【正文】 基于單片機(jī)的二線制數(shù)據(jù)傳感器設(shè)計(jì) I 摘 要 工業(yè)上普遍需要測(cè)量各類非電物理量，例如溫度、壓力、速度、角度等。都需要轉(zhuǎn)換成模擬量電信號(hào)才能傳輸?shù)綆装倜淄獾目刂剖一蝻@示設(shè)備上，這種將物理量轉(zhuǎn)換成點(diǎn)信號(hào)的設(shè)備稱為變送器。工業(yè)上最廣泛采用的是用 4~20mA 電流來傳輸模擬量。 采用電流信號(hào)的原因是不容易受到干擾，并且電流源內(nèi)阻無窮打，導(dǎo)線電阻串聯(lián)在回路中不影響精度，在普通雙絞線上可以傳輸數(shù)百米。取 20mA 是因?yàn)榉辣囊螅?0mA 的電流通斷引起的火花能量不足引燃瓦斯；下限沒有取 0mA 的原因 是為了能檢測(cè)斷線，正常工作時(shí)不會(huì)低于 4mA，當(dāng)傳輸線因故障 斷路，環(huán)路電流 降為 0mA 所以常取 2mA 作為斷線報(bào)警值。 本課題通過分析二線制、三線制、四線制變送器的各自特點(diǎn)，在總結(jié)典型變送器設(shè)計(jì)思路與方法的基礎(chǔ)上，提出了一張經(jīng)濟(jì)實(shí)用的二線制智能變送器設(shè)計(jì)方案。該方案單片機(jī)為核心，能對(duì)特殊的非線性的傳感器進(jìn)行線性修正處理。主要解決問題是兩條線既要提供工作電流， 又要傳輸測(cè)量信號(hào)，需要協(xié)調(diào)一致，不能相互沖突；由于零點(diǎn)電流為 4mA，因此必須保證整個(gè)變送器的工作電流要在 之內(nèi)；線制的輸出電流反饋電路比較特殊，要選擇合理的電路方案，保證輸出電流即工作電流不隨負(fù)載與工作電壓變 化而變化。 關(guān)鍵詞 ： 兩線制變送器 V/I 變換電路 調(diào)理電路 單片機(jī) II Abstract Industry generally need to measure all kinds of nonelectric physical quantity, such as temperature, pressure, speed, Angle and so on. Needs to be converted into analog electrical signals can transmit to hundreds of meters outside of the control room or display device, the convert quantity into point signal device called a transducer. Industry is the most widely used to transmit analog 4 ~ 20 ma current. Adopt the cause of the current signal is not easily disturbed, and infinite, current source internal resistance wire resistance in series in the circuit will not affect the accuracy. Sad take 20 ma because explosionproof requirements, 20 ma electric current caused by broken spark ignition gas energy shortage。 Floor didn39。t take 0 ma in order to detection of bolt, is the cause of not less than 4 ma in normal working conditions, when the transmission line circuit because of malfunction, the loop current is reduced to. Often take 2 ma as a disconnection alarm value. This topic by analyzing the two wire, three wire system and four wire transducer characteristics, summarizing the typical transducer, on the basis of design idea and method, put forward a two wire system intelligent transmitter design scheme of economical and practical. To a single chip microputer as the core, special nonlinear sensor linear correction processing. Due to the zero current is 4 mA, so must ensure that the transducer working current to within mA。 A special wire output current feedback circuit, choose reasonable circuit scheme, guarantee the output current is not along with the load current and work voltage changes. Keywords: twowire transmitter, V/I inverter, recuperating circuit, Single chip microputer III 目 錄 摘要 ................................................................................................................. I Abstract ......................................................................................................... II 目錄 .............................................................................................................. III 前言 ................................................................................................................ 1 1 緒論 ............................................................................................................ 3 概述（課題來源及意義） .............................................................. 3 國內(nèi)外研究概況及研究現(xiàn)狀 .......................................................... 3 二線制變送器概述 ................................................................ 3 智能變送 器的研究現(xiàn)狀 ........................................................ 4 2 二線制變送器系統(tǒng)介紹 ............................................................................ 7 智能變送器概述 .............................................................................. 7 變送器分類 ............................................................................ 7 二線制 變送器特點(diǎn) ................................................................ 9 設(shè)計(jì)目的和要求 ............................................................................ 10 3 二線制變送器硬件設(shè)計(jì) .......................................................................... 11 普通電路的設(shè)計(jì) ............................................................................ 11 二線制變 送器電路原理分析 ........................................................ 12 系統(tǒng)總體設(shè)計(jì)思路 ........................................................................ 14 系統(tǒng)電路原理及設(shè)計(jì) .................................................................... 15 電源變換模塊 ...................................................................... 15 調(diào)理電路模塊設(shè)計(jì) .............................................................. 16 V/I 變換模塊設(shè)計(jì) ................................................................. 18 電流接收電路設(shè)計(jì) .............................................................. 19 24 位 AD 轉(zhuǎn)換電路設(shè)計(jì) ...................................................... 19 顯示電路設(shè)計(jì) ...................................................................... 20 MSP430 單片機(jī)簡(jiǎn)介 ............................................................ 21 4 軟件設(shè)計(jì) .................................................................................................. 23 總體系統(tǒng)原理 ................................................................................ 23 數(shù)據(jù)采集和處理模塊 .................................................................... 24 顯示模塊 ........................................................................................ 24 5 系統(tǒng)測(cè)試 .................................................................................................. 26 變換精度測(cè)試 ................................................................................ 26 IV 電阻值非線性度測(cè)試 .................................................................... 26 結(jié)果驗(yàn)算 ........................................................................................ 26 總結(jié) .............................................................................................................. 27 致謝 .............................................................................................................. 28 參考文獻(xiàn) ...................................................................................................... 29 附件 1 設(shè)計(jì)源程序 .........