【正文】 .................................11表 22 利用 R0、R1 位來(lái)設(shè)定分辨力和最大轉(zhuǎn)換時(shí)間 .......................................................11表 23 DS18B20 中溫度字節(jié)中的位定義 ..............................................................................12表 24 DS18B20 溫度與數(shù)字輸出的對(duì)應(yīng)關(guān)系 .....................................................................12表 25 64 位激光 ROM 構(gòu)成 ...................................................................................................12表 26 暫存器的內(nèi)容 ..............................................................................................................13表 27 暫存器命令集 ..............................................................................................................13圖 25 暫存器操作命令流程圖 ..............................................................................................14 DS18B20 的工作協(xié)議 ................................................................................................................15表 28 DS18B20 的 ROM 操作指令與代碼對(duì)應(yīng)表 ...............................................................15表 29 存儲(chǔ)器操作指令與代碼對(duì)應(yīng)表 ..................................................................................15 DS18B20 的通信協(xié)議 ................................................................................................................17基于 DS18B20 的溫度報(bào)警器 IV 圖 26 復(fù)位和應(yīng)答脈沖時(shí)隙 ..................................................................................................17圖 27 讀寫(xiě)時(shí)序 ......................................................................................................................18 DS18B20 的溫度計(jì)算 ................................................................................................................18 單片機(jī)介紹 ........................................................................................................................................19 單片機(jī)的選用 ............................................................................................................................19 AT89S52 的主要性能： ............................................................................................................19 AT89S52 的功能性描述 ............................................................................................................19 AT89S52 引腳及其介紹。 ...........................................................................................................20圖 28 AT89S52 40LEAD PDIP 引腳圖 ................................................................................20表 210 P1 口部分引腳的第二功能 ........................................................................................21表 211 P3 口部分引腳的第二功能 ........................................................................................21 DS18B20 與單片機(jī)的接口電路 .......................................................................................................22 7 段 LED 數(shù)碼管電路及原理 ...........................................................................................................22圖 29 LED 共陽(yáng)接法 ..............................................................................................................23圖 210 LED 共陰接法 ............................................................................................................23圖 211 LED 各段的對(duì)應(yīng)圖 ....................................................................................................24第 3 章 系統(tǒng)硬件設(shè)計(jì) ...........................................................................................................25 總體框圖設(shè)計(jì) ....................................................................................................................................25圖 31 總體設(shè)計(jì)方框圖 ..........................................................................................................25 各模塊電路設(shè)計(jì) ................................................................................................................................25 主控制器及其外圍電路設(shè)計(jì) ....................................................................................................25圖 32 單片機(jī)及其外圍電路設(shè)計(jì) ..........................................................................................26 晶振電路 ....................................................................................................................................26圖 33 晶振電路 ......................................................................................................................26 顯示電路 ....................................................................................................................................27圖 34 LED 數(shù)碼管顯示電路 ..................................................................................................27 按鍵電路 ....................................................................................................................................27圖 35 按鍵電路 ......................................................................................................................28 蜂鳴器報(bào)警電路 ........................................................................................................................28圖 36 蜂鳴器報(bào)警電路 ..........................................................................................................28第 4 章 系統(tǒng)軟件設(shè)計(jì) ...........................................................................................................29 主程序 ................................................................................................................................................29圖 41 主程序流程圖 ..............................................................................................................29 讀出溫度子程序 ................................................................................................................................29圖 42 讀溫度子程序流程圖 ..................................................................................................30 溫度轉(zhuǎn)換命令子程序 ........................................................................................................................30圖 43 溫度