng) ........................................................................................ 28 鍵盤電路與 AT89S52 的接口電路設(shè)計 ................................................................... 30 4 系統(tǒng)軟件設(shè)計 ................................................................................................................... 33 主程序設(shè)計 ................................................................................................................ 33 C 語言在單片機中的應(yīng)用 ...............................................................................