do luong dieu khien

8/7/2019 do luong dieu khien

1/52

Trong qu trnh o cc thng s ca cc th nghim vt l, ho hc hay sinh hc,... (cc ilng trong t nhin), Ngi ta thng bin i cc i lng khng in thnh cc ilng in nh cc b cm bin (sensor) tn dng c cc tnh nng u vit ca cc tnhiu in (pht, truyn, thu nhn v x l mt cch thun tin). Cc tn hiu t b cmbin ( c trng cho thng tin) c truyn vo cc b thu thp thng tin ri c m hov truyn qua knh thng tin, sau c thu nhn li, gii m v x l ti to li cc

dng tn hiu gc cung cp cc thng tin v din bin ca hin tng cn o. Qu trnh bini, m ho, truyn tin li b nh hng ca cc phn t nhiu (tp m) t mi trng nhhng lm tn hiu km trung thc. Do qu trnh x l tn hiu cn thit khi phc lidng gn nht ca tn hiu gc ban u.

M U : H O V IU KHIN1/ TN HIU :

Trong qu trnh o cc thng s ca cc th nghim vt l, ho hc hay sinh hc,... (cc ilng trong t nhin), Ngi ta thng bin i cc i lng khng in thnh cc i lngin nh cc b cm bin (sensor) tn dng c cc tnh nng u vit ca cc tn hiu in (pht, truyn, thu nhn v x l mt cch thun tin). Cc tn hiu t b cm bin ( c trng chothng tin) c truyn vo cc b thu thp thng tin ri c m ho v truyn qua knh thngtin, sau c thu nhn li, gii m v x l ti to li cc dng tn hiu gc cung cp ccthng tin v din bin ca hin tng cn o. Qu trnh bin i, m ho, truyn tin li b nhhng ca cc phn t nhiu (tp m) t mi trng nh hng lm tn hiu km trung thc. Do

qu trnh x l tn hiu cn thit khi phc li dng gn nht ca tn hiu gc ban u.

Trc y cc tn hiu thng c x l bng k thut tng t (analog). Nhng ngy nay vicpht trin ca cc my tnh c nhn (PC) khin cho vic p dng cc k thut x l tn hiu sngy cng c s dng rng ri.(DSP). K thut x l s cho php thc hin nhng cng vicx l phc tp nht m vn m bo c tnh mm do cao nht (iu m k thut x l tnhiu tng t khng th lm c).

Tn hiu : L biu hin vt l ca thng tin (information). cc thng tin xut hin t mt qutrnh no trong t nhin. Cc thng s ca tn hiu c th thay i theo thi gian v nhiu i

lng khc.

Tn hiu c th l cc i lng vt l khng in ( p sut, nhit , sng, t thng, pH)v cng c th l cc i lng in ( hiu th mV hai u cp nhit in,... ). Nhng thchin c cc k thut x l s ngi ta phi bin i tn hiu t cc i lng khng in thnhcc i lng in trong khi tin hnh qu trnh o. v th y ta coi rng tn hiu l tn hiuin.

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2/52

Tn hiu lin tc : L tn hiu m s thay i ca n theo thi gian v bin l lin tcTn hiu ri rc : L tn hiu m bin ca n ch xc nh trong nhng khong thi gian xcnh.

Cc tn hiu tc dng vo u vo v u ra ca thit b o tu thuc vo c tnh ca tn hium c th chia thnh bn loi nh sau :- Tn hiu tng t(analog signal) : L tn hiu lin tc c v bin ln thi gian.- Tn hiu c lng t ho (Quantified Signal) : L tn hiu lin tc theo thi gian nhngbin c lng t ho.- Tn hiu ri rc (Discrete Time Signal) : L tn hiu c ly ri rc theo thi gian nhngbin vn gi lin tc. Hm tn hiu ch c gi tr xc nh nhng thi im xc nh. Ta cth thu nhn c tn hiu ri rc bng cch ly mu tn hiu tng t (sampling). V vy tnhiu ri rc cn c gi l tn hiu c ly mu (sampled signal).- Tn hiu s (Digital Signal) : L tn hiu ly ri rc theo thi gian v bin cng c lng

t ho.

1.2/ CC H O V IU KHIN

Khi ni my tnh vi mt h thng o, iu khin hay vi mt th nghim vt l, ho hc cnbin i cc tn hiu li ra ca cc b cm bin cho ph hp vi li vo my tnh. Cc qu trnhchuyn i in p tng t thnh tn hiu s yu cu cc b chuyn i tng t s (AD). Bctip theo thng lin quan n vic iu kin ho cc tn hiu sinh ra bi cm bin. My tnhcng c th thc hin chc nng iu khin. Theo ngha ca hai chc nng ny ( o v iukhin), my tnh c th tham gia (tng tc) vi mt tin trnh no : Bng vic lp trnh chnh

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xc, my tnh c th iu khin mt tin trnh trn c s thu nhn v x l cc tn hiu phn hit tin trnh .Ngy nay c th s dng cc thit b khc nhau cho mc ch ny :- Thit b ghp ni theo giao din RS 232

- Cc board thu thp s liu cm thm- Thit b giao din IEEE-488- Thit b VXIVi cc ng dng khc nhau cc thit b ghp ni khc nhau c s dng, tt nhin l cng cs khc bit v c tnh v gi thnh gia cc thit b khc nhau.Cc thit b n gin nh cp nhit in, ng h o tc , thit b t ghi d liu c th cthc hin qua ghp ni RS-232. Chun ghp ni ni tip ny c s dng khi cnni thit b ngoi vi vi my tnh qua mt khong cch di. Ghp ni ni tip truyn d liu tngbt mt qua mt ng dy tn hiu ti mt my tnh khc. Do u cm RS-232 hu nh lchun cho tt c cc my tnh PC v vy khng cn thm cc phn cng b xung. V ngun gc,RS-232 c thit k ni cc my tnh (hay thit b u cui) vi cc MODEM ( ni ving in thoi).

Cuc cch mng cc b chuyn i tng t s v cc thit b iu kin ho tn hiu khincho cc board thu thp d liu cm thm tr nn ph bin. Gi s vi yu cu o vi giiin p t -5v n +5V chnh xc yu cu l khng ln hn 1 : Board thu thp d liu2048 bt l mt s la chn t nhin. Trn mt board thng tch hp nhiu chc nng :chuyn i AD, chuyn i DA, vo ra I/O, cc hot ng m, nh thi gian. Cc boardthu thp d liu cm thm cung cp nhiu kh nng mm do hn so vi mt thit b nc.

Giao din ghp ni IEEE- 488 cn c bit n nh GPIB (Bus ghp ni mc ch chung)thit k cho vic s dng vi cc ng dng i hi tc truyn d liu cao (c1MByte/giy). IEEE 488 nh ngha c cc lin kt phn cng ln giao thc lnh kt nithit b. a s cc thit b nh cc giao ng k nh v cc my pht chc nng u c

giao din IEEE-488 i km.

BUS VXI ra i nm 1987, l mt mt bng pht trin cho cc ng dng thi gian thc tc cao. Mt trong cc phng n kh thi l cc my tnh nhng trong cc khung VXI(frame). CPU, thit b o v b nh cng tch hp lun trong cc khung VXI v ghp nitrc tip qua cc BUS VXI 32 bt. Tc truyn d liu cc i c 20MByte / giy.

lin lc gia cc my tnh v thit b ngoi vi ngi ta thc hin cc nghi thc mc ni(handshaking).

Nhm mc ch h tr cho vic iu kin ho tn hiu , cc thit b c bit (gi l front-end) c s dng kt hp vi cc board thu thp d liu nhm cch ly my tnh vi thit bo (v mt in trnh hng hc). Cc thit b front-end ny thng sn c ngun cung

cp, b khuych i ( hai b khuych i vi cc li vo vi sai) v cc b lc thp ( hai b).Nhiu u ni 2mm ni vi card ghp ni.

Trong cc kt ni song song hai chiu gia thit b o v my tnh. Cc my tnh thngthng khng c sn cc cng kt ni song song nh vy. Tuy nhin ngi ta c th sdng cc b tip hp ring trn cc khe cm m rng,V d nh cc board ghp ni

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UIA/UIB thc hin cc knh I/O hai chiu, chuyn i AD v mt vi chc nng b xungkhc. (phng th nghim my tnh Trung tm ITIMS)

Card ghp ni UIA/UIB h tr nhiu kh nng o, n c bn li vo tn hiu tng t.

Cc b chuyn i tng t / s ni lin khong cch gia th gii tn hiu s v tng t.Mt h thng tng t / s in hnh li vo h thng nhn cc kch thch vt l, ho hchay sinh hc; b chuyn i chuyn nhng tn hiu ny ra dng tn hiu in tng t(sensor p sut, nhit , nh sng ...). cc tn hiu c sinh ra do b chuyn di thngtng i nh v cn c khuych i ln ( n mc in p yu cu ) trc khi cchuyn i sang dng tn hiu s tng ng. Cc gi tr s i din cho tn hiu sau sc cc my tnh hay b vi x l lu tr hay x l ri c ti to li thnh cc tn hiuin nh b chuyn i s / tng t DAC.

2/ CC H THU THP D LIU (DATA AQUISITION)

2.1/ CHUYN I TN HIU TNG T THNH TN HIU SCc b chuyn i ADC ( tng t / s ) ni lin khong cch gia th gii tn hiu s v tngt. Hnh v di y biu din mt h thng tng t / s in hnh. Li vo h thng nhn cc

kch thch vt l, ho hc hay sinh hc; b chuyn i chuyn nhng tn hiu ny ra dng tnhiu in tng t ( sensor p sut, nhit , nh sng ...). cc tn hiu c sinh ra do bchuyn di thng tng i nh v cn c khuych i ln ( n mc in p yu cu ) trckhi chuyn sang dng tn hiu s tng ng. B chuyn i tng t / s (ADC ) chuyn tnhiu dng tng t ny thnh tn hiu dng s. My tnh hay b vi x l sau s ct hay x lcc gi tr s ny to ra cc tn hiu in qua b chuyn i s / tng t DAC. Lu rng ttc cc h thng tng t / s khng nht thit phi c c cc li vo v cc li ra. N c th chc cc li vo tng t hoc cc li ra tng t.

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My tnh s : L mt thit b thu thp v x l tn hiu s, trong khi cc tn hiu o t cc qutrnh gm c tn hiu tng t. V vy s khi y ca vic x l tn hiu bng tnh strong cc thc nghim nh sau :

Tn hiu tng t t thc nghim a vo b lc thng thp LF1, c ly mu qua b trch vgi mu S&H (sample and hold) thnh tn hiu ri rc. Sau c a qua b bin i tngt s ADC (Analog digital-converter) thnh tn hiu s v a vo my tnh PC x l.Tn hiu s sau khi x l c bin i tr li thnh tn hiu tng t qua b bin i stng t DAC (Digital-analog-converter) ri li a qua b lc thng thp LF2 thnh tn hiuli ra. Tc dng ca hai b lc thp LF1 v LF2 s c ni r sau. Tuy nhin tn hiu s khia vo my tnh x l khng nht thit phi ly ra t ADC m c th c ly trc tip t ccqu trnh s khc. Cng nh vy, tn hiu s sau khi x l khng bt buc phi qua b bin iDAC chuyn i li thnh tn hiu tng t m c th c ly ra ngay iu khin cc qutrnh s khc.

Hnh v - H thng tng t-s

Thit b chuyn i nhng tn hiu tng t bin i lin tc t cc thit b theo di cc iukin nh s chuyn ng, nhit , cng sng, m thanh ...thnh cc s nh phn dng trongmy tnh. C th l mt chip n hay mt mch in thit k cng mt chp gi l b chuyn itng t s (Analog Digital Converter).

Vai tr ca cc b chuyn i l chuyn dng ny ca nng lng ( nh sng, nhit ... ) ra

thnh cc dng khc ( tn hiu in ).

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6/52

iu khin l mt vai tr quan trng trong ghp ni my tnh vi ngoi vi, vic iu th hin kh nng lp trnh mm do cc cu lnh my tnh h thng t ng lm nhng cng vicnht nh (m khng c s can thip ca con ngi). Cng vi h thu thp d liu, h x l, iukhin h thng l thnh phn ct li ca cc robot iu khin t ng cng nghip.

3/ IU KHIN H THNG:

3.1.1/ VO RA SONG SONGH thng o v iu khin :iu hon khng kh :- Bt tt l si trung tm (bt/ tt)- Ni un (bt/tt)- Qut (bt/tt)- Airgrid ( m/ng )- Ti nc (bt/tt)- M ca s (m/ng)- D phng (c/khng)Cc qu trnh tip din- Nhit ti hn- p sut ti hn- Nng cn ti hnThang my- Chuyn ng (ln/xung)- Gi t trong ra (ln/xung)- Gi t ngoi vo (ln/xung)- m n gi tr 0 (c/khng)- Ca thang my (m/ng)- Hm khn cp- Chung (bt / tt )Cng c th xt ti cc h thng iu khin cho n giao thng, thit b gia nh nh mygit, my ra chn, un nc si, l nng, l si ...

3.1.2/ IU KHIN SLu khi s dng chc nng iu khin vi my tnh:- Li ra ch c th iu khin li vo tng tch TTL- Ngun cung cp 5 V trn cp ch chu c c 100mA (UIA) 200mA(UIB)Ni chung cc li ra ny nn c dng m ng mt transitor iu khin mt rler.Hnh v n LED s bt sng khi transitor dn in.V d iu khin l :n (bt/tt)

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7/52

iu khin motor ca h thng si trung tm (bt/tt)Qut (bt/tt)Cungcp gas (bt/tt)nh la in (bt/tt)CUng cp xy (bt/tt)Cung cp nc (bt/tt)

La chn in pLa chn tn sM t bc (bt/tt)

3.1.3/ H PHN HI (FEEDBACK)Trong cc qu trnh phn hi : Vic kch hot hay tt iu khin bng tin trnh o trc n.

Cu hi :- Nu mt s v d v iu khin h thng- H phn hi l g, v d ?

3.2/ CHUYN I S TNG T (DAC)Chuyn i DAC chuyn mt gi tr s thnh mc th hay dng tng t tng ng. Huht cc DAC hot ng song song, l cc bt c np vo song song v do khngcn cc ngun xung nhp, li ra s t c mc th ngay sau khi mch c n nh.

Khi nim c s ca DAC l cc bt c dng bt ON hay tt OFF cc mc th hay dngtrng s. Chng c cng thm vo v li ra s l mc tng t tng ng vi gi tr sli vo. Bt nhiu ngha nht c trng s bng na ca ton thang ... Mt DAC cngthn gin biu din trn hnh v :

tin hnh ghp ni, card ghp ni hay cc board ghp ni l phn cng thit yu ng vai trtrung gian, ca ng gia my tnh v cc thit b ngoi vi, c th l mt thit b chp hnh, mtthit b o,...card hay board ghp ni c th c ci t (install) trong my tnh c nhn hay quacc giao tip thng thng ca my tnh nh cng usb, cng ni tip COM hay cng my in

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song song LPT. Trong bi hc ny chng ta s tm hiu mt card ghp ni chuyn dng dngtrong cc bi thc tp ti ITIMS, card ghp ni vn nng UIB (Univesal Inteface Bus)

CARD GHP NI UIA/UIB

thc hin cc ng dng my tnh lin quan ti cc h thng o v iu khin, Cc my tnhPC (kiu MS-DOS) cn card m rng khng phi l cc card chun i km vi cc my tnh.Card gh ni vn nng UIA/UIB kt hp cc mch in cn thit thc hin hu ht cc chcnng o lng, iu khin cho cc ng dng c bn.Card UIA / UIB c thc hin ti khoa Vt L trng i hc tnghp Amsterdam ( H lan).

Khoa ny thc hin cc pht trin ng dng cc thc nghim trn c s my tnh rt sm (tnm 1982). Hp tc vi cc k thut vin, nh vt l chuyn gia o to v gio vin, thit ku tin ca UIA ra i nm 1987. T nm 1988 card ghp ni vn nng UIA c s dngtrong hng trm trng hc ti H lan. B tng hp UIA tr thnh chun cho vic lin ktcc th nghim vi cc my tnh PC (nn DOS).Card m rng UIB l version ci tin ca UIA. ci tin quan trong nht l cc li vo tng t.B chuyn i ADC kiu 12 bt ( 8 bt trong UIA), cha cc chc nng trch v gi mu nhanhhn rt nhiu. Gii in p li vo cng c ci thin i vi mc th m. Nhnng ci tin nylm tng tnh ng dng ca cc b tng hp ny

CC LINH KIN CHNH TRN CC UIA :

- 8255 PPI (Programable Peripheral Interface) : Gm 24 ng I/O c th s dng trongnhiu MODE t hp vo ra khc nhau.- 8254 PIT (Programable Interval Timer ) IC ny c 3 b m 16 bt c lp c th s dng to ra cc xung v sng vung vi tn s c th lp trnh c- Cng tc mm : thit lp cu hnh cc b m (nh thi) v cc phng n ngt cth c thit lp bng cc lnh chng trnh- Ngun xung nhp ni (1MHz 4MHz, chn bng JUMPER) : Cho php dnh thi 8254 clp vi ng h h thng ca my tnh.- ADC0844 cng vi b tin khuych i, chuyn i AD, c bn knh cho in p gia 0v 5 V ( knh 1 v 2) hay gia 0 v 1 V (knh 3 v s 4). Chuyn i th tng t thnh s8 bt mt 40

Hnh v :(Hnh 2.3_trang 15 - Lu khi ca UIB )

THNH PHN CHNH CHO CARD UIB :- 82C55 PPI (Programable Peripheral Interface) : Gm 24 ng I/O c th s dng trongnhiu MODE t hp vo ra khc nhau.- 8C254 PIT (Programable Interval Timer ) IC ny c 3 b m 16 bt c lp c th sdng to ra cc xung v sng vung vi tn s c th lp trnh c- Cng tc mm : thit lp cu hnh cc b m (nh thi) v cc phng n ngt cth c thit lp bng cc lnh chng trnh.- Ngun xung nhp ni (1MHz 4MHz, chn bng JUMPER) : CHo php dnh thi 82C54 c

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lp vi ng h h thng ca my tnh.- ADS7803 v tin khuych i : CHuyn i tng t s vi bn li vo tn hiu tng t.Cc knh 1 v 2 c th hot ng vi gii in p t 5 n +5V, vi cc knh 3 v 4 giiin p vo c th t qua JUMPER t 1 n +1V hay 2V n +2V; -5 V n +5V v -10Vn +10V. Qu trnh s. chuyn i mt in p tng t ra m s 12 bt mt khong 10

iu khin ADC :n v iu khin kch hot chuyn i ADMi knh ny c th c khi ng qu trnh chuyn i bng lnh chng trnh (phnmm) hay khi ng bng li ra xung ca b m 0 vi tng knh xc nhThanh ghi b tr :a/ Chn mc tch cc cho cng GATE1b/ Bt hay tt ngun cung cp in p +5V trn u cm 9 chn.

ADC TRN CARD GHP NI UIA/UIBC s khc bit gia UIA v UIBUIA : ADC0844 l b chuyn i AD vi li vo multiplexer 4 knh tn hiu tng t. Cc livo tng t ca ca card UIA c m (knh 1 v 2) hay c tin khuych i ( knh 3v 4 ). Theo cch ny khong th li vo knh 3 v 4 l t 0 1 V. Tn hiu gi cht

trong khong . th vo ca ADC. Tt c cc knh c tr khng vo c 100Ks. in p 5V c th sai lch khong +-0.2 V (4.8 Thi gian chuyn i c 40 5.2 V)hnh v :Cc MODE ADC : Bng cch vit ra t iu khin ln a ch ca ADC, ADC c th c lptrnh cc MODE khc nhau. Khun dng ca t iu khin theo bng di y

Khun dng t iu khin cho knh/MODE ( a ch 0x308)Bn bt thp ca t iu khin vit ra cht a ch MUX (multiplexer). Cc bt ny xc nhhai knh no c chn v cc in p tng ng s c du nh th no (dng hay m).Qua b cng th, nhng th ny s c kt hp v sau x l bi b chuyn i ADC.( gio trnh Tin hc I phn II - phng th nghim my tnh Trung tm ITIMS)

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MODE n cc l MODE thng dng, ngha ca n l t iu khin quyt nh chn knhchuyn i ADC. Sau khi vit t iu khin, qu trnh s. chuyn i c t ng bt u.Kt qu c th c c sau 40 Trong MODE ny chu k gia mt knh xc nh v ttng t (AGND) c chuyn i bi ADC.Vi trng hp outportb(0x308) = 4; // 0000 0100 th ca knh 1 ( tng i so viAGND) c chuyn i thnh gi tr byte tng ng.

Trong MODE vi sai, ADC chuyn i chu k gia hai knh ( in p so snh ).MODE gi vi sai c th ni chung thng khng c s dng chnh xc, v s khc bit v nhy gia cc knh.

UIB : ADS7803 :Hnh v :ADS7803 cha b chuyn i ADC 12 bt vi mch ly mu tn hiu v gi mu trc tiptrc qu trnh chuyn i. y l mt b MUTIPLEXER 4 knh vo tngt. ADS7803 dngphng php xp x lin tip, mc in s). Phn p vo c s ho thnh 12 bc xp xlin tip ( 12x0,5 cng cho php ly mu tc 100kHz. Tn hiu vo vi tn s n50kHz c th o c.Khong th vo ca ADS7803 l 0 n 5V. Mi li vo u c tin khuych i. Vi knh1 v 2 ca li vo cp 9 chn gii in p t 5V n 5V. Gii in p cho knh 3 v 4 l

c la chn bng JUMPER t 1V n + 1V hay 2V n + 2V ; -5 V n + 5V hoc 10Vn + 10V). Cc li vo u c tr khng 1 00KMc th thp nht trong gii in p vo l nhn gi tr s l 0 trong khi mc cao nht(mc trn) gi tr s l 4095.

Khi to qu trnh chuyn i nh sn ln ca li vo khi ng (Sart Conversion) vi mttn hiu hp l t li vo knh gii m v ng chn chip (CS). Knh chuyn i tng tc chn ly mu tn hiu mt 5 chu k xung nhp. Mt php chuyn i xp x lin tips tin hnh trong chu k 6 n 17.

c d liu : D liu t ADS7803 c c trong hai byte : byte thp ( a ch 0x308) vbyte cao 0x309. Cc byte ny c th c theo bt k th t no. Bt 7 ca byte cao ADC

biu din trng thi ca tin trnh chuyn i. Nu =1 th qu trnh chuyn i ang cthc hin, nu l 0 th qu trnh chuyn i hon tt.

MODE cht li ra :Trong MODE ny d liu t qu trnh chuyn i ch c cht vo haicht li ra 8 bt sau khi qu trnh chuyn i hon thnh v c gi cho n khi qutrnh chuyn i tip theo hon tt. D liu kt qu ca qu trnh chuyn i cn hp l cho

trong khi qu trnh chuyn i tip theo ang thc hin. iu ny cho php c d liu cngay c khi mt qu trnh chuyn i mi tip theo bt u. Lm cho h thng nhanhhn.Mode cht li ra kch hot nh vic vit s 1 ra bt 0 ca thanh ghi chc nng c bit caADC (0x30B)

MODE trong sut (Transparent) : Trong MODE ny thanh ghi xp x lin tip l trong sut Vd 4 bt nhiu ngha nht c th c c sau khi kt thc chu k th 9 ca qu trnhchuyn i. D liu 12 bt y c th sau khi EOC chuyn v 0. Lc bt ngun b

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chuyn i t MODE trong sut theo mc nh.

Do cch thc hin ca ADS7803 trong Card UIB m qu trnh chuyn i c th c thchin hai cch khc nhau :- Chuyn i bng lnh chng trnh : Khi mt ch th c vit ra a ch 0x308 (hay0x309) khi ng mt chu k ca knh c chn, ly mu v chuyn i. Cc ng d

liu D0 v D1 qui nh knh mun chuyn i, v d : outportb(0x308,1) khi ng qutrnh chuyn i knh 2. ( s knh l 1 .. 4 tng ng vi cc m 0 .. 3). Cch ny khito qu trnh chuyn i c chn khi bt #2 ca thanh ghi MODE ly mu a ch 0x30Cbng 0. y l thit lp mc nh sau khi my tnh khi ng. ( hoc sau mt RESET cng)s) t b m 0 - Chuyn i khi to bng mt xung m ( c trng 1 (PIT). Mode nyc chn nu bt #2 ca thanh ghi MODE ly mu a chr 0x30C t l cao. Bt #0 v #1nh nghi knh c chn. V d, sau lnh outportb(0x30C,6); qu trnh chuyn i knh3 c thc hin (tun t) sau mi xung li ra ca b m 0.

Kt qu chuyn i :Sau khi khi ng qu trnh chuyn i (vi mt trong hai cch trn), cn phi i chon khi qu trnh chuyn i hon thnh trc khi c th c c kt qu. Bt cao nht a ch 0x309 s bng 1 trong sut qu trnh chuyn i. Vng lp di y c th c

dng kim tra :do x = inportb(0x309) while(( x & 0x80 )!= 0 )Nu iu kin ny tho mn ( bt cao nt ca bin x bng 0), th x gi 4 bt cao nht cakt qu gi tr chuyn i 12 bt. byte thp c th nhn c ti a ch 0x308, sau mtphp cng iu chnh s cho kt qu ca php chuyn i inportb(0x308) + x*256.u im ln nht ca vic khi ng qu trnh chuyn i trc tip t b m 0 (MODE 2)l vic nh thi chnh xc thi im ly mu, bng khong thi gian gia hai ln mm.Xung li ra ca b m 0 c th dng sinh ra mt ngt. ng thi vi khi ng qutrnh chuyn i, chng trnh qun l ngt s c gi. Chng trnh qun l ny s phii cho n qu trnh chuyn i hon thnh v k kt qu c th c ct gi trongmt mng.

CHUYN I DAC(thc nghim) Card DAC 12 bt tng thch vi cc my tnh AT vi li ra DAC c gii inp t -5V n +5V v mt knh DAC c gii in p t 0V n +10V.Card DAC c s dng cng vi card UIB nh s b xung do card ghp ni UIB khng tchhp sn chc nng chuyn i DA trn card.Gii a ch card DAC c dng trong khong t 0x210 - 0x240 v knh th hai gii ach 0x310 - 0x340. Gi tr mc nh ca card l 0x210 cho knh DAC0 v 0x310 cho knhDAC1. Nh vy nn t card UIB ti a ch 0x300 trnh xung t a ch.Cng c th t li cc a ch ny bng cch t li cc JUMPER trn card.Bng cch vit mt t 12 bt ra a ch DAC, hai cht d liu 8 bt s cht d liu v sau truyn d liu cho b chuyn i DAC. Nu DAC va chn ng tn hiu U5a/b s yng IO CS16 xung thp v cho php mt php truyn d liu 16 bt. ng tn hiu I/ORDY trn khe cm PC (ISA) khng c dng. Thng bt ny c s dng cho cc card PC

tc chmbng cch hu b mt chu k vit mi cho n khi d liu c x l xong. Vicard loi ny ngi lp trnh cn cnh gic khi mt chu trnh vit nhanh c th dn n ktqu chuyn i nhm ln nu chu trnh vit ang trong khong thi gian tr do qu trnhchuyn i ang tin hnh ( v d nh khi mun to ra cc dng song vi tn s cao ).( gio trnh Tin hc I phn II - phng th nghim my tnh Trung tm ITIMS)

Khuych i OPAM ng vai tr b m phi hp tr khng c tri nh v dng d nh,tc cao. B chuyn i DAC th nht s dng hai b OPAM : mt ng vai tr m phihp tr khng nh in tr phn hi ni ca DAC v ci kia khuych i tng dch tn

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hiu thnh mc lng cc. Mt mch dch th mt chiu b xung dng thay i thoffset ca U6 vi P2. H s khuych i ca DAC0 c th thay i bng cch chn ng gitr in tr cho R3, R7 v R9. Thng R9 s l mt ) v R3 khng c ni. R7 l in trchnh xc cao in tr dy (0 10K (0.1%)iu chnh khuych i ca DAC1 khng cn thit trong khi cc in tr ni U9 cdng. In p Offset c th thay inh chit p P1.

Cc khuych i Burr Brown c th c thay th bng cc vi mch TL051 r tin hn vhu nh c cng c tuyn.Li ra ca chuyn i DA c th dng vi cc ti tr khng thp, hay dn, nn ni thm vib khuych i ngoi.

Chng trnh kim tra :outport(0x210, 0x0); // DAC 0 = -5 Voutport(0x210, 0xFFF; // DAC 0 = + 5V

outport(0x310, 0x0); // DAC 1 = 0 Voutport(0x310, 0xFFF); // DAC 1 = 10 V

A CH DAC:

C th chn qua cc JUMPER

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Lu vi card ghp ni UIA : cc a ch 0x309,0x30A v 0x30B tng ng vi 0x308( cng tng t vi cc gii a ch khc)Lu vi UIB : a ch 0x30E tng ng vi 0x30C, 0x30F tng ng vi 0x30D ( vtng t cho cc gii a ch khc)

CC THIT LP H THNG :Trc khi ci t cn kim tra :- My tnh ca bn c tha t nht mt khe cm m rng (ISA)- Mt trong cc a ch 0x100 .. 0x10F, 0x110 .. 0x11F v 0x300 .. 0x30F cn cha s dng- t nht mt trong cc mc ngt 2, 3, 4, 5 cn rnh- Tc nhp ca h thng khng vt qu 8MHz.JUMPER : Trc khi cm UIA/UIB vo khe cm trong my tnh, cn xc lp mt s JUMPERging nhau trn c UIA v UIB. Cc board UIB c 4 JUMPER la chn b xung gii in pvo cho cc knh 3 v 4.- JUMPER J1 dng t mc ngt, mc nh l 2. C th ngt ny b s dng bi ccboard m rng khc, trong trng hp ny s khng s dng c ng chc nng ngt.Th vi cc ngt 3, 4 hay 5. Trong hu ht cc my tnh XT mc ngt 2 s c th dng

c. Cc my AT thng t mc ngt 5.- JUMPER J2 dng chn khong a ch, mc nh l 0x300 0x30F. Nu cc card mrng khc dng mt gii a ch ny th th cc chn la khc nh : 0x100 0x10F(256-271); 0x110 0x11F ( 272-287); 0x300 0x30F (768 783) v 0x310 0x31F( 784 799 ).- JUMPER J6 xc nh tn s xung nhp ni. 1MHz v 4MHz. Mc nh l 1 MHz, chng trnhcng thng gi thit l tn s nhp 1MHz nn nu t 4MHz th thng gp li.Ring cho board UIBJUMPER J3a v J3b cng nhau xc n gii in p vo cho knh 3 theo s sau :

- JUMPER J4a v J4b cng nhau xc nh gii in p vo cho knh 4 theo cng cch dint vi knh 3- JUMER J5 ni tn hiu xung nhp 2MHz vi b chuyn i AD. Nu g ra ADC s s dngng h xung nhp ni ring ca n. Qu trnh chuyn i s chm hn mt cht, nhngmc n c th c hn ch.

CI T :- M my tnh

- Chm tay vo v my khong mt pht gim tnh in- Tho dy ngun- G v my- Chn card UIA/UIB vo khe cm ISA cn trng trongmy ( ch khong cch gia cccard m rng trnh chp)- Vt nh cc c- Lp li v myU NI :-u ni 9 chn :

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1/ Li vo knh 1 (CH1)UIA : 0- 5VUIB : -5V 5V. trong nhiu fth nghim Tr khng vo ca li vo tng t l 100K vi UIA/UIB skhng nh hng n h thng. Gii in p vo c lng t ho ra thnh 256 mc(UIA) v 4096 mc (UIB) in p bng nhau.

2/ Li vo knh 3 (CH3)UIA : 0 1VUIB : gii in p tu thuc vo xc lp JUMPER3/ t cho tn hiu tng t4/ t cho tn hiu s5/ Li vo xung nhp cho b m 1Li vo CLOCK v GATE l cc triger Schmitt, H qu l khng c cc yu cu c bit vitc chuyn mc logic cho cc cng( B m gim di mt mi ln chuyn t mc thp ln mc ri v mc thp ( xung dng))Mc cao v thp ngha l +5V v 0 V tng ng(TTL). Trong thc tin cc in p vo trn+2.0V c xem nh mc cao. di +0.8V xem nh mc thp. Vi li ra TTL: thp nghi ldi +0.4V v cao l trn +2.4V. in p vo trn +5.5V v di 0.5V nn trnh, ccmcc in p ny c th gy ra h hng mch in.

6/ Li vo cho knh 2 (CH2)UIA : 0- 5VUIB : -5V 5V7/ Li vo cho knh 4 (CH4)UIA : 0 1VUIB : gii in p tu thuc vo xc lp JUMPER8/ in p ra 5V. Ngun ny b gii hn dng cc i 100mA (0.5W), c th dng cho mts loi sensor9/ Cng vo GATE cho b m 1Li ny cho php hay hu b qu trnh m ca b m 1Cng GATE c th s dng o chu k ca mt xung dng ( hay c xung m vi UIB ).Xung dng ngha l mc th thay i t mc thp ( gn 0V) n mc cao (gn 5V) v tr

v.Hnh v :u ni 25 chn :Tt c cc li vo v ra l tng thch TTL. Li ra c ti vi 1 li vo TTL, CLK 0, CLK 1 v GATE 1 l cc li o triger SCHMITT.1-8/ Cng A : cng vo ra 8 bt c th lp trnh cPAO l bt t ngha nht, gi tr 1 l cao; 0 nu l thp.PA7 l bt nhiu ngha nht. gi tr 128 nu mc cao v 0 nu l mc thp14-17 Cc bt thp cng C (PC0 PC3)18 21Cc bt cao cng C (PC4 PC7)Na cao v na thp cng C c th lp trnh ring bit cho c vo hay vit ra.10/ Li vo nhp cho b m 0. m xung 1 mi xung dung ( thp cao thp)

11/ Li vo cng GATE ch b m 0 ( mc inh l cao ). Hot ng m b cm nu cngnyb t xung mc thp.12/ Li ra b m 0. Tnh cht tu thuc vo xc lp cho MODE m.13/ Li ra cho b m 223/ Li vo xung nhp cho b m 124/ Li vo cng GATE cho b m 125/ Li ra cho b m 19/ t22/ Th li ra +5V, dng cc i l 100mA (0.5W) cho UIA v 200mA (1W) cho UIB.

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Bo v : Cc card ghp ni UIA/UIB- Trnh a nhng in p qu cao hay qu thp (ngoi gii o) n cc li vo. Trnh ccphng in tnh in vi cc ng tn hiu ni trc tip.- Cc li vo tng tu c th chu c cc in th gia 30V v 30V- cc li vo s khng nn chu cc gi tr di 0.5V hay trn +5.5V.

- Th li vo l c gi bi cc diod. Kh nng chu ng tu thuc vo dng trn li vo.Cc peaks in p t ngun cng hn ch nh cc diod ny- Li ra s cng c th chu c s ngn mch vi t trong mt thi gian ngn. Vi cc lira in p ngn mch +5V nn trnh.

CC PHP TON THAO TC BITSANSI-C cung cp su php ton thao tc bt c th p dng vi cc ton hng kiu nguyn(char, short, int v long c du hay khng du). Cc php ton ny v kiu kt qu cm t trong bng di y :

Lnh code = code 1 dch cc bt i 1 v r sang phi cn bt 7 bng 0v d :17 & 7 =

0x17 & 0x07 =0xFC | 0xC3 =~ 0x55 =6 >> 2 =2


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duy tr khng i trong khi iu khin bt 3. C th xy dng c hm nh sau iukhin qu trnh :magnet_control ( high_voltage, on)

void magnet_control ( int bit_nr, int value){

int mask;static int ctrl_code;mask = 1


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Peripheral Inteface ).

16 ng I/O cho hai cng 8 bt A v C c ni vi jack cm 25 chn trn card UIA/UIB.Mi cng c a ch ring. Vic gi v nhn d liu c thc hin qua vic c v vit raa ch cng tng ng. C th s dng cng A cho c vic vo v ra d liu trong viMODE khc nhau. Trong khi o cng C c chia ra lm hai cng 4 bt Pclower (na bytethp PC0 PC3) v PC upper (na byte cao PC4 PC7) c th lp trnh c lp cho mi na MODE c vo hay vit ra. Cng C ch hot ng mt MODE. MODE hot ng c lachn bng cch vit t iu khin cho thanh ghi iu khin. Thanh phn ca t iu khinc biu din di y :Vi card UIA/UIB, cng B lun c t MODE ra (MODE 0) v n c dng iu khincc cng tc mm. ( gio trnh Tin hc I phn II - phng th nghim my tnh Trung tmITIMS)

V d : outportb(0x303,145) // 1001 0001 s t cng A trong MODE 0 c vo , cng BMODE 0 vit ra v cng C (thp) MODE c vo v na cao MODE vit ra.Ring cng C ( khi MODE vit ra) tng bt ring bit c th c xc lp ln 1 hay v 0( m khng nh hng ti cc bt khc) bng cch vit t SET/RESET bt ( bt 7 lun lunbng 0) ra t iu khin.V d :outportb(0x303,6); // 0000 0110 t bt PC3 xung thp

outportb(0x303,7); // 0000 0111 t bt PC3 ln mc cao

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4.1.1/ NH DNG T IU KHIN CHO VIC T / XO BT CNG C

Cc MODE PPI : Vic lp trnh cho MODE cng A tu thuc vo cch truyn d liu vithit b ngoi vi.a/ MODE0 : Vo ra c s :- MODE 0 vit ra : Mt byte c vit ra cng v s c cht li ngha l n xut hintrn kt ni vi cng v s duy tr cho n khi mt byte mi c vit ra cng .- MODE 0 c vo : VIc c trn mt cng s cho bit gi tr ca mt byte hin hnhtrn cng ( ti thi im c ).

Nu chng trnh s dng cng A MODE 1 hay 2, cng A s dng cc tn hiu mc ni.Cc ng tn hiu mc ni ny c mn t cng C (khi cng C khng th c dng MODE vo ra thng thng na ). MODE 0 cng A khng thc hin vic mc ni nn ccbt cng C u c th s dng hot ng vo ra thng thng.

b/ MODE 1 : Vo ra STROBE ( nhp nhy )Mc ni c thc hin m bo th t truyn d liu. Vi cc hot ng vo hay ra sdng cc tn hiu mc ni khc nhau.

MODE 1 c vo dng :- STB ( li vo STROBE). Khi ngoi vi ni t li vo ny xung mc thp, byte hin hnhc np vo vng m vo, d liu c th dc t cng sau .- IBF ( Input Buffer Full) mc cao ch ra rng c mt byte va c ti vo vng m vcha tng oc c. Chng trnh iu khin nhn ra c mt byte mi va nhn c vngoi vi bit rng khng nn gi byte tip theo v byte trc cha c x l.- INTR (Interrupt Request). Nu c php, mt ngt s c sinh ra khi byte c ti vovng m c. Vic c t cng s lm INTR xung thp li.

MODE 1 vit ra : dng cc ng :- OBF ( Output Buffer Full ) : ng ny xung thp khi mt byte va vit ra cng vn cncha c thit b ngoi vi chp nhn ( c ). Bng cch ny, chng trnh thy rng nkhng th gi d liu mi ( do byte trc vn cha c ngoi vi x l (chp nhn) vthit b ngoi vi nhn ra c mt byte mi nhn c.- ACK (Acknowledge). Thit b ngoi vi xc nhn rng byte va c chp nhn bng ccha ACK xung mc thp. iu ny lm cho li ra OBF ln cao mt ln na, chng

trnh bit n c th gi mt byte mi.- INTR ( Interrupt Request) Nu cho php, ngt s sinh ra khi vng m ra l trng ( thitb vit ra sn sng nhn d liu mi). Vit ra cng s t li ng INTR xung thp.

NGT:Trong chng trnh , trng thi ca ng INTR (PC3) c th c kim tra lin tc ( thmd) bit c byte mi no oc c vo hay vit ra cng A khng. Trong hu ht trnghp, cch hiu qu hn l 8255 PPI sinh ra ngt. ng INTR c th c kch hot haykhng kch hot nh cc triger INTE ( cho php ngt ). Hay l cc cng tc mm cc ng

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INTR ca PPI c th c ni vi mt trong cc mc ngt ( ng yu caa ngt ) ca mytnh.Cng A dng cc flipflop INTE khc nhau cho li vo v li raLi vo cng A : INTE-A c bt/tt bng cch t bt SET/RESET PC4Li ra cngA : INTE-A c bt hay tt (SET/RESET) nh bt PC6

c/ MODE 2 : Vo ra hai chiu Strobe.Mode ny ch c th vi cng A v c ngha kt ni vi mt thit b ngoi vi qua mt busd liu 8 bt theo c hai chiu, gi v nhn (I/O song cng ). trng thi bnh thng cngA c t MODE vo. Di iu kin thit b ngoi vi iu khin ACK xung thp, bytetrong vng m ra c t ra li ra. Nu khng thit b ngoi vi c th t d liu ln cngv ti nhng d liu ny vo cht d liu vo nho vic t mt xung (thp) ln li voSTB. CHc nng ca cc tn hiu mc ni tng t nh trong MODE 1. flipflop INTE cho livo (PC4) v li ra (PC6) c th c bt hay tt c lp vi cc thit b ngoi vi khc.

Chc nng cc ng tn hiu trn cng C

Cng C cc ng cn li, thng tin trng thiTrong MODE 1 v 2 cng A mn cc bt ca cng C thc hin mc ni. Cc bt cn li cth c dng vo ra I/O thng thng.Cng C c th c c thng thng. Trong byte kt qu cc bt tng ng vi cc ngmn cho bit trng thi ca cc ng ny. Cng C ng vai tr nh thanh ghi trng thicc ng tn hiu mn. V d chng trnh c th c trng thi ca OBF hay IBF. Nucng C c lp trnh MODE vo, cc bt cn li phn nh mc tn hiu trn nhng ngny. Nu MODE ra, cc ng PC4 PC7 ch c th c iu khin bng chc nng t /xo bt. Cc ng PC0 PC3 cng c th c iu khin bng cch vit mt byte ra cngC ( c kh nng l cc bt mn PC3 s khng thay i gi tr ).

2/ II - Timer/ Counter _PIT-82C54 :Trn c s vi mch PIT 82C54 : l b m c th lp trnh c, n gm 3 b m c lp,

mi b m c mt li vo xung nhp (Clock), mt li vo cng (Gate) v mt li ra (Out).Li ra cng v li vo nhp ca b m 0 v 1 c ni ra cng 25 chn (UIB). Ni vo nhpca cng b m 1, cng ni vi cng 9 chn ca UIB, b m 2 ch c li ra vi cng 25chn. Mi b m hot ng tu thuc vo mode c lp trnh. ( gio trnh Tin hc I phnII - phng th nghim my tnh Trung tm ITIMS)

Mi n v m gm c :- Mt triger sn dng kch hot mt b m li 16 bt- Hai thanh ghi li vo 8 bt ct gi tr khi u b m ( gi tr m bt u )

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- Hai thanh ghi li ra cht gi tr m tc thi- Mt thanh ghi iu khin v mt n v iu khin iu khin b m theo MODE cchn- Mt thanh ghi cht trng thi c trng thi hin ti ca b m.Phn t m (b m li c th t li c), mt thanh ghi m (ct d liu c vit vob m), mt cht d liu li ra, ct d liu c ra t b m v mt n v iu khin

logic (iu khin b m tu theo mode lp trnh ). Di nhng Iu kin nht nh tuthuc vo mode ca b m, s m ban u c np vo phn t m, sau bt uqu trnh m li. Khi b m t n gi tr 0 (N xung sau khi np gi tr N vo thanh ghim) n v logic Iu khin hot ng tng ng tu thuc vo mode lp trnh. Phn tm m li i 1 mi mt xung nhp trn li vo nhp, li vo cng (Gate) l li vo iukhin. Chc nng ca n tu thuc vo mode lp trnh. Cc ng li vo gate c treoln vi cc in tr PullUp v mc logic nu khng ni l bng 1. Mode b m c xc lpbng vic vit t iu khin n thanh ghi iu khin. Sau khi vit t iu khin, cc byteca s m ban u c vit ln lt vo b m.Ch thch:CRM ,CRl : Thanh ghi m (dng lu tr d liu c ghi ln b m).CE : Phn t m (B m gim dn ng b vi nhng thit lp c t trc).OLM ,OLM : Cht li ra (Cha d liu c c t b m).

Hnh v: nh dng ca cng tc chuyn mch mm ( Cng B ca PPI-8255A, a ch$301). Cng B gm 8 bit c xc nh t PB0-->PB7, dng xc lp ch kt ni chob m vo.

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Khi to b m : Vic khi to b m c thc hin nh vit mt byte t iu khin raa ch thanh ghi iu khin b m PIT theo th t bng sau y

Cc bt 7 v 6 xc nh b m no s c khi to. Bt 4 v 5 xc nh cch vit gi trkhi to cho b m xc nh bi cc bt 7 v 6 ni trn., c th vit mt byte n ( c

phn byte cao hoc byte thp) hay vit c hai phn ln lt ln b m . Cc bt 3, 2, 1xc nh MODE m. Bt 0 qui nh kiu m l m nh phn hay m nh thp phn (BCD

Binary Coded Decimal)

4.2.1/ VIT B M :Hu ht cc ng dng u dng b m hai byte. Nh vy gi tr khi to cn np (vit)

vo thanh ghi li vo theo ng trt t : bt t ngha nht trc (lsb), bt nhiu nghatip theo (msb). Sn xung dng ca xung nhp (ngoi) u tin s copy gi tr khi uvo b m.

4.2.2/ C B M:Khi ang tin hnh qu trnh m, gi tr b m c th b thay i trong qu trnh c dnn kt qu c c khng chnh xc, iu ny c th trnh c nh vic tm dng qutrnh m bng cch t cho cng Gate xung mc thp 0. Trong hu ht cc trng hp

ngi ta mun c gi tr b m m khng nh hng n qu trnh m th c 2 cch t c iu ny:

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lnh cht b m (Bit 5,4 =00) Lnh c li b m (Bit 7,6 =11)

a/ Lnh cht b m: Khi c vit vo thanh ghi iu khin, th gi tr b m c chtvo thanh ghi li ra v s liu ny c th c gi nguyn chng trnh c li sau .Lu : phi c 1 hoc 2 byte , nu khng c th lnh cht tip theo s b b m

b qua v gi tr u vn c gi nguyn.

b/ Lnh c li b m: hot ng ging nh lnh cht b m nhng n cho php chtgi tr ca nhiu b m ng thi, mi b m c cht cho n khi n c c (hoc lb m c lp trnh li), cng c th cht byte trng thi, byte trng thi thu c bngcch c b m .

D liu c cht ca mt lnh cht hoc lnh c li cn phi c c hon ton nukhng lnh c li tip theo s khng c nh hng trn b m . Bit m NULL (D6=1)trong byte trng thi ch ra rng mt s m ban u va c vit ln b m cha c

np vo trong phn t m dn n vic c b m s khng c ngha

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c/ Mode b m: mode ca b m c nh ngha bi cc bit 1,2,3 ca t iu khin.+ Mode 0: (ngt khi kt thc m) Sau khi b m va t l mode 0 th li ra OUT l thp(=0), ngay khi gi tr m va c np vo th bt u qu trnh m li, khi t n 0, li

ra OUT ca b m bt ln cao (=1, c th c dng sinh ra mt ngt) vit mt gi trm mi s lp li qu trnh ny, tc l OUT li thp xung v qu trnh m li li tinhnh. Qu trnh m c php nu cng Gate l cao, khi cng gate l thp th cc xung

nhp b b qua (khng m).(Tm li: trong mode 0, nu gi tr OUT=0 th qu trnh m ca b m vn ang ctin hnh, Nu OUT=1 th chm dt qu trnh m. Gi tr OUT ca b m s c kimtra qua vic c Byte trng thi ca b m - kim tra bit D7 ca b m - sau khi thc

hin lnh c thanh ghi).

+ Mode 1: (kch hot bng xung phn cng) Ban u li ra OUT l mc cao (=1) vi mtxung sn ln li vo cng gate th li ra OUT s xung thp v gi nguyn mc thptrong khi m li.

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+ Mode 2: (my pht xung) mode ny l mode lin tip, li ra OUT xung thp mt chu kxung nhp ngay khi qu trnh m kt thc (s m =1). Sau OUT li ln mc cao mtln na v gi tr m ban u li c np li. Nh vy c sau mi chu k N xung nhp, lira OUT li xung thp trong mt chu k. cng Gate c th c dng ng b b m:sau mt xung mc thp trn cng gate, b m khi ng li t gi tr m ban u.

+ Mode 3 (my to sng vung): mode ny tng t mode 2, qu trnh m xung s cthc hin hai ln, nhng vi s bc gp i. Vi s m ban u l chn th OUT s caotrong na u ca chu k ( N, N-2, N-4, .... , 2) v thp trong na cn li ( N-1, N-3,..., 1).Vi s ban u l l, th chu k mc cao ca li ra OUT s gi lu hn mt xung nhp sovi chu k thp. Cng nh vi mode 2, li vo gate c th c dng ng b b m.

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+ Mode 4 (khi ng mm): OUT s khi u l cao sau khi s m ban u c vit thb m bt u m li ngay khi t n gi tr 0, OUT s thp trong mt chu k xung nhp.

Li vo gate cho php qu trnh m khi mc cao v cm khi mc thp.+ Mode 5 (kch hot cng): OUT bt u mc cao. Khi gate t n mc cao, s m banu c np v qu trnh m li bt u. Khi gi tr m t n 0, OUT xung thptrong mt chu k xung nhp. ( gio trnh Tin hc I phn II - phng th nghim my tnh Trung tm ITIMS)

V d: To my pht xung vung iu khin c t bn phm

Hnh : Khai bo v hm to xung vung dng b m C2

Hnh : Chng trnh chnh vi vng lp bt phm iu khin tn s

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Hnh : Mn hnh kt qu trong DOS- bm ESC thot khi chng trnh

4.3/ CHUYN I TNG T - S ADC

Chuyn i tng t s phc tp hn chuyn i s tng t. y cp n kiu phbin nht ADC xp x lin tip.

ADC s cn mt thi gian hu hn tnh ton cc gi tr s. N cng cn bo hiu khi noth bt u qu trnh chuyn i v tr li tn hiu khi kt thc qua trnh ny. Khi nhn c

tn hiu kt thc, my tnh c t li ra ADC. Nhng ng tn hiu chnh iu khin qutrnh mc ni ny nh trn hnh v.

ng tn hiu SC ( bt u chuyn i ) ln mc kch hot cao (HIGH) bo vi ADC btu qu trnh chuyn i (tnh ton ). Sau khi kt thc li ra EOC xung mc thp (LOW)bo hiu gi tr li ra ca ADC n nh du bo rng y l ng hot ng mcthp. gin thi gian ca chu trnh chuyn i nh trn hnh v.

4.3.1/ ADC XP X LIN TIP

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Phng php xp x lin tip l phng php ph bin cho cc kiu ADC do tc , chnhxc v d thit k ca n. Hot ng nh vic so snh th c sinh vi th li vo. Mtmch dy v mt DAC to ra th so snh nh trn hnh v :

Phng php xp x lin tip : phng php trn c s ng v sai. Tn hiu li vo cxp x lin tip bng mt na ln ca bc trc . Nh trn hnh v :

Bc th nht kim tra xem nu in th vo Vin ln hn mt na khong in th(Vranger) ca ADC. Gi s rng li ra l ng th php xp x tip theo s kim tra xemnu Vin ln hn (1/2 + ) gii in p Vranger. Gi s kt qu l sai. Php so snh th bas kim tra xem liu Vin c ln hn (1/2 + + 1/8) ca gii in ap Vranger. Qu trnh nys lp li cho n khi th vo xp x chnh xc.

Nh vy ADC xp x lin tip gm b so snh, mt chuyn i s tng t (DAC), mt ngh xung nhp v mt thanh ghi xp x lin tip SAR.

B so snh :Khuych i thut ton s dng so snh hai gi tr in th cng ln ( bin ),nu khng dng ch c phn hi. Li ra ca mt b thut ton l tng l +15V. NuV + ln hn V v bng 15V nu V + nh hn V - . Nhng mch nh vy c gi l bso snh ( comparator ). Trong trng hp ny, Vout l gii hn v 0 tng ng vi 5 V li ra c th tng thch TTL.Chuyn i DAC : B chuyn i DAC chuyn i s nh phn thnh th tng t tng ngt l v ln (bin ) vi gi tr ca s .

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Khi u qu trnh chuyn i th so snh c t bng na thang o li vo. Nu th sosnh qu ln ln lt s thit lp php so snh gia mt tp cc gi tr mt na cc gi trgia gii hn thp v im mt na trc . Nu th so snh qu nh th th t lin tipphp so snh gia im gia v ton thang. Qu trnh ny tip tc cho n khi t nkhong tng nh nht. M trn li ra l gi tr s tnh c. Hnh v biu din php so snh

vi b chuyn i 4 bt v chu trnh ly mu xp x lin tip.

C th thy s php so snh cn thit bng s bt trong mu. nh vy s chu k xung nhpcn thit cho php tnh xp x lin tip bng s bt li ra.

4.3.2/ ADC LI RA SONG SONG

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B chuyn i song song N bt ( hay b chuyn i kiu flash) dng cc thang in tr to ra 2N - 1 mc lng t t LSB (bt t ngha nht ) n (2N-1) ln LSB. Mi chng sosnh vi th vo dng 2N - 1 b so snh. Nu th trn li vo thun (+) ca b so snh ln

hn li vo o (-) th li ra s mc cao , khc i s l mc thp. Th ngng c avo li vo li vo (+) v th vo a vo li vo (-). Nh vy li ra ca mi b so snh scao khi th vo ln hn th ngng v thp khi nh hn. Mt b gii m (decode) s dchli ra t cc b so snh thnh m nh phn. Hnh v biu din mt ADC song song 3 bt vi7 b so snh. bng di y cng lit k s lng cc b so snh cn thit cho ADC vi phn gii khc nhau. C th thy DC 16 bt cn 65535 mc th v b so snh.

ADC flash khng yu cu xung nhp v tc ca n ch b gii hn bi thi gian thit lpca tn hiu. Thng thng c dng trong cc ng dng tc cao nh b gii m mutrn cc mn hnh VGA / SVGA, cc ng dng rada,...

4.3.3/ LP TRNH CHO CARD IU KHIN ADC

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Hai ng iu khin s ng b vic truyn d liu gia my tnh v ADC. Chng l ccng SC ( bt u chuyn i ) v EOC ( kt thc chuyn i ). ng SC l ng li voADC v dng khi ng mt qu trnh chuyn di. EOC l li ra t ADC dng ch rarng qu trnh chuyn i kt thc d liu trn ADC l hp l v c th bt u c vomy tnh. Tn hiu ny mc kch hot thp.Nh vy khi SC mc cao, bt u mt qu trnh chuyn i khc vi EOC mc thp khi

ADC thc hin xong vic chuyn i. PPI c th c dng iu khin v quan st ccng tn hiu mc ni ny bng cch ni hai ng vi 2 bt trn cng C ( iu khin SCv quan st EOC )

ng EOC l li vo vi PPI v SC l li ra. My tnh khi ng qu trnh chuyn i ADCbng cch t SC ln cao. Tip theo my tnh s quan st EOC cho n khi no n xungmc thp. Khi s tin hnh c ti cng (A) m li ra ADC ni vi n.Cng C c th tch ra thnh hai na vo v ra C ( cao ) v C (thp). Khi ny C thp l livo ( ni vi EOC ) v C (cao) l li ra ( SC). lu nh sau :

1/t SC ln cao (PC4 - 1)2/Quan st EOC (PC0 ) cho n khi n xung thp (0)

3/c t cng A4/t SC (PC4) xung thp (PC4 - 0 )5/Tr mt cht6/Quay tr li 1

a/Ghp ni vi ADC qua PPI vi mode 1Vn chnh vi Mode 0 l my tnh phi thng xuyn quan st ng EOC. K thut ci tin l cho php PPI thng bo cho ADC bit d liu vng m ca cng cha c cv ng vit thm d liu mi vo. iu ny t c nh vic s dng PPI mode 1.Trong mode ny cng C c dng mc ni

Khi gi s liu vo my tnh, thit b ngoi t STB xung mc kch hot thp (0), d liusau c c vo vng m vo. Tip theo PPI t ng t IBF ln cao v d nguyncho n khi PC c xong d liu t vng m. ng ny c dng bo cho ngoi ving gi thm bt k d liu no n PPI. Mt khi d liu c c IBF tr li mc thpbo cho ngoi vi (ADC) c th tip tc gi d liu.

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Hnh v biu din cc thit lp c lin quan n chng trnh iu khin. y l hot ngmc ni in hnh, ch c iu cn n mt b o gia IBF v SC cho php cc tn hiuc thch hp.

Khi vng m ca cng y v ng PC5 (IBF) l khng mc kch hot ( thp ). Kt niny thng qua b o n SC ca ADC. Khi ng n mc cao s bt u qu trnhchuyn i ca ADC. Khi kt thc EOC xung thp ng ny li ni trc tip vi PC4 (STB)khin cho d liu trn cng A c th c np vo vng m vo ca cng. PPI sau tng t bt PC5 (IBF) ln cao ( gy ra SC chuy xung thp v reset ADC ) ng ny dnguyn cho n khi PC c xong d liu t vng m vo. Khi ng IBF xung thplm cho SC ln cao. ADC li bt u mt qu trnh chuyn i mi

b/ Lp trnh mode 1V PC4 (STB) xung thp li ra ca ADC c c vo vng m. Khi xy ra iu ny thPC5 (IBF) t ng ln mc cao bo hiu vng m vo y. Nh vy PC phi kim trang ny pht hin nu c s liu hp l trn vng m vo cha. Lnh((inportb(PORTC) & 0x20 ) == 0x20) c mt byte t cng C v mt n kim tra bitPC5 (IBF). Nu bt ny l 1 th ng ny l cao v d liu trong vng m l hp l.

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4.3.4/ CHUYN I T S THNH GI TR TUYT ITrong hu ht cc trng hp gi tr s c c t ADC cn phi chuyn i sang gi trthc t nh p sut hay nhit . xc nh nhit tuyt i cn thit phi c c trngchuyn i nhit sang in p ca cm bin (sensor) v h s khuych i s dng.Thng thng, th li ra t sensor nhit oc a vo b khuych i vi c tn hiun cc ln tn hiu lng cc.

Hnh v biu din c tuyn nhit . Ci u l khong th n cc vi mc th 5V biudin cho nhit 100oC v 0V biu din cho 0oC. chuyn i gia th li ra (V) v nhit s theo cng thc :T = 20xV oCCi th hai l gii in p lng cc. Th +5V biu din nhit 100oC v -5V biu din0oC. Cng thc chuyn i s nh sau :

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T = 10xV + 50oC

Th ra ca b khuych i c a vo ADC hoc loi n cc hoc loi lng cc. hnh vbiu din php chuyn i gia gi tr s v nhit . Chuyn i ny gi thit rng th vocc i m ho 255 v cc tiu l 0. T c th c c th chuyn i ga gi tr lymu (s) v nhit o c.

V d : H ROBOT n ginHai diod nhy sng gn vi mt trc ca mt motor bc in t c th thc hin cchc nng ca mt h ROBOT n gin ( h t ng trn c s phn hi)

Motor bc :Cc xung TTL p dng vi cc cun dy ca mot, lm quay trc i cc bc ri rc, theocc gc. Cc transitor ngun NPN- (kiu BD677) s dng iu khin cc cun ny.

iu khin m t theo mt hng xc nh, Cc tansitor cn c iu khin bt tt (dn)theo mt chui tun t xc nh. Cc bc lin tip nh vy to ra mi ln tun t btngun cho cun dy tip theo v tt ngun cho cun trc o. Mot quay ngc li khi mtrc c t ln cun. Chui tun t cc m cho bn cun dy ca m t bc ccho trong bng.Nu t 1 ln li vo ca mt transitor n s dn in v cun tng ng c kch hot.H thng cm bin :Hai diod nh sng c ni vi mt b so snh analog. Li ra so snhs l 1 hoc 0 tu thuc vo photo diod no c chiu sng hn.

H ROBOT :Li ra b so snh c dng phn hi tr li my tnh quyt nh vic iu khinmot quay tri hay phi. ( theo chiu kim ng h hay ngc li chnh l hng ti ni cnhiu nh sng hn hay sng t hn tu thuc vo cch lp trnh )

Lu : v hai diod khng bao gi c chiu sng nh nhau nn MOTOR s khng bao gidng li gia hai v tr.Mt h thng nh th gi l h SERVO

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Bi tp iu khin m t bc: Dng ngn ng lp trnh C vit chng trnh iu khin mt bc (4 li iu khin) quay phi, quay tri, tng tc, gim tc dng bn phm

1) Khai bo chng trnh

Hnh : Khai bo bin mng gi cc gi tr nh phn dng iu khin 4 bt thp cng A, ccbin iu khin khc

2) Lp 2 hm iu khin m t quay phi hoc quay tri

Hnh : Khai bo 2 hm iu khin phi, tri dng 2 vng lp xc nh, iu kin thot khi gphm

3) Khai bo thn chng trnh, bt phm

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Hnh : Khi to ch Mod, by phm c g

4) X l r nhnh iu khin

Hnh: iu khin r nhnh cho cc trng hp bm phm mi tn, phm ESC

5) Mn hnh kt qu

Hnh: Mn hnh kt qu trong DOS

4.4/ Chuyn i s tng t (DAC)Chuyn i t mt gi tr s thnh mc th tng t . Thng d thc hin hn ADC v cth c xy dng trn c s cc chuyn mch in t v mt b cng th.PC c th ghp ni vi DAC nh ni trc tip cc bt ca mt cng PC vi cc li vo caDAC. V d nh khi ni cng A vi cc bt ca mt DAC 8 bt. Lu rng khng cn thitxung nhp ngoi cng nh cc phn cng ng b.

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Dng ca mt xung tam gic c th c biu din trn hnh v v m phng li vi DAC .

vi 256 mc, vit ra cng PPI cc gi tr t 0 - 255 ra DAC. Hiu ng xung tam gic s tc nh vic m ln t 0 255 ri ngc lai n 0. Tin trnh ny lp li cho n khi cmt phm c bm. nu c th quan st dng sng trn giao ng k v o thi gian giacc vi bc lin tip.

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Th vin uiblib.c gip cho vic lp trnh ghp ni tr nn d dng

S dng :

Copy file th vin uiblib.c th vin vo th muc C:\TC\include

Khai bo th vin u chng trnh#include

hoc khai bo

#include "uiblib.c" nu file ny nm trong th mc hin ti (th mc ca sinh vin)

Lu : Cc my tnh thc tp ti ITIMS ci sn th vin ny nn cc bn dng cch khai both nht s dng cc hm trong th vin.

Hnh : Hm c gi tr mt knh ADC (t 1.4) tr v gi tr 12 bt

Hnh : Hm kim tra trng thi hin ti ca mt b m bng cch cht s dng lnh c li bm vi 3 b m C0..2 v kim tra bit 7

Hnh : Hm kim tra xem mt b m c np hay cha bng cch s dng lnh c li bm v kim tra bt 6

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Hnh : Hm c v tr v gi tr 1 b m 16 bt

ng dng th vin uiblib.c

Hnh : To mt dao ng k in t

Hnh : To mt dao ng k in t cch khc

Di y l cc bi tp chnh trong phn thc hnh mn hc, mc ch cc bi tp ny l giplm quen vi mt s k thut thc nghim khi ghp ni my tnh vi thit b ngoi vi, thu thpd liu t ngoi vi qua cc b cm bin, iu khin ngoi vi, phn x l tn hiu s khng phi ltrng tm trong phn ny.

DANH MC BI TP :1/ GHP NI VO RA SONG SONG (PPI - 8255)1.1/ Vit chng trnh nhp mt s thp phn t bn phm v vit gi tr m nh phn racng A (C) ca vi mch vo ra 8255 trn card UIB, quan st m s nh phn li ra. (to mGRAY)

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1.2/ Vit chng trnh c mt s nh phn t cng A (C) ca vi mch 8255 trn card UIBqua giao din FRONT-END hin thi ra dng s thp phn, hexa, nh phn trn mn hnhmy tnh1.3/ Vit chng trnh iu khin n giao thng ti mt ng t gi s dng 3 bt thp trncng A iu khin mt chiu v 3 bt cao iu khin chiu cn li.1.4/ Vit chng trnh to n qung co

- n nhp nhy- n chy1.5/ Xy dng chng trnh c mt s t cng A ri quay cc bt ca s theo chiu kimng h v ngc li.1.6/ Vit chng trnh iu khin mot bc : chiu quay, tc

2/ LP TRNH NH THI (PIT - 8254 )2.1/ Vit chng trnh m s kin ( s xung t mt cng tc chng rung anti-bounce)2.2/ Vit chng trnh to my pht xung vung vi tn s nhp vo t bn phm.2.3/ Vit chng trnh o khong thi gian ( cng tc chn rung, xung vung TTL)2.4/ Vit chng trnh o tn s sng vung

3/ LP TRNH IU KHIN ADC

3.1/ Vit chng trnh thc hin chc nng ca mt ng h hin s (Volt k) trong giiin p o t 0 5V.3.2/ Vit chng trnh thc hin mt my t k (RECORDER ) ghi tn hiu t 4 knh ADC ramt tp d liu KQ.DAT v v kt qu ra mn hnh.3.3/ Vit chng trnh m phng chc nng ca mt dao ng k nh in ra mn hnh ( 1knh 4 knh )

Hnh : To mt dao ng k in t

4/ LP TRNH VI DAC4.1/ Vit chng trnh cp in p mt chiu vi gi tr nhp vo t bn phm4.2/ Vit chng trnh to tn hiu dng xung (rng ca, vung, sin, tam gic )

5/ Lp trnh ghp ni nng cao5.1/ Vit chng trnh ghp ni hai FRONT-END vi nhau qua cng A s dng MODE 1

5.2/ Vit chng trnh ghp ni hai FRONT-END vi nhau qua cng A s dng MODE 25.3/ Vit chng trnh o thi gian phn ng (PIT)5.4/ Vit chng trnh o v hin th kt qu chuyn i ADC kt hp vi b m 0 nhthi chnh xc thi im o5.5/ Vit chng trnh o cm ng t ca mt nam chm khi i qua cun dy cm ng5.6/ Vit chng trnh o nhit s dng cm bin cp nhit in5.7/ Vit chng trnh o cng sng s dng cm bin sng5.8/ Vit chng trnh o cm ng t s dng cm bin HALT5.9/ Xy dng h ROBOT n gin vi m t bc iu khin bng ngun sng5.10/ Vit chng trnh thu tn hiu t mt my pht chc nng cng nhiu, xy dng thut

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ton lc nhiu ca s trt, trung bnh ho a knh, ...5.11/ Xy dng chng trnh iu khin ng h thng qut gi, thay i tc theo nhit mi trng, iu khin bt tt n theo sng.5.12/ Vit chng trnh bo ng khi nhit vt qu mt gii hn nht nh.5.13/ Vit chng trnh iu khin tc quay ca mt m t mt chiu5.14/ Vit chng trnh thc hin chc nng mt ADC xp x lin tip vi mt b chuyn i

DAC, so snh, v PPI cng A.5.15/ Vit chng trnh o c trng phng in ca mt t in trong mch RC.

Lp trnh ghp ni ni tip vi vi mch 8251Vit chng trnh cho php mt my tnh truyn thng bo n mt my tnh khc qua giaodin RS232 (COM2)Vit chng trnh cho php 2 my tnh ni chuyn vi nhau qua giao din RS232 (COM2)Vit chng trnh cho php truyn tp qua giao din RS232Lp trnh vi cng my inVit chng trnh cho php my tnh in ra cc k tVit chng trnh cho php hai my tnh trao i thng tin vi nhau qua giao din my in(LPT1)

XY DNG MT S PHP O THC NGHIM

I- PPI-8255AThit lp cng card ghp ni UIB :- S dng khong a ch chun 300h 30Fh- Ngt chun : ngt 5- Ngun xung nhp t 1MHz

1/ o in p knh 1 : Ni mt chit p chia th vi knh 1 ADC : chy chng trnh oin p, kim tra xem gi tr in p 5 V c ng bng 255 hay 4095 (UIB, ADC 12bt )

khng.

2/ c th trong vng lp : Ni mch in nh hnh v.F , C = 220 Chn gi tr R = 10K- Np cho t bng cng tc S- Bt cng tc chuyn sang ch phng- o v v c trng ng phng ca t inTrn c s gi tr o c c th xc nh gi tr R*C = (tkt thc - tbt u )/ln(Vbtu/Vkt thc)Vi gi tr o c vi php o khng dng nh thi ca card, c th xc nh c thigian tr tng ng : tcalc = (tkt thc - tbt u )/9 = [R*C*ln(Vbt u /Vkt thc)]/9Thay i hng s phng np bng chit p R (thay i gi tr ca R)

3/ o in p theo thi gian :Thi gian trn 1000 ms ca chng trnh trong khi lp nhiu khi khng n nh, S dngngun xung nhp ni ca card ghp ni (1MHz) nh thi cho vic c in p trn knh1 ca ADC . Trc khi tin hnh o cn nhp thi gian gia cc php o lin tip.

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4/ o nhit vi in tr NTC ( in tr vi h s nhit m) xc nh nhit sau nhng khong thi gian xc nhHnh v :

5/ o sng vi LDR( in tr ph thuc sng ). o sng ( hay trong sut )

ca cht lng trong cc phn ng ho hay ho sinh.Hnh v :

6/ Chng trnh o th kch hot bng xung : Xy dng mch in nh hnh v : bmcng tc khi ng qu trnh o, in p c c vo qua knh 1, in p ca 1 in ramn hnh mi khi bm cng tc.

7/ C th tin hnh o pH :Khi c mt git dung dch ri vo cht dung mi, pH c o. Cng transitor nh snghot ng nh triger kch hot qu trnh o: Khi tia sng b che bi git dung dch, mtxung dng c a vo b m.

8/ o trn 2 knh :Xy dng mch in chia p nh s :Xy dng chng trnh o : Mc th trn knh 1 v 2 c c sau khi bm 1 phm. Miphm bm c 2 php o th c tin hnh (V1 v V2) v in ra mn hnh di dng bnghay 1 im trn th :- o in p ti cc im khc nhau trn mch in- Vi mt gi tr R bit, dng I , c trng V c th o c vi cc trng hp n, diodhay in tr NTC.

9/ o thi gian :

Xy dng mch in, Thi gian n khi tia sng chiu ln phototransitor c o theo ms :- Xc nh giai on thi gian ( hay tc trung bnh ) m mt i tng vt qua mtcng GATE.10/ m s kin : Xy dng h thng theo s : S git dung dch ri qua mt cngsng s c m. ( gio trnh Tin hc I phn II - phng th nghim my tnh Trung tmITIMS)11/ m s s kin trong mt giy : Ni li ra TTL ca mt my pht chc nng vi livo b m. Tn s tn hiu o c s c in lin tc ra mn hnh- o s vng quay ca mt bnh xe : mt a vi cc l c gn vo bnh xe; Nh cngnh sng, s vng trong 1 giy c th o c.12/ H thng o v iu khin :iu hon khng kh :- Bt tt l si trung tm (bt/ tt)

- Ni un (bt/tt)- Qut (bt/tt)- Airgrid ( m/ng )- Ti nc (bt/tt)- M ca s (m/ng)- D phng (c/khng)Cc qu trnh tip din- Nhit ti hn- p sut ti hn

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- Nng cn ti hnThang my- Chuyn ng (ln/xung)- Gi t trong ra (ln/xung)- Gi t ngoi vo (ln/xung)- m n gi tr 0 (c/khng)

- Ca thang my (m/ng)- Hm khn cp- Chung (bt / tt )Cng c th xt ti cc h thng iu khin cho n giao thng, thit b gia nh nh mygit, my ra chn, un nc si, l nng, l si ...

1/ Vit chng trnh c t cng A v vit ra mn hnh2/ Iu khin s: Lu khi s dng chc nng iu khin :- Li ra ch c th iu khin li vo tng tch TTL- Ngun cung cp 5 V trn cp ch chu c c 100mA (UIA) 200mA(UIB)Ni chung cc li ra ny nn c dng m ng mt transitor iu khin mt rler.Hnh v n LED s bt sng khi transitor dn in.

Cc v d iu khin l :n (bt/tt)iu khin motor ca h thng si trung tm (bt/tt)Qut (bt/tt)Cungcp gas (bt/tt)nh la in (bt/tt)CUng cp xy (bt/tt)Cung cp nc (bt/tt)La chn in pLa chn tn sM t bc (bt/tt)

1/ Vit chng trnh nhp mt byte t bn phm v vit ra cng C2/ H phn hi (FEEDBACK) Trong cc qu trnh phn hi : Vic kch hot hay ttiu khin bng tin trnh o trc n.c mt gi tr t cng A, tnh ton sau vit ra cng C (tt c gi tr c c v tnhc u c vit ra mn hnh)3/ Vit chng trnh to ra xung tn s cao v thp trn li ra ca b m 2. ( cth thy qua n ch th trn OUT-2 nhp nhy)Mc ni : Cc lnh c v vit ra cng c th c thc hin ti nhng v tr nht nh trongchng trnh. Cng c th c ngt ra trong chng trnh hin hnh nh cc ngt v utin vi mt lnh I/O. Trong cc trng hp nh vy cn n tn hiu mc ni. Tn hiu mcni chy qua 5 ng cao nht ca cng C (PC3-PC7).

o thi gian v tn sTa bit khi cng Gate mc cao (=1) th qu trnh m c tin hnh, nu li vo mc thp (=1) th gi tr b m s khng thay i gi tr xung nhp li vo, o mtkhong thi gian ngi ta dng tn hiu ging nh ..... vi li vo b m, ni tn hiu vili vo Cng gate v ni ngun xung (vi chu k xc nh vo li vo xung nhp ca bm). Hiu s gia gi tr b m trc v sau khi cng Gate mc cao (1) chia cho tn sca xung nhp li vo cho ta gi tr thi gian.Php o tn s:

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Mt c trng ca tn hiu tun hon l tn s ca tn hiu, c 2 cch o tn s:o s xung trong 1 khong thi gian bit , t tnh ra tn s(o tn s cao).o chu k: o 1 chu k n v tnh ra tn s (o tn s thp) .

Php o tn s cao:Tn hiu Sensor c ni vo xung nhp ca b m, b m th 2 c dng nh l b

chia tn iu chnh thi gian o, li ra ca b chia tn nn li vo cng vo Gate ca bm, khi tn hiu trn cng Gate =1 th b m bt u m s xung. Khi tn hiu trn cnggate =0 th b m dng qu trnh m v my tnh x l v tnh ra tn s.

Php o tn s thp:Nu tn hiu Sensor c tn s thp th php o s hiu qu hn trong mt chu k, tn hiu tsensor nn c gi n b chia 2 (VD: Triger JK), li ra ca Triger l 1 trong mt chu kc lp vi chu k ca tn hiu, li ra ca Triger s ni ra cng gate ca b m. Vi mt bchia tn di o c th iu chnh, gii php tt nht l dng ngun xung nhp cao nht cth v ghp ni tip cc b m chia tn.

Bi tp:1. Vit chng trnh s dng b m PIT 82C54 hin th s xung m c khia xung vo Clock 1.

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2. Vit chng trnh s dng b m PIT 82C54 o khong thi gian gia 2 lnnhn/nh cng tc.

3. Vit chng trnh s dng b m PIT 82C54 o tn s( My pht 1Mhz ni viClock 0, Clock 1 ni vi External)

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Hnh : Khi to bi tp m xung

Hnh : Thn chng trnh bi tp m xung

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Hnh: Khi to bi tp o thi gian

Hnh: Thn chng trnh bi tp o thi gian

62


50/52

Hnh : Khi to bi tp o tn s

63


51/52

Hnh : Thn chng trnh bi tp o tn s

Hnh : Kim tra kt ni cng DAC - 0x210 hoc 0x310

Hnh : Khai bo bi tp to dao ng k

Hnh : Hm to xung vung dng DAC

Hnh : Hm to xung tam gic

64


52/52

Hnh : Hm to sng SIN

Hnh : Chng trnh chnh gi n cc hm to dng sng dng DAC

Hng dn

do luong dieu khien

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