\'~lO hai \'(in de: 51! plW tllLl()( ella thai gian tre \',10 llU'6ng truyen till hi~u; 8(} chfnh x ic Clb \'J~C \ik di.nh thai gian [r~, Trong lll(}t -;0 lhie'[ hi, thai gian tre phI! thuc?e \'ao IIlI{rng tfuycn clla tin hJ~lI nl. 86i v{ri nhlJ"ng thi0't hi nlllf \'~Iy, t!Jcrj gitln oc lin hi¢u ra Wng tLf '0' ~ , I' \'il giilll1 tLr '1' ~ '0' kllile nhau kha xa. Vi dl) tmng nhCmg lll, tch MOS, lhiri gian dc thid 1(lp ;.>Lfan xuullg eua tin hi¢u ( thai gian tn': ella suo-n xu6ng .0. 1 ) 16n hem thai gian thi~t 14P sU'an ICn ( Illcyi gian tn~ cua sU'an len .0.1{) kh()~lllg htl I~in. Dc me} IiI !lhiing tn.mg Ihil.i nuy, ta duu ru giil. (ri. thai gian In! cua su'&n len (risl:) va thai gitlll tre eua slran xu6ng ([all) .0.j{ y~t !' F d6i \'(jj Ilt"Ilg ph,in tir. Trong nhilng lru'ClJJg hqp nlIlf v(ly khi me hinh hOi't hO' lt d(mg cua mi.leh, d(l dill cua xung s0 lang. Them van do, d6i \'oi nhilng giil. tr! lhb'j gian tre suan ICn va xuong kh,ie nhau, eo Ihe: xU<lt hi~n nhiJng trU'i:mg hqp khong c6 tfen Illl.rc te khi mo hinh 11m! m' Iell, TruClllg hap n~IY Ctl [ill: th:ty Iren hlnh 5.25. Trang hinh 5.25, Iru<:mg hqp a), tin hi¢u ra c6 tho'i gian tre Till hll'lI V'dO C, _ l ~ __ . __ _ -~ * I • ___ ._L_I __ _ il)j.r,=l. \=3 c) _\, "" 3. :\ = J : lJUiJilg IIlnh 5,25 Vi liu \'c moll'mll Ire \111m!en \'~l"Lr!jll XliOJlg. hup khong lile \:ry fa. Stf<Jn xu6ng !' r btlllg btl ebn thai gian tre sLfon len IXlng nH?l, lrang IndllIg Il<,)p 1l~ly dQ elili cua till hi¢u ra tilng, Truong hqp b), tIll hi¢u ra c6 lhh'i gian [ft sL1C1!1 xuong !' r- bing IllOt con Illcri gian tre Slr<1n len .11! btlng h,-li, lrong trUll"ng hqp n~IY eft) di"li ella tin hi¢u fa giiim, Trang tru<)"]1g h(JP c), tfn lli¢lI fa c6 IhO'i gian Ife sU'()"n xuong !' r. bilng m(}1 con Ihbi giun Ire sL1cm len !' I{ bang ba, tin hi¢u ra co suO'n xuong nf91 IWoe slfi:m Jell - di6u khong the' x,iy ra trang Illl;fC Ie, Nhilng lmo-ng Ilqp nhLf ,,(IY ph,ii dLfqc IrJi.li bi) trang qUii trinh mc} hinh hoa va 1116 phong, h. Tn~ qu<ill tinh Mqi m~lch di~n d~ dn !l<lllg ILrqng de ehuytn tr'.lllg [hi.li. 1'\,l{Ulg hf9"llg ciw lin hi~u Iii ham so cua bien ttl) viI d¢ dai lin hi~u. Neu (/\! d:.i eLla ;ill hi~u qU{1 llgfll1, tin hi~u khong the' beh hOi.lt de philn ILr chuyen Ir',lug lila I. 8(1 (Eli ttli liJiC:u cua tfn hi~u CUll \,;'10 tlu de kfeh hO,-,ll Jlli.lCh c1n .Jlg [h,'li llLrc,Je g9i 121) la thoi gian Ire quan tinh dau \,~IO eua ph[il1 Ill' "~l k)' hi¢u lit .6.[. 0JhiIng tin hi¢u co lit) dai nho hem n[ Sl: dUrjc g9i lit xung nhqn \,'il sc kh()ng dUrje ph,in tLr eho di qua. Ne'u dl) d~li eua lin hi¢u ,,':10 16n han hO(le h,lng il[, lin hieu sc duqe di qua mi leh \'Iyi de) tre bang thai gian tn~ Ian truycl1 ella pkin ILL Vi~e clLra tr~ qUi.l.n Hnh driu \'ilO eho ph~p m() hlnh hoa nhilng: tmong ht,IP d(IC hiel Hung de sO do Ihl!c khi ph[in tLr nglillg Iilln vi¢e voi nhilng xung r[I'1 ht;p. f I j I o Hlnh 5.26 dUd ra minh h9;\ Iruang IH!p tn~ quan Iinh d[iu ";\0 \'oi xung e6 d() n)ng Ilinh 5.26 I\llI1h hO.l eho [lien [lfong tre qUilll tinh (tiU ,·ilo. b'-Illg ha \.;\ Xl111~ c6 dt) fe)ng bimg lllt)1. Ph,i.n Ill" co d() tre quan tinh lUU \'ilO l\ == 2 d tf~' Ian Iruycn .6.1' = I. Kili dl) r(Hlg eua xung btmg m<)t thl lin hi¢u khCmg 16i dLfqc d:tu nI. Trong nhieu Imang hop. kCI qUi.! eua vi¢c m() hlnh ho,i tn~ l]ll,in tinh ph~J thu()c \,~IO vi¢e Ire quan [[nh xu[!1 IlL¢n Ci cUu \'ilO hO(le doiu ra eua pldn lu,. Tre qUiil1 tfnh xu:!t hi~n if (.1[\u fa d(le Irung cho \'i¢e drill ra cua phrin Ill' kh6ng Ih~ tlLra ra lill hi¢u co (1<) cl2li nht) han n l . Xung lin hi¢u {'.Ii (Hill ra c6 the dU'0C xung tin hi¢u d[iu "ilo "inh ra, nhung eung co Ihe" h~ loai be) neu co d() fbi ,~D-, __ o o ( \I=~) Ihnh 5.27 Str kh;iL- bid khl tre quan rinh xlIiil hien t;.\l (hIli vao villai (hiu ra. D o , _ ,0 ,- __ qua nh6. Ta hay xet phfin lir OR ba d:iu \'~IO voi Ihong so thai gian Ire Ian tfUy~Jl .6.[' = 2 V,I 1\ = 2. Cic lin 11l¢u dau v,lo deu co dQ d,li bang I v;\ t,\c d,)ng I:m IUCJI n.'ji de) Ire hilllg 1. Trong Iruang hqp Ire quan Iinh dU~1C d~11 I' ti driu ra, ba tin hi~u dfiu \"~lO Ifin luq1. sinh ra C<IC xung gi;i 11'\ 'I' e6 tI() dili hilllg 1 lien tlep. CiIC xung nay hqp th2111h tin hi¢ll gi,i trj 'I' co d() d2u h,\ng 3 121 t' Ii dfiu ra. Tin hi¢u oay ,,1: xuat hi¢o treo duu ra VI co d() dai 16n hon th6ng so tre quan tinh driu ra ( 3 > 2 :::: ~I)' Trong truang hQ'p thu' h'-li khi tre qUitO tloh dlIQ'c d(\t Wi driu vao, ba tfn hi¢u dau vito d~u co dl) dai nh6 han thCmg so tre quan tinh do dl) khong the' kfch hOi~t phun tlr. Dieu nay dan t6"i vi¢c tin hi~u diu ra kh6ng dlIQ'C hloh thanh. NhlI v~y vi¢c 016 htnh hoa qua trlnh tre quail tlnh gan lien voi cae d<~c tfllh v~t ly cua phao tlr Va can th~lO tr9ng khi nghien cuu. Hioh 5.28 cho ta thily nhfrng aoh hlICmg khac nhau CU'-l cac m6 hlnh tn~ tai vi¢c hinh thitnh tin hi¢u duu ra doi voi phan tu AND hai driu vao. De: qua trlnh 1110 hlnh hmi lTI~ch dlIQ'C chinh xac 1'-1 cfin ph,'ti nghicn euu t6 hQ'p nhfrng di~ng khac nhau clm thai gian tre. Nhung dieu nay l~ltn ung thoi <I. i\ = 2 c +~ , , .jo L 1I'"h 5.211 S" ",,,11 de \\1(' IItnil '!u'; ll'llh "~ l,"n 11I~u ~)T,01''''lLuyL·nll)lJ.;'' nhJI; h) Ttl' ,u,"mlcn 'i, ,uinl xurlllg, <") T16 lil,"'"g 'k ,t!nil, d) fri' 'lu,in linh (ll\~'u un.!' Ihu h~r ~ulIg );~) Tl~ 'luuLllfnh fl. L\I =2 c. L\, =2. 6 =2 gian thlfc hi90 !TIO hinh hoa va 016 phoog. dieu nay khong the chap nh(Hl dLfqc trong ky thu~t. Nhu V~ly. de thlfc hi~n 1m) hlnh hoa qua trlnh tre tin bi~u v:t khong lam <'mh 11l16ng t6i thai gian !TI6 ph,'mg t'-l co the '>v dl}ng trinh ttrsau: 122 Kic'm nghi(:m logic cua mi;ich Slr d~ng ffil) hinh chi gom cae tre thuan nhXl; Thl!c hi¢n m6 htnh hoa va md phong tfnh toi '>If khac bi¢t ella thai gian tre SUOll len va Sl1an xuong; Su dl}ng mo hloh tre khong xac djnh trong qua trinh mo hlnh hoa va 016 ph6ng; ThljC hi¢n qua trlnh mo hloh hoa su dl}ng dc phl10ng phap thong ke doi v6i nhfrng t6 hqp kh,k nhau eua qua tr1nh tn~ tuO'11g (mg. 2. M6 hlnh h6a qua trinh tre tin hi~u qua cae phan hI chue nan~ va thanh ghi Cae chilc nang logic va dc d(lC linh thoi gian clla d.c ph[in IU chLrc n[mg phLrc ti.lp han so voi dc phtin lillogic ca bAn. Ta hay xct vi ill,! mo ta hanh vi s o 0 , S R C 0 Q QN l·g;rr~ , ._ ;c- 0 0 I x x I 0 c." = 4: c.,~)" == ~ r I I 0 x x 0 I .\ = 3: 6., ,,=4 C ON I I I t 0 0 I c. 1 • = 8; S., ~ = 6 R 0 I I t I I 0 L\' .' 6: A\ .'()"_-~ x 0 0 x x " " lllnh 5.29 11111h hoa db Ire vaa/ra doi v6"i [111[111 Itr ch(rc liang trigo' D. hOi lt d¢ng coa philn tu triga 0 l~lln vi¢c theo Sl10n Ien voi hai throng tin hi¢u kh6ng dong b¢ thiet l~p S ( set) va khoi t<;io R ( reset) ( hlnh 5.29 ). Trong bang tren hlnh 5.29, kg hi¢u "!1110" chi d¢ tn~ cua dap Ung t~i dau l'i.I '0' doi vai tac dt)ng toi dau V~lO '1'; cac kg hi¢u t::,.' va t::,.1 chi dt) Ire wan len vii sunil xuong clla phan tu. Ta xct mQt dong clla b,lng. vi dl,! dong IhLr ha. Dong nay chi ra rang: neu tr<;lng Ihai han duu clm pM.n IU q = 'I' va t'.1i d.c duong tin hi~u S. R khong co tac dt)ng ( S = '1'. R = '1' ), sl! chuycn tr~mg Ih,li CU:'I xung dong h6 C tu '0' sang' l' se l~un cho driu ra Q nh(\I1 gi,,\, trj clla duo·ng D V0j thOi gian tr~ suan xu6ng t::,.IClQ = 8; cGng tuang ttl nhu \'~y. duu ra QN chuycn tit '0' sang' l' voi dQ tre !1'CIQN = 6. Dong cuoi cung cihl b<ing chi ra dng. neu cac dau vao R va S nh(m gia tr! cam "00", cii hai duu ra sc cung nh,~m gia Irj 'U'. Cling tuang tt! nhl1 doi voi pilrln til logic. khai ni¢m d<;J tre quan tLnh dau vilo co tht: ma r<;lng cho phan Ill' triga neu ta oua vao dc thong so chi dQ rt)ng ct!c lieu cua xung tac d¢ng doi voi cae dau vao C, S. R. Nhfrng duong tin hi¢u nay co tac dl.tng kich hO<,lt qua trinh chuycn tr<;lng tll,l.i cua trigo. Doi voi phan ttr triga 0 noi tn~n, trong nhi~u Iruang hqp. ta dn dua ra nhfrng yeu cau v~ oQ dili cua tin hi¢u dt: tninh hi~n tuqng ch<;lY c1ua gifra Ci.lc duang tin hi¢u C va D. Hai Ihong so thai gian khoi t<;to (setup time) va Ihoi gian ton ti li (hold time) lil nhfrng thong. so chi khoang thoi gian nhc) nhat truoc va sau thai di~m ehuytn Ir,!-ng thai Iren duong C trong do gia trj tren 123 dt['i.1'ilg: Illl hicu D ph:ii (;n djnh ( khong Ihay (!(ji ) de trigo ho •. 11 dl)ng ehlBh Xiic. etC qu,i ldnh mo hlnh ho,i logIc va m6 philllg ph,'li pll,lll anh ctuqc de yell du nllY. D6i \"t'5i nhQ"ng philn tV ph(['c tap han nlm dlc thanh glli, qU;1 tdnll Ire lin hi~ll dul.'J"C !llO tii it chi tiel hl1n. Trang nhicu truang IWp, c_lc 1m) hlnh trcn 111(['C Ihanh ghi ~ll: Ch;lllg cac chu trlnh thai gian l~p V~I nell trong do co xi.ie djnh dc Ihong s6 Ire, de thong so nilY ~2 du~"iC coi El d(> tre Ian Iruyen. ~5.5. M(. hlnh hoa trt'll mlfc de phan (if I()gic Cae phuung phap ditu khien qua Irlnh the ·hi~n trinh H.I tlwe hi¢ll mo hlnh hml va nhlrng phuong phap xV Iy gan lien vCii 'lU{1 lrinh m6 phong nweh. Trong phuallg phap bien djch, trlnh IV Ihy'e hi~1l mo hinh hoa duqc x{le djnh b{lIlg vi¢e ph,ln IWng cac phfin tv. Nhu v,Jy, vi¢c ngtlt cae vang rhiin h,)L trong nhi1"ng n:i.,lCh Weill tt! Vi:I phtm iWng philn tv ehinh EI pillro'ng rh'-Ip dicu khien qu{\ Irlnh m(l hinh hm'!. D6 chinh la nguyen nhtm dtin t6i \'i~e kh(lllg the Slf dyng cae m6 hlnh Ire IrLI" 1110 hlnh \'6"i ct,) Ire h,'mg kh6ng. Tmng nwe lI~ly C!lUllg la nghi2n cuu cae phuong phar c1ieu khien tmng qUii trinh 1110 hlnh hoa huong s\f ki¢n nlur mot phuung ti¢n mo hiBb bOlt IH' leh vCri d(l Ir~ kh,ic khong. Khi slr d~lllg phuong ph(jp mo hlnh hoa huollg sv ki~n ne'u gi,'\ Irj 1111 hi¢u , ; \"(.,') ti ti Ihai di6m tllai I);,,, d.u," f ; ,"c'" Hitlh 5.30 ~Illlh hoa oallh ~,ich w kicn. gian To khae gi:1 tri L'(j) h.ti thai di6m Inr6e, di0u do co nghlil I~I xutlt hi~n Sl.r ki¢n, ta se eoi dtng tin hieu Ihay dOl uia tri \,~lO l!lo-i e . di6m To + ~l . trong do ~ la do tre Ian truv':n ,. ~ ella philn IV dang xcI. De m6 t,i W xu<"it hi¢n su kien tn~n dc dLHlng tin hi¢u tmng m:.leh thea thai 124 gian ta eh(l'" cae S~l' ki¢n dlo danh siich luye'n t[nil e6 th,tng hidu chcn Ir0n hlnh 5,30 va gl.li 1;1 danil "'{Ieh s~r ki~n. TucJ'ng (rng v6i mbi tllt)t tilbi di~lll Ihhi gian , la sO::: e6 m{lt danh siieh de S\f ki¢n XU[lt hi¢l1 V~IO lilfJi diC:1l1 cl6. Khl e6 Illl)1 sl! ki~'n m6i xu[\1 hi¢l\. ';I,r kl¢n ni\y duqe (lLl'a \';10 danh ';,lcli s~r ki¢n g;\11 lien v6i m(l( thh'i di~m thi:Ji gian xiie djnil. '1'<1 Ilfll Y Ill{)\ diCL! nlm sau. ,W XLiAI hl¢1l clli\ nH)t theri diem Ihefi gian dU'(l"e (bnll diYu tfong qu,t Irlnh m() h)l1h ho(j kh6ng phl,l thu(>e V~IO ehuoi lh(Ji gian. Do d6, de x<-le djnh \'j Iri eua de tl}(')'j diem '.1;1 dll'Q'c \ [nh tm'Cie trong danh ';iieh Slf ki¢n, cilllng ta c£ill ph,li c6 cllUt'li th0i ginn tuong: (mg vtii danh siieh dU\1e xlr IY. Dieu !lay c6 Ihe' ctlfl/e lime hi¢n d~ra V~IO de <-inh X'.I thl)'i gW!l. Khi LL ';tf dllng phcp ,Inh X' I thi)i gian. day de thl1i (hem theri gian dU\iC xiie djnh \'('JI khoilllg tho'i gian deh dell !' m()i s~r ki¢ll trong h¢ Ih6ng 0 dU"t/e Xilc djnh dua \'ZIO de tho'i Ji~m thoi gian n~IY. Kho,'mg tillii gian i\ du<)'c X{IC dPlll b;\ng Lf6e ,.,6 chung Ion nh£it ella ella thb'i gian IJ"uyen till IUC'1l d de) Ire ella de ph<.lll 11'1 Il"Ong m<.leli. Do gi{)'i Il<.ln \'C h(> ,il16 dLlIlg de Iinye hl~'ll qUii 2 3 Innh 5.JI Von!; de Ihb'i diem tiliJi gi'1I1 m() phong. Irlnh 1ll() hlnh ho,i In'.leh. 1<1 xae dinh gia tfj gi6i h'.l!l ella tlll')'i (110111 Ihl\i gian elie d,~i biing \1. NllLI \'i)y, eae Iheri JiC:m Ih(ii giJ.n ~all Iho'j ditlll cue d'.li "'C quay L,lI b[1[ (till ILf IhCli diem ban (Hill V:1 1;,tO t!Jttnh \,l>ng qLlay Ihl')'i gtan (h'lnh xc theri gian). ThC)]lg I[url)']]g. kho;[;lg tlllij gian L\ tLIong Ihfeh \'o'i d6 trc eua cue ph:lll Ill' lrong mach. Trong nitLfIlg tru0ng h</p kili Irong 1ll'.lCh e6 nhung ph:ln tLl' \'('ii ell? tr~ I{m, kl1m'tng titeti giaJl D. co the Vm}1 qU[1 thai gian gi6i h;,tIl M, dicu n~ly (Em 16·i vice theri dtC:m m6 ph(mg VU\11 ra ngo~li n'lllg I [1(\i gj,lIl \'il grl)' nCll hi~n lU'qng tr:tn. Dc gi:ti quyc't v,-YLl dc nil)'. ta X:IY (h;JJlg danh ~,-ieh bC) In,r de [lrLl trLt de tillfi diem trim viI gqi 1~1 danh '-;<-leh tran. Trong tru()'ng hqp Slf dung dauh sikh tdUl. moi khi banh xc titt\i gian tlure hi¢n ctw!e m(lt \'ong quay. la dn thlre hiGll Ihao t,ie Ir,-i de thai diell11rong danh s{l(h Irilll ve ellll Irlnh xLi I)' theo \'bng thai gian. 125 Khi till!e hi~n qua 1rinh 1116 hlnh hoa thea vong thai gian, cae oU'O'e eua qUii 1rinh 1116 phong e() the c1uqe bieu (lien duai d'.lOg sau: HI: Thie~t l~lp cae gia trj ban duu ella tin hi~u li.li thai diem I +- II! va d(tt cae gi.:i Ir! do Ihanh gia Ir! hi¢n Ihai. B2: D(,)C cae giiJ tfi dilu vao. Neu gia Ir! nay khae cae gia tr! hi~n Ihai, ta ctva chung vao 1~IP hqp LT lrang do 1" = t + t T . B3: Nell LT = 0, ta ehuyen lai bUlk 135, trang truang hqp ngu(~e h.li, la ehuyen lai buue B4. ll4: Ntu gia Irj lrang LT Irung vui gia tr! hi~n thlfi, la giiJ nguyen gia Irj hi¢n Ihai; neu cae gia tl"j nay khae nhau, t;.\ Eun e(lp nh(11 gia trj hi~ll Ih6i va c1U<l vaa L" 1" = t + t. r . Giin I+- f+ I va quay ve bu6c 02. Ta hay xel 1119t vi dy minh hQa thu(tt tmin 1116 hinh hoa hU6ng Sl! ki~n d6i vO'i lni \Ch bieu dicn tren hinh 5.32. Cae gia trj '1' va '0' tr6n m0t dU'ling lin hi~LI bat ky, vi dl,l 1a tren duang (I, se duqc ky hi~u HI (a: 1 ) Y~I (a: 0 ). Giil thief ning cae lin hi¢u driu vao thay doi theo giJ.n do thoi gian tren hlllh 5.32. phcill tlf OR co dQ Ire Ian truyen t.T:: 2. Trang truang hqp nay qUii Irlnh m(J hlnh hoa huang sl! ki~n sc dLrqe tlwe hi¢n Ihea tdnh II! du6i dCly. a b O , ~ ~ c = a OR b 2 3 ~ 5 G IJlnh 5.32 l"Ifinh hoa lhuil.l toanlllu hinh hm! hwJn.Q SH kll:ll. I. B I: T;',li thdi di~m ban (tiu t = til ( til = 1 ); Cic gia II"! b~\I1 Mu: (a;O), (b:O), (cO): 2. B2:D0egiiltrjdauvao:(a:l)~LT+\I=L,=1(c:I)J; 3. B3: Kiem Ira Lp LI = 0, ehuy~n tai bU(rc BS: 4. Wi: t +- I + 1 ( t = 2 ); Quay i<.li bLroe B2; S. 02: D9c gia Irj dilu vao ( h; 1 ): LT+,\I = L, = 1 (e; I ) J: 126 6. H3: Kiem tm L 2 , Lc = 0 , ehuyc'n t6i bu6e 85; 7. B5: t +- I + 1 (I = 3 ): Quay I'.li btJac H2: 8. 132: D(,)C gii\ tfj driu vao ( a; 0 ); 9. 133: Kiem Ira L" L\ = ! (e; 1 ) }, L,.;to 0; Tiwe hi¢n buoe B4; 10. B4: Giil trj hi~n thoi duqc thiet h~p h~lIg (e; 1 ): . tr:tn. Dc gi:ti quyc't v,-YLl dc nil)'. ta X:IY (h;JJlg danh ~,-ieh bC) In,r de [lrLl trLt de tillfi diem trim viI gqi 1~1 danh &apos ;-; <-leh tran. Trong tru()'ng. be) neu co d() fbi ,~D-, __ o o ( I=~) Ihnh 5.27 Str kh;iL- bid khl tre quan rinh xlIiil hien t;.l (hIli vao villai (hiu ra. D o , _ ,0 ,- __ qua nh6. Ta hay xet. hi¢u ra c6 lhh'i gian [ft sL1C1!1 xuong !' r- bing IllOt con Illcri gian tre Slr<1n len .11! btlng h,-li, lrong trUll"ng hqp n~IY eft) di"li ella