摘 要

本論文在分析了國(guó)內(nèi)外稱重技術(shù)發(fā)展的基礎(chǔ)上，著重對(duì)一個(gè)用于工業(yè)控制且功能較齊全的自動(dòng)稱重系統(tǒng)進(jìn)行設(shè)計(jì)。隨著自動(dòng)化和管理現(xiàn)代化的進(jìn)展，自動(dòng)在線稱重，快速動(dòng)態(tài)稱重在整個(gè)稱重系統(tǒng)中有了很大的發(fā)展。因此，進(jìn)一步采用新技術(shù)，開(kāi)發(fā)各種自動(dòng)稱重系統(tǒng)和提高稱重的準(zhǔn)確度已經(jīng)成為了多數(shù)國(guó)家科技發(fā)展的重中之重。
本稱重系統(tǒng)除了有關(guān)于數(shù)據(jù)的收集，處理，運(yùn)行和通信之外，還有更多的其他輔助功能：自動(dòng)稱重系統(tǒng)除了能夠儲(chǔ)存數(shù)據(jù)資料到資料庫(kù)中，還可以將資料以打印稿的形式呈現(xiàn)。最重要的是，該自動(dòng)稱重系統(tǒng)還可以隨時(shí)對(duì)資料庫(kù)進(jìn)行訪問(wèn)和查詢。
本論文所設(shè)計(jì)的自動(dòng)稱重系統(tǒng)是應(yīng)用于工業(yè)上的乳粉包裝自動(dòng)稱重中的，它的實(shí)現(xiàn)有兩個(gè)過(guò)程，第一階段由異步電機(jī)帶動(dòng)粗螺旋推進(jìn)器給料，這一階段可看成為粗調(diào)過(guò)程，給料重量一定要小于額定重量。第二階段由步進(jìn)電機(jī)帶動(dòng)細(xì)螺旋推進(jìn)器進(jìn)料，可看成是細(xì)調(diào)過(guò)程，使實(shí)際重量等于要求的額定重量。
本稱重系統(tǒng)采用單片機(jī)AT89C51為控制核心，實(shí)現(xiàn)稱重儀的基本控制功能。系統(tǒng)的硬件部分包括數(shù)據(jù)采集和數(shù)據(jù)處理兩大部分，其中數(shù)據(jù)采集部分由稱重儀模擬器、信號(hào)的前級(jí)處理（采用儀表放大器INA121）和 雙積分A/D 轉(zhuǎn)換部分組成。由于稱重儀設(shè)計(jì)中電路的精度及抗工頻干擾能力要求較高，故選用精度較高的儀表放大器INA121和抗工頻干擾能力較強(qiáng)的雙積分A/D轉(zhuǎn)換器MC14433。
本系統(tǒng)通過(guò)應(yīng)用傳感器，各種芯片及單片機(jī)使得該稱重系統(tǒng)的實(shí)際操作性更強(qiáng)，便于應(yīng)用于工業(yè)上。


關(guān)鍵詞 雙積分A/D轉(zhuǎn)換；儀表放大；AT89C51單片機(jī)；數(shù)據(jù)采集

The Design of Weighing and Packing of Milk Powder Based on Singlechip
Abstract

Basis on the researching of the progress of the weighing technology, this paper introduces the development of automatic weighing system which has a complete function.
With the progress of automation in industry and modernization in management, there is much progress in weighing online, fast and dynamic weighing and system of weighing.Adopting newer technology, developing diversified automatic weighing system, improving accuracy and enhancing network function are emphasized in every country nowadays. .
Besides the function of collecting, processing, displaying and communication of data about weight, the automatic weighing system can also save data in database and print data in report form. It can also visit and query the records in database.
The article introduced the automatic named weighing system which is applied in the industry, its realization has two processes, the first stage is the spiral propeller by the asynchronous machine belt to afford the material, this age which is worthy of looking at is because of the coarse adjustment process,certainly it must be smaller than the schedule weight for the material weight. The second stage is impetus which is much more precise than the first spiral propeller feeding, it may be regarded as the special process. This system has been applied in the sensor, each kind of chips and monolithic integrated circuits.
This system is based on single chip AT89C51, it can make electronic scale's basic control function come true. System's hardware includes smallest system board and the acquisition of data. The smallest system 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 anti-power frequency disturbance, the selection of the high precision appliance such as the amplifier INA121 and double integral A/D switch MC14433.
The system would be stronger by using different elements,and it would have better performance in application of the industry.


Key words double integral A/D transformation; measuring appliance enlargement; AT89C51 single chip; collection of data



目 錄

第1章 緒論 1
1.1 引言 1
1.2 電子稱重技術(shù)的發(fā)展趨勢(shì) 1
1.2.1 稱重傳感器 2
1.2.2 稱重儀表 3
1.2.3 承載器 4
1.3 論文研究的目的及意義 4
1.4 本課題研究的主要內(nèi)容 4
第2章 主要元器件選型……..........................................................................................................5
2.1 轉(zhuǎn)換電路芯片選擇 5
2.2 主控芯片選擇 6
2.3 儀表放大器選擇 7
2.4 電源選擇 9
2.5 顯示模塊選擇 10
2.6 本章小結(jié) 10
第3章 硬件系統(tǒng)的設(shè)計(jì) 11
3.1 電路總體原理框圖設(shè)計(jì) 11
3.2 主芯片引腳應(yīng)用 11
3.3 控制模塊與轉(zhuǎn)換模塊的連接 14
3.4 前級(jí)放大模塊INA121 15
3.5 自動(dòng)稱重模塊 16
3.6 顯示模塊與控制模塊的連接 16
3.7 本章小結(jié)……………………………………………………………………………..18
第4章 軟件系統(tǒng)的設(shè)計(jì)……........................................................................................................19
4.1 主程序模塊 19
4.2 子程序模塊 19
4.3 中斷程序模塊圖 20
4.3.1 T0中斷程序 21
4.3.2 T1中斷子程序 .21
4.4 調(diào)零程序模塊圖……………………………………………………………………..21
4.5 顯示程序流程圖…………………………………………………………………..