【正文】 21 DS18B20引腳圖 引腳功能（如 表 21） 表 01 引腳功能表 序號 名稱 引腳功能描述 1 GND 電源地 2 DQ 為數(shù) 據(jù)輸入輸出引腳， 開漏單總線接口引腳。 C/LSB形式表示。溫度轉(zhuǎn)換命令被執(zhí)行 ,而后DS18B20保持等待狀 態(tài)。 硬件電路設計 智能數(shù)字溫度計硬件電路以智能控制器件 單片機的控制為核心 ,包括三個部 分 :單片機最小系統(tǒng)電路、溫度傳感器 DS18B20測溫電路、 LED數(shù)碼管顯示電路。利用單片機的 P0口控制數(shù)碼管的八段段碼 ,利用 4個數(shù)碼管的位碼 ,并采用動態(tài)掃描方式動態(tài)顯示溫度值。 信號調(diào)理電路中包括電橋和放大部分。 (3)單片機保存十進制 溫度值 該子程序?qū)嚎s BCD碼溫度數(shù)據(jù)拆分后裝入顯示緩沖區(qū) 70Ⅱ 73Ⅱ中。如圖 3— 3所示。 本系統(tǒng)在設計過程中也可以根據(jù)不同的使用人群 ,選擇不同的 LED數(shù)碼管。經(jīng)過幾周的奮戰(zhàn)我的畢業(yè)設計終于完成了。自己要 學習的東西還太多，以前老是覺得自己什么東西都會，什么東西都懂，有點眼高手低。在設計過程中，我通過查閱大量有關資料，與同同事交流經(jīng)驗和自學 ，并向老師請教等方式，使自己學到了不少知識，也經(jīng)歷了不少艱辛，但收獲同樣巨大。 感謝這篇論文所涉及到的各位學者。 //閃爍間隔標志 bit beep_st。 //狀態(tài)標志 uchar state=0。 //上限報警溫度，默認值為 33 嘉興職業(yè)技術(shù)學院畢業(yè)論文（設 計） 12 signed char xiaxian=5。 TH0=0x3c。 x++。set_st==1) { shangxian。set_st==2) { xiaxian。amp。amp。 c=ReadTemperature()。 //顯示 P2 = 0xf7。 P2 = 0xfd。 P2 = 0xff。 P0 =LEDData[abs(m)%10]。 P0 =LEDData[abs(m)/10abs(m)/100*10]。 else if(m/100)P0=LEDData[m/100]。 P2 = 0xff。 P2=0xf7。 Delay(200)。 if(set_st==1){P0=0x76。 P2=0xfe。 P2 = 0xff。amp。amp。HB=1。 //初始化定時器 EA=1。 IT1=1。z++) { Disp_init()。 if(state1)state=0。 do{}while(SET==0)。 if(set_st2)set_st=0。 //關閉外部中斷 0 EX1=0。 //報警檢測 } else if(set_st==1amp。LB=1。x=0。state==1) { BEEP=1。 //開啟外部中斷 0 EX1=1。} } } } /*****END*****/ include define DQ P3_4 //定義 DS18B20總線 I/O /*****延時子程序 *****/ void Delay_DS18B20(int num) { while(num) 。 //稍做延時 DQ = 0。 x = DQ。 for (i=8。 DQ = 1。 } /*****寫一個字節(jié) *****/ void WriteOneChar(unsigned char dat) { unsigned char i=0。 DQ = datamp。 dat=1。 float tt=0。 //啟動溫度轉(zhuǎn)換 Init_DS18B20()。 //讀低 8位 b=ReadOneChar()。 tt=t*。 disdain for this taxation without representation (socalled because the colonies had no voice in the establishment of the taxes) gave rise to revolts such as the Boston Tea Party. However, even after the Revolutionary War and the adoption of the . Constitution, the main source of revenue for the newly created states was money received from customs and excise taxes on items such as carriages, sugar, whiskey, and snuff. Ine tax first appeared in the United States in 1862, during the Civil War. At that time only about one percent of the population was required to pay the tax. A flatrate ine tax was imposed in 1867. The ine tax was repealed in its entirety in 1872. Ine tax was a rallying point for the Populist party in 1892, and had enough support two years later that Congress passed the Ine Tax Act of 1894. The tax at that time was two percent on individual ines in excess of $4,000, which meant that it reached only the wealthiest members of the population. The Supreme Court struck down the tax, holding that it violated the constitutional requirement that direct taxes be apportioned among the states by population (pollock v. farmers39。s new deal, imposed a five percent excise tax on dividend receipts, imposed a capital stock tax and an excess profits tax, and suspended all deductions for losses (June 16, 1933, ch. 90, 48 Stat. 195). The repeal in 1933 of the eighteenth amendment, which had prohibited the manufacture and sale of alcohol, brought in an estimated $90 million in new liquor taxes in 1934. The social security act of 1935 provided for a wage tax, half to be paid by the employee and half by the employer, to establish a federal retirement fund (Old Age Pension Act, Aug. 14, 1935, ch. 531, 49 Stat. 620). The Wealth Tax Act, also known as the Revenue Act of 1935, increased the maximum tax rate to 79 percent, the Revenue Acts of 1940 and 1941 increased it to 81 percent, the Revenue Act of 1942 raised it to 88 percent, and the Individual Ine Tax Act of 1944 raised the individual maximum rate to 94 percent. The postWorld War II Revenue Act of 1945 reduced the individual maximum tax from 94 percent to 91 percent. The Revenue Act of 1950, during the korean war, reduced it to percent, but it was raised the next year to 92 percent (Revenue Act of 1950, Sept. 23, 1950, ch. 994, Stat. 906). It remained at this level until 1964, when it was reduced to 70 percent. The Revenue Act of 1954 revised the Internal Revenue Code of 1939, making major changes that were beneficial to the taxpayer, including providing for child care deductions (later changed to credits), an increase in the charitable contribution limit, a tax credit against taxable retirement ine, employee deductions for business expenses, and liberalized depreciation deductions. From 1954 to 1962, the Internal Revenue Code was amended by 183 separate acts. In 1974 the employee retirement ine security act (ERISA) created protections for employees whose employers promised specified pensions or other retirement contributions (Pub. L. No. 93406, Sept. 2, 1974, 88 Stat. 829). ERISA required that to be tax deductible, the employe