bÀi tẬp lỚn mÔn ktmt

7/28/2019 BI TP LN MN KTMT

1/21

MC LC

I/ Khi nim v phn loi mch ngt. .............................................................................. 31/ Khi nim v mch PIC 8259A. ............................................................................. 32/ Phn loi mch ngt. ............................................................................................... 3

2.1/ Ngt cng. ...................................................................................................... 32.2/ Cc ngt mm. ................................................................................................ 42.3/ Cc ngt a ch. ............................................................................................. 4

II/ S chn v chc nng cc chn tn hiu. ............................................................... 41/ S chn. ............................................................................................................. 42/ Chc nng cc chn tn hiu. .................................................................................. 5

III/ S khi , chc nng cc khi v cc thanh ghi. ................................................... 61/ S khi. .............................................................................................................. 62/ Chc nng cc khi. ............................................................................................... 6

2.1/ Khi x l mc u tin ca ngt. ................................................................... 62.2/ Khi m bus d liu (Data bus Buffer) ....................................................... 72.3/ Khi logic iu khin c/ghi (Read /Write control Logic ) ......................... 72.4/ Khi so snh v x l song song ( Cascade Buffer /Comparator ): ............... 7

3/ Chc nng cc thanh ghi. ....................................................................................... 8IV/ S ghp ni, c ch hot ng ca vi mch v h thng ngt cng PIC 8259A. 9

1/ S ghp ni. ....................................................................................................... 92/ Nguyn tc ghp ni. .............................................................................................. 93/ C ch hot ng. ................................................................................................. 13

3.1/ Hot ng c bn ca vi mch 8259A. ........................................................ 133.2/ Cc ch hot ng khc. .......................................................................... 14

3.2.1/ Ch hot ng y ( Fully Nested Mode ) ................................. 14

3.2.2/ Ch hon i th t u tin ( Rotating Priority Mode .................. 14

3.2.3/ Ch che c bit ( Special Mask Mode- SMM ) ............................ 15

3.2.4/ Ch quay vng (Polled Mode): ....................................................... 15

V/ Lp trnh cho vi mch 8259A. .................................................................................. 171/ Trng thi ca 8259 : ............................................................................................ 172/ Lp trnh cho vi mch 8259 : ................................................................................ 17


2/21

DANH SCH SINH VIN NHM 6 V TI

Ni dung

Trnh by c s chn, chc nng cc chn tn hiu. S khi, chc nng cckhi, cc thanh ghi, s ghp ni trong my tnh thy c c ch hot ngca vi mch v h thng ngt cng PIC 8259A.

M sinh vin H v tn ti

0741360034 Th Thanh Dung

Nghin cu tm hiu v vi mchiu khin u tin ngt PIC82589A( Priority Interrupt

Controller).

0741360004 La Vn Dng

0741360059 V Vn Thnh

0741360060 Vn Qung

0741360070 Nguyn Vn Qung

0741360027 Nguyn Quang Long


3/21

I/ Khi nimv phn loi mch ngt.

1/ Khi nim v mch PIC 8259A.Mi khi mt thit b phn cng hay mt chng trnh cn n s gip ca CPU ngi i mt tn hiu hoc lnh gi l ngt n b vi x l ch nh mt cng vic c thno m n cn CPU thc hin .Khi b vi x l nhn c tn hiu ngt n thngtm ngng tt c cc hot ng khc v kch hot mt chng trnh con ang c trong

b nh gi l chng trnh x l ngt tng ng vi tng s liu ngt c th .Sau khichng trnh x l ngt lm xong nhim v, cchot ng ca my tnh s tip tc lit ni b tm dng lc xy ra ngt .

2/ Phn loi mch ngt.

C ba loi ngt chnh ,u tin l cc ngt c to ra bi mch in ca my tnh

nhm p li mt s kin no nh nhn phm trn bn phm ..Cc ngt ny c biu khin ngt 8259A qun l , 8259A s n nh mc u tin cho tng ngt rigi n CPU . Sau l cc ngt do CPU to ra khi gp phi mt kt qu bt thngtrong khi thc hin chng trnh nh chia cho 0 chng hn ..Cui cng l cc ngt dochnh chng trnh to ra nhm gi cc chng trnh con xa ang nm trong ROMhoc RAM, cc ngt ny gi l ngt mm chng thng l b phn ca cc chngtrnh con phc v ca ROM-BIOS hoc ca DOS.

Ngoi ba loi ngt trn cn c loi ngt c bit l ngt khng b che NMI i hiCPU phc v ngay khi c yu cu. Loi ngt ny thng c dng bo hiu s c

nh st ip p hay li b nh . Nh vy NMI l mc ngt c u tin cao nht .

2.1/ Ngt cng.- Ngt cng l s kin CPU phi tm dng chng trnh ang thc hin chuynsang thc hin tin trnh phc v ngt khi c yu cu ngt t phn mch bn ngoi giti CPU v CPU chp nhn ngt c m tnh hnh sau :

Chng trnh con phc v ngt

Lu li thn tin ti n trnh b ng t Phc h i thng tin ti n trnh b ng t

Ti n trnh b ng t ti p tc thi hnhTi n trnh ng t

Tn hiu yu c u ng t IRQ t mch ph n cngbn ngoi gi ti CPU

Hinh 1: M t qu trnh ngt cng.


4/21

2.2/ Cc ngt mm.

-Nhng ngt ny l mt phn ca cc chng trnh ROM -BIOS ,cc s hiu dnh chocc ngt ca ROM- BIOS l 5 ,t 10h n 1C hex v 48h .

-Ngoi ra cn c cc ngt DOS v ngt BASIC phc v h iu hnh DOS v chngtrnh BASIC .

2.3/ Cc ngt a ch.

-Ba trong s cc ngt ny tr n ba bng rt quan trng l bng khi to mn hnh,bng c s a v bng cc k t th .Cc bng ny cha cc tham s c ROMBIOS dng khi khi ng h thng v to cc k t th .Cc s hiu d nh cho ccngt ny l t 1Dhex n 1Fhex .

II/ S chn v chc nng cc chn tn hiu.

1/ S chn.

Hnh 2: S chn.

Gii thch cc chn tn hiu:

PIC 8259A gm c 27 chn (nh hnh v).

Gm c : - 8 chn IR c nh s tIR0 n IR7.l cc chn cnh s th t l 18,19, 20,21,22,23,

24,25.

- 8 chn D c nh s tD0 n D7.l cc chn c nh s theo th

t l 4,5,6,7,8,9,10,11.- 3 chn CAS nh s tCAS0 n CAS2.l cc chn 12,13,15.


5/21

- 1 chn SP/EN l chn th 16.

- 1 chn INT l chn th 17.

- 1 chn CS l chn th nht.

- 1 chn WR l chn th 2.

- 1 chn RD l chn th 3.

- 1 chn INTA l chn th 26.

- 1 chn AO l chn th 27.

2/ Chc nng cc chn tn hiu.

-D0- D7: u ghp ni d liu hai chiu c ni vi na cao hay thp cu bus d liuca 8088 .

- IR0 - IR7: u vo yu cu ngt ni vi slave trong h thng c nhiu 8259A .

- WR : ni vi phn thp hoc phn cao ca tn hiu ghi .

- RD :u vo ni vi tn hiu IORC

- INT -interrupt : ni vi INTR ca 8088 ch master v ni vi cc chn IR trongch slave .

- INTA : u vo ni vi tn hiu INTA ca h thng ,trong h thng c mt master v

nhiu slave ch c INTA ca master c ni .

- A0: u vo chn cc t lnh khc nhau trong 8259A

- CS .: Tn hiu chn mch

- SP /EN Slave Program / Enable Buffer : Chn hai chc nng ,khi 8259A ch m y l u ra iu khin qu trnh trao i ca bus d liu. Khi 8259A khng ch m chn ny c lp trnh thit b nh l master hoc slave .

- CAS2 - CAS 0 -Cascad line : u ra t master ti slave khi s dng nhiu 8259Atrong h thng .


6/21

III/ S khi , chc nng cc khi v cc thanh ghi.

1/ S khi.

Hnh 3: S khi.

2/ Chc nng cc khi.

2.1/ Khi x l mc u tin ca ngt.

y l khi logic c chc nng quytnh mc u tin ca cc bit trong thanh ghiIRR . Bit c u tin cao nht s c chn v c gi n bit tng ng trongthanh ghi ISRtrong khong thi gian c xung INTA .

-INT ( Interrupt)

Tn hiu ra ny c a trc tip vo u vo INT ca 8088 .Mc cao ca tn hiuny lun tng thch vi mc tn hiu vo ca 8088 .

-INTA (Interrupt Acknowledge)


7/21

Tn hiuvo ny c to ra bi 8228 (System controler and Bus controler ) trong hthng . 8228 s gi ba xung tn hiu ring bit INTA ti 8259 ,tn hiu ny s iukhin 8259 gi 3 byte lnh CALL ln bus d liu.

2.2/Khi m bus d liu (Data bus Buffer)

y l b m 8 bit ,3 trng thi ,hai chiu c s dng ghp ni 8259 vi bus dliu ca 8088 . Cc t iu khin , thng tin trng thi c trao i thng qua b mny .

2.3/ Khi logic iu khin c/ghi (Read /Write control Logic )

Chc nng ca khi ny l nhn lnh iu khin t 8088 . Khi ny bao gm thanh ghit lnh khi to ( ICWR- Initionlize Command Word) v thanh ghi lnh hot ng(OCWR - Operation Command Word Register ) . Cc thanh ghi ny cha cc t lnhiu khin hot ng ca 8259 .

- RD (Read)

Mc thp ca tn hiu vo ny cho php 8259 gi i t trng thi ca thanh ghi IRR ,thanh ghi ISR , thanh ghi IMR hoc mc ngt ln bus d liu .

- WR ( Write)

Mc thp ca tn hiu vo ny cho php CPU ghi cc t lnh iu khin (ICW ,OCW )vo 8259 .

- A0

Tn hiu vo ny c s dng kt hp vi WR ,v RD ghi t lnh vo cc thanhghi khc nhau ngay khi va c cc thanh ghi trng thi ca vi mch .

- SP : (Slave program ):

Khi c nhiu vi mch 8259 cng c s dng trong h thng tng thm mc ngt (v d 64 mc ) .Trong trnghp ny mt vi mch 8259 ng vai tr master cn cc vi

mch khc ng vai tr slave. Mc ca u vo tn hiu ny xc nh vi mch no lmaster ,cn mc thp xc nh cc vi mch ng vai tr slave .

2.4/ Khi so snh v x l song song ( Cascade Buffer /Comparator ):

Khi ny c chc nng lu tr v so snh vai tr ca tt c cc vi mch 8259 s dngtrong h thng .Cc chn tn hiu CAS0 -CAS2 l cc u ra khi vi mch 8259 ngvai tr master ( SP =1 ) v l cc u vo khi cc vi mch ny c s dng lm slave( SP= 0 ). Khi hot ng vi vai tr master ,8259 gi tn hiu ngt ca thit b ra ccng CAS0- CAS2 . Cc vi mch slave tng ng c chn s gi a ch ca

chng trnh ngt ca chng ln bus d liu.


8/21

3/ Chc nng cc thanh ghi.

- Thanh ghi yu cu ngt v thanh ghi phc v ngt :

Cc tn hiu yu cu ngt c iu khin bi hai thanh ghi ng thi , l thanh ghiyu cu ngt ( Interrupt Request Register- IRR ) v thanh ghi phc v ngt ( Interrupt

Service Register- ISR) . Thanh ghi IRR c s dng lu cc mc ngt ang cnc s l v thanh ghi ISR c s dng lu cc mc ngt ang c phc v .

Khi c bt c sn dng ca xung tn hiu c a vo cc u vo yu cu ngt IR,cc bit ca thanh ghi IRR c xc lp v tn hiu INT c t mc cao .. Tuy vytn hiu vo yu cu ngt -IR phi lun c gi mc cao cho n khi c xung INTAu tin xut hin . Thanh ghi IRR c khi to bng tn hiu INTA .

Cc bit ca thanh ghi c xc lp bng xung tn hiu INTA ( cng trong thi imny bt tng ng ca thanh ghi IRR c khi to li ). Bit ny gi nguyn trng thi

trong sut thi gian hot ng ca chng trnh ngt cho n khi 8259 nhn c lnhEOI ( End Of Interrupt ).

on chng trnh thc hin qu trnh tr li chng trnh chnh t cc chng trnhngt c thc hin nh sau :

DI

OUT OCW2 ( gi lnh EOI )

POP PSW

EI

RET


9/21

IV/ S ghp ni, c chhot ng ca vi mch v h thng ngtcng PIC 8259A.

1/ S ghp ni.

2/ Nguyn tc ghp ni.khi ghp vo CPU th PIC 8259A c ghp nh sau:

u tin cnh v s hiu ngt tng ng c th hin trong bng sau :


10/21

IRQ# Interrupt type DEVICE

0 08H System timer

1 09H Keyboard

2 0AH reserved (2nd

8259)

3 0BH serial port (COM 1)

4 0CH Serial port (COM 2)

5 0DH Hard disk

6 0EH Floppy Disk

7 0FH Printer(LPT1)

Trong my tnh th hc ch s dng mt IC 8259A th th tu tin l0,1,2,3,4,5,6,7.trong cc my tnh hin i s dng hai IC 8259A th th tu tin l0,1,(8,9,10,11,12,13,14,15),3,4,5,6,7.Cc IRQs t8 n 15 thay th IRQ2

Cc IRQs cch s dng c th hin trong bng sau:

IRQ ng BUS u tin Mc nh sdng in hnh

s dng thng thng khc

0 no 1 Gih thng None


11/21

1 no 2 Biu khinbn phm

None

2 no

(rerouted)

n/a Biu khinbn phm

Modem,card

video,COM3(cng ni tipth 3),COM4 (cng ni tip

th 4)

3 8/16-bit 11 COM2 (second

serial port)

COM4 (cng ni tip tht),modem,card m

thanh,mng lith,accelerator th

4 8/16-bit 12 COM1 (first

serial port)COM3(cng ni tip th 3)Modem, card m

thanh,mng lith,accelerator th

5 8/16-bit 13 Sound card on old PC/XT

6 8/16-bit 14 Floppy disk

controllerLPT2(hai cng song

song)LPT3(cng song songth 3), COM3(cng ni tip

th ba) COM4(cng ni

tip tht),modem,cardmng,biu khin acng

7 8/16-bit 15 LPT1 (first

parallel port)

LPT2(hai cng songsong),COM3(cng ni tip,COM4(cng ni tip th

t),modem,th mthanh,mng li th,bng

accelerator th.

8 no 3 Real-time clock None


12/21

9 16-bit only 4 Card mng,card mthanh,SCSI b thch ngch,PCI thit bn inh

tuyn ng lai IRQ2 thitb

10 16-bit only 5 Card mng,card mthanh,SCSI b thch ng

ch,trung knh IDE,thit bPCI

11 16-bit only 6 Card mng ,card mthanh,my ch SCSI,cardmn hnh,quaternary kenh

IDE,thit b PCI

12 16-bit only 7 PS/2 mouse

Card mng,card mthanh,my ch SCSI,cardmn hnh, quaternary kenh

IDE,thit b PCI

13 no 8 Floating Point

Unit (FPU /

NPU / Math

Coprocessor)

None

14 16-bit only 9 Primary IDE

channel

B thch ng ch SCSI

15 16-bit only 10 Secondary IDE

channel

Card mng, SCS


13/21

3/ C chhot ng.

3.1/ Hot ng c bn ca vi mch 8259A.

Qu trnh hot ng c bn ca vi mch din ra nh sau :

+ u tin tn hiu vo mt trong cc chn yu cu ngt (IR7 - IR0 ) c chuyn vmc cao thng bo vi 8259 l c yu cu phc v t thit b ngoi vi .

+ 8259 chp nhn yu cu ngt ny , x l mc u tin v sau gi tn hiu INT tib vi x l trung tm CPU - 8088 .

+ CPU 8088 ghi nhn yu cu ngt ny v tr li bng cch pht i mt xung INTA .

+ Nhn c tn hiu INTA t CPU ,8259 gi ra bus d liu mt lnh CALL ( m11001101 ) di dng m nh phn 8 bit qua cc ng dy d liu ca n ( D0 - D7) .

+ Lnh CALL ny s yu cu CPU gi thm hai xung INTA ti 8259.

+ Hai xung INTA ny cho php 8259 a a ch chng trnh ngt ca n ln bus dliu . 8 bit thp ca a ch c gi khi c xung INTA th nht ,v 8 bit cao cnli c gi khi c xung INTA th hai . Kt thc vic truyn cc byte ca ln h CALLln bus d liu .

+ Thanh ghi phc v ngt (ISR) s c gi nguyn trng thi v khng c khi toli cho n khi kt thc chng trnh ngt ,khi c mt lnh EOI (End Of Interrupt )

c gi ti 8259 .

Bng sau minh ho cc hot ng c bn ca 8259.

A0 D4 D3 RD WR CS Input Operation (READ)

0

0 1 0 IRR, ISR or Interrupt Level data bus

(1)

1

0 1 0 IMR data bus

Output Operation ( Write)

0

0 0 1 0 0 data bus OCW2

0

0 1 1 0 0 data bus OCW3


14/21

0

1 1 0 0 data bus ICW1

0

1 0 0 data bus OCW1, ICW2,ICW3

Disable Function

1 1 0 data bus 3 - state

1 data bus 3 - state

(1) : Vic chn la thanh ghi IRR ,ISR hoc mc u tin ca ngt da vo ni dungca t lnh OCW3 c ghi trc qu trnh c.

trong khong thi gian hai xung INTA tip theo .

3.2/ Cc ch hot ng khc.

3.2.1/Ch hot ng y ( Fully Nested Mode )

8259 hot ng trong ch ny ngay sau khi thc hin qu trnh khi to m khngcn n cc t iu khin hot ng OCW. Trong ch ny ,cc yu cu ngt csp xp theo cc mc u tin t 0 n 7 .Khi mt yu cu ngt c chp nhn ,yucu ngt c mc u tin cao nht c thc hin v vector a ch ca n c truynln bus d liu . Ngoi ra,mt bit ca thanh ghi phc v ngt c t bng 1 . Bit nygi nguyn gi tr cho n khi 8088 pht lnh EOI ngay trc khi tr v t chu trnh

phc v . Trong khi bit ca thanh ghi ISR bng 1 ,tt c cc ngt c mc u tin thp

hn ,nhng ngt ny ch c chp nhn nu c 8088 chp nhn thng qua iukhin bng phn mm) b loi b.

Sau khi thc hin qu trnh khi to , tn hiu yu cu ngt vo IR0 c mc u tincao nht v vo IR7 s c mc u tin thp nht . Th t u tin c th thay i t rongch hon i th t u tin c cp sau y.

3.2.2/ Ch hon i th t u tin ( Rotating Priority Mode ):

8259 hot ng trong ch ny khi trong h thng c cc thit b c cc yu cu ngt

c mc u tin tng ng nhau nh cc knh truyn thng ...C hai ch hon imc u tin l ch hon i t ng v ch hon i c bit :


15/21

+ Ch t ng : (Auto Mode )

Trong ch ny ,thit b sau khi c phc v ,c gn cho mc u tin thp nht ,v vy mt thit b yu cu ngt phi i thm ch c th phi i cho n khi 7 thit bkhc c phc v xong.

+ Ch khng t ng :( Specific Mode )

Trong ch ny ngi lp trnh vin c th thay i th t u tin ngt bng cch lptrnh mc ngt c u tin thp nht v bng cch ny xc lp mc ngt c u tin caonht v d nu IR5 c lp trnh c mc u tin thp nht th IR6 s c mc u tincao nht .

Lnh iu khin c xc nh trong OCW2 , trong R =1 , SEOI =1 , cc bitL2,L1,L0 xc nh mc u tin ( tnh theo h thp phn ) ca thit b c mc u tinthp nht .

Cn ch ch ny hot ng c lp vi lnh EOI v qu trnh hon i mc utin c th thc hin trong khi thc hin lnh EOI .

-- EOI ( End Of Interupt ) v SEOI ( Specific EOI)

Mt lnh EOI lun phi c a ti 8259 trc khi kt thc chng trnh ngt khi to bit tng ng trong thanh ghi ISR . EOI v SEOI l hai dng ca lnh EOI lnon - specific ( khng xc nh ) v specific (xc nh) .Khi 8259 trong ch hotng y ( Fully Neste Mode) n c th xc nh bit no trong thanh ghi ISR cn

khi to bng lnh EOI . Khi nhn c mt lnh non- specific EOI ,8259 s t ngkhi to bit cao nht trong s cc bit c xc lp . Tuy nhin ,khi mt ch cxc lp n s gynh hng n ch hot ng y nh trong ch hon ith t u tin (Rotating Priority Mode ),8259 s xc nh mc ngt cui cng c ghinhn. Trong trng hp ny mt lnh mt lnh EOI xc nh c gi n 8259 trong bao gm c cc bit cn khi to trong thanh ghi IS . Lnh EOI c thc hin khithc hin khi EOI = "1" trong t iu khin OCW2 . Lu rng mc d lnh hon ic th thc hin trong sut qu trnh EOI=1 nhng n khng cn thit phi lm nhvy .

3.2.3/ Ch che c bit ( Special Mask Mode- SMM )

Ch ny c s dng khi c mt s bit c xc lp (che - mask) bi thanh ghimt n ( Interrupt Mask Register ) bng t lnh OCW1. Trong ch ny cc mcngt u tin thp hn c cho php hot ng cho n khi ch hot ng c khito li. Cc mc u tin cao hn khng c tc dng. Ch ny c xc lp bng tiu khin OSW3 trong ESMM=1 ,SMM=1 v c khi to li khi ESSM=1 vSMM=0 .

3.2.4/ Ch quay vng (Polled Mode):

Trong ch ny ,8088 cm ng vo INT ca n . Cc phc v dnh cho thit bc thc hin bng lnh Poll .


16/21

Lnh Poll c thc hin bng cch t bit P ="1" trong t lnh OCW3 trong sut qutrnh c xung WR .8259 coi xung RD tip theo nh tn hiu xc nhn ngt , xc lp ccmch lt tng ng ca n nu c mt yu cu ngt v c mc u tin ca ngt.

T iu khin trn bus d liu trong qu trnh RD l :

Ch ny c u th khi c mt chu trnh lnh thng dng i vi mt vi mc utin v th nn khng cn n tn hiu INTA . Cc ng dng khc thng s dng ch ny m rng s lng cc mc u tin ngt ln hn 64 mc .

* Cascading :

Trong ch ny cc vi mch 8259 c ni vi mt vi mch 8259 c vai tr masternhm tng s mc u tin ngt ln ti 64 mc nh trong hnh v sau :

Trong h thng ny mt vi mch 8259 ng vai tr master iu khin cc vi mchslave thng qua cc ng tn hiu CAS0- CAS2 . Cc ng tn hiu ra yu cu ngtc ni vi cc u vo tn hiu yu cu ngt ca vi mch master. Khi mt slave cyu cu phc v ngt th sau khi c tn hiu chp nhn ,vi mch master s pht lnhCALL trong khong byte th nht ca INTA v cho php slave tng ng a ra ach ca chng trnh ngt ca thit b trong khong byte th hai v th ba ca INTA .

Cc ng dy cascade thng thng mc thp v s cha a ch ca slave trong

khong thi gian t sn ln ca xung INTA u tin cho ti sn ln ca xung INTAth ba . Nh vy mi vi mch 8259 trong h thng phi hot ng ring bit tun t,v c th c lp trnh hot ng trong cc ch khc nhau. Mt lnh EOI phi


17/21

c pht hai ln ,mt lnh cho master v mt cho slave tng ng . ng thi tng vimch 8259 trong h thng ny cn phi c gii m a ch qua tn hiu CS .

V/ Lp trnh cho vi mch 8259A.

1/ Trng thi ca 8259 :

c th lp trnh iu khin c vi mch 8259 ta cn phi bit ,c c cc thngtin v trng thi ca vi mch . Vic c ,kim tra cc trng thi ca vi mch c ththc hin thng qua vic c trng thi cc thanh ghi bn trong . Cc thanh ghi sau yc th c c khi a cc t lnh (OCW) thch hp cng vi tn hiu RD cho bus dliu :

- Thanh ghi yu cu ngt (IRR):

y l thanh ghi 8 bit cha thng tin v cc mc u tin ngt ang yu cu v yu cungt c chp nhn . Mc yu cu ngt c u tin cao nht c khi totrongthanh ghi IRR khi mt ngt c chp nhn.

Trng thi thanh ghi IRR c th c c trc khi c xung RD, c mt xung WRcng vi t lnh OCW3 v ERIS =1 ,RIS = 0 .

- Thanh ghi phc v ngt (ISR):

Thanh ghi 8 bit ny cha thng tin v mc u tin ca ngt ang c phc v .

Thanh ghi ISR c cp nht khi c mt lnh EOI .Trng thi thanh ghi ISR c th c c trong ch tng t ,khi EIRS =1,RIS =1 .

- Thanh ghi che ngt (IMR):

Thanh ghi 8 bit ny cha thng tin v cc yu cu ngt ang b che .

2/ Lp trnh cho vi mch 8259 :

Vi mch 8259 c iu khin bng hai loi t lnh a ti t CPU l :

* T lnh khi to (Initialization Command Word - ICW).

Trc khi cc hot ng bnh thng c th bt u ,mi vi mch 8259 trong h thngphi c xc lp tun t v mt trng thi ban u khi c xung WR . Qu trnh nyc miu t trong lc sau :


18/21

Cc dng t lnh khi to ca 8259 c dng nh sau :

- T lnhkhi to 1 v 2 (ICW1 v ICW2 ).

Khi mt t lnh khi to vi A0 = 0 v D4= 1 n c gi l t lnh khi to 1(ICW1) v bt u chu trnh khi to mt ch t ng nh sau :

a. Sau khi c lnh khi to mt tn hiu yu cu ngt phi c chuyn t mc thpln mc cao to ra mt ngt .


19/21

b. Thanh ghi che ngt (IMR) b xo .

c. u vo IR7 c gn mc u tin l 7 .

d. Ch che c bit v trng thi c c khi to .

Cc thit b yu cu ngt (8) phi c 8 a ch tng ng trong b nh .Cc a ch nyc th gm 4 hoc 8 byte ;v chim 32 n 64 byte riing bit trong b nh . A0 -A4c 8088 xc nh mt cch t ng v A6 - A15c lp trnh bng t lnhICW1 v ICW2.

Cc dng a ch xc nh bi 8259 c minh ho trong bng sau :

+ Cc bit F v S nh ngha bi ICW1 nh sau :

Bit F : Khong a ch ca lnh CALL .F=1 th khong ny bng 4 ,ngc li F = 0 thkhong ny bng 8.

Bit S : Single ,S =1 ch ra rng ch c mt 8259 trong h thng trnh phi lp trnhICW3.

- T lnh khi to 3 (ICW3).

T lnh ny c dng gi thanh ghi 8 bit slave . Chc nng ca thanh ghi ny nhsau :

a. Nu 8259 l master ,cc slave trong h thng c t bng 1. Master sau s gibyte 1 ca lnh CALL v s cho php slave tng ng gi tip hai byte 2 v 3 theo ccng CAS.

b. Nu 8259 l slave , cc bit 0 n bit 2 c dng nhn dng slave . Slave so snhcc u vo CAS ca chng ( tn hiu gi ti t master )vi cc bit ny . Nu chng

bng nhau ,byte 2 v byte 3 ca lnh CALL s c gi ra .

Trong trng hp bit S =1 trong ICW1 ,s khng cn lp trnh ICW3.


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Sau khi cc cc t lnh khi to (ICWs) c lp trnh cho 8259 ,vi mch sn sngnhn yu cu ngt ti cc ng tn hiu vo ca n .

* T lnh hot ng (Operation Command Word - OCW).

y l nhng t lnh iu khin 8259 hot ng trong cc ch khc nhau nh

nu trn . Cc t lnh iu khin ny c th c gi ti 8259 trong bt c lc notrong qu trnh hot ng .

Cc dng t lnh hot ng ca 8259 nh sau :


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bÀi tẬp lỚn mÔn ktmt

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