畢業(yè)論文基于80C51單片機(jī)的電子密碼鎖設(shè)計(jì)

1、目 錄1緒論11.1引言11.2電子密碼鎖的背景11.3本設(shè)計(jì)特點(diǎn)12設(shè)計(jì)要求22.1設(shè)計(jì)任務(wù)22.2設(shè)計(jì)要求23硬件電路設(shè)計(jì)23.1設(shè)計(jì)方案的選擇3 3.1.1方案一3 3.1.2方案二3 3.1.3方案確定33.2密碼輸入方式的選擇4 3.2.1方案一4 3.2.1方案二4 3.2.3方案確定43.3主要元器件簡(jiǎn)介43.4硬件系統(tǒng)結(jié)構(gòu)5 3.4.1復(fù)位電路5 3.4.2晶振電路6 3.4.3存儲(chǔ)電路6 3.4.4報(bào)警電路74.程序設(shè)計(jì)84.1程序清單84.2 proteus/keil仿真圖17 4.2.1電子密碼鎖開(kāi)機(jī)仿真結(jié)果17 4.2.2電子密碼鎖修改密碼仿真結(jié)果175.總結(jié)18參考文

2、獻(xiàn)191.緒論1.1引言在日常生活和工作中，鎖是每個(gè)人都離不開(kāi)的，它是保護(hù)個(gè)人財(cái)產(chǎn)安全、保護(hù)資料檔案的關(guān)鍵元素。隨著電子技術(shù)的飛速發(fā)展，傳統(tǒng)彈子鎖的缺點(diǎn)漸漸被放大，社會(huì)對(duì)新式電子密碼鎖的需求越來(lái)越大，前景廣闊。本課題主要采用單片機(jī)完成了一套具有按鍵輸入、顯示、解鎖、報(bào)警及密碼修改等多種功能的電子密碼控制系統(tǒng)。據(jù)有關(guān)資料介紹，電子密碼鎖的研究從20世紀(jì)30年代就開(kāi)始了，在一些特殊場(chǎng)所早就有所應(yīng)用。這種鎖是通過(guò)鍵盤(pán)輸入一組密碼完成開(kāi)鎖過(guò)程。研究這種鎖的初衷，就是為提高鎖的安全性。由于電子鎖的密鑰量（密碼量）極大，可以與機(jī)械鎖配合使用，并且可以避免因鑰匙被仿制而留下安全隱患。電子鎖只需記住一組密碼，

3、無(wú)需攜帶金屬鑰匙，免除了人們攜帶金屬鑰匙的煩惱，而被越來(lái)越多的人所欣賞。電子鎖的種類(lèi)繁多，例如數(shù)碼鎖，指紋鎖，磁卡鎖，IC卡鎖，生物鎖等。但較實(shí)用的還是按鍵式電子密碼鎖。目前使用的電子密碼鎖大部分是基于單片機(jī)技術(shù)，以單片機(jī)為主要器件，其編碼器與解碼器的生成為軟件方式。1.2電子密碼鎖的背景隨著社會(huì)科技的進(jìn)步，鎖已發(fā)展到了密碼鎖、磁性鎖、電子鎖、激光鎖、聲控鎖等等。在傳統(tǒng)鑰匙的基礎(chǔ)上，加了一組或多組密碼，不同聲音，不同磁場(chǎng)，不同聲波，不同光束光波，不同圖像。（如指紋、眼底視網(wǎng)膜等）來(lái)控制鎖的開(kāi)啟。從而大大提高了鎖的安全性，使不法之徒無(wú)從下手，人們也就能對(duì)自身財(cái)產(chǎn)安全有了更多的保障。當(dāng)今安全信息系

4、統(tǒng)應(yīng)用越來(lái)越廣泛，特別在保護(hù)機(jī)密、維護(hù)隱私和財(cái)產(chǎn)保護(hù)方面起到重大作用，而基于電子密碼鎖的安全系統(tǒng)是其中的組成部分，因此研究它具有重大的現(xiàn)實(shí)意義。1.3本設(shè)計(jì)特點(diǎn)本系統(tǒng)由24C02和12864顯示的電子密碼鎖設(shè)計(jì)單片機(jī)系統(tǒng)、43矩陣鍵盤(pán)、12864顯示和報(bào)警系統(tǒng)等組成，具有設(shè)置、修改六位用戶密碼、超次報(bào)警、超次鎖定、密碼錯(cuò)誤報(bào)警等功能（本設(shè)計(jì)由P0口控制LCD顯示，密碼正確則進(jìn)入系統(tǒng)。密碼錯(cuò)誤顯示“密碼錯(cuò)誤，重新輸入密碼”）除上述基本的密碼鎖功能外，依據(jù)實(shí)際的情況還可以添加遙控功能。本系統(tǒng)成本低廉，功能實(shí)用。2.設(shè)計(jì)要求2.1設(shè)計(jì)任務(wù)設(shè)計(jì)一種基于單片機(jī)的密碼鎖2.2 設(shè)計(jì)要求2.2.1密碼用鍵盤(pán)

5、輸入（4-8位）2.2.2用戶可預(yù)置密碼（4-8位）2.2.3用LED數(shù)碼管或LCD顯示密碼值，密碼設(shè)置成功或開(kāi)鎖后顯示“*”2.2.4密碼輸入成功后開(kāi)鎖，密碼輸入錯(cuò)誤時(shí)數(shù)碼管或者LCD提示錯(cuò)誤信息，并且紅色的LED亮，三次輸入錯(cuò)誤后，揚(yáng)聲器報(bào)警。3.硬件電路設(shè)計(jì)3.1設(shè)計(jì)方案的選擇3.1.1方案一采用數(shù)字密碼鎖電路的好處就是設(shè)計(jì)簡(jiǎn)單。用以74LS112雙JK觸發(fā)器構(gòu)成的數(shù)字邏輯電路作為密碼鎖的核心控制，共設(shè)了9個(gè)用戶輸入鍵，其中只有4個(gè)是有效的密碼按鍵，其它的都是干擾按鍵，若按下干擾鍵，鍵盤(pán)輸入電路自動(dòng)清零，原先輸入的密碼無(wú)效，需要重新輸入；如果用戶輸入密碼的時(shí)間超過(guò)40秒（一般情況下，用戶

6、不會(huì)超過(guò)40秒，若用戶覺(jué)得不便，還可以修改）電路將報(bào)警80秒，若電路連續(xù)報(bào)警三次，電路將鎖定鍵盤(pán)5分鐘，防止他人的非法操作。電路由兩大部分組成：密碼鎖電路和備用電源(UPS)，其中設(shè)置UPS電源是為了防止因?yàn)橥ｋ娫斐傻拿艽a鎖電路失效，使用戶免遭麻煩。密碼鎖電路包含：鍵盤(pán)輸入、密碼修改、密碼檢測(cè)、開(kāi)鎖電路、執(zhí)行電路、報(bào)警電路、鍵盤(pán)輸入次數(shù)鎖定電路。3.1.2方案二采用一種是用以80C51為核心的單片機(jī)控制方案。利用單片機(jī)靈活的編程設(shè)計(jì)和豐富的IO端口，及其控制的準(zhǔn)確性，不但能實(shí)現(xiàn)基本的密碼鎖功能，還能添加調(diào)電存儲(chǔ)、聲光提示甚至添加遙控控制功能。其原理如圖所示。80C51單片機(jī)矩陣鍵盤(pán)控制輸入錯(cuò)誤

7、鎖定鍵盤(pán)延時(shí)報(bào)警控制電路24C02掉電存儲(chǔ)開(kāi)鎖控制電路指示電路串口顯示電路圖3-1系統(tǒng)總設(shè)計(jì)結(jié)構(gòu)圖3.1.3方案確定通過(guò)比較以上兩種方案，單片機(jī)方案有較大的活動(dòng)空間，不但能實(shí)現(xiàn)所要求的功能而且能在很大的程度上擴(kuò)展功能，而且還可以方便的對(duì)系統(tǒng)進(jìn)行升級(jí)，所以我們采用后一種方案。另外從經(jīng)濟(jì)實(shí)用的角度出發(fā)，采用80C51單機(jī)，研制了一款具有防盜自動(dòng)報(bào)警功能的電子密碼鎖。該密碼鎖設(shè)計(jì)方法合理，簡(jiǎn)單易行，成本低，符合住宅、辦公室用鎖要求，具有一定的推廣價(jià)值。3.2密碼輸入方式的選擇3.2.1方案一指紋輸入識(shí)別：指紋識(shí)別技術(shù)主要涉及四個(gè)功能：讀取指紋圖像、提取特征、保存數(shù)據(jù)和比對(duì)。通過(guò)指紋讀取設(shè)備讀取到人體

8、指紋的圖像，然后要對(duì)原始圖像進(jìn)行初步的處理，使之更清晰，再通過(guò)指紋辨識(shí)軟件建立指紋的特征數(shù)據(jù)。軟件從指紋上找到被稱(chēng)為“節(jié)點(diǎn)”（minutiae）的數(shù)據(jù)點(diǎn)，即指紋紋路的分叉、終止或打圈處的坐標(biāo)位置，這些點(diǎn)同時(shí)具有七種以上的唯一性特征。通常手指上平均具有70個(gè)節(jié)點(diǎn)，所以這種方法會(huì)產(chǎn)生大約490個(gè)數(shù)據(jù)。這些數(shù)據(jù)，通常稱(chēng)為模板。通過(guò)計(jì)算機(jī)模糊比較的方法，把兩個(gè)指紋的模板進(jìn)行比較，計(jì)算出它們的相似程度，最終得到兩個(gè)指紋的匹配結(jié)果，從而判斷輸入結(jié)果的正確與否。3.2.2方案二矩陣鍵盤(pán)輸入識(shí)別：由各按鍵組成的矩陣鍵盤(pán)每條行線和列線都對(duì)應(yīng)一條I/O口線，鍵位設(shè)在行線和列線的交叉點(diǎn)，當(dāng)一個(gè)鍵按下就會(huì)有某一條行線

9、與某一條列線接觸，只要確定接觸的是哪兩條線，即哪兩個(gè)I/O口線，就可以確定哪一個(gè)鍵被觸動(dòng)。行線設(shè)計(jì)成上拉口線，初始時(shí)被置高電位，列線懸空，初始置低。通過(guò)不斷讀行線口線，或者中斷方式觸發(fā)鍵位掃描。當(dāng)發(fā)現(xiàn)有鍵按下，將列線逐一置低，其他列線置高，讀行線口線。當(dāng)某條列線置低時(shí)，某條行線也被拉低，則確定這兩條線的交點(diǎn)處的按鈕被按下。3.2.3方案確定考慮到方案一軟硬件太過(guò)復(fù)雜，而且成本也高，故不采用，而方案二每個(gè)按鍵都可通過(guò)程序賦予功能，從而完成密碼識(shí)別本方案簡(jiǎn)單易行，故采用。3.3主要元器件簡(jiǎn)介3.3.1 24C02串行E2PROM是基于I2C-BUS 的存儲(chǔ)器件，遵循二線制協(xié)議，由于其具有接口方便，

10、體積小，數(shù)據(jù)掉電不丟失等特點(diǎn)，在儀器儀表及工業(yè)自動(dòng)化控制中得到大量的應(yīng)用。隨著世界上各公司對(duì)該器件的開(kāi)發(fā)，市場(chǎng)上推出了許多牌號(hào)的24C02器件，甚至還有一些冒牌的24C02器件，這樣就使批量生產(chǎn)的單片機(jī)控制系統(tǒng)的質(zhì)量出現(xiàn)時(shí)好時(shí)壞的問(wèn)題。筆者經(jīng)過(guò)大量的設(shè)計(jì)實(shí)踐和試驗(yàn)摸索找出了24C02在應(yīng)用中之所以出現(xiàn)數(shù)據(jù)被沖掉的原因，并總結(jié)了一套保護(hù)24C02數(shù)據(jù)安全的軟硬件設(shè)計(jì)方法。3.3.2 80C5180C51單片機(jī)屬于MCS-51系列單片機(jī)，由Intel公司開(kāi)發(fā)，其結(jié)構(gòu)是8048的延伸，改進(jìn)了8048的缺點(diǎn)，增加了如乘（MUL）、除（DIV）、減（SUBB）、比較（CMP）、16位數(shù)據(jù)指針、布爾代數(shù)運(yùn)

11、算等指令，以及串行通信能力和5個(gè)中斷源。采用40個(gè)引腳雙列直插式DIP（Dual In Line Package），內(nèi)有128個(gè)RAM單元及4K的ROM。3.3.3 1286412864液晶是一種統(tǒng)稱(chēng)，只說(shuō)明類(lèi)屏的一個(gè)特征，就是128*64個(gè)點(diǎn)構(gòu)成。對(duì)于液晶屏的特性則沒(méi)有說(shuō)明。3.4硬件系統(tǒng)結(jié)構(gòu)3.4.1復(fù)位電路單片機(jī)復(fù)位是使CPU和系統(tǒng)中的其他功能部件都處在一個(gè)確定的初始狀態(tài)，并從這個(gè)狀態(tài)開(kāi)始工作，例如復(fù)位后PC0000H，使單片機(jī)從第個(gè)單元取指令。無(wú)論是在單片機(jī)剛開(kāi)始接上電源時(shí)，還是斷電后或者發(fā)生故障后都要復(fù)位。在復(fù)位期間（即RST為高電平期間），P0口為高組態(tài)，P1P3口輸出高電平；外部

12、程序存儲(chǔ)器讀選通信號(hào)PSEN無(wú)效。地址鎖存信號(hào)ALE也為高電平。根據(jù)實(shí)際情況選擇如圖2-1所示的復(fù)位電路。該電路在最簡(jiǎn)單的復(fù)位電路下增加了手動(dòng)復(fù)位按鍵，在接通電源瞬間，電容C1上的電壓很小，復(fù)位下拉電阻上的電壓接近電源電壓，即RST為高電平，在電容充電的過(guò)程中RST端電壓逐漸下降，當(dāng)RST端的電壓小于某一數(shù)值后，CPU脫離復(fù)位狀態(tài)，由于電容C1足夠大，可以保證RST高電平有效時(shí)間大于24個(gè)振蕩周期，CPU能夠可靠復(fù)位。增加手動(dòng)復(fù)位按鍵是為了避免死機(jī)時(shí)無(wú)法可靠復(fù)位。圖3-2復(fù)位電路3.4.2晶振電路80c51引腳XTAL1和XTAL2與晶體振蕩器及電容C4、C5按圖2-2所示方式連接。晶振、電容

13、C4C5及片內(nèi)與非門(mén)（作為反饋、放大元件）構(gòu)成了電容三點(diǎn)式振蕩器，振蕩信號(hào)頻率與晶振頻率及電容C4、C5的容量有關(guān)，但主要由晶振頻率決定，范圍在033MHz之間，電容C4、C5取值范圍在530pF之間。根據(jù)實(shí)際情況，本設(shè)計(jì)中采用12MHZ做系統(tǒng)的外部晶振11。電容取值為20pF。圖3-3晶振電路3.4.3存儲(chǔ)電路AT24C02是一個(gè)2K位串行CMOSE2PROM，內(nèi)部含有256個(gè)8位字節(jié)，CATALYST公司的先進(jìn)CMOS技術(shù)實(shí)質(zhì)上減少了器件的功耗。AT24C02有一個(gè)16字節(jié)頁(yè)寫(xiě)緩沖器。該器件通過(guò)IC總線接口進(jìn)行操作，有一個(gè)專(zhuān)門(mén)的寫(xiě)保護(hù)功能。采用兩線串行的總線和單片機(jī)通訊，電壓最低可以到2.

14、5V，額定電流為1mA，靜態(tài)電流10Ua(5.5V)，芯片內(nèi)的資料可以在斷電的情況下保存40年以上，而且采用8腳的DIP封裝，使用方便。圖3-4存儲(chǔ)電路3.4.4報(bào)警電路報(bào)警部分由陶瓷壓電發(fā)聲裝置及外圍電路組成，加電后不發(fā)聲，當(dāng)有鍵按下時(shí)，“?！甭暎堪匆幌拢l(fā)聲一次，密碼正確時(shí)，不發(fā)聲直接開(kāi)鎖，當(dāng)密碼輸入錯(cuò)誤時(shí)，單片機(jī)的P2.1引腳為低電平，三極管T3導(dǎo)喇叭發(fā)出噪鳴聲報(bào)警。圖3-5報(bào)警電路4.程序設(shè)計(jì)4.1 程序清單*/#include#include#include#include#define uchar unsigned char#define uint unsigned intsbi

15、t LED1=P15;sbit LED2=P16;sbit INIT=P22;sbit SOUND=P17;ucharidata key6=0,0,0,0,0,0;ucharidataiic6=0,1,2,3,4,5;void press(uchar *s)uchardat;/* P3=0xf0;/保存第一位密碼while(P3=0xf0);dat=key_scan();if(dat!=0x0a)&(dat!=0x0b) *s=dat;Left(); star_12864(star,0x05,16); s+;/* P3=0xf0; /保存第二位密碼while(P3=0xf0);dat=key_

16、scan(); if(dat!=0x0a)&(dat!=0x0b) *s=dat;Left(); star_12864(star,0x05,24); s+;/* P3=0xf0; /保存第三位密碼while(P3=0xf0);dat=key_scan();if(dat!=0x0a)&(dat!=0x0b) *s=dat;Left(); star_12864(star,0x05,32); s+;/* P3=0xf0; /保存第四位密碼while(P3=0xf0);dat=key_scan();if(dat!=0x0a)&(dat!=0x0b) *s=dat;Left(); star_12864(

17、star,0x05,40); s+;/* P3=0xf0; /保存第五位密碼while(P3=0xf0);dat=key_scan();if(dat!=0x0a)&(dat!=0x0b) *s=dat;Left(); star_12864(star,0x05,48); s+;/* P3=0xf0; /保存第六位密碼while(P3=0xf0);dat=key_scan();if(dat!=0x0a)&(dat!=0x0b) *s=dat;Left(); star_12864(star,0x05,56); /* doP3=0xf0;/鍵入Enter鍵盤(pán)繼續(xù)執(zhí)行下面語(yǔ)句，否則等待while(P3=

18、0xf0);dat=key_scan();while(dat!=0x0b);void Delay10ms(void) /延時(shí)10ms uinti,j,k;for(i=5;i0;i-)for(j=4;j0;j-)for(k=248;k0;k-);void main()uchardat;uchar i=0,j=0,k;uchar x; LED1=1; LED2=1; SOUND=0; INIT=1; if(INIT=0) /密碼初始化 x=SendB(iic,0x50,6);Delay10ms(); /首先從IIC器件中讀出密碼以供下面輸入密碼進(jìn)行比較 x=ReadB(iic,0x50,6); I

19、nit_12864();/for(i=0;i150;i+)Delay10ms();/*若密碼不正確，循環(huán)執(zhí)行dowhile（）*do P3=0xf0;while(P3=0xf0);dat=key_scan();while(dat!=0x0b);if(dat=0x0b) do LED1=1; System(); /顯示：請(qǐng)輸入密碼字幕press(key); if(key0=iic0)&(key1=iic1)&(key2=iic2)&(key3=iic3)&(key4=iic4)&(key5=iic5) /密碼比較,若密碼正確責(zé)進(jìn)入系統(tǒng)，若密碼不正確則顯示密碼錯(cuò)誤，重新輸入密碼 true();do

20、 P3=0xf0;/鍵入1或2繼續(xù)執(zhí)行下面語(yǔ)句，否則等待while(P3=0xf0);dat=key_scan();while(dat!=0x01&dat!=0x02); if(dat=1) /開(kāi)鎖 LED1=0;unlock();for(i=0;i100;i+)Delay10ms();continue; if(dat=2)/修改密碼 doSystem(); press(key);again();press(iic); if(key0=iic0)&(key1=iic1)&(key2=iic2)&(key3=iic3)&(key4=iic4)&(key5=iic5) succeed();/修改密

21、碼成功for(i=0;i100;i+)Delay10ms();Delay10ms(); x=SendB(iic,0x50,6);Delay10ms(); x=ReadB(iic,0x50,6);break; else /修改密碼不成功，重新修改 repeat();for(i=0;i100;i+)Delay10ms(); while(1); else /密碼不正確，重新輸入密碼j+;if(j=3)for(i=0;i8;i+) LED2=0;for(k=0;k5;k+)Delay10ms(); LED2=1;for(k=0;k5;k+)Delay10ms();j=0; error();for(i=

22、0;i50;i+)Delay10ms(); while(1); 4.2 proteus/keil仿真圖4.2.1電子密碼鎖開(kāi)機(jī)仿真結(jié)果4.2.2 電子密碼鎖修改密碼仿真結(jié)果5.總結(jié)使用單片機(jī)的制作的電子密碼鎖具有軟硬件設(shè)計(jì)簡(jiǎn)單，易于開(kāi)發(fā)，成本較低，安全可靠，操作方便等特點(diǎn)，可應(yīng)用于住宅、辦公室的保險(xiǎn)箱及檔案柜等需要防盜的場(chǎng)所，有一點(diǎn)的實(shí)用性。該電路設(shè)計(jì)還具有按鍵有效提示，輸入錯(cuò)誤提示，控制開(kāi)鎖電平，控制報(bào)警電路，修改密碼等多種功能。通過(guò)本次課程設(shè)計(jì)，讓我對(duì)單片機(jī)有了進(jìn)一步的熟悉和了解，從理論到實(shí)踐，在這段日子里，可以說(shuō)得是苦多于甜，但是可以學(xué)到很多很多的東西，同時(shí)不僅可以鞏固了以前所學(xué)過(guò)的知識(shí)

23、，而且學(xué)到了很多在書(shū)本上所沒(méi)有學(xué)到過(guò)的知識(shí)。通過(guò)這次課程設(shè)計(jì)使我懂得了理論與實(shí)際相結(jié)合是很重要的，只有理論知識(shí)是遠(yuǎn)遠(yuǎn)不夠的，只有把所學(xué)的理論知識(shí)與實(shí)踐相結(jié)合起來(lái)，從理論中得出結(jié)論，才能真正為社會(huì)服務(wù)，從而提高自己的實(shí)際動(dòng)手能力和獨(dú)立思考的能力。此次設(shè)計(jì)也讓我明白了思路即出路，有什么不懂不明白的地方要及時(shí)請(qǐng)教或上網(wǎng)查詢，只要認(rèn)真鉆研，動(dòng)腦思考，動(dòng)手實(shí)踐，就沒(méi)有弄不懂的知識(shí)，收獲頗豐。特別感謝為輔導(dǎo)我們這次課程設(shè)計(jì)，一直辛苦工作的梁芳老師。參考文獻(xiàn)1李建忠 余新拴 閔永智. 單片機(jī)原理及應(yīng)用.(第三版). 西安電子科技大學(xué)出版社. 2013.102 王為青程國(guó)鋼.單片機(jī)Keil Cx51 應(yīng)用開(kāi)發(fā)

24、技術(shù).人民郵電出版社,2007.2 3朱定華單片機(jī)原理及接口技術(shù)實(shí)驗(yàn)北京：清華大學(xué)出版社北方交通大學(xué)出版社2002.014蔡明文 馮先成單片機(jī)課程設(shè)計(jì)武漢：華中科技及大學(xué)出版社2007.08請(qǐng)刪除以下內(nèi)容，O(_)O謝謝！ The term autism refers to a cluster of conditions appearing early in childhood. All involve severe impairments in social interaction, communication, imaginative abilities, and rigid, repet

25、itive behaviors. To be considered an autistic disorder, some of these impairments must be manifest before the age of three. The reference book used by mental health professionals to diagnose mental disorders is the Diagnostic and Statistical Manual of Mental Disorders , also known as the DSM. The 20

26、00 edition of this reference book (the Fourth Edition Text Revision known as DSM-IV-TR ) places autism in a category called pervasive developmental disorders . All of these disorders are characterized by ongoing problems with mutual social interaction and communication, or the presence of strange, r

27、epetitive behaviors,interests, and activities. People diagnosed with these disorders are affected in many ways for their entire lives. Description Each child diagnosed with an autistic disorder differs from every other, and so general descriptions of autistic behavior and characteristics do not appl

28、y equally to every child. Still, the common impairments in social interaction, communication and imagination, and rigid, repetitive behaviors make it possible to recognize children with these disorders, as they differ markedly from healthy children in many ways. Many parents of autistic children sen

29、se that something is not quite right even when their children are infants. The infants may have feeding problems, dislike being changed or bathed, or fuss over any change in routine. They may hold their bodies rigid, making it difficult for parents to cuddle them. Or, they may fail to anticipate bei

30、ng lifted, lying passively while the parent reaches for them, rather than holding their arms up in return. Most parents of autistic children become aware of the strangeness of these and other behaviors only gradually. Impairments in social interaction are usually among the earliest symptoms to devel

31、op. The most common social impairment is a kind of indifference to other people, or aloofness, even towards parents and close care-givers. The baby may fail to respond to his or her name being called and may show very little facial expression unless extremely angry, upset, or happy. Babies with auti

32、sm may resist being touched, and appear to be lost in their own world, far from human interaction. Between seven and 10 months of age, most infants often resist being separated from a parent or well-known caregiver, but these infants may show no disturbance when picked up by a stranger. Other childr

33、en with autism may be very passive, although less resistant to efforts by others to interact. However, they do not initiate social interaction themselves. Still others may attempt to engage with adults and peers, but in ways that strike others as inappropriate, or odd. In adolescence and adulthood,

34、some of the higher-functioning individuals with autistic disorders may appear overly formal and polite. They may react with little spontaneity, as if social interaction doesnt come naturally or easily to them, and so they are trying to follow a pre-determined set of rules. Some individuals with auti

35、sm have normal intelligence, and many have special talents in areas such as music or memory. However, individuals with autism may have other mental or emotional problems that co-exist with their autism. Some of these other disorders may include impulse control disorders, obsessive-compulsive disorde

36、r , mood and anxiety disorders, and mental retardation . PSYCHOLOGICAL AND FAMILY FACTORS. Although Henry Maudsley, in the late 1800s, was the first psychiatrist to focus on very young children with mental disorders, it was the psychiatrist Leo Kanner who coined the phrase early infantile autism in

37、1943. Kanner believed that the parents of children with autistic behaviors were emotionally cold and intellectually distant. He coined the term refrigerator parents to describe them. His belief that parental personality and behavior played a powerful role in the development of autistic behaviors lef

38、t a devastating legacy of guilt and self-blame among parents of autistic children that continues to this day. Recent studies are unequivocal, however, in demonstrating that parents of autistic children are no different from parents of healthy children in their personalities or parenting behaviors. I

39、n fact, many families with an autistic child also have one or more perfectly healthy children. Because autistic children can be extremely sensitive to change, any change within the family situation can be potentially traumatic to the autistic child. A move, divorce, birth of a sibling or other stres

40、sors that occur in the lives of most families may evoke a more extreme reaction from an autistic child. While there is no single neurological abnormality found in children with autistic disorders, some research using non-invasive brain imaging techniques such as magnetic resonance imaging (MRI) sugg

41、ests that certain areas of the brain may be involved. Several of the brain areas being researched are known to control emotion and the expression of emotion. These areas include the temporal lobe (large lobe of each side of the brain that contains a sensory area associated with hearing), the limbic

42、system, the cerebellum, the frontal lobe, the amygdala, and the brain stem, which regulates homeostasis (body temperature and heart rate). Recent research has focused particularly on the temporal lobe because of the finding that previously healthy people who sustain temporal lobe damage may develop

43、autistic-like symptoms. In animal research, when the temporal lobe is damaged, social behavior declines, and restless, repetitive motor behaviors are common. When measured by MRI, total brain volume appears to be greater for those with autistic disorders. Other neurological factors include lesions t

44、o the brain, congenital rubella, undiagnosed and untreated phenylketonuria (PKU), tuberous sclerosis, and Retts disorder (a related condition in which the baby develops in an apparently normal manner through age five months, and then begins to lose communicative and social interaction skills). There

45、 is also evidence of a higher proportion of perinatal complications (complications arising around the time of giving birth) among children with autistic symptoms. These complications include maternal bleeding after the first trimester and meconium in the amniotic fluid. (Meconium is a substance that

46、 accumulates in the bowel of the developing fetus and is discharged shortly after birth.) Some evidence suggests that the use of medications during pregnancy may be related to the development of autistic symptoms. As newborns, children with autistic behaviors show a higher rate of respiratory illnes

47、s and anemia than healthy children. ALLERGIES, INFECTIONS, AND IMMUNIZATIONS. Some professionals believe that autistic disorders may be caused by allergies to particular fungi, viral infections, and various foods. No controlled studies have supported these beliefs, but some parents and professionals

48、 report improvement when allergens and/or certain foods are eliminated from the diet. Viral infections of the mother, such as rubella, or of the young child, such as encephalitis, mumps, and measles, occasionally appear to cause autistic disorders. The common childhood immunization series known as M

49、MR (measles, mumps, rubella) has recently come under scrutiny as a possible cause of some autistic conditions.Basketball can make a true claim to being the only major sport that is an American invention. From high school to the professional level, basketball attracts a large following for live games

50、 as well as television coverage of events like the National Collegiate Athletic Association (NCAA) annual tournament and the National Basketball Association (NBA) and Womens National Basketball Association (WNBA) playoffs. And it has also made American heroes out of its player and coach legends like

51、 Michael Jordan, Larry Bird, Earvin Magic Johnson, Sheryl Swoopes, and other great players. At the heart of the game is the playing space and the equipment. The space is a rectangular, indoor court. The principal pieces of equipment are the two elevated baskets, one at each end (in the long directio

52、n) of the court, and the basketball itself. The ball is spherical in shape and is inflated. Basket-balls range in size from 28.5-30 in (72-76 cm) in circumference, and in weight from 18-22 oz (510-624 g). For players below the high school level, a smaller ball is used, but the ball in mens games measures 29.5-30 in (75-76 cm) in circumference, and a womens ball is 28.5-29 in (72-74 cm) in circumference. The covering of the ball is leather, rubber, composition, or synthetic, although leather covers only are dictated by rules for college play, unles