gnmt - ntl(for print) - 10-2010

8/4/2019 GNMT - NTL(for Print) - 10-2010

1/128

Nguyn Tun Linh BM KTMT

Khoa in tKhoa in tKhoa in tKhoa in t

i hc k thut cng nghip Thi Nguyni hc k thut cng nghip Thi Nguyni hc k thut cng nghip Thi Nguyni hc k thut cng nghip Thi Nguyn

K thut ghp niK thut ghp niK thut ghp niK thut ghp nimy tnhmy tnhmy tnhmy tnh

Thng 5/2010


2/128

2 Nguyn Tun Linh BM KTMT Khoain T


3/128

Nguyn Tun Linh BM KTMT Khoain T 3

Bi ging mn hc: K thut ghp ni my tnh

CHNG 1. I CNG V K THUT GHP NI MY TNH ............. 61.1. Cu trc chung ca h thng ................................................................................. 7

1.2. Yu cu trao i tin ca my vi tnh i vi mi trng bn ngoi ..................... 81.2.1 Yu cu trao i tin vi ngi iu hnh ................................................................81.2.2 Yu cu trao i tin vi thit b ngoi trong ho lng iu khin ...................81.2.3 Yu cu trao i tin trong mng my tnh ...............................................................8

1.3. Dng v cc loi tin trao i gia my vi tnh v thit b ngoi (TBN) ............... 81.3.1 Dng tin (s) ............................................................................................................81.3.2 Cc loi tin ...............................................................................................................9

1.4. Vai tr v nhim v ca khi ghp ni (KGN) ..................................................... 91.4.1 Vai tr ......................................................................................................................91.4.2 Nhim v..................................................................................................................9

1.5. Cu trc chung ca mt h ghp ni my tnh .................................................... 111.5.1 Cu trc ng tn hiu ca KGN vi My tnh ...................................................111.5.2 Cu trc chung ca mt khi ghp ni ..................................................................11

1.6. Chng trnh phc v trao i tin cho khi ghp ni ......................................... 121.6.1 Lp trnh hp ng (assembly) ................................................................................121.6.2 Lp trnh Pascal......................................................................................................131.6.3 Lp trnh C/C++ .....................................................................................................13

CHNG 2. GIAO TIP VI TN HIU TNG T.................................. 152.1. Khi nim tn hiu analog v ho lng iu khin s .................................... 162.2. Chuyn i tn hiu s sang tng t DACs ...................................................... 16

2.2.1 Cc tham s chnh ca mt DAC ...........................................................................17

2.2.2 DAC chia in tr(Resistive Divider DACs) .......................................................182.2.3 DAC trng s nh phn (Binary Weighted DACs) ................................................182.2.4 DAC iu bin rng xung (PWM DACs) ........................................................19

2.3. Chuyn i tn hiu tng t - s ADC: ............................................................. 202.3.1 Cc tham s chnh ca mt ADC ...........................................................................202.3.2 B bin i AD theo hm dc................................................................................212.3.3 A/D xp x tim cn ...............................................................................................222.3.4 Tch phn sn dc ................................................................................................232.3.5 Flash ADC .............................................................................................................242.3.6 Mt s vi mch ADC thng dng ..........................................................................25

M t chc nng ca cc chn: ........................................................................... 27CHNG 3. TH TC TRAO I DLIU CA MY TNH ................. 30

3.1. Cc ch trao i d liu ca my vi tnh ........................................................ 313.2. Trao i tin ngt vi x l ..................................................................................... 32

3.2.1 Cc loi ngt ca my PC ......................................................................................323.2.2 X l ngt cng trong IBM - PC: ..........................................................................353.2.3 Lp trnh x l ngt cng:......................................................................................37

3.3. Trao i tin trc tip khi nh............................................................................ 393.3.1 Cch hot ng: ..................................................................................................393.3.2 Hot ng ca DMAC: ..........................................................................................393.3.3 Chip iu khin truy nhp b nhtrc tip DMAC 8237 .....................................40

CHNG 4. GHP NI QUA RNH CM MRNG ................................ 454.1. t vn ............................................................................................................ 454.2. Bus PC ................................................................................................................. 47


4/128


4.3. Bus ISA (16 bit) .................................................................................................. 474.4. Bus PCI ............................................................................................................... 504.5. Ghp ni qua khe cm mrng .......................................................................... 50

4.5.1 Mt sc im ca Card ISA ............................................................................. 504.5.2 Gii m a ch v kt ni Bus d liu .................................................................. 50

CHNG 5. GHP NI TRAO I TIN SONG SONG ................................ 535.1. Khi ghp ni song song n gin ..................................................................... 535.2. Cc vi mch m, cht (74LS245, 74LS373) ..................................................... 55

5.2.1 Vi mch m 74LS245: ......................................................................................... 555.2.2 Vi mch cht 74LS373: ......................................................................................... 55

5.3. Vi mch PPI 8255A ............................................................................................ 565.3.1 Gii thiu chung .................................................................................................... 565.3.2 Cc lnh ghi v c cc cng v cc thanh ghi iu khin ................................... 575.3.3 Cc tiu khin ................................................................................................... 575.3.4 Ghp ni 8255A vi My tnh v TBN ................................................................. 62

5.4. Ghp ni song song qua cng my in ................................................................. 655.4.1 Ghi thiu chung ................................................................................................... 655.4.2 Cu trc cng my in ............................................................................................. 665.4.3 Cc thanh ghi ca cng my in: ............................................................................ 675.4.4 EPP - Enhanced Parallel Port ................................................................................ 69

CHNG 6. GHP NI TRAO I TIN NI TIP ...................................... 756.1. t vn ........................................................................................................... 756.2. Yu cu v th tc trao i tin ni tip: .............................................................. 76

6.2.1 Yu cu: ................................................................................................................. 766.2.2 Trao i tin ng b: Synchronous ....................................................................... 776.2.3 Trao i tin khng ng b - Asynchronous: ........................................................ 77

6.3. Truyn thng ni tip s dng giao din RS-232: .............................................. 786.3.1 Qu trnh truyn mt byte d liu: ........................................................................ 796.3.2 Cng ni tip RS 232 ............................................................................................ 79

6.4. Giao tip USB ca my PC: ............................................................................... 966.4.1 Gii thiu chung. ................................................................................................... 966.4.2 M t h thng USB .............................................................................................. 976.4.3 Giao din vt l ..................................................................................................... 996.4.4 Sim danh ....................................................................................................... 1046.4.5 Cc kiu truyn USB ........................................................................................... 1046.4.6 Giao thc USB .................................................................................................... 105

6.4.7 Khun dng cc gi tin ........................................................................................ 108CHNG 7. GIAO TIP VI CC THIT B NGOI VI CBN ......... 1117.1. Giao tip vi bn phm v chut ....................................................................... 112

7.1.1 Bn phm ............................................................................................................. 1127.1.2 Chut ................................................................................................................... 117

7.2. Giao tip PC Game ........................................................................................... 1187.3. Monitor v card giao din ho ..................................................................... 120

7.3.1 Nguyn l hin nh trn monitor ......................................................................... 1207.3.2 Card giao tip ha ........................................................................................... 121


5/128


Gii thiu mn hc Tn mn hc:

Giao tip my tnh

K thut ghp ni my tnh(Computer Interfacing)

Mc tiu:

- Trang b cho sinh vin cc kin thc cbn v ghp ni my tnh vvai tr ca ghp ni my tnh trong cc h thng tng.

- Nghin cu cc giao tip cbn ca my tnh vi cc thit b ngoi vinh: cc khe cm (ISA, PCI, ..), cc cng vo ra (LPT, COM,USB,).

- Thit k v xy dng cc h thng ghp ni my tnh p ng cc yucu c tht ra trong thc t.

Ti liu tham kho

[1]. Ng Din Tp, Kthut ghp ni my tnh, NXB KHKT,

[2]. Ng Din Tp,o lng v iu khin bng my tnh, NXB KHKT

[3]. Nguyn Mnh Giang, Kthut ghp ni my vi tnh, NXB Gio dc, 2tp.

[4]. Xun Tin, Kthut lp trnh iu khin h thng, NXB KHKT[5]. Ng Din Tp, L p trnh ghp ni my tnh trong Windows, NXB

KHKT


6/128

Chng 1: i cng v k thut ghp ni my tnh


CHNG 1.I CNG V K THUT GHP NI MY TNH

Mc tiu:

Hiu c cu trc tng quan ca h vi x l; V tr, chc nng v cu trcchung ca khi ghp ni trong trong mt h thng my tnh trong o lng iukhin. Xc nh c yu cu, cc thnh phn v lp trnh iu khin cho khi ghpni

Tm tt chng:

- Cu trc chung ca h thng

- Yu cu trao i tin ca my vi tnh i vi mi trng bn ngoi- Dng v cc loi tin trao i gia my vi tnh v thit b ngoi (TBN)

- Vai tr v nhim v ca khi ghp ni (KGN)

- Cu trc chung ca mt h ghp ni my tnh

- Chng trnh phc v trao i tin cho khi ghp ni


7/128



1.1. Cu trc chung ca h thng

My vi tnh hay h vi x l u c cu trc chung do Von Newman xut gmkhi x l trung tm (CPU), b nh(Memory) v cc cng vo/ra (I/O), nh hnh 1.1.Ngoi ra, My tnh cn cn phi trao i d liu vi mi trng bn ngoi, v d nhgiao tip vi ngi s dng qua bn phm, mn hnh, trao i d liu vi cc thit bngoi vi thng dng, cc thit b ngoi trong ho iu khin, v cc My tnh khctrong mng. Do cc khi ghp ni (KGN) thit b ngoi vi c xy dng, gm:

KGN cc thit b vo chun nh bn phm, chut,

KGN cc thit b ra chun nh mn hnh, my in,

KGN cc b nhngoi chun nh cng, CD,

KGN vi cc my tnh khc trong mng nhiu my tnh

KGN vi h vi iu khin, vi x l

KGN vi ho iu khin

Hnh 1.1. Cu trc ca h ghp ni my tnh vi thit b ngoi vi

Trong :VXL: Vi x lRAM: Random Access Memory B nhtrong RAMROM: Read-only Memory B nhtrong ROMBGN: B ghp ni, khi ghp niCN: Cng nghipK: iu khin

c bit trong ho lng - iu khin, My tnh nhn d liu trng thi vt l ca

hthng (nhit , p sut, in p, dng in) di dng tn hiu in, tu dcc b cm bin (sensor), b chuyn i (tranducer), b pht hin (detector). V


8/128



My tnh cn nhn thng tin v trng thi sn sng hay bn ca thit bo.My tnh sau a tn hiu chp nhn trao i d liu vi TBNV, thu thp v

x l d liu, tnh ton cc tn hiu iu khin a ra cc ccu chp hnh (cc vanng m, cc rle trong mch in, cc mch ng lc iu tc ng cin),hay a ra cc thng s k thut cho thit b.

Ngoi ra, My tnh cn cn lu tr d liu trn cng, a compact (CD-ROM)

tra cu lc cn, hin th kt quo di dng bng s liu, dng th hay hnhv ho trn mn hnh.

1.2. Yu cu trao i tin ca my vi tnh i vi mi trng bn ngoi

1.2.1 Yu cu trao i tin vi ngi iu hnh

Ngi iu hnh trao i thng tin vi my tnh thng qua cc thit b nhp/xutcbn nh chut, bn phm, mn hnh. Vic trao i c thc hin thng qua mtgiao din trn mn hnh my tnh. Trng thi hot ng ca h thng c th hintrn giao din, ngi s dng tc ng vo h thng qua giao din ny s dng cc

thit b nhp nh chut, bn phm,Vic trao i thng tin vi ngi s dng cn m bo nhanh, chnh xc ng thi

phi thun tin, an ton cho ngi s dng.

1.2.2 Yu cu trao i tin vi thit b ngoi trong ho lng iu khin

Trong ho lng iu khin, my tnh nhn d liu trng thi vt l ca hthng (nhit , p sut, in p, dng in,..) di dng tn hiu in, t cc b cmbin (sensor), b chuyn i (transducer), b pht hin (detector), v my tnh cn

nhn thng tin v trng thi sn sng hay bn ca thit b.My tnh sau trao i d liu vi thit b ngoi vi, thu thp v x l d liu,

tnh ton cc tn hiu iu khin a ra cc ccu chp hnh (cc van ng m, ccr le trong mch in, cc mch ng lc iu tc ng cin,..) hay a ra ccthng s thit lp ch hot ng cho thit b.

Ngoi ra my tnh cn lm nhim v lu tr d liu tra cu, thng k hoc hinth kt qu trng thi hot ng ca thit b di dng th hay cc hnh v trcquan.

1.2.3 Yu cu trao i tin trong mng my tnh

Mt my tnh trong mng cn trao i tin vi nhiu ngi s dng mng, vinhiu my vi tnh khc, vi nhiu thit b ngoi nh: cc thit bu cui, cc thit bnhngoi, cc thit b lu tr v biu din tin.

1.3. Dng v cc loi tin trao i gia my vi tnh v thit b ngoi (TBN)

1.3.1 Dng tin

My tnh ch trao i tin di dng s vi cc mc logic 0 v 1


9/128



Thit b ngoi li trao i tin vi nhiu dng khc nhau nh dng s, dng k t,dng tng t, dng m tn hnh sin tun hon

1.3.2 Cc loi tin

My tnh a ra thit b ngoi mt trong 3 loi tin:

Tin va ch: l cc tin ca a ch TBN hay chnh xc hn, l a ch ccthanh ghi (register) ca khi ghp ni i din cho TBN.

Tin v lnh iu khin: l cc tn hiu iu khin khi ghp ni hayTBN nhng mthit b, c hoc ghi mt thanh ghi, cho php hay tr liyu cu hnh ng, v.v..

Tin v s liu: l cc s liu cn a ra cho thit b ngoi.

My tnh nhn tin vo tTBN v mt trong hai loi tin:

Tin v trng thi ca TBN: l tin v s sn sng hay yu cu trao i tin, v

trng thi sai li ca TBN. Tin v s liu: l cc s liu cn a vo My tnh

1.4. Vai tr v nhim v ca khi ghp ni

1.4.1 Vai tr

Khi ghp ni nm gia My tnh v TBN ng vai tr bin i v trung chuyntin gia chng

1.4.2 Nhim v

Phi hp v mc v cng sut tn hiu- Mc tn hiu ca My tnh thng l mc TTL (0V 5V) trong khi TBN c

nhiu mc khc nhau, thng thng cao hn ( 15V, 48V) hay mc in

cng nghip (220V/380V hoc ln hn)- Cng sut ng tn hiu My tnh nh (cchc mA), trong khi cng sut cn

cho TBN thng rt ln, c bit trong cng nghip.

Ngun

MVT

Ngunnhn

Ngunnhn

TBN

Ngunpht

Ngunpht

Ngunnhn

Ngunnhn

Ngunpht

Ghp ni ngdy MVT

Ghp ni ngd TBN

V tr v vai tr ca khi hp ni


10/128



- Do KGN phi bin i in p v khuch i cng sut cho ph hp giamy tnh v thit b.

- Pha my tnh thng dng cc vi mch 3 trng thi ghp ni tn hiuvo/ra. u vo/ra smc trkhng cao khi khng c trao i d liu, clp thit b vi my tnh, hn ch tiu th cng sut ng tn hiu v bo vmy tnh.

Phi hp v dng dliu:

Trao i tin ca My tnh thng l song song dng s, c th truyn theo 8, 16hoc 32 bit, ca TBN i khi l ni tip hoc ch yu l tn hiu tng t

Phi hp v tc trao i tin

My tnh thng hot ng vi tc cao (tn s ln ti hng GHz) trong khi thitb thng hot ng chm hn nhiu. Do cn phi thc hin ng b v mt tc. Vic ny thng c s kt hp gia phn cng v phn mm. Trn KGN phi cb nhm m d liu gia my tnh v thit b. KGN nhn t my tnh v lud liu b nhm ri truyn cho thit b theo nhp chm ca thit b, gii phng chomy tnh lm nhim v khc (phc v thit b khc, x l d liu hoc iu khin hinth,..) Tng t, KGN nhn d liu t thit b v chmy tnh c d liu vo.

Phi hp v phng thc trao i tin

m bo trao i tin mt cch tin cy gia My tnh v TBN, cn c KGN vcch trao i tin din ra theo trnh t nht nh.

Vic trao i tin do my tnh khi xng

(1) My tnh a lnh d khi ng TBN hay khi ng KGN(2) My tnh c tr li sn sng trao i hay trng thi sn sng ca TBN. Nu

c trng thi sn sng mi trao i tin, nu khng, chv c li trng thi(3) My tnh trao i khi c thy trng thi sn sng

Vic trao i tin do TBN khi xng:(1) gim thi gian chi trng thi sn sng ca TBN, My tnh c th khi

ng TBN ri thc hin nhim v khc. Vic trao i tin din ra khi:(2)TBN a yu cu trao i tin vo b phn x l ngt ca KGN, a yu cu

ngt chng trnh cho My tnh

(3)Nu c nhiu TBN a yu cu ng thi, KGN sp xp theo u tin nh sn,ri a yu cu trao i tin cho My tnh

(4)My tnh nhn yu cu , sa son trao i v a tn hiu xc nhn sn sngtrao i

(5)KGN nhn v truyn tn hiu xc nhn cho TBN(6)TBN trao i tin vi KGN v KGN trao i tin vi My tnh (nu a tin vo)(7)My tnh trao i tin vi TBN qua KGN (nu a tin ra)


11/128



1.5. Cu trc chung ca mt h ghp ni my tnh

1.5.1 Cu trc ng tn hiu ca KGN vi My tnhBt c KGN no cng ni vi My tnh v TBN c cc nhm sau Nhm ng tn hiu a ch A0 - An- Cc tn hiu ny c gii m trong cc KGN chn cc TBN cn lin lc

vi My tnh- Tp hp cc tn hiu ny to thnh bus a ch (Address bus) Nhm ng tn hiu iu khin- ng tn hiu c, ng tn hiu vit truyn lnh c (RD) hay vit cho

KGN.- ng tn hiu hi thoi t chc phi hp hnh ng gia My tnh v KGN,

m bo s hot ng nhp nhng, tin cy gia chng nh:Hi - tr liYu cu (t KGN vo My tnh) v chp nhn (t My tnh ra KGN) : yu

cu ngt INTR v chp nhn ngt INTA

- ng tn hiu lnh iu khin KGN hay TBN Nhm ng tn hiu nhp thi gian Nhm ng tn hiu in p ngun

1.5.2 Cu trc chung ca mt khi ghp ni

Khi phi hp ng tn hiu My tnh- Phi hp mc v cng sut tn hiu vi bus My tnh. Thng dng vi mch

chuyn mc, vi mch cng sut- C lp ng tn hiu khi khng c trao i tin

X l ngt

Thanh ghitrn thi

Thanh ghiiu khin

Thanh ghim c

Thanh ghim vit

Gii ma ch -

lnh

Lnh c

Lnh vitA0 - An

DO0 - DOn

DI0 - DIn

Phihpn

gdym

y

tnh

Phihpn

gdythi

tb

ngoi

Lnh c

Lnh vit

Lnh vit

Lnh c

DI0 - DIn

DO0 - DOn

iu khin A

iu khin B

Yu cu A

Yu cu B

cm ngt

Yu cu (INTR)

Xc nhn (INTA)

n

dm

tnh

S

stem

bus

Cu trc chun khi h ni

Cc lnhchn chip


12/128



Khi gii m a ch - lnh: Nhn cc tn hiu t bus a ch, cc tn hiu c,ghi, cht a ch (ALE), t hp thnh cc tn hiu c, ghi v chn chipcho tng thit b ca KGN v TBN.

Cc thanh ghi m- Thanh ghi iu khin ch- Thanh ghi trng thi hay yu cu trao i ca TBN

- Thanh ghi m s liu ghi- Thanh ghi m s liu c Khi x l ngt- Ghi nhn, che chn yu cu trao i tin ca TBN. X l u tin v a yu cu

vo My tnh Khi pht nhp thi gian- Pht nhp thi gian cho hnh ng bn trong KGN hay cho TBN. i khi

ng b, khi cn nhn tn hiu nhp ng h (clock) t bus my tnh Khi m thit b ngoi- Bin i mc tn hiu, cng sut v bin i dng tin Khi iu khin : iu khin hot ng ca khi nh pht nhp thi gian, ch

hot ng

1.6. Chng trnh phc v trao i tin cho khi ghp ni

Mi khi ghp ni cn c mt chng trnh phc v trao i tin, cc chng trnhny thng vit di dng cc chng trnh con, tp hp cc chng trnh con iukhin thit b thng c cung cp km vi thit b thng qua cc th vin. Cc thvin ny c thc ng gi vi nhiu dng khc nhau nh th vin lp trnh (.h,.lib), th vin lin kt ng (.dll), cc iu khin ActiveX (.ocx), cc device driver.

Vi chng trnh phc v trao i tin, cn c cc thao tc sau:

Khi ng KGN

Ghi che chn v cho php ngt

c trng thi TBN

Ghi s liu ra

c tin s liu

C th xy dng chng trnh iu khin bng nhiu ngn ng lp trnh v mitrng lp trnh khc nhau nh: Assembly, Pascal, C/C++, Visual C, Visual Basic,

Trong ti liu ny ch yu cung cp cc phng php lp trnh bng cc ngn ngbc thp v trong mi trng DOS.

1.6.1 Lp trnh hp ng(assembly) Xut dliu tbin data ra cng c a ch address:

mov dx, address

mov ax, data

out dx, ax


13/128



V d:

mov dx, 300H

mov ax, F0H

out dx, ax

Nhp s liu tcng a ch address vo bin datamov dx, address

in ax, dx

mov data, ax

data, address l s nh phn 16 bit.

c/ghi thanh ghi:1.6.2 Lp trnh Pascal

c thanh ghi:

:= port[a ch thanh ghi];

Ghi vo thanh ghi

Port[a ch thanh ghi] := ;

Lp xa bit:

Lp bit:

Port[$301]:=port[$301] OR $02; {Lp C1}

Xa bit:

Port[$301 ]:=port[$301] AND $EF; {Xa C4}

Kim tra bit:

kt:=port[$300] AND $04; {kim tra bit S2}

kt = 0 S2 = 0

kt 0 S2 = 11.6.3 Lp trnh C/C++

c/ghi thanh ghi:

c thanh ghi:

= inp (a ch thanh ghi);

Ghi vo thanh ghi

outp (,)

Lp xa bit:


14/128



Lp bit:

Outp (0x301,inp (0x301)||0x02);{Lp C1}

Xa bit:

Outp (0x301,inp (0x301) && 0xEF); {Xa C4}

Kim tra bit:

kt:=inp (0x300) && $04; {kim tra bit S2}

kt = 0 S2 = 0

kt 0 S2 = 1


15/128

Chng 2: Giao tip tn hiu tng t


CHNG 2.GIAO TIP VI TN HIU TNG T

Mc tiu:

Cung cp cc kin thc cbn v giao tip gia my tnh vi tn hiu tng ttrong cc h thng o lng v iu khin. Tm hiu cu trc, nguyn l hot ngca cc loi vi mch bin i tn hiu tng t -s (ADC/DAC) v ng dng cachng.

Tm tt chng:

- Khi nim tn hiu analog v ho lng iu khin s- Chuyn i tn hiu s sang tng t DACs

- Chuyn i tn hiu tng t - s ADC:


16/128



Khi nim tn hiu tng t v ho lng iu khin s

Vic s dng phng php s trong x l thng tin v iu khin ang ngy cnghiu qu v thun li. Tuy nhin hu ht cc tn hiu trong th gii thc li l tn hiudng tng t (analog). Do bt k h thng no mun x l cc tn hiu thc tbng phng php s th n phi c kh nng chuyn i cc thng tin tng t thnhdng s v ngc li. Thao tc thng c thc hin bng cc thit b ADC(Analog to Digital Converter) v DAC (Digital to Analog Converter).

Hnh 2.1: M hnh h thng x l tn hiu tng t bng phng php s

H thng x l tn hiu tng t bng phng php s ni chung l mt h lai,trong s liu tng t sc truyn, lu tr , hay x l bng phng php s nhcc b vi x l s. Trc khi s l, tn hiu tng t phi c chuyn thnh tn hius nhb chuyn i tn hiu tng t sang s (ADC). Kt qu ca php x l sc chuyn ngc li thnh dng tng t nh b

chuyn i tn hiu s thnh tng t (DAC).2.1. Chuyn i tn hiu s sang tng t

DACs

Mt b chuyn i tn hiu s thnh tng t DACl mt dng c bit ca mt b gii m. N gii mtn hiu su vo v chuyn thnh tn hiu tng tu ra.Bng chn l ca n c th c dng nh sau:

Hnh 2.2: Bng gi tr chn l ca mt DAC


17/128



2.1.1 Cc tham s chnh ca mt DACTham s n v Gii thch

phn gii(revolution)

Bit

y l s bit m DAC x l. Nu DAC c n bit th gi trinp u ra c th phn thnh n trng thi c gi tr cch unhau. Mi gi tr tng ng vi mt m su vo. S bit n

cng cao th DAC c phn gii cng lnGii in p thamchiu (Vref) FSR

VCh ra mc in p ln nht v nh nht c thc s dngnhin p tham chiu t bn ngoi

phi tuyn viphn(Non-Linearity,Differential - DNL)

LSBhay

%Vref

L chnh lch gia thay i gi trip p ra thc t vi thay i in p ra l tng trong trng hp u vo sthay i mt bit LSB , hay d thay i gia hai gi tr s knhauVD: +/- 1 LSB; +/- 0.001% FSR

phi tuyn tch

phn (Non-Linearity, Integral -INL) hay chnhxc tng i(Relative Accuracy)

LSBL sai s ln nht gia u ra vi ng thng ni gia im 0v im ton thang (gi tr ln nht ca thang o) ngoi tr saisim khng v sai s ton thangVD: +/-1 LSB typ.; +/- 4 LSB's max.

Gii u ra tngt hay gii tonthang

VL chnh lch gia gi tr tng t ln nht v nh nht mDAC c th cung cpVD: -3V to +3V, Bipolar Mode

Mc in p logiccao u vo, V

ih(Logic "1")

VL in p nh nht ca tn hiu su vo DAC m boc nhn l mc logic 1VD: 2.4 V min.

Logic InputVoltage, Vil (Logic"0")

VL in p ln nht ca tn hiu su vo DAC m cnhn l mc logic 0"VD: : 0.8 V max

in p ngundng (+Vs)

VL di in p c th dng lm ngun cung cp dng choDACVD: +4.75V min.; +5.0V typ.; +13.2V max.

in p ngun m

Analog NegativePower Supply (-Vs) V

L di in p c th s dng lm ngun cung cp m cho

DACVD: -13.2V min.; -5V typ.; -4.75V max.

in p mc logicdng (+VL)

VL di in p c th s dng cho mc logic dng ca DAC:VD: +4.75V min.; +5.0V typ.; +13.2V max.

in p mc logicm (-VL)

VL di in p c th s dng cho mc logic dng ca DACVD: -13.2V min.; -5V typ.; -4.75V max.


18/128



2.1.2 DAC chia in tr

DAC theo phng php chia in tr(Resistive Divider DAC) c l l kiu DACn gin nht. DAC kiu ny s dng mt chui in trmc ni tip vi nhau tora mt tp cc gi trin p cch u nhau gia +Vref v Vref. Tn hiu su voxc nh tn hiu in p no c ni vi b khuch i thng qua cc cc b chuyn

mch.

Mc d phng php chia in trc th d hiu, nhng n trnn km hiu quvi cc b DAC c phn gii cao. Mi bit thm vo cho phn gii ca DAC ihi tng gp i sin trv cng tc. V d nh vi DAC 12 bit th phi cn ti4095 in trv 4096 cng tc.

Hnh 2.3: DAC chia in tr

2.1.3 DAC trng s nh phn

Khi phn gii ca DAC t ti 6 hay 7 bit, kin trc thang in trthng chomt phng php hiu qu hn

Phng php ny cho ta li ch chnh l chng tit kim din tch vi mch. Chnghn nh mt DAC 9 bit ch cn 1 in trv 1 cng tc thm vo so vi DAC 8 bit

Hnh 2.1DAC trng s nh phn


19/128



2.1.4 DAC iu bin rng xung

Phng php DAC iu bin rng xung (Pulse width modulation PWM) lphng php rt n gin v hu nh hon ton s dng phng php s, s dng rtt mch tng t

PWM iu chnh in p u ra s dng chui xung tn s cao vi rng xungc th thay i c thay i cng sut u ra

di xung cng ln th in p u ra cng gn vi in p ti a (VOH) caDAC, v ngc li di xung ngn nht tng ng vi in p ti thiu (VOL)

Tn hiu u ra sc a qua mt b loc thng thp to tn hiu analog

Hnh 2.2: DACiu bin rng xung

DAC dng PWM cng kh thu c DAC vi phn gii cao, bi v c phn gii cao, DAC phi iu chnh chui xung theo cc khong thi gian rt nh.iu yu cu phi c mt xung clock (master clock) vi tn s rt cao iukhin rng xung

V d vi DAC 16 bit, cn c phn gii theo thi gian bng 1/65536 ln chu k

chui xung. V xung tn hiu cn phi a qua b lc thng thp to ra tn hiutng t, tn s xung i hi phi gp nhiu ln ( thng thng l gp 100 ln) tn scao nht ca tn hiu tng tu ra. Do mt b DAC 16 bit cho cc ng dng xl m thanh c bng thng 20kHz cn c mt b to xung clock c tn s l 65536 x100 x 20000 = 131 GHz. R rng rng tn s ny l khng tht c vi cng nghhin nay


20/128



2.2. Chuyn i tn hiu tng t- s ADC:

Tn hiu trong th gii thc thng dng tng t (analog), nn mch iu khinthu thp d liu ti tng iu khin v (thng qua cc cm bin) cng dngtng t. Trong khi , biu khin ngy nay thng l cc P, C x l d liu dng s (digital). V vy, cn phi chuyn i tn hiu dng tng t thnh tn hiudng s thng qua b bin i AD.

Gii php thng dng a tn hiu tng t vo x l bng cc b x l sl dng b chuyn i tn hiu tng t sang s (analog-to-digital converter - ADC).Hnh di l mt v d cho mt b ADC n gin. u vo cho b ny l hai tn hiu:mt tn hiu tham chiu (reference) v tn hiu cn chuyn i. N c mt u ra biudin mt t m dng s 8 bit. T m ny vi x l c thc v hiu c

C nhiu phng php bin i AD khc nhau, y ch gii thiu mt s phngphp in hnh.

2.2.1 Cc tham s chnh ca mt ADC

Tham s n v Gii thch

phn giiResolution

Bits

Nu mt ADC c n bit, th phn gii ca n l 2n , cngha l s trng thi hay s m c th s dng chiau vo analog. S bit cng cao th phn gii cngln v cng phn bit c nhiu trng thi

Sai s tuyn tnh viphnNon-Linearity,Differential (DNL)

Bits(withno

missing

codes)

Vi mi ADC, tn hiu s bin i theo tng bit LSB. chnh lch gia cc gi tr l tng c gi l phi tuyn vi phn.Example of an Actual Spec: 10 Bits min

Sai s tuyn tnh tchphnNon-Linearity,Integral (INL)

LSB

Hm truyn ca mt ADC l mt ng thng ni tim 0 ti im ton thang. Sai s ln nht ca mtm s vi ng thng ny c gi l sai s tchphn ca ADCExample of an Actual Spec: +/- 2 LSB's max

Di in p tng tu vo hay di tonthang(Analog InputRange or Full-ScaleRange)

V

L chnh lch gia gi tr tng t ln nht v nhnht ng vi ADC c thVD:0V to +10 V, Unipolar Mode;-5V to +5V, Bipolar Mode


21/128



Thi gian chuyn i(Conversion Time)

secThi gian cn thit ADC hon thnh mt ln chuyniVD: 15 sec min.; 25 sec typ.; 40 sec max.

Ngun nui dng(+ Power Supply -

V+)

VDi in p c th s dng lm ngun nui dng choADC

VD: +4.5V min.; +5.0V typ.; +7.0V max.

Ngun nui m- Power Supply (V-)

VDi in p c th s dng lm ngun nui m choADCVD: -12.0V min.; -15V typ.; -16.5V max.

2.2.2 B bin i AD theo hm dc

Hnh 2.3: Bin i ADC theo hm dc

y l b bin i n gin nht theo m hnh b bin i tng qut trn. Ndng mt counter lm thanh ghi v c mi xung clock th gia tng gi tr nh phn chon khi vAX vA. B bin i ny c gi l bin i theo hm dc v dng sng vAXc dng ca hm dc, hay ni ng hn l dng bc thang. i khi n cn c gi lb bin i AD loi counter.

Hnh trn cho thy s mch ca b bin i AD theo hm dc, bao gm mtcounter, mt b bin i DA, mt OPAMP so snh, v mt cng AND cho iukhin. u ra ca OPAMP c dng nh tn hiu tch cc mc thp ca tn hiuEOC. Gi s vA dng, qu trnh bin i xy ra theo cc bc :

- Xung Start c a vo reset counter v 0. Mc cao ca xung Start cngngn khng cho xung clock n counter.

- u vo ca b bin i DA u l cc bit 0 nn p ra vAX = 0v.- Khi vA > vAX th u ra ca OPAMP (EOC) mc cao.

+

-

vA

u vo analog

CounterB bin

i DA ...

vAX

Kt qu digital

So snh

OPAMPEOC

Start

Clock

Reset

Clock

vAX

Start

vA

EOC

tC

Khi chuyni hontt, counterngngm


22/128



- Khi Start xung mc thp, cng AND c kch hot v xung clock c avo counter.

- Counter m theo xung clock v v vy u ra ca b bin i DA, vAX, giatng mt nc trong mt xung clock

- Qu trnh m ca counter c tip tc cho n khi vAX bng hoc vt qua vAmt lng vT (khong t 10 n 100v). Khi , EOC xung thp v ngn

khng cho xung clock n counter. T kt thc qu trnh bin i.- Counter vn gi gi tr va bin i xong cho n khi c mt xung Start cho

qu trnh bin i mi.

T ta thy rng b bin i loi ny c tc rt chm ( phn gii cng caoth cng chm) v c thi gian bin i ph thuc vo ln ca in p cn bin i.

2.2.3 A/D xp x tim cn

y l b bin c dng rng ri nht trong cc b bin i AD. N c cu tophc tp hn b bin i AD theo hm dc nhng tc bin i nhanh hn rtnhiu. Hn na, thi gian bin i l mt s cnh khng ph thuc gi trin pu vo.

S mch v gii thut nh sau :

S mch tng t nh b bin i AD theo hm dc nhng khng dngcounter cung cp gi tr cho b bin i DA m dng mt thanh ghi. n v iukhin sa i tng bit ca thanh ghi ny cho n khi c gi tr analog xp x p votheo mt phn gii cho trc.

- Chuyn i n bit cn n bc- Cn c tn hiu Start v End

+

-

vA

u vo analog

n v iukhin

Thanh ghiMSB LSB

B bin i DA

. . .

vAX

So snh

OPAMP

EOC

Clock

. . .

Start

START

Xa tt c cc bit

Bt u MSB

Set bit = 1

VAX > VA ? Clear bit = 0

Xon ht bit ?

Qu trnh bin i ktthc v gi tr bin i

nm trong thanh ghi

END

ng

Sain bitthp k

Sai

ng


23/128



- Thi gian chuyn i thng thng: 1 to 50 ms

- phn gii thng thng 8 to 12 bits

2.2.4 Tch phn sn dc

B bin i loi ny l mt trong nhng b c thi gian bin i chm nht

(thng l t 10 n 100ms) nhng c li im l gi c tng i r khng dng ccthnh phn chnh xc nh b bin i AD hoc b bin i p sang tn s.

Nguyn tc chnh l da voqu trnh np v x tuyn tnh cat vi dng hng. u tin, tc np trong mt khong thigian xc nh t dng in khngi ng vi in p vo vA. V

vy, cui thi im np, t s cmt in p t l vi in p vo.Cng vo lc ny, t c xtuyn tnh vi mt dng hng rtra tin p tham chiu chnh xc vref. Khi in p trn t gim v 0 th qu trnh xkt thc. Trong sut khong thi gian x ny, mt tn s tham chiu c dn nmt counter v bt u m. Do khong thi gian x t l vi in p trn t lc trckhi x nn cui thi im x, counter s cha mt gi tr t l vi in p trn t

trc khi x, tc l t l vi in p vo vA.

Hnh 2.4: ADC tch phn theo sn dc

Ngoi gi thnh r th b bin i loi ny cn c u im chng nhiu v s trinhit. Tuy nhin thi gian bin i chm nn t dng trong cc ng dng thu thp dliu i hi thi gian p ng nhanh. Nhng i vi cc qu trnh bin i chm (cqun tnh ln) nh l nhit th rt ng xem xt n.

-

+IN

R

S Enable

N-bit Output

Q

Oscillator Cl

Cou

StartConversion

StartConversion

02

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16

Voltage

accross

the

capacitor

Time

Vin

Counting time


24/128



2.2.5 Flash ADC

- Bin tn hiu c so snhvi mt tp 2n gi tr thamkho (refference)

- o lng trc tip vi 2n-1 bso snh (comparator)

- Hiu sut thng thng:- 4 ti 10 -12 bits- 15 - 300 MHz- Tiu th nng lng ln- ng dng trong s ho dng

sng tn hiu

Hnh 2.5: ADC flash

B bin i loi ny c tc nhanh nht v cng cn nhiu linh kin cu thnh nht.C th lm mt php so snh: flash AD 6-bit cn 63 OPAMP, 8-bit cn 255 OPAMP,v 10-bit cn 1023 OPAMP. V l m b bin i AD loi ny b gii hn bi sbit, thng l 2 n 8-bit.V d mt flash AD 3-bit :Mch trn c phn gii l 1V, cu chia in p thit lp nn cc in p so snh (7mc tng ng 1V, 2V, ) vi in p cn bin i. u ra ca cc OPAMP cni n mt priority encoder v u ra ca n chnh l gi tr digital xp x ca inp u vo.

Cc b bin i c nhiu bit hn d dng suy ra theo mch trn.


25/128



2.2.6 Mt s vi mch ADC thng dng

Hin nay, trn th trng c rt nhiu loi IC chuyn dng cho b bin i ADC.

Di y l loi IC rt hu dng v c s dng nhiu trong thc t.

3.1 B bin i ADC 0809

y l loi bi mch ADC ch to da trn k thut ADC xp x lin tip.

S chn:

c im cu to:Thang in tr256 R vi ng chuyn mch

analog.

Thanh ghi xp x lin tip.

B multiplexing.

B cht a ch ng vo.B gii m.

Bm ng ra.

Tt c nhng vi mch trn c tch trnmt chip CMOS n khi v khng i hicc linh kin ph khc mc thm bn ngoi.

Ti mi thi im ch c th mu1 trong 8 knh analog vo qua mch phn knh 3 sang 8.

S khi:

AddressLatch

enable

Tri-stateoutput

Latchbuffer

8digita

loutput

AddressLatchAnd

decoder

3bitAddress

Controla timing

SAR

Switchestree

256 RegisterLadder

8 chanelmultiplexing

analogswitch

8analoginput

Vcc

GROUND

REF+

REF-

START CLOCK

EOC8 BIT AD

OE

U1

ADC0809

26

27

28

1

2

3

4

5

12

16

10

9

7

17

14

15

8

18

19

20

21

25

24

23

6

22

IN0

IN1

IN2

IN3

IN4

IN5

IN6

IN7

REF+

REF-

CLK

OE

EOC

D0

D1

D2

D3

D4

D5

D6

D7

A0

A1

A2

START

ALE


26/128



c im kthut ca ADC 0809:ADC0809 c tc bin i nhanh, sai s lng ha thp v cng tiu tn thp.

Ngun cung cp 5v DC, in p chun 5v DC.

Thi gian chuyn i l 100s.

C 8 knh analog ng vo.

in p ng vo t 0 n 5V.

Tn s xung CLOCK t 10 1280KHz.

Nguyn tc hot ng :

Ti mt thi im, 1 trong 8 ng vo analog c chuyn i. Vic chn ngvo c xc nh bi 3 ng a ch A, B, C thng qua b phn knh 3 sang 8. Quatrnh chuyn i c bt u khi 3 ng a chc chn v khi xung START vxung ALE bt ln mt. Khi , ALE cht a ch knh c chn v sa tn hiu

vo b so snh, xung START bt u thc hin vic chuyn i, EOC mc 0, busd liu trng tng trcao.

Sau khong thi gian 100s, qu trnh chuyn i kt thc, tn hiu analog cchuyn thnh 8 bit d liu sng ra. Lc ny xung EOC bt ln 1 v d liu c

a vo vng m. a d liu t vng m ln bus, phi t xung OE ln 1.

Nhbm 3 trng thi nn d dng kt ni vi data bus ca CPU.Gin thi gian:

CLOCK

START

ALE

AD

ANALOGINPUT

OE

EOC

DATA

Tri - state


27/128



Cc sliu kthut: phn gii : K = 5/256 = 0.196VDy ng in trvo :

Trong iu kin :Vcc = Vref (+) = 5VVref (-) = GND

CLK = 640 KHzth tng trvo t 1 2.5 K.

Mc logic ca tn hiu ra :Trong iu kin 4.75V Vcc 5.5V th mcin p logic 1 l V Vcc 0.4 v mc in p logic 0 l V 0.45v

Tc chuyn i : 100sCng sut tiu tn : 15 mW.

ADC ICL7109:

ICL7109CPL l b bin i AD 12-bit dng n phin, bin i theo phng

php tch phn hai dc, cng vi cc bit ch cc tnh, bit bo qu thang o c thgiao tip vi P, C theo hai cch :- Ghp trc tip vo bus : thng qua chn chn

chip, hai chn cho php xut byte cao, bytethp.

- Ghp theo chun cng nghip UART : cng dng trong truyn nhn d liu t xa, ngra c bin i v a n mt UART trongch bt tay, trao i d liu ni tip.

ICL7109CPL c chnh xc cao, tri nhitnh hn 1V/0C. c ng dng trong nhiu trongnhng h thng thu thp d liu do gi thnh thp, cngsut tiu tn v dng phn cc nh. Cc c im chyu nh sau :

- Pha zero-integrator gip khi phc qu tinhanh.

- Loi b vng tr v nhiu.- Ci tin kh nng li bus.

- Ng ra 3 trng thi.- UART ch bt tay giao tip ni tip.- C sn ngun tham chiu chun.- 30 ln bin i trong 1 giy.- Khi n, cng ngh CMOS c cng sut thp

M t chc nng ca cc chn:

GND : Ni t.STATUS : ng ra. Khi mc cao, b bin i ang trong pha integrate hocpha de-integrate cho n khi d liu c cht. Khi mc thp, b bin i ang

pha auto-zero hoc de-integrate sau khi d liu c cht.POL : bit ch cc tnh (polarity), nu mc cao, ch ra rng tn hiu vo l pdng.


28/128



OR : bit ch qu thang (over-range), nu mc cao, ch ra rng ng vo vtqu gii hn cho php.

B1B12 : ng ra ba trng thi, l cc bit d liu tng ng.TEST : ng vo, khi TEST = 1 th ADC hot ng bnh thng, TEST = 0 th ttc bit d liu ra u mc cao, cn khi khng kt ni th cc cht ng ra bm

c cho php. Trong hot ng bnh thng : ni TEST ln +5v.LBEN : ch trc tip (MODE = 0 v CE/LOAD = 0) th LBEN l ng vo,khi mc tch cc s cho php xut byte thp; ch bt tay (MODE = 1) thLBEN l ng ra, c chc nng l cbyte thp.HBEN : ch trc tip (MODE = 0v CE/LOAD = 0) th HBEN l ngvo, khi mc tch cc s cho phpxut byte cao; ch bt tay(MODE = 1) th HBEN l ng ra, cchc nng l cbyte cao.

CE/LOAD : ch trc tip, l ngvo, khi tch cc s cho php xut ra 12bit d liu B1B12, POL, OR nuLBEN, HBEN tch cc. ch bttay, l ng ra strobe.MODE : ng vo, khi mc thp :ADC hot ng ch trc tip, cnkhi mc cao : ADC hot ng ch bt tay.OSC IN : ng vo ca b dao ng.

OSC OUT : ng ra ca b dao ng.OSC SEL : ng vo, dng chn b dao ng. ICL 7109 c mt b dao ngvi 3 ng, n c th hot ng vi b dao ng RC hay dao ng thch anh, cngc th hot ng vi ngun xung clock bn ngoi.

Nu chn OSC SEL h (c pullup ko ln) hay ni vi mc cao th xungclock s ly t b dao ng RC bn ngoi. Khi , xung clock s cng pha, cng tns vi tn hiu trn chn BUF OSC OUT v tn s xung clock tnh theo cng thc :

RC

f45.0

=

in trnn chn l 100K, t chn sao cho khong thi gian ca 2048 chu kxung clock gn vi mt bi s tch phn ca 50Hz loi tr nhiu 50Hz, nhngkhng nn nh hn 50pF.

Nu chn OSC SEL c ko xung mc thp th xung clock ly t dao ngthch anh bn ngoi c tn s t 1MHz n 5MHz. Tn s xung clock bn trong khi s bng tn s ca tn hiu trn chn BUF OSC OUT chia cho 58.

BUF OSC OUT : ng ra ca b dao ng c m, tin dng lm ngun xung

clock cho cc IC khc.


29/128



RUN/HOLD : sau khi pha autozero hon tt trong khon thi gian nh nht, cnc mt xung ln cao t nht 200ns tc ng vo chn RUN/HOLD bt u mt qutrnh bin i. Tuy nhin cn ch rng nu c bt k xung no xut hin trong qutrnh bin i hay trong vng 2048 chu k xung clock sau khi chn STATUS xungthp s b b qua. Nu ICL 7109 ang vo thi im kt thc pha autozero, mt qu

trnh bin i sc bt u v chn STATUS s ln cao trong vng 7 chu k xungclock sau khi RUN/HOLD ln cao.

Thm vo , bt u v kt thc mt qu trnh bin i, chn ny cng cthc s dng cc tiu thi gian bin i. Bi v mt qu trnh bin i bnhthng s tn mt 8192 chu k xung clock, trong ring pha de-integrate ly mt4096 chu k xung clock v c lp vi in p vo. Nhng nu sau khi STATUSxung thp, RUN/HOLD xung thp theo th ICL 7109 s nhy tc thi n phaautozero hn l phi mt ton b 4096 chu k xung clock cho pha de-integrate.

SEND : ng vo, bo hiu rng thit b bn ngoi chp nhn d liu khi ADChot ng ch bt tay. Ni ln +5v nu khng s dng.V- : ngun m cho ICL 7109, thng ni n -5v.REF OUT : ng ra in p tham chiu, thng nh hn V+ l 2,8v.BUF : ng ra b khuch i m.AZ : c ni n t CAZ.INT : c ni n t CINT.COMMON : chn chung ca tn hiu tng t.

IN LO : cc m ca in p vo vi sai.IN HI : cc dng ca in p vo vi sai.REF IN+ : ng vo dng ca in p tham chiu.REF CAP+ : cc dng ca t tham chiu.REF CAP- : cc m ca t tham chiu.REF IN- : ng vo m ca in p tham chiu.V+ : Vcc (5v).


30/128

Chng 3: Th tc trao i tin ca my vi tnh


CHNG 3.TH TC TRAO I DLIU CA MY TNH

Mc tiu:

Trnh by cc kin thc cbn v cc th tc trao i d liu s dng gia mytnh v cc thit b ngoi vi. Nguyn l, u nhc im v ng dng ca mi loi thtc trao i d liu. Lp trnh khi to v iu khin cho mi th tc.

Tm tt chng:

- Cc ch trao i d liu ca my vi tnh

- Trao i tin ngt vi x l

- Trao i tin trc tip khi nh


31/128



3.1. Cc ch trao i dliu ca my tnh

Ch trao i tin ca My tnh vi thit b ngoi Trao i tin theo ch chng trnh

S trao i tin c VXL iu khin theo mt trong hai loi lnh sau

Cc lnh vo (IN) hay ra (OUT). Cc lnh chuyn (MOV) gia thanh ghi A v thanh ghi m s liu ca KGN

c a ch nhxc nh. Trao i tin trc tip b nh

Sau khi VXL c khi ng, s trao i tin hon ton do KGN iu khin thaycho VXL v cc cng vo ra ca VXL trng thi in trcao (VXL b c lp). Lcny, KGN iu khin mi hot ng ca b nhM v KGN, c th l:

Pht a ch cho khi nhhoc TBN.

Pht lnh c (/RD) hay ghi (/WR) s liu. Cc s liu c, ghi c trao i gia khi nhM va TBN thng qua cc

thanh ghi m ca KGN.

Th tc trao i tin trong ch chng trnh ch trao i tin theo chng trnh, c th trao i tintheo mt trong ba phng php sau:

- Trao i ng b- Trao i khng ng b hay hi trng thi (Polling)

- Trao i theo ngt chng trnh1. Trao i ng b

Sau khi khi ng TBN, My tnh khng cn quan tmti TBN c sn sng trao i tin haykhng m a lun cc lnh trao i tin (c vo, ghi ra hay truyn s liu ).Phng php trao i tin ny chcthc hin khi:

- TBN lun sn sng trao i tin.

- Tc trao i tin ca My tnh vTBN lun ph hp nhau hoc TBNtrao i tin nhanh.

nh gi:- u im: Nhanh, khng tn thi gian

chi- Nhc im: Thiu tin cy, b mt tin

v c th c s c lm TBN cha snsng trao i.

2. Trao i khng ng b hay hi trng thi

(Polling)Trnh t trao i din ra nh sau:

- My tnh a tin iu khin TBN.

Trao i tin

Chng trnh

Chng trnh

TBN sn sng ?

Trao i tin

S


32/128



- My tnh chv kim tra trng thi sn sng trao i tin ca TBN bng cch:o c tin v trng thi sn sng ca TBN.o Kim tra trng thi sn sng. Nu cha, My tnh li c v kim tra

trng thi sn sng.- My tnh trao i tin vi TBN.Phng php trao i ny thc hin khi tc trao i tin ca TBN chm so vi

My tnh3.2. Trao i tin ngt vi xl

Phng php trao i tin ny khc phc nhc im ca ccphng php trn. Trnh t nh sau:

(1)My tnh ang thc hin chui lnh ca mt chngtrnh no .

(2)TBN c yu cu trao i tin, s gi tn hiu yu cutrao i tin ( yu cu ngt INTR)

(3)My tnh (c th l VXL ) a tn hiu chp nhn (xcnhn ngt INTA)(4)Chng trnh chnh b ngt, My tnh chuyn sang

chng trnh con phc v ngt tc l chng trnh contrao i tin cho TBN yu cu.

(5)Chng trnh chnh li tip tc thc hin ch b ngt.

3.2.1 Cc loi ngt ca my PC

Cc loi ngt

Ngi ta chia ngt thnh hai loi: ngt cng v ngt mmNgt cng: cn gi l ngt ngoi v do nguyn nhn bn ngoi. VXL c cc livo dnh cho ngt ngoi. Khi c tn hiu vo li vo ny, chng trnh VXL angthc hin s b dng.

Ngt NMI( Non maskable Interrupt) - Ngt khng che c : Khi c ngt ny,VXL dng chng trnh sau lnh ang thc hin, thanh ghi a ch lnh (IP) vthanh ghi ch th flag c lu gi, 2 bit IF (Interrupt Flag) va TF (Trap Flag)b xo v 0 cm ngt ngoi tip theo v khng c by. Mun cho php haykhng cho php ngt ny xy ra, chng ta dng mt triger (flip flop) mc

li vo ngt trc khi a vo li vo ngt NMI. Ngt INTR:

o Ngt ny c cho php hay cm ngt bng cch lp hay xo bit IF cathanh ghi flag. Lp bi lnh STI (Set Interrupt), xo bi lnh CLI (Clearinterupt)

o Thng c ni vi li ra yu cu ngt ca vi mch x l u tin ngt(8214, 8259).

Ngt reset :

Chng trnh

Ngt

Chn

gtrnh

con

phcvn

gt


33/128



Ngt mm: (hay ngt bn trong do lnh ca chng trnh) do VXL gp cc lnhgy ra ngt hoc tnh hung c bit khi thc hin lnh (ngt logic) v ngt ca hiu hnh.- Ngt do lnh: l ngt khi thc hin cc lnh CALL, HLT, INT- Ngt logic hay cc ngoi tr: xy ra khi gp cc tnh hung c bit sau:

o Chia mt s cho 0o Trn ni dung thanh ghi hay b nho Thc hin tng bc (vector 1)o im dng ( Break point) chng trnh do ngi dung chng trnh s

dng nh trc (Vect3)- Ngt ca hiu hnh: l cc ngt do hiu hnh quy nh phc v trao

i tin ca cc TBN (bn phm, my in, vv) nh INT 10, INT 16, INT 21,.v.v..)

Ngt ca My tnh PC (8086, 80286 )

Cc ngt khng hon ton c lin kt vi cc thit b ngoi. H VXL 8086 cungcp 256 ngt, a phn trong s chng l ch phc v nh ngt phn mm. H 8086c mt bng vecter ngt gia ch ca cc chng trnh phc v ngt. Mi a ch l4 byte.

Trong cc my PC, ch c 15 ngt dnh cho phn cng v 1 ngt khng che c.Phn cn li c s dng cho cc ngt phn mm v cc b x l ngoi l. B x lngoi l l cc chng trnh tng t nh ISR nhng x l cc ngt khi xut hin li.V d nh vector ngt u tin gia ch ca ngoi l Divide by Zero (li chia cho

0). Khi xut hin li ny VXL nhy sang a ch 0000:0000 v thc hin chng trnhc a ch lu y.

INT(Hex)

IRQ Common Uses

00 - 01 Exception Handlers -

02 Non-Maskable IRQNon-Maskable IRQ (Parity

Errors)

03 - 07 Exception Handlers -

08 Hardware IRQ0 System Timer09 Hardware IRQ1 Keyboard

0A Hardware IRQ2 Redirected

0B Hardware IRQ3 Serial Comms. COM2/COM4

0C Hardware IRQ4 Serial Comms. COM1/COM3

0D Hardware IRQ5 Reserved/Sound Card

0E Hardware IRQ6 Floppy Disk Controller

0F Hardware IRQ7 Parallel Comms.

10 - 6F Software Interrupts -70 Hardware IRQ8 Real Time Clock


34/128



71 Hardware IRQ9 Redirected IRQ2

72 Hardware IRQ10 Reserved


74 Hardware IRQ12 PS/2 Mouse

75 Hardware IRQ13 Math's Co-Processor76 Hardware IRQ14 Hard Disk Drive


78 - FF Software Interrupts -

Th tc x l (p ng) ngt chng trnh

Khi c mt tin hiu yu cu ngt chng chnh a vo chn yu cu ngt

(INTR), qu trnh ngt chng trnh c din ra theo cc bc sau:

Lu gi tin v trng thi ca VXL lc c tn hiu yu cu ngt v ni chngtrnh b gin on.

VXL gi tn hiu xc nhn hay cho php ngt INTA v c vector ngt.

Chuyn sang chng trnh phc v ngt.

Trv ch chng trnh chnh b ngt v tip tc thc hin chng trnh .

Lu gitin v ch b ngt chng trnh:

cui mi chu trnh lnh, VXL 8086 ( cng nh 80286) kim tra xem c yu cu

ngt no gi ti khng. Nu c yu cu, VXL tin hnh lu tr tin v ni b ngtchng trnh ( dng lnh PUSH vo vng nhngn xp m a ch ch th bi thanhghi SP).Cc tin l:

- Thanh ghi cFlag FR (Flag Register)- Con tr lnh IP (Instruction Pointer)- Thanh ghi on lnh CS (Code Segment register)

Gi tn hiu cho php (xc nhn ) ngt v c vector ngt:

Sau khi lu tr tin v v tr b ngt ca chng trnh chnh, VXL gi tn hiu

xc nhn ngt INTA (Interrupt Acknowledge) cho KGN ca TBN. Tu cch t chcngt v to vector ngt, VXL s dng tn hiu ny c vector ngt tng ng caKGN vo thanh ghi cha A. VXL c ni dung ca nhc a ch l vector ngt bit c a chu tin ca chng trnh con phc v ngt ( chng trnh trao itin).

Thc hin chng trnh con phc v ngt

l chng trnh m a ch lnh u tin nm trong nhc a ch l vectorngt. Kt thc chng trnh con ny, c lnh trv (RET - return) VXL tip tc

thc hin chng trnh chnh. Tip tc thc hin chng trnh chnh:


35/128



Sau khi gp lnh trv (RET), VXL tin hnh c v hi phc cc tin ca VXLlc b ngt chng trnh ghi nhch ngt chng trnh (bng lnh POP cc nhngn xp). Qua trnh c ra ny xy ra ngc li vi qu trnh ghi vo (o quy lutLIFO Last In First Out) v ni dung ca:

Thanh ghi con tr lnh (IP) tr v lch (offset) ca a ch lnh tip theo ca

chng trnh chnh b ngt trong mng nhlnh (CS). Thanh ghi mng lnh (CS) va chon u tin ca vng nhdnh cho

chng trnh chnh b ngt.

Thanh ghi flag lc b ngt chng trnh.

3.2.2 Xl ngt cng trong IBM - PC:

VXL 80x86 c 3 chn dng cho ngt cng l:INTR: Interrupt Request

NMI: NonMaskable Interrupt/INTA: Interupt Acknowledge

INTR l tn hiu u vo yu cu ngt ca VXL v n c th che hay cho phpthng qua lnh CLI (Clear Interrupt) v STI (Set Interrupt)NMI tng t INTR nhng khng che c bng lnh

INTR v NMI c thc kch hot t bn ngoi bng cch ni vo in p 5Vvo chn tng ng ca VXL.

Nh vy VXL ch c kh nng phc v mt yu cu ngt cng t TBN. m

rng kh nng phc v ngt ngoi IBM - PC s dng thm vi mch x l ngt cnglp trnh c PIC (Programmable Interrupt Controller) 8259. S dng PIC 8259 nivo chn INTR c th mrng s lng ngt cng ln n 64

RAM

KGN1VXL

InterruptController KGN8

. . .IR0IR7

ROM

INTINT

/INTA

NMIResetC ch thc hin ngt cng

System bus

. . .


36/128



Vi mch xl ngt 8259S khi:

Cc chn:IR0 IR7 (Chn 18 25) : Cc li vo yu cu ngt

D0 D7 (Chn 11 4) : Cc bit s liu (2 chiu)A0 (chn 27) : a ch chn thanh ghi lnhCS (Chn 11) : Chn vi mch (chip select)WR (chn 2) : Li vo lnh ghiRD ( chn 3) : Li vo lnh cCAS0 2 (Chn 12,13,15) : Li vo mc ni tngSP (chn 16) : Trong ch khng m, nu SP = 1 th 8259l ch (Master).

SP = 0 th l t(Slave)

INTA (chn 26) : Li vo xc nhn ngtINT (chn 17) : Li ra yu cu ngt chng trnh

Cu trc PIC 8259

Thanh ghi yu cu ngt IRR (Interrupt Request Register): ghi tm mc ngt(IR0 IR7) t TBN.

Thanh ghi Ngt ang phc v ISR (In Service Register): ghi mc ngt angs dng.

Thanh ghi mt n ngt IMR (Interrupt Mask Register).

Mch logic gii quyt u tin PR (Priority Resolver)

CAS0CAS1CAS2

Bmd liu

Logicc/ghi

B so snhv ni tng

Logic iu khin

Thanhghi

phc v(ISR)

Giiquytu tin(PR)

Thanhghi yu

cungt

Thanh ghi che ngt (IMR)

D0 D7

A0

IN

IR0....

IR

nd

n

i

S khi 8259


37/128



Khi logic iu khin: x l ngt, a yu cu (INT) v xc nhn ngt (INTA)

Bm ng tn hiu s liu: m ghi vo cc thanh ghi v m c ccs liu t cc thanh ghi.

Logic iu khin c/ghi: to cc tn hiu ghi v c cc thanh ghi m.

Bm ni tng/so snh: chn cc vi mch 8259 ttrong mt vi mch 8259ch.

i vi IBM - PC, 2 PIC c s dng mrng ra 15 ngt cng. PIC1 qunl u vo ngt IRQ0 - 7, PIC2 dnh cho IRQ8 - 15. PIC2 c ni tng ?ln PIC1qua ng IRQ2 (Do nu ta chn ngt IRQ2 th ton b IRQ 8 - 15 cng b che.

3.2.3 Lp trnh xl ngt cng:

Trong my IBM - PC c 2 PIC c nh v ti cc a ch l PIC1 - 20H, PIC2 -A0H. Cc PIC c khi to bi BIOS, do ta ch cn quan tm ti 2 lnh khi lm

vic vi chng. Lnh th nht tc ng vo t iu khin OCW1 thit lp vic che ngt

Nu mun che ngt no th ta xo bit tng ng vi ngt v 0. Tiukhin OCW1 c gi ti a ch base + 1.

Lnh th 2 l lnh End of Interrupt (EOI). Lnh ny c gi ti PIC khi ktthc chng trnh con x l ngt reset PIC. Lnh EOI c gi ti PICbng cch ghi gi tr 20H vo thanh ghi c a ch base.

Cu trc chung ca mt chng trnh c s dng phng php vo ra bng ngt vit

bng Pascal nh sau:

program ;

MPU

IR0IR1

IR2IR3

IR7

INT

/INT

IR1

IR2

IR7

INT

/INT

CAS0-2

INT

/INT

CAS0-2

Pri PIC

Sec PIC

IR 0

IR 1

IR 3

IR 7

IR 8

IR 9

IR 1

IRQ1

: : :

: :

Port 20H

Port A0H

S ghp ni ni tng PIC trong IBM - PC


38/128



uses

Crt, Dos;

const

{PIC Constants}

PIC1 = $20;

PIC1_OCW1 = $21;

PIC2 = $A0;PIC2_OCW1 = $A1;

var

OldVector: procedure;

{$F+}

procedure MyISR; interrupt;

var

begin

...

{Chng trnh iu khin vo/ra d liu}

...` Port[MasterPIC] := EOI;

end;

{$F-}

{Chng trnh chnh}BEGIN

{Thit lp vector ngt}GetIntVec ($0C,@OldVector); {Lu vector ngt c}SetIntVec ($0C,Addr (MyISR)); {Thay vector ngt}

Port[MasterOCW1] := Port[MasterOCW1] and $EF;{cho phpngt IRQ3}

. . .

{Chng trnh chnh}. . .

SetIntVec ($0C,@OldVector); {Tr li vector ngt c}Port[MasterOCW1] := Port[MasterOCW1] or $10; {Che ngt

IRQ3}

END.


39/128



3.3. Trao i tin trc tip b nhPhng php trao i d liu theo chng trnh s chm do:

- VXL phi gii m v thc hin lnh.- Trao i d liu thc hin tng byte thng qua thanh ghi AX ca VXLK thut vo/ra DMA (Direct Memory Access) l phng php truy nhp trc tip

ti b nh.

3.3.1 Cch hot ng:

VXL khi to TBN.

TBN khi xng vic truyn s liu bng cch s dng cc thng tin cung cpbi VXL thng qua qu trnh khi to.

Khi d liu c truyn trc tip gia TBN v b nhthng qua siukhin ca biu khin DMA (DMAC).

3.3.2 Hot ng ca DMAC:

Khi to: Trc khi a DMAC vo hot ng, Phi c chng trnh khi tocho n. Qu trnh khi to s cung cp cho DMAC thng tin cn thit hot ng. l cc thng tin nh: a ch bt u ca khi d liu, kch thc khi d liu,chiu c/ghi d liu, s hiu cng ca TBN.

Hot ng:

Xt trng hp truyn mt khi d liu t b nhra TBN.(1)Bc 1: TBN yu cu DMA bng cch t tn hiu DREQ ln mc cao(2)Bc 2: DMAC t tn hiu mc cao vo chn HRQ (Hold Request) gi tn

hiu yu cu treo bus cho VXL, bo cho VXL bit DMAC cn s dng bus.

VXLDMAC MEMORY

DiskController

HOLD

HLDADACK

DRE

Data Bus

Address Bus

Control Bus (IOR, IOW, MEMR, MEMW)

Hot ng ca DMAC


40/128



(3)Bc 3: VXL kt thc chu k bus hin ti, chuyn cc cng ghp ni vi bussang mc trkhng cao v tr li yu cu DMA bng tn hiu mc cao chn HDLA ( Hold Acknoledge) bo cho DMAC c quyn s dng bus

(4)Bc 4: DMAC kch hot tn hiu DACK bo cho TBN bit n s bt uiu khin vic truyn d liu.

(5)Bc 5: DMAC bt u truyn d liu t b nhti TBN nh sau:- DMAC t a ch ca byte u tin ca khi d liu ln bus a ch- Kch hot tn hiu /MEMR c byte d liu t b nhln bus d liu- t a ch ca cng TBN ln bus a ch- Kch hot tn hiu IOW ghi byte d liu ang c trn bus d liu ra TBN- Gim gi trm v tng gi tra ch- Lp li qu trnh trn cho ti khi gi trm bng 0.

(6)Sau khi qu trnh DMA kt thc, DMAC xo gi tr HRQ xung mc thp,tr quyn iu khin bus cho VXL.

3.3.3 Chip iu khin truy nhp b nhtrc tip DMAC 8237

DMAC 8237 c th thc hin truyn d liu theo 3 kiu: kiu dc (t b nhrathit b ngoi vi), kiu ghi (t thit b ngoi vi n b nh) v kiu kim tra.

Khi Timing and Control (nh thi v iu khin):

To cc tn hiu nh thi v iu khin cho bus ngoi(external bus). Cc tn hiu ny c ng b vi xungclock a vo DMAC (tn s xung clock ti a l 5 MHz).

Khi Priority encoder and rotating priority logic (mho u tin v quay mc u tin):

DMAC 8237A c 2 m hnh u tin: m hnh u tincnh (fixed priority) v m hnh u tin quay (rotatingpriority). Trong m hnh u tin cnh, knh 0 s c mcu tin cao nht cn knh 3 c mc u tin thp nht. Cni vi m hnh u tin quay th mc u tin khi khidng ging nh m hnh u tin cnh nhng khi yu

cu DMA ti mt knh no d c phc v th sct xung mc u tin thp nht.

Khi Command Control (iu khin lnh):Gii m cc thanh ghi lnh (xc nh thanh ghi sctruy xut v loi hot ng cn thc hin).


41/128



Cc thanh ghi:

DMAC 8237A c tt c 12 loi thanh ghi ni khc nhau:

Chc nng cc chn ca 8237A:CLK (Input): tn hiu xung clock ca mch. Tn hiu ny thng c ly t

8284 sau khi qua cng o.


42/128



CS (Input): thng c ni vi b gii m a ch.

RESET (Input): khi dng 8237A, c ni vi ng RESET ca 8284. Khi Resetth thanh ghi mt nc lp cn cc phn sau b xo:

Thanh ghi lnh

Thanh ghi trng thi Thanh ghi yu cu

Thanh ghi tm

Flip-flop du/cui (First/Last flip-flop)

READY (Input): ni vi READY ca CPU to chu ki khi truy xut ccthit b ngoi vi hay b nhchm.

HLDA (Hold Acknowledge) (Input): tn hiu chp nhn yu cu treo t CPU

DRQ0 DRQ3 (DMA Request) (Input): cc tn hiu yu cu treo t thit b ngoivi

DB0 DB7 (Input, Output): ni n bus a ch v d liu ca CPU

IOR , IOW (Input, Output): s dng trong cc chu k dc v ghi

EOP (End Of Process) (Input,Output): bt buc DMAC kt thc qu trnh DMAnu l ng vo hay dng bo cho mt knh bit l d liu chuyn xong

(Terminal count TC), thng dng nh yu cu ngt CPU kt thc qu trnhDMA.

A0 A3 (Input, Output): chn cc thanh ghi trong 8237A khi lp trnh hay dng cha 4 bit a ch thp.

A4 A7 (Output): cha 4 bit a ch

HRQ (Hold Request) (Output): tn hiu yu cu treo n CPU

DACK0 DACK3 (DMA Acknowledge) (Output): tn hiu tr li yu cu DMAcho cc knh.

AEN (Output): cho php ly a ch vng nhcn trao i

ADSTB (Address Strobe) (Output): cht cc bit a ch cao A8 A15 cha trongcc chn DB0 DB7

MEMR , MEMW (Output): dng dc / ghi b nh.

Cc thanh ghi ni:

Cc thanh ghi ni trong DMAC 8237A c truy xut nhcc bit a ch thp A0 A3


43/128



Bit a ch ach Chn chc nng R/W?

A3 A2 A1 A0

0 0 0 0 X0 Thanh ghi a ch b nhknh 0 R/W

0 0 0 1 X1 Thanh ghi m t knh 0 R/W







1 0 0 0 X8 Thanh ghi trng thi / lnh R/W

1 0 0 1 X9 Thanh ghi yu cu W

1 0 1 0 XA Thanh ghi mt n cho mt knh W

1 0 1 1 XB Thanh ghi ch W

1 1 0 0 XC Xo flip-flop u/cui W

1 1 0 1 XD Xo ton b cc thanh ghi /c thanhghi tm

W/R

1 1 1 0 XE Xo thanh ghi mt n W

1 1 1 1 XF Thanh ghi mt n W

a chcc thanh ghi ni dng ghi /c a ch:

Knh /IOR /IOW A3 A2 A1 A0 Thanh ghi R/W?

0 1010

0101

0000

0000

0000

0011

a ch csv a ch hin hnha ch hin hnhBm csv bm hin hnhBm hin hnh

WRWR

1 1010

0101

0000

0000

1111

0011


WRWR

2 1010

0101

0000

1111

0000

0011


WRWR

3 101

0

010

1

000

0

111

1

111

1

001

1

a ch csv a ch hin hnha ch hin hnhBm csv bm hin hnh

Bm hin hnh

W RW R

a chcc thanh ghi trng thi v iu khin:


44/128



/IOR /IOWA3 A2 A1 A0 Thanh ghi

1 0 1 0 0 0 Ghi thanh ghi lnh

0 1 1 0 0 0 c thanh ghi trng thi

1 0 1 0 0 1 Ghi thanh ghi yu cu1 0 1 0 1 0 Ghi thanh ghi mt n

1 0 1 0 1 1 Ghi thanh ghi ch

1 0 1 1 0 0 Xo flip-flop u/cui

1 0 1 1 0 1 Xo tt c cc thanh ghi ni

0 1 1 1 0 1

1 0 1 1 1 0 a ch csv a ch hin hnh

0 1 1 1 1 0 a ch hin hnh

1 0 1 1 1 1Bm csv bm hinhnh

0 1 1 1 1 1 Bm hin hnh

Mch 8237A-5 cha 4 knh trao i d liu DMA vi mc u tin lp trnhc. 8237A-5 c tc truyn 1 MBps cho mi knh v 1 knh c th truyn 1mng c di 64 KB. c th s dng mch DMAC 8237A, ta cn to tn hiuiu khin nh sau:

Tn hiu iu khin cho h thng lm vic vi DMAC 8237A

Tn hiu AEN t 8237A dng cm cc tn hiu iu khin t CPU khi DMAC nm quyn iu khin bus.


45/128

Chng 4: Rnh cm mrng


CHNG 4.GHP NI QUA RNH CM MRNG

Mc tiu:

Trnh by cc vn v ghp ni my tnh vi thit b ngoi vi thng qua cc khecm (slot) ca my tnh PC. Cu trc, nguyn l v cch ghp ni ca cc khe cmthng dng nh ISA, PCI.

Tm tt chng:

- t vn

- Bus PC

- Bus ISA (16 bit)

- Bus PCI

- Ghp ni qua khe cm mrng


46/128

Chng 4: Rnh cm mrng


t vn

Khi bn lun v cu trc my tnh ta thng cp n cc cu trc bus, cc ngdn bus nh bus d liu, bus iu khin , v.v. Cc rnh cm mrng l mt dng thhin bng phn cng ca bus trn bn mch chnh, trn c th cm thm cc card mrng thay i hoc nng cp cu hnh ca my tnh.

S ra i ca cc loi rnh cm mrng gn lin vi s pht trin ca k thut mytnh. T trc n nay c n 8 kiu bus mrng c s dng cho my tnh cnhn. Vic phn loi cc bus mrng da trn s cc bit d liu m chng x l ngthi. l cc bus:

- Bus PC (Cn gi l ISA 8 bit)- Bus ISA (16 bit)- Bus PC/MCIA (16 bit)- Bus VESA local (32bit)

- Bus SCSI (16/ 32 bit)- Bus EISA (32 bit)- Bus MCA (32 bit)- Bus PCI (32/ 64 bit)- Bus AGP (32/ 64 bit)

S chn khe cm ISA 8 bitPha mch in Pha linh kin

GND B01 A01 /IOCHCKReset B02 A02 D7

+ 5V B03 A03 D6IRQ2 B04 A04 D5- 5V B05 A05 D4

DREQ2 B06 A06 D3- 12V B07 A07 D2

D tr B08 A08 D1+ 12V B09 A09 D0GND B10 A10 /IOCHRDY

/MEMW B11 A11 AEN/MEMR B12 A12 A19

/IOW B13 A13 A18/IOR B14 A14 A17

/DACK3 B15 A15 A16DERQ3 B16 A16 A15/DACK1 B17 A17 A14DREQ1 B18 A18 A13/DACK0 B19 A19 A12

CLK B20 A20 A11IRQ7 B21 A21 A10IRQ6 B22 A22 A9

IRQ5 B23 A23 A8IRQ4 B24 A24 A7IRQ3 B25 A25 A6

/DACK2 B26 A26 A5TC B27 A27 A4

ALE B28 A28 A3+ 5V B29 A29 A2OSC B30 A30 A1GND B31 A31 A0


47/128

Chng 4: Rnh cm mrng


4.1. Bus PC

Bus PC l loi bus xut hin trn my tnh PC/XT u tin nn c gi lun l busPC. Loi bus ny tn dng kin trc ca b VXL Intel 8088, nn c mt bus d liu 8bit v ngoi v bus a ch 20 bit. Rnh cm ni vi bus PC c 62 chn cho php cmvo mt card m rng lm t mch in 2 mt. V trn bus ny c 8 bit d liu c

truyn ng thi nn bus PC cn c gi l bus PCI 8 bit Tc truyn ca bus PC c cnh 4.77 MHz

i vi bus ISA 8 bit ta cn quan tm n mt sng tn hiu chnh sau:Tn hiu Hng M t

A0 - A19 I/O 20 ng tn hiu a ch dng nh a ch cho b nhvcc thit b ngoi vi

D0 - D7 I/O 8 ng tn hiu to thnh BUS d liu cho vi x l, b nhv cc thit b ngoi vi

Reset Out Sau khi bt my tnh hoc sau khi khi ng li, ng dn

Reset s kch hot trong thi gian ngn a card ccm vo n mt trng thi ban u xc nh.

/IOW Out Input/Output/Write:Tn hiu ny s kch hot khi truy nhp ghi ln mt card mrng. Mc thp ch ra rng cc d liu c gi trang cha ra bus d liu. Cc d liu c n nhn bng sntrc

/IOR Out Input/Output/Read:Mc thp ca ng dn a ch ny bo hiu s truy nhpc trn mt card mrng. Trong thi gian ny cc d liu

c gi tr cn phi sp xp sau c n nhn bngsn trc

AEN Out Address Enableng dn iu khin AEN dng phn bit chu trnh truynhp DMA v chu trnh truy nhp b vi x l. mc caoDMA gim st qua bus a ch v bus d liu. ng dn chiu lc mc thp. ng dn ny cn phi c s dngcho qu trnh gii m a ch bi card mrng.

4.2. Bus ISA (16 bit)Do cch t chc rnh cm nh vy nn mt card PC vn c th cm vo mt khe

cm ca bus ISA. Card ISA rt ph bin bi v chng th hin tnh nng u vit i vihu ht cc ng dng ghp ni. Cc linh kin c s dng trn card u rt r, cho nntrn thc t vic ghp ni bng cc card m rng ISA t ra l cng ngh qua ththch v ng tin cy.

T tn gi cho thy : y l loi bus c kin trc theo tiu chun cng nghip(ISA: Industry standard architecture). Trong cc ti liu gi bus PC l bus ISA 8 bit th

loi bus ny thng c phn bit r l ISA 16 bit. Cng ty my tnh IBM phttrin bus ISA (kin trc theo chun cng nghip) dng cho my tnh AT (AdvancedTechnology) da trn b vi x l 80286. im mnh r nt ca bus ny l c th cho


48/128

Chng 4: Rnh cm mrng


php cng mt lc x l hoc trao i vi 16 bit d liu. bo m tnh tng thchvi bus PC, cc nh thit k b xung rnh cm th hai thng hng vi rnh cm PC 8Bit, trn c cha 8 bit d liu v 4 ng dn a ch. Nh vy, bus ISA c mt busd liu 16 bit v chnh v l i khi bus ISA cn c gi r l ISA 16 bit phnbit vi 8 bit. Ngoi ra bus ISA cn c mt bus a ch 24 bit, cho php nhiu nht l 16

Mbyte b nhc thnh a chc v ging nh bus PC n s dng tc ng hcnh, nhng khc v gi tr, c th l bng 8,33MHz. Nh vy tc truyn d liucc i l 2 byte (16 bit) trong mi chu k gi nhp, cho ra mt lu lng cc i l 16MB/giy. Trong cc my tnh c tn s gi nhp chy nhanh hn 8 MHz, bus ISA chychm hn nhng phn cn li ca my tnh.Do cch t chc rnh cm nh trn nn mtcard PC vn c th cm c vo trong rnh cm ca bus ISA. Cc card ISA rt phbin bi v chng th hin tnh nng u vit i vi hu ht cc ng dng ghp ni. Cclinh kin c s dng trn card u rt r, cho nn trn thc t vic ghp ni bng cardmrng ISA t ra l cng ngh qua th thch v ng tin cy.

Nhng ng dng tiu biu c th k l: Card vo/ra ni tip v song song, card nimng v card m thanh. C cc tip im c b tr trn hai mt, c nh s lA,B,C,D.

Cc ng a ch:

Sng a ch trong cc my tnh l khc nhau, cc XT c 20 ng a ch,ccmy AT c 24 ng a ch t A0 (A23 tuy nhin cc ng A20 (A23 dng cho vicqun l,nn thc t cc ng a ch cn li l A0 ( A19

Cc ng t A0 ( A19 i ra t my tnh hot ng mc th cao, cc ng nyc dng a ch ho b nhhay thit b vo ra .A0 l cc bit gi tr nh nht (LSB),A19 c gi tr cao nht (MSB) cc ng ny c iu khin nhVXL trong chutrnh bus c v vit b nhhay cng vo ra. Ngoi ra chng cn c iu khin nhlogic xm nhp trc tip vo b nhtrong chu trnh DMA.

B vi x l qua vic s dng cc lnh in v out c tha ch 64Kbyte a ch cngvo ra nhng thit k PC khng cho php s dng ton b cc a ch ny v cng vora chim cc nh t 300h 3FFh nn ch c 10 bit thp nht ca ng a ch lc s dng a ch ca thit b v a ch cng vo ra. Nh vy ch cc ng a chA0-A19 l c s dng cho vic gii m a ch cc thit b v a ch cng vo ra.

Bit 9 l mt bit c ngha c bit:-Khi bit ny khng tch cc h ch cho php s liu t cc thit b ngoi vi v cc

thit b vo ra trong Mainboard trao i vi n khi bit 9 l khng tch cc chng chima ch t 000h 0FFh .

Khi 9 bit tch cc l cc bit cho php s lu c ghi c t cc cng vo ra cakhe cm chng chim cc a ch 300h 3FFh.

iu ny c ngha l vi cng vo 1024 a chc chia lm 2 phn 512 a chdng cho Mainboard v 512 a ch dng cho khe cm.

Cc ng s liu:


49/128

Chng 4: Rnh cm mrng


Cc ng ny chuyn s liu gia VXL vi cng vo ra v b nh .S lngcc ng bus s liu quyt nh s bit c th truyn ng thi n hoc i t b nh.Cc my XT c 8 ng s liu D0 ( D7 c ngha l c th truyn 1 byte. My AT cos16 ng s liu D0 ( D15 tc c th truyn ng thi 2 byte.

Cc ng s liu D0 ( D15 l cc ng 2 chiu c th hot ng mc th cao

.D0 l (LSB), D15 l (MSB) khi VXL a ra chu trnh bus n iu khin bus ti a chca nhhay cng vo ra xc nh, iu khin hng truyn ni nhn s liu.

Khi chu trnh ghi bt u s liu trn bus l s liu sc ghi vo b nhhay cngvo ra .S liu phi n nh trc sn tng ca tn hiu iu khin IOW v MEMW .Sn tng ca cc tn hiu ny thng dng to nhp cho s liu trn bus s liu ghivo b nhhoc cc thanh ghi ca cng vo ra.

Trong chu trnh s liu a ch nhhay a ch thanh ghi cng vo ra s liu phit ln bus s liu trc sn tng ca tn hiu iu khin IOW v MEMW . Mc chca chu trnh l a s liu ra mt trong cc a ch nhhoc cng vo ra.

Tn hiu cho php cht a ch ALE

y l tn hiu ra c iu khin nhbiu khin bus n c ch rng bus ach by gi n nh c th bts u chu trnh bus. Tn hiu ny dng cht thng tina ch t bus a ch hoc bus s liu ca b ca VXL. Tn hiu ALE ng b vi chutrnh knh ca Bus khi n bt u chu trnh Bus cc a ch ca b VXL c vi sngim ca tn hiu ALE.

Tn hiu cho php a ch AEN .

Tn hiu ny c s dng bo cho b VXL v cc thit b t cc knh vo/ra cho

php truyn DMA c thc hin khi ng ny tch cc. Biu khn DMA iu

khin Bus a ch cc ng c lch v ghi s liu.

Tn hiu c cng vo/ra .

Tn hiu ny hot ng mc thp cng l tn hiu ra t my tnh c iu khin bi

biu khin Bus.Nhtn hiu ny thit b vo ra t s liu ln bus s liu v bo cho

cng vo ra bit chu trnh bus ca VXL lc ny l chu trnh c. Cng vo ra v a ch

trong bus a ch (l a ch ca cng vo ra) phn ng li bng cch t s liu cachng ln bus s liu. V tn hiu ny hot ng mc thp nn cng vo ra cn phi

nhs liu trn bus s liu m bo cho VXL nhn c s liu.

Tn hiu ghi ca cng vo ra.

Tn hiu ny hot ng mc th thp c iu khin t biu khin bus. N ch ra

rng chu trnh ca bus ca h VXL l chu trnh ghi ca cng vo ra. a ch trong bus

a ch l a ch ca cng vo ra.


50/128

Chng 4: Rnh cm mrng


Khi tn hiu ny mc th thp th s liu trong bus s liu n nh nh vy cng s

liu cn phi to nhp hay cht bng vic s dng sn tng ca tn hiu ny.

Khi xut hin chu trnh ca bus tn hiu ny quy nh bi biu khin DMA. Sau

tn hiu /IOW c dng vit s liu ln bus s liu t b nh. Cng vo/ra c

chn nhtn hiu.

4.3. Bus PCICng ty Intel xy dng nn mt tiu chun ghp ni mi c tn l bus cc b

PCI (Peripheral Component Interconnection - Kt ni cc thnh phn ngoi vi) hay

thng gi tt l bus PCI, dng cho b x l Pentium. Bus ny cho php truy nhp

rt nhanh ti b nh, biu khin a, card m thanh, card ho. Vi mch ghp ni

dng cho bus ny l chip PCI 82430 cho php ghp ni trc tip vi bus.

Mt sc im chnh:- Bus PCI truyn d liu bng tc ca ng h h thng cho php truyn d

liu vi tc cao hn nhiu so vi bus ISA.- C th hot ng vi 64 bit - Tc ti a t c l 264 Mbyte/s- Rnh cm PCI c mt chn cao hn do vy khng tng thch vi cc card

ISA.

4.4. Ghp ni qua khe cm mrng

4.4.1 Mt sc im ca Card ISA

Kch thc ln nht ca cc card ISA 8 bit l:

Chiu cao: 106,7 mm (hay 4.2 inch)

Chiu di 333.5 mm ( hay 13.13 inch)

Chiu dy - k c linh kin - 12.7 mm (hay 0.5 inch)

Cc ng tn hiu ca khe cm b tr c 2 pha, v vy card mrng bao gicngphi l bn mch in 2 mt.

4.4.2 Gii m a ch v kt ni Bus dliu

i vi my PC vng a ch 300 - 31FH c d tnh dnh ring cho card mrng cm thm vo. Cc ng a ch s dng i vi vng ny l A0 - A9.

Trn mt card mrng thng c nhiu khi chc nng nh b bin i tng t/sADC, b bin i s - tng t DAC, khi xut nhp d liu s, iu khin hin th,.v.v. . Cc khi ny c trao i di nhng a ch khc nhau t my tnh. Do ,trn card mrng phi c thm mt b gii m a ch. B gii m a ch c nhim vso snh a ch trn bus a ch ca my tnh vi cc a ch c thit lp trc chocc khi chc nng ca card mrng. Khi a ch c s thng nht vi khi no thkhi tng ng sc kch hot thng qua mt ng tn hiu logic tu ra ca b

gii m. Khi c kch hot, khi mi c th tin hnh s trao i thng tin vi mytnh.


51/128

Chng 4: Rnh cm mrng


B gii m a ch 74HC688 so snh cc ng dn a ch A2 - A9 xem c thngnht vi a ch thit lp trc ca card mrng bng chuyn mch DIP. 74HC688so snh cc cp bit xem c ging nhau khng. Khi cc cp ng nht thi s to ra mttn hiu mc thp u ra. Ngoi ra khi gii m cn phi quan tm n ng tn hiuAEN (Address ENable). ng ny cho bit CPU hay DMAC ang chim quyn sdng bus. Khi tn hiu ny mc thp th card mrng mi c s dng cc bus. Tnhiu AEN c a ti u vo /G ca 74HC688 cho php b gii m hot ng.

Cc ng tn hiu A0, A1, IOR, IOW cng c s dng trong b gii m bng

cch kt hp vi cc IC cng logic AND, OR v vi mch gii m 74HC138 tothnh cc ng iu khin c ghi cho tng khi chc nng trn card

B gii m logic ng thi m nhn vai tr iu khin b m bus 2 chiu74HC245. B ny ni cc ng dn d liu ca rnh cm PC vi cc ng dn cacard m rng. Cch ghp ni ny rt quan trng, nh vy m cc mc tn hiu trnng dn d liu khng bnh hng. N c cha 8 vi mch m vi cc li ra 3trng thi trao i thng tin gia cc ng dn bus d liu theo 2 hng. Hngtruyn d liu c xc nh bng chn DIR: DIR = 0, d liu c chuyn t B sangA. Vic chuyn hng d liu cho php qun l n gin bng tn hiu /IOR. Ta c th

ni trc tip ra chn DIR. Qua m bo bm ch cho php d liu a vo t bn


52/128

Chng 4: Rnh cm mrng


ngoi a ln bus d liu ca my tnh khi PC thc hin mt qu trnh truy nhp c(/IOR = 0)


53/128

Chng 5: Ghp ni trao i tin song song


CHNG 5.GHP NI TRAO I TIN SONG SONG

Mc tiu:Trnh by cc kin thc cbn v ghp ni v trao i d liu qua cc giao din

song song. Tm hiu cc giao din song song t c bn n nng cao v cu trc,nguyn l hot ng, cch ghp ni v lp trnh iu khin cho cc giao din ny.

Tm tt chng:

- Khi ghp ni song song n gin

- Cc vi mch m, cht (74LS245, 74LS373)

- Vi mch PPI 8255A

- Ghp ni song song qua cng my in


54/128



Khi ghp ni song song n gin

Cng vo n gin: Gm mt b gii m a ch - lnh v cc cng vo 3 trngthi a trc tip s liu song song t thanh ghi m s liu t TBN vo ng tnhiu s liu (D0 - Dn) ca My tnh

Cng ra n gin: Cng c b gii m a ch - lnh, nhng c thm cc thanhghi cht s liu ra ghi s liu a ra t My tnh. Li ra c th c thm s3 trng thi c lp TBN vi bus ca My tnh

DI0

DI1

DI2

DI3

Gii m aA0 - An

RD

D0

D1

D2

D3

S ca vo n in

Gii m i ch

WR

A0 - An

D Q

C

D Q

C

D Q

C

D Q

C

D0

D1

D2

D3

DO0

DO1

DO2

DO3

Ca ra n gin khng c i thoi


55/128



5.1. Cc vi mch m, cht (74LS245, 74LS373)

5.1.1 Vi mch m 74LS245:

Vi mch 74LS245 cho tn hiu vo ra 2 chiu dng m s liu trong my tnhPC/XT (VXL 8086). Vi mch ny c 2 ng iu khin chnh, tn hiu /G l tn hiucho php vi mch hot ng, khi /G mc cao, cc chn d liu ca vi mch trngthai trkhng cao.

Tn hiu DIR xc nh chiu truyn d liu. DIR = 1 d liu c truyn t Asang B, ngc li, khi DIR = 0 d liu c truyn t B sang A

5.1.2 Vi mch cht 74LS373:

Vi mch bao gm cc vi mch cht v cc vi mch cng3 trng thi. Vi mch ny thng c dng cht a ch trong my PC/XT v chtd liu trong cc ng dng ghp ni my tnh. C 2 ng tn hiu iu khin l /OEv LE. Tn hiu /OE l tn hiu cho php hot ng ca vi mch. Khi /OE mc cao,cc cng ca vi mch trng thi trkhng cao. Tn hiu LE l tn hiu cho phpcht, tn hiu ny tch cc mc dng. i vi 74LS373, khi LE mc cao, tnhiu a vo t cng D c a ra cng Q. Khi LE chuyn sang mc thp, tn hiucng Q c cht li.

Inputs FunctionOutputs

G DIR

A bus B bus

L LOutpu

tInput A = B

L H Input Output B = AH X High Impedance Z


56/128



5.2. Vi mch PPI 8255A

5.2.1 Gii thiu chung

Vi mch vo ra song song lp trnh c PPI (Programable Parallel Interface)8255 do hng Intel ch to. Ngoi kh nng cho php to mt giao din song song lp

trnh c ghp ni vi my tnh, n cn c th hot ng vi cc ch khcnhau v kh nng lp xo bit cng C cho i thoi. Vi mch 8255 ny rt thng dng,thng c trong cc my tnh PC/XT, PC/AT v cc thit b trao i tin khc.

Vi mch gm:- Bm s liu trao i tin v s liu hai chiu gia PPI v bus ca my

tnh.- B logic iu khin c vit: tc l b gii m a ch lnh cho cc thanh ghi

m v thanh ghi iu khin.Phn ghp ni vi TBN c:Cng A: thanh ghi m s liu (8 bit), vo hoc ra tu theo chng trnh khi phtCng B: thanh ghi m s liu (8 bit), vo hoc ra tu theo chng trnh khi phtCng C: Chia lm 2 na, cao v thpTu theo ch s dng cho bi tiu khin cng C c thc dng

- Trao i s liu vo hoc ra

- iu khin hoc i thoi vi TBN v VXL khi cng A v B ch xc lpv xo tng bit PCi

Cng A8

Cng Cna thp

4

Cng B8

8 IO

PA0 - PA7

Cng Cna cao

4

4 IO

PA7 - PA4

4 IO

PA3 - PA0

8 IO

PA0 - PA7

8

4

4

8

iukhinnhm

A

iukhinnhm

B

m

sliu

D0 - D7

iu

khin

lgic

c

ghi

A1

A0

S khi ca PPI 8255A

Reset


57/128



- iu khin hoc i thoi vi TBN v VXL khi cng A v B ch 1 v 2Cc mch iu khin ni b: C cc khi iu khin (nhm A, nhm B) cc cng A,B v C.

5.2.2 Cc lnh ghi v c cc cng v cc thanh ghi iu khin

Vi t hp cc tn hiu a ch (A0, A1), chon vi mch (CS), v cc lnh c ghi

(RD, WR) ca VXL, ta c cc lnh ghi c khc nhau cho cc cng (A, B, C ) vthanh ghi iu khin nh bng 3.2, to ra s di chuyn s liu gia ng tn hiu sliu, cc cng v thanh ghi iu khin.

Nh vy, vi mch 8255 c c im l khng c lnh c thanh ghi trng thi mdng lnh c cng C khi vi mch ch 1 v 2, cn ch 0, khng c trngthi.

A1 A0 CS RD WR Lnh (ca VXL)Chiu di chuyn s liu

(vi VXL)

0 0 0 0 1 c cng A Cng A -> D0 - D70 1 0 1 1 c cng B Cng B -> D0- D71 0 0 1 1 c cng C Cng C -> D0- D71 1 0 0 1 Khng c gi tr0 0 0 1 0 Ghi cng A D0 - D7 -> Cng A0 1 0 1 0 Ghi cng B D0 - D7 -> Cng B1 0 0 1 0 Ghi cng C D0 - D7 -> Cng C

1 1 0 1 0 Thanh ghi iu khinD0 - D7 -> Thanh ghiiu khin

X X 1 X X Trng thi in trcao Khng c trao i dliuCc lnh ca 8255A

5.2.3 Cc tiu khin

Tiu khin thit lp ch:

D7 D6 D5 D4 D3 D2 D1 D0

Nhm BCng C thp

1 = Li vo0 = Li ra

Cng B1 = Li vo0 = Li ra

Mode1 = Mode 10 = Mode 0

Nhm ACng C cao

1 = Li vo0 = Li ra

Cng A1 = Li vo0 = Li ra

Mode00 = Mode 001 = Mode 1

0X = Mode 2

Mode Flag1 = Active

Control Word (T iu khin)


58/128



Tiu khin lp xo bit:

Ch 0

Ch ny cn c gi l ch vo/ra csv:- Cc cng A, B, v 2 na ca cng C c s dng c lp vi nhau- Cc cng c th l cng vo hoc ra tu tiu khin ch ghi vo thanh ghi

iu khin- S liu ra c cht

- S liu vo khng c cht- Khng c tn hiu i thoi vi VXL cng nh TBN. Nu mun c tn hiu i

thoi, phi dng cc bit ca cng no ( thng l cng C) cc lp ln 1v sau l xo v 0 bng cch ghi s liu hoc bng cch xc lp/ xo mt bitPCi ca cng C bi tiu khin vi D7 = 0. Khi cng C phi thit lp ch ra.

- Lp xo tng bit ca cng PC- ch 0, ngi ta c th dng cc bit PCi ca cng C lp (t ln 1) v

xo (xo v 0) iu khin hoc i thoi vi TBN. Mun vy phi ghi li

lnh vi D7 = 0 vo thanh ghi iu khin ca 8255A sau khi ghi li iukhin ch.

D0 - D7 A0, A1, CSWR, RD

Port C Port APort B

PB0 - PB7 PA0 - PA7PC0 - PC3 PC4 - PC7

I/O I/O I/O I/O

8255A

D7 X X X D3 D2 D1 D0

0: Lp xa bit Bit D3 D2 D1PC0 0 0 0PC1 0 0 1PC2 0 1 0PC3 0 1 1PC4 1 0 0PC5 1 0 1PC6 1 1 0PC

71 1 1

0: xo1: lp

Clp/xo

TIU KHIN LP XO BIT CA VI MCH 8255


59/128




60/128



Ch 1:

Ch ny cn gi l ch vo ra c i thoi vi cc bit cng C. Chia thnh 2nhm.

Nhm A gm cng A trao i s liu v na C cao (PC3 PC7) i thoivi VXL v TBN.

Nhm B gm cng B trao i s liu v na C thp (PC0 PC2) i thoivi VXL v TBN.

Chiu v ch 1 ca cng A v B do tiu khin quyt nh, cn cc tn hiui thoi PCi cn ph thuc chiu cng vo hay ra ca cng A, B

PC0 lun l tn hiu ra INTRB: tn hiu yu cu ngt chng trnh cho B

PC3

lun l tn hiu ra INTAA:

tn hiu yu cu ngt chng trnh cho A

PC2 lun l tn hiu vo, nhn cc tn hiu yu cu STBBv xc nhn /ACKBca thit b ngoi cho cng B chung cho c 2 chiu vo hay ra. Cn na A, nul cng vo, PC4 nhn /STBA ca thit b ngoi v PC6 nhn /ACK ca thit bngoi nu cng A l cng ra.

Cc bit cn li ca cng C l vo hay ra tu tiu khin chCh ra:

Mi khi d liu c ghi ra cng, tn hiu /OBF chuyn sang mc tch cc 0 thng

bo cho TBN bit d liu c cht cngra v sn sng cho TBN c. Khi c c dliu, TBN kch hot tn hiu /ACK cho bit c d liu, khi tn hiu /OBF c tng chuyn v mc cao.

/OBF(Output Buffer Full): L tn hiura thng bo cho TBN bit d liu c cht cng ra A hoc B.

/ACK(Acknowledge): Tn hiu xcnhn bo v t TBN lm cho chn OBF chuyn ln mc cao. Tn hiu nythng bo cho 8255 bit TBN nhn d liu.

Port APort B

PB0 - PB7 PA0 - PA7

I/O I/O

IBFB STBB IBFASTBA I/O I/O

INTRB

INTRA

OBFB OBFAACKB ACKAI/OI/O

PC0 PC1 PC2 PC3 PC4 PC5 PC6 PC7

Ca vo

Ca ra

i thoi ca Ai thoi ca B

Cn A: Ch 1 chiu


61/128



INTR: Tn hiu ny thng thng dng ngt VXL mi khi TBN gi li tnhiu /ACK

INTE(Interrupt Enable): Bit ni, dng cho php hay cm tn hiu INTR.

INTEAc lin kt vi PC6 nu cng A hot ng ch ra. PC4 nu ch vo

INTEB lin kt vi PC2 vi c chiu ra v vo ca cng BCh vo:

/STB: Chn nhn tn hiu xung cht. Khi c mt xung mc thp tc ng vochn ny, d liu a t TBN vo 8255 sc cht cng vo.

IBF: Khi tn hiu /STB tch cc tn hiuIBF sc chuyn sang mc cao, bocho TBN bit 8255 cht d liu cng

vo. Tn hiu ny s trv mc thp khiVXL c tn hiu ang cht cng (khitn hiu /RD tch cc)

INTR: Tn hiu ngt VXL, tch cc khi/STB chuyn sang mc cao. Khi c tnhiu /RD tn hiu ny s thi tch cc.

Ch 2:

Ch ny ch dng cho cng A vi vo ra hai chiu v cc bit PC3 PC7 dnglm tn hiu hi thoi. Cng B lc ny c th hot ng ch 0 hoc 1, chiu vohay ra c tht bng tiu khin.

V d:Gi thit ta cn thit lp:PPI hot ng ch 0. Cng A vo, B ra, C cao vo, C thp ra.-> Ta c gi tr ca tiu khin l 98H

Cng B hot ng ch 1, vo. Cng A hot ng ch 0, ra. Cng C cao ra,cng C thp khng quan tm

Port APort B

PB0 - PB7 PA0 - PA7

I/O I/O

IBFA

STBA

INTRA

OBFAI/O (Ch 0)i thoi (Ch 1)

ACK

PC0 PC1 PC2 PC3 PC4 PC5 PC6 PC7

Ca B c thch

0 hoc 1

Ca A chi

thoi 2 chiu

(2 chiu)

Cng A: Ch 1, chiu


62/128



- > Gi tr tiu khin: 87H hoc 86H

Ttrng thi

Thng thng khi s dng 8255 ch 1 v 2, ta thng dng phng phpiu khin bng ngt chng trnh. Tuy nhin ta c th s dung phng php hivng trng thi bng cch c cng C bit c trng thi hot ng ca 8255. Do

ta c th coi a ch cng C trong ch 1 v 2 l a ch ca thanh ghi trng thica 8255. c thanh ghi trng thi ny, ta c th bit c cc thng tin sau:

C yu cu ngt chng trnh trao i tin ca cc cng A (INTRA) hay B(INTRB)

Cc thanh ghi m s liu vo c s liu (IBFA=1, IBFB=1)

Cc thanh ghi m ra c s liu (/OBFA = 0, /OBFB = 0)

Hoc ring vi ch 2, khi c ngt xy ra, ta cn phi c t trng thi bitc nguyn nhn gy ra ngt l do 8255 nhn c d liu hay gi c dliu c cc hot ng tng ng.

5.2.4 Ghp ni 8255A vi My tnh v TBN

S ghp ni cng vo ra theo chng trnh vi VXL v TBN nh hnh di.PPI 8255A t gia VXL v TBN, ng vai tr trung chuyn tin gia VXL v TBNqua cc ng tn hiu ca My tnh v TBN.

Phn ghp ni vi My tnh

Cc tn hiu v s liu (data bus) D0 D7, a ch thp (A0,A1), lnh c(RD), lnh ghi (WR) c ni thng vi cc li vo tng ng ca PPI 8255A

Tn hiu /CS (Chip Select) ca PPI c ni vi b gii m cc a ch cao (A2 An) ca VXL

Cc tn hiu ra yu cu ngt chng trnh (INTRA , INTRB) ca 8255 c nivo li vo INTR ca VXL qua mt vi mch logic OR

D0 D7

A0A1

8

RST

D0 D7

Gii m

gnmt - ntl(for print) - 10-2010

Documents