摘 要:本設(shè)計以51系列單片機STC89C52RC為控制核心，實現(xiàn)電子秤的基本控制功能。在設(shè)計系統(tǒng)時，為了更好地采用模塊化設(shè)計法，分步的設(shè)計各個單元功能模塊，系統(tǒng)的硬件部分可以分為最小系統(tǒng)、數(shù)據(jù)采集、人機交互界面(鍵盤以及顯示)和系統(tǒng)電源四大部分。最小系統(tǒng)部分為STC89C52RC系統(tǒng)；數(shù)據(jù)采集部分由壓力傳感器、信號的前級處理和A/D轉(zhuǎn)換部分組成，包括運算放大器OP07和A/D轉(zhuǎn)換器ADC0809；人機交互界面為鍵盤輸入和數(shù)碼管顯示，主要使用5X5鍵盤、CH423數(shù)碼管控制芯片及13位數(shù)碼管顯示，可以方便的輸入數(shù)據(jù)并直觀的顯示重量、單價和總價。系統(tǒng)電源是以LM7805、 LM7812為核心設(shè)計電路以提供系統(tǒng)正常工作電源。軟件部分應用單片機C51語言進行編程，實現(xiàn)了該設(shè)計的基本控制功能。該電子秤可以實現(xiàn)基本的稱重功能（稱重范圍為0～10Kg，重量誤差不大于±0.02Kg）,重量、單價、總價的計量可以精確到兩位小數(shù)，鍵盤設(shè)置有數(shù)字鍵（‘0’～‘9’、‘.’）、儲存鍵、單價1～單價8調(diào)用單價鍵、清除鍵、去皮鍵等；發(fā)揮部分有8種不同物品的單價記憶功能、99種消費商品價格累計功能、；待發(fā)揮部分為講電子秤與打印機連接，能打印消費記錄（小票），超量程和欠量程的報警功能。本系統(tǒng)結(jié)構(gòu)簡單，使用方便，功能齊全，精度高，具有一定的開發(fā)價值。

關(guān)鍵詞：單片機 采樣電路A/D轉(zhuǎn)換器 CH423數(shù)碼管驅(qū)動芯片 數(shù)碼管顯示 工作電源









the design of electronic scales based on Single-chip Microcomputer

ABSTRACT :The design for the control of 51 computers STC89C52RC the core, to achieve the basic control functions of electronic scales. In designing the system, in order to better modular design, the design of each unit step function modules, the system can be divided into the minimum hardware system, data acquisition, man-machine interface (keypad and display) and the system power 4 most. Minimum system partly STC89C52RC system; data collection in part by the pressure sensor, signal processing and the first class A / D conversion components, including the operational amplifier OP07 and the A / D converter ADC0809; man-machine interface for the keyboard and digital display The main use of 5X5 keypad, CH423 digital control chip and 13 digital display, can easily enter data and visual display weight, unit price and total price. System power is based on LM7805, LM7812 as the core design of the circuit to provide normal power supply system. Software part of the application MCU C51 language programming, the design of the basic control functions. The electronic weighing scales can realize the basic functions (weighing range of 0 ~ 10Kg, the weight of the error is not greater than ± 0.02Kg), weight, unit price, total measurement is accurate to two decimal places, the keyboard settings are the number keys ( '0 '~ '9','.'), storage key, Unit 1 to Unit 8 Unit call key, clear key, peeled keys, etc.; play a part in 8 different items priced memory, 99 kinds of consumer goods prices cumulative function; play a part to be about electronic scales and printers connected to print consumption records (small notes), over range and under-range alarm. The system is simple, easy to use, fully functional, high precision, has some value for development.

Key words： microcontroller sampling circuit A/D converter CH423 digital tube driver chip digital display Power Supply





目錄

第一章 緒 論 1
1.1引言 1
1.2 選題背景與意義 1
第二章 系統(tǒng)方案的設(shè)計 2
2.1 電子秤的設(shè)計要求 2
2.1.1 基本要求 2
2.1.2 特色與創(chuàng)新 2
2.2實驗原理及設(shè)計基本思路 2
2.2.1系統(tǒng)工作原理 2
2.2.2 系統(tǒng)設(shè)計基本思路 2
2.3 系統(tǒng)總體設(shè)計方案比較與論證 3
2.4單片機的選型 4
2.5 數(shù)據(jù)采集部分的方案確定 4
2.5.1 傳感器 4
2.5.2 前級放大器部分 7
2.5.3 A/D 轉(zhuǎn)換器 9
2.6人機交互部分 11
2.6.1 鍵盤輸入 11
2.6.2 輸出顯示 11
2.7系統(tǒng)電源 12
2.8 具體實施方案簡介 13
第三章 系統(tǒng)硬件設(shè)計 15
3.1 基于STC89C52RC的主控電路 15
3.1.1芯片介紹 15
3.2 系統(tǒng)電源 18
3.2.1 芯片介紹 18
3.2.2 電源電路 19
第四章 軟件流程 20
4.1 主程序流程圖 20
4.2 鍵盤掃描流程圖 21
第五章 結(jié) 論 22
5.1 論文總結(jié) 22
5.2 感想 22
致 謝 24
參 考 文 獻 25
附錄A：原理圖 26
附錄B：源程序 29