CHNG 4 GII THIU BUS CHUN CHO GHP NI M RNG LT6

4.1

KHI NIM V BUS M RNG Bus m rng l h thng ng tn hiu cho php ghp ni nhiu thit b vo mt h thng vi x l, cho php vic m rng h thng iu khin. Cc bus m rng c th c thc hin di nhiu dng khc nhau nh: Cc bo mch sn sng cho vic lp thm cc linh kin m rng, cc cng kt ni, cc khe cm (slot). c tnh quan trng ca cc bus l cho php nhiu thit b cng kt ni ti h thng trn cng mt bus, v ti mt thi im ch c mt thit b truyn d liu vi CPU trn bus. thc hin c nguyn tc kt ni trn, trn bus thng cung cp y cc tn hiu a ch, d liu, iu khin v c ngun cung cp. Tuy nhin, i vi cc thit b giao tip yu cu cung cp cng sut ln cn cung cp ngun ring t bn ngoi. Cc tn hiu iu khin trn BUS c th l cc tn hiu iu khin chun cung cp t CPU, c th l cc tn hiu thng bo trng thi thit b, cc tn hiu bt tay truyn d liu, . Bus m rng c th dng song song, khi cc bit d liu, a ch v cc tn hiu iu khin s c cc ng dy dn in ring, trn cc bo mch giao tip cn thit k cc b gii m a ch sao cho thit b giao tip c a mt a ch ring, khng trng vi a ch ca cc thit b trong h thng v cc thit b m rng khc. Bus m rng cng c th truyn d liu di dng ni tip, khi cc gi tr a ch, d liu v iu khin u c sp vo khung truyn d liu trn bus. Sau u s ln lt gii thiu mt s loi bus m rng thng dng trong cc h thng vi x l v my tnh 4.2 BUS ISA Bus ISA ln u tin xut hin cng vi PC XT c thit k dng 8 bit, s dng tn s 4,77MHz (bng vi xung b x l). Sau nhiu nm ci tin, chun c chnh thc cng nhn v mang tn Industry Standard Architecture (ISA) vo nm 1982. Trong h thng IBM PC/AT 80286, bus ISA c nng ln 16 bit. Vo lc ny, tc bus h thng mi ch t 6 MHz; sau khng lu th t 8 MHz.

Hnh 4.1: Cu to bus ISA Bus ISA dng giao tip 16 bit, xung 8MHz (mc xung chun ca b x l) v t tc truyn d liu trn l thuyt l 16MBps. Tuy nhin, tc thc t b gim i 77

mt na (cn 8MBps) v cn dnh 1 ng bus cho a ch v mt ng bus khc cho d liu 16 bit. Thit b dng khe m rng ISA pht trin cho n cui thp nin 1990 bi v kh nng p ng ca thit b ngoi vi lc ny mi ch mc 5MBps.

GND RESET DRV + 5V IRQ2 -5V DRQ2 -12V OWS +12V GND /SMEMW /SMEMR /IOW /IOR /DACK3 /DRQ3 /DACK1 DRQ1 /DEF CLK IRQ7 IRQ6 IRQ5 IRQ4 IRQ3 /DACK2 T/C ALE +5V OSC GND

B1

A1

B10

A10

B20

A20

/I/O CH CK D7 D6 D5 D4 D3 D2 D1 D0 I/O CH RDY AEN A19 A18 A17 A16 A15 A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1

B31

A31

A0

Hnh 4.2: V tr cc tn hiu trn bus ISA Trn cc my tnh c nhn, khi b x l tr nn nhanh hn v cn bng thng d liu ln hn th chun ISA khng p ng ni. Cui thp nin 90, hu ht card ISA cn li u ch mang tnh i din cho cng ngh 8 bit. Cc thit b dng ng truyn 16 bit nh b iu khin a cng, b x l ha v card mng bt u cm thy 78

"cht chi" trong gii hn bng thng ca ISA. Ci cht ca ISA c chnh thc vn bn ha trong ti liu PC99 System Design Guide do Intel v Microsoft bin son vo nm 1999. C kh nhiu lnh vc cn n tc nhanh hn ISA nh hin th ha phn gii cao, chiu phim v hot nh; ngoi ra, tc a cng v giao tip mng cng vt qua mc p ng ca ISA. i vi cc thng vi x l iu khin khc, chun ISA vn c th m nhn c cc chc nng giao tip vi cc h thng thit b yu cu tc chm v chun ny vn cn c s dng kh ph bin trong cng nghip. Bus ISA thc hin vic m cc tn hiu a ch, d liu, v iu khin trong h thng trung tm a ra khe cm c th thc hin cc bo mch giao tip bn ngoi. Bus ISA chun c thc hin theo cu trc ca b vi x l 8088 nn c bus d liu 8 bit v bus a ch 20 bit. Rnh cm ISA chun c 62 chn, cho php thc hin cc bo mch m rng hai mt. Cu to khe cm bus ISA chun 8 bit nh trn hnh 4.1, v tr cc tn hiu trn bus c m t trn hnh 4.2, v chc nng ca cc tn hiu m t trong bng 4.1. Bng 4.1: M t chc nng cc tn hiu trn bus ISA Tn hiu A0-A19 Tn Bus a ch (tn hiu hai chiu) AEN M t Hai chc (20) bit thp hn ca bus i ch h thng, i khi h hiu l SA0-SA19

Cho php i ch Chn Address enable cho php dng 1 card m (Address enable - tn rng cm khi logic gii m a ch I/O cc b hiu ra) ca n. N kch hot mc cao khi hot ng, tn hiu ny ch cho thy hoc qu trnh truy nhp trc tip b nh (DMA) hoc qu trnh lm ti li ang c iu khin trn cc bus. Bus d liu (tn hiu hai chiu) Tm bit d liu cho php truyn gia bus ch v card m rng Thc hin gi nhp bus c t bng 4,772727MHz i vi bus PC v 8.33MHz i vi bus ISA, m bo vic ng b ho i vi qu trnh truyn d liu (tn hiu ny c bt ngun t xung ng h OSC). Cht a ch bus ch cho bus m rng thy l tn tn hiu iu khin bus i ch v chu trnh bus l hp l. Nh vy n ch cho thy ch bt u ca mt chu trnh bus trn bus m rng.

D0- D7

CLK

Tn hiu gi nhp (tn hiu ra)

ALE

Cht i ch (Address latch, hiu ra)

IOR

c vo ra I/O read Tn hiu lnh c vo/ra ch ra cho thy mt chu 79

(tn hiu hai chiu) IOW Ghi vo/ra

trnh c I/O ang c tin hnh

Tn hiu lnh ghi vo/ra ch cho thy mt chu (I/O write, tn hiu trnh bus ghi I/O ang c tin hnh hai chiu) c b nh h thng Tn hiu c b nh h thng bo hiu mt chu (System memory trnh bus c b nh h thng trong phm vi bus read, tn hiu ra) a ch 20 bit ( 0h FFFFFh)

SMEMR

SMEMW Ghi vo b nh h Tn hiu ghi vo b nh vo h thng ch cho thng (System thy mt chu trnh bus ghi vo b nh h thng memory write, tn trong phm vi a ch 20 bit (0h n FFFFFh) hiu ra) IO CH RDY OWS Bus read ,bus sn Tn hiu bus sn sng cho php mt card m sng (tn hiu vo) rng ko di thi lng cn c cho 1 chu trnh bus Trng thi ch bng Trng thi ch i zero (hay khng c trng thi 0 (Zero wait states - ch) cho php 1 card m rng rt bt thi lng tn hiu vo) cn c cho mt chu trnh bus. DMA request, yu Tn hiu yu cu truy nhp trc tip ch cho thy cu DMA (tn hiu mt thit b ghp ni ang ngh truy nhp b vo) nh trc tip Xc nhn DMA Xc nhn DMA ch cho thit b ghp ni ang (DMA acknowledge, yu cu bit DMA s l yu cu ca n tn hiu ra) Refresh (tn hiu ra) Tn hiu lm ti li c s dng bo tin cho bn mch bit n s lm 1 chu trnh lm ti li.

DRQ1DRQ3 DACK1DACK3 REF T/C

m u cui Chn ny cho thy truy nhp DMA tip hnh (Terminal count - tn xong v tt c cc byte c truyn hiu vo) Interrupt request. Yu Tn hiu yu cu ngt, n ch cho thy l thit b cu ngt ghp ni ang ngh b vi x l phc v B dao ng Tn hiu t b dao ng tinh th cung cp tinh th (crystal cho cc ng dng m rng. Tc ng h ny oscillator - tn hiu bng 3 ln tc SLK ra) t li trng thi ban t li v trng thi ban u cho bn mch m u (Reset drive, tn 80

IRQ2IRQ7 OSC

RESET

DRV I/O CHCHK 5V 12V v GND

hiu ra)

rng cm vo bus ISA

Kim tra vo/ra (I/O Tn hiu kim tra vo ra cho thy b nh ca Check - tn hiu vo) thit b ghp ni b pht hin c 1 li chn l Ngun nui (tn hiu Cung cp in p ngun cho card m rng. ra)

Hnh 4.3: Cu to bus ISA 16 bit

/MEM CS16 /I/O CS16 IRQ10 IRQ11 IRQ12 IRQ13 IRQ14 /DACK0 DRQ0 /DACK5 DRQ5 /DACK6 DRQ6 /DACK7 DRQ7 Vcc /MASTER GND

D1

C1

D10

C10

D18

C18

/SBHE LA23 LA22 LA21 LA20 LA19 LA18 LA17 /MEMR /MEMW SD08 SD09 SD10 SD11 SD12 SD13 SD14 SD15

Hnh 4.4. S rnh cm th hai ca Bus ISA

81

Bus ISA 16 bit c cu trc theo tiu chun cng nghip (ISA - Industry Standard Architecture). u im ca bus ny l c th cho php cng mt lc x l vi 16 bit d liu. Vic m rng thm mt rnh cm b sung cho php c c tnh tng thch vi bus PC, rnh cm th hai thng hng vi ISA chun 8 bit trn cha 8 bit d liu v 4 ng dn a ch (hnh 4.3). Ngoi ra bus ISA cn c bus i ch 24 bit cho php nhiu nht l 16 Mbyte b nh c th nh a ch c v ging nh bus ISA chun, n s dng tc ng h c nh bng 8MHz. Trong cc my tnh c tn s gi nhp nhanh hn 8MHz , bus ISA chy chm hn nhng phn cn li ca my tnh. Cc tn hiu thm trong bus ISA 16 bit m t trn hnh 4.4, v chc nng ca chng cho trong bng 4.2.

Bng 4.2: Cc tn hiu thuc rnh cm th 2 ca bus ISA 16 bit Tn hiu Tn M t

LA17-LA23 Bus a ch (tn hiu hai Bt cao ca a ch ca bus a ch h chiu) thng. SBHE Cho php byte cao ca h Chn ny cho thy d liu c ch i 8 thng (System byte high bit pha trn ca bus d liu (D8-D15) enable)

SD08-SD15 Bus d liu (tn hiu hai Bt trn ca bus d liu cung cp na th chiu) hai ca bus d liu 16bit MEMR c b nh (Memory read Lnh c b nh cho thy mt qu trnh c Ng ra) khi a ch ca nh trong phm vi 100000h FFFFFFh (16 M byte) ca b nh Ghi vo b nh (ng ra) Lnh ghi vo b nh, cho ta thy 1 qu trnh ghi b nh a ch b nh trong phm vi 100000h-FFFFFFh.

MEMW

MEMCS16 IO CS 16 DRQ0, DRQ5DRQ7 DACK0, DACK5DACK7

B nh 16 bit dng cho Cho bit thit b ghp ni c nh a thit b ghp ni. ch l thit b c b nh 16 bit Thit b ghp ni vo ra 16 Ch cho bit thit b ghp ni nh a ch bit (16 bit I/O slave) l thit b ghp ni vo ra 16 bit Cc ng dn yu cu Cc ng dn yu cu truy nhp trc tip DMA (DMA request lines) b nh ch cho thy l thit b ghp ni ang yu cu truy nhp DMA. ng xc nhn truy nhp ng ny b sung, cho thit b ghp ni trc tip b nh (DMA) ang yu cu bit l DMAC ang x l yu cu ca n. 82

MASTER

Bus sn sang (bus ready, Tn hiu ny cho php b vi x l khc iu ng vo) khin: ng dn iu khin ,ng dn d liu v ng dn a ch ca h thng. Yu cu ngt (Iterrrupt Tn hiu yu cu ngt b sung cho thy card request, ng vo) m rng ang yu cu b vi x l phc v (ch ng IRQ13 thng thng a cng s dng v c bao gm trong bus IDE) in p ngun +5V Cung cp in p ngun

IRQ10IRQ12; IRQ14 IRQ15 Vcc

U28 5 Do D1 D2 D3 D4 D5 D6 D7 2 3 4 5 6 7 8 9 1 19 VCC 20 A1 A2 A3 A4 A5 A6 A7 A8 DIR OE VCC 74HC245 2 1 U24 Ao A1 /IOW /IOR 1 2 A Y B 1 2 3 3 VCC 6 4 5 G1 G2A G2B 74LS138 2 1 19 3B

INTR DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 ADC0804

B1 B2 B3 B4 B5 B6 B7 B8

18 17 16 15 14 13 12 11

Do D1 D2 D3 D4 D5 D6 D7

11 12 13 14 15 16 17 18

WR RD CS CLKIN CLKR VREF/2 -IN +IN

3 2 1 4 19 9 7 6 ANALOG IN

A2 A3 A4 A5 A6 A7 A8 A9

2 4 6 8 11 13 15 17 3 5 7 9 12 14 16 18 1 20

P0 P1 P2 P3 P4 P5 P6 P7 Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7 OE VCC

VCC AEN VCC

74HC688

Hnh 4.5: Mch kt ni b bin ADC trn bus ISA Hnh 4.5 l mt v d in hnh cho k thut ghp ni BUS ISA. Vi mch 74HC688 c chc nng so snh a ch c a vo t cc ng a ch ca BUS ISA v a ch c t trc cc chn Q0 n Q7 ca vi mch ny. Nu = s c mt mc logic 0 u ra P=Q. Mc logic ny s dng iu khin b m BUS (74HC245) v b gii m a (74HC138). Vi mch ADC0804 c ghp vo BUS 83

A A Y

Y

3

B

A B C

Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7

15 14 13 12 11 10 9 7

P=Q

ISA thng qua 74HC245 v c la chn bng mt u ra ca 74HC138. Cu to in hnh ca mt card ISA nh trn hnh 4.6.

Hnh 4.6: Card ISA 8 bit v 16 bit 4.3 PCI (Peripheral Component Interconnect) Bus PCI c Intel pht trin giao tip vi cc thit b ngoi vi tc cao vo nhng nm 1992, v hin ang dn thay th cc bus c in ISA v EISA. S pht trin ca bus PCI thay i qua nhiu phin bn, c th k n nh sau: PCI phin bn 1.0: ra i vo nm 1992 bao gm hai loi: loi chun (32 bit) v loi c bit (64 bit) PCI phin bn 2.0: ra i nm 1993 PCI phin bn 2.1: ra i nm 1995 PCI phin bn 2.2: ra i thng 1 nm 1999 PCI-X 1.0 ra i thng 9 nm 1999 mini-PCI ra i thng 11 nm 1999 PCI phin bn 2.3 ra i thng 3 nm 2002 PCI-X phin bn 2.0 ra i thng 7 nm 2002 PCI Express phin bn 1.0 ra i thng 7 nm 2002 v t lu sau l 1.1 PCI Express phin bn 2.0 ra i 15 thng 1 nm 2007 PCI Express phin bn 3.0 s ra mt khong nm 2010. Bus PCI tc 33,33 Mhz, rng 32 bit l bus PCI thng dng nht cho n thi im nm 2007 dng cho cc bo mch m rng (bo mch m thanh, bo mch mng, bo mch modem gn trong...Tuy nhin c mt s bus PCI khc nh sau: PCI 66 Mhz: rng bus: 32 bit; Tc bus: 66 Mhz; D liu chuyn trong mt xung nhp: 1; Bng thng: 266 Mbps PCI 64 bit: rng bus: 64 bit; Tc bus: 33 Mhz; D liu chuyn trong mt xung nhp: 1; Bng thng: 266 Mbps PCI 64 Mhz/66 bit: rng bus: 64 bit; Tc bus: 66 Mhz; D liu chuyn trong mt xung nhp: 1; Bng thng: 533 Mbps

84

PCI-X 64: rng bus: 64 bit; Tc bus: 66 Mhz; D liu chuyn trong mt xung nhp: 1; Bng thng: 533 Mbps PCI-X 133: rng bus: 64 bit; Tc bus: 133 Mhz; D liu chuyn trong mt xung nhp: 1; Bng thng: 1066 Mbps PCI-X 266: rng bus: 64 bit; Tc bus: 133 Mhz; D liu chuyn trong mt xung nhp: 2; Bng thng: 2132 Mbps PCI-X 533: rng bus: 64 bit; Tc bus: 133 Mhz; D liu chuyn trong mt xung nhp: 4; Bng thng: 4266 Mbps Nhng bus PCI 66 Mhz hoc 64 bit theo lit k trn khng thng dng trong cc my tnh c nhn, chng thng ch xut hin trn cc my ch hoc my trm. Hnh dng cc khe cm PCI v PCI X nh trn hnh 4.7. Bng 4.3 m t chc nng cc tn hiu trn bus PCI v bng 4.4 m t v tr ca chng trn rnh cm.

Bng 4.3: Chc nng cc tn hiu trn bus PCI 32 bit. CLK RST# ADO AD31 C/BEO 3# BUS (Command BytesEnables) PAR IRDY# (Initiator Ready) TRDY# (Target Ready) STOP# Hai d liu bt tay gia b pht v b nhn d liu trn tuyn PCI Tn hiu target bo cho initiator chm dt giao dch, initiator l ch ca tuyn (bus master) cn target l bus slave. Xung nhp 33MHz, 66MHz Tn hiu reset Tuyn a ch khi FRAME# mc thp Cho bit loi ca truyn d liu (c/vit b nh, ngoi vi) Kim tra parity ca ADO31 v C/BEO3 Xung nhp 33MHz, 66MHz Tn hiu reset Tuyn a ch khi FRAME# mc thp Cho bit loi ca truyn d liu (c/vit b nh, ngoi vi) Kim tra parity ca ADO31 v C/BEO3

CLK RST# ADO AD31 C/BEO 3# BUS (Command BytesEnables) PAR IRDY# (Initiator Ready) TRDY# (Target Ready) STOP#

Hai d liu bt tay gia b pht v b nhn d liu trn tuyn PCI Tn hiu target bo cho initiator chm dt giao dch, 85

initiator l ch ca tuyn (bus master) cn target l bus slave. Vic truyn d liu do initiator bt u thng qua C/BE v IRDY cn target tr li thng qua TRDY# v STOP# LOCK# IDSEL (Initialigation Devia Select) DEVSEL# (Device Select): REQ# GNT# REQ# PERR# (Parity Error) SERR# (System Error) INTA#, INTB#, INIC#, INID# SBO# SDONE(Snoop Backoff)(Snoop done) PRSNT 1 2# CLKRUN# (Clock Running) MGGEN (66 MHz enable) AD 32 63 C/BE 4 7# Sai h thng Cc tn hiu ngt Dng cho card memory Cho bit c board cm vo slot v cng sut tiu th ca board Cho php iu khin xung nhp CLK Cho bit xung nhp 33 MHz hay 66 MHz 32 ng a ch v d liu cao trong PCI 64 bit. Dng khi truyn 64 bit kt hp vi REQ 64# v ACK 64#, PAR 64 Tn hiu initiator bo dnh ring mt s a ch ca target. Tn hiu chn chip Ca n trn tuyn PCI do target iu khin khi n thy a ch ca n trn tuyn PCI Yu cu dng bus (request) Cho bit yu cu c chp nhn (grant)

REQ 64# (Request 64 bit transfer) ACK 64# (Acknowledge 64 bit transfer) TCKTDITDOTMSTRST#(Test clock)(Test data input)(Test output)(Test mode Select)(Test Reset) Cc tn hiu th

86

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

-12V TCK Ground TDO +5V +5V INTB# INTD# PRSNT1# Reserved PRSNT2# Ground Ground Reserved Ground CLK Ground REQ# +5V (I/O) AD[31] AD[29] Ground AD[27] AD[25] +3.3V C/BE[3]# AD[23] Ground AD[21] AD[19] AD[18] AD[17]

Bng 4.4: V tr cc tn hiu trn bus PCI TRST# 1 -12V TRUST +12V TMS TDI +5V INTA# INTC# +5V Reserved +5V (I/O) Reserved Ground Ground Reserved RST# +5V (I/O) GNT# Ground Reserved AD[30] +3.3V AD[28] AD[26] Ground AD[24] IDSEL +3.3V AD[22] AD[20] Ground +3.3V AD[16] 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 TCK Ground TDO +5V +5V INTB# INTD# PRSNT1# Reserved PRSNT2# +12V TMS TDI +5V INTA# INTC# +5V Reserved +3.3V (I/O) Reserved 3.3V key 3.3V key

Connector Key Connector Key Reserved Ground CLK Ground REQ# +3.3V (I/O) AD[31] AD[29] Ground AD[27] AD[25] +3.3V C/BE[3]# AD[23] Ground AD[21] AD[19] AD[18] AD[17] +3.3V (I/O) Ground Reserved AD[30] +3.3V AD[28] AD[26] Ground AD[24] IDSEL +3.3V AD[22] AD[20] Ground +3.3V AD[16] Reserved RST#

87

33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

C/B Ground IRDY# +3.3 DESVEL# Ground LOCK# PER +3.3 SER +3.3 C/BE[1]# AD[14] Ground AD[12] AD[10] Ground

+3.3V FRAME# Ground TRDY# Ground STOP# 3.3V SDONE SBO# Ground PAR AD[15] +3.3V AD[13] AD[11] Ground AD[09]

33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

C/BE[2]# Ground IRDY# +3.3V DESVEL# Ground LOCK# PERR# +3.3V SERR# +3.3V C/BE[1]# AD[14] Ground AD[12] AD[10] M66EN Ground Ground AD[08] AD[07] +3.3V AD[05] AD[03] Ground AD[01] 3.3V (I/O) ACK 64# +5V +5V

+3.3V FRAME# Ground TRDY# Ground STOP# 3.3V SDONE SBO# Ground PAR AD[15] +3.3V AD[13] AD[11] Ground AD[09] Ground Ground C/BE[0]# +3.3V AD[06] AD[04] Ground AD[02] AD[00] 3.3V (I/O) REQ 64# +5V +5V 32 bit end64 bit spacer 64 bit spacer

Connector Key Connector Key AD[08] AD[07] +3.3 V AD[05] AD[03] Ground AD[01] +5V (I/O) ACK 64# +5V +5V C/BE[0]# +3.3V AD[06] AD[04] Ground AD[02] AD[00] +5V (I/O) REQ 64# +5V +5V

5V key 5V key

Connector key Connector key

Connector key Connector key

88

(a) Rnh cm PCI X

(b) Rnh cm PCI

Hnh 4.7 : Cu to cc rnh cm PCI Do s phc tp ca tuyn PCI, vic t thit k v ch to card PCI tng i kh khn, i hi s dng cc linh kin FPGA c mt tch hp cao, mch in nhiu lp v cng ngh dn, ngoi ra vic lp trnh cho card ny cng khng phi d dng m phi thng qua cc hm Windows API. Vic thit k s tr nn d dng hn nu dng cc b PCI development kit c sn. Cc b kit ny gip to cc ng dng PCI khc nhau cng vi phn mm km theo. Cu to mt card giao tip PCI nh vy nh trn hnh 4.8. Ngoi ra, do chun PCI c s dng rng ri trong k thut, nn cc hng khc nhau ch to kh nhiu cc card PCI vi cc tnh nng khc nhau. Cc card ny c th l cc card giao tip s, tng t a dng hoc cc card chuyn dng cho cc ng dng khc nhau trong thc t. Bng 4.5 gii thiu mt s card giao tip qua bus PCI ca hng Advantech. Bng 4.5: Cc card giao tip PCI ca hng Advantech PCL10501 Adapter, analog I/O channels to DB-37 connector vo ra tng t Digital I/O port extender Cng vo ra s m rng Adapter, dual flat cables to DB-37 connector Giao tip DB37 cp dp 330 kS/s, 12-bit High-Speed Multifunction Card - Card a nng tc cao PCL711B PCL711S 8-channel 25 kHz Multifunction DAS Card 8-channel 25 kHz Multifunction DAC Card PCL818H PCL818HD PCL812PG Multilap Analog and Digital I/O Card - Vo ra s v tng t. 32-channel S.E. Isolated A/D Card ADC cch ly 16-bit High-resolution DAC Card DAC 16 bit

PCL10502 PCL10503

PCL813B PCL-816

PCL1800

PCL-816DA-1

2-channel D/A Module for PCL-816 Hai knh DAC 16-channel 100 kHz Multifunction DAC Card 16-channel 100 kHz Multifunction DAS Card 89

PCL-720

Digital I/O and Counter Card

PCL818HG PCL818L PCL818LS PCL-832

16-channel 100 kHz High-gain DAS Card 16-channel 40 kHz Multifunction DAS Card 16-channel 40 kHz Multifunction DAS Card 3-Axis Servo Motor Control Card 3-Axis Quadrature Encoder and Counter Card 6-channel Counter/Timer Card 3-axis Stepping Motor Control Card Dual-port Isolated CANbus Interface Card

PCL-722

144-bit Digital I/O Card

PCL-724

24-bit Digital I/O Card

PCL-725

Relay Actuator and Isolated D/I Card 6-channel D/A Output Card

PCL-726

PCL-833

PCL-727

12-channel D/A Output Card

PCL-836

PCL-728

Isolated 2-channel D/A Output PCL-839 Card 32-channel Isolated Digital I/O Card PCL-841

PCL-730

Hnh 4.8 : Card pht trin ng dng giao tip trn bus PCI

90

Hnh 4.9 : Card PCI cung cp cc tn hiu cho cc thit b bn ngoi 4.4 USB USB (Universal Serial Bus) l mt chun kt ni tun t trong my tnh. USB s dng kt ni cc thit b ngoi vi vi my tnh, chng thng c thit k di dng cc u cm cho cc thit b tun theo chun cm-l-chy (plug-and-play) m vi tnh nng gn nng (hot swapping) thit b (cm v ngt cc thit b khng cn phi khi ng li h thng). USB l mt giao thc truyn d liu tun t gia my vi tnh (hay ch USB) vi cc thit b ngoi vi. My vi tnh c coi nh ch ca h thng bus. Nguyn tc kt ni ny hon ton tng t cch trao i thng tin trong mng my tnh. D liu s c truyn trn USB theo hai ch : - Ch tc cao (full-speed mode) vi tc 12 Mbs. - Ch tc chm (low-speed mode) vi tc 1,5 Mbs. Thit b ngoi vi lm vic v tr t c ni trc tip vi my tnh ch hay gin tip qua b tip ni hub. Hub l b tip ni c xp t theo cu trc hnh sao v mi hub u nm trung tm ca hnh sao . Hnh 4.10 cho thy v d cch b tr mt mng USB. Nhng u im ln ca USB l: - Ghp ni n gin do cm c chun ha, - Linh hot trong s dng, - Trin khai n gin, v r tin Mt u im na ca USB l tnh nng cm-l-chy nng (hot plug-and-play). Ngi s dng c th cm thm hoc tho ra mt thit b ngoi vi khng cn tt my ch hay ci t li h thng. Thit b ngoi vi cng khng cn bn mch ph trn my ch v chc nng ny c phn mm h thng m nhim. Khi pht hin ra mt thit b ngoi vi mi, h iu hnh s t ng ci t cc phn mm iu khin thit b. Vi 7 bit a ch, ngoi my ch USB c th qun l ti a 127 thit b ngoi vi. Cu trc tng ca USB c miu t trong hnh 4.11. 91

Hnh 4.10: S cu trc ghp ni cc thit b ngoi vi dng USB

Hnh 4.11: S cu trc ghp ni tng ca cc thit b ngoi vi dng USB

Ch USB thng l mt my vi tnh c nhn vi h iu hnh c kh nng qun l USB. Trong my tnh, vi mch PCI-ChipSet m nhim v phn cng iu khin mng USB. Cu trc phn mm iu khin USB c chia thnh tng phn nh sau: - Phn iu khin ch kt ni phn cng USB vi phn cn li ca cu trc phn mm. - Phn mm c tc dng nh mt lp (layer) gia phn iu khin ch v phn mm iu khin t, - Phm mm t cho php trao i vi thit b ngoi vi giao tip qua cng USB.

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Mt mng USB ch c php c mt ch USB. My tnh s dng phn cng v phn mm USB lm vic nh mt ch bus. My tnh nhn bit vic cm thm hay rt ra mt thit b ngoi vi khi ng qu trnh nh s (enumeration) v cc qu trnh truyn d liu khc trong bus. My tnh cng c trch nhim kim tra trng thi, thng k hot ng v kim tra ghp ni in gia b iu khin ch v cc thit b USB ngoi vi. Cp USB bao gm 4 dy. Hai dy (D+, D-) c s dng truyn ti d liu theo phng php vi sai. Hai dy cn li l dy ngun (Vbus) v dy tip t (GND). Cp r tin v khng c chn bo v thng c dng cho thit b chm (1,5Mbs). Thit b nhanh (12Mbs) i hi cp c chn bo v. Phch cm ca cp c chia ra lm hai loi: loi A ni vi my tnh, loi B ni vi thit b ngoi vi. trnh nhm ln, hai phch cm ny cu to c hc khc nhau v khng i ch cho nhau c.

Hnh 4.12: S cu trc cp USB

pha cc thit b ngoi vi, cc u (D+, D-) c bo v bi in tr cui. Thit b tc nhanh cn c in tr ni t cho u D+, thit b chm cn in tr ni ngun cho u D-. Nhng in tr ny to nn cc mc in th khc nhau gia D+ v D-, gip cho my ch pht hin c vic cm hay rt mt thit b ra khi mng USB. Cc thit b ngoi vi USB c chc nng t trong mng bus, chng c chia ra lm hai loi thit b USB: - Hub thng gm c mt b iu khin hub v mt b lp li (repeater). Mt hub c nhim v chuyn hng mt cm USB thnh nhiu cm. V d mt hub c th c mt cm hng v my ch (ngc) v 4 cm ra thit b (xui) dng cm hub mi hay cc thit b chc nng. - Thit b chc nng l cc thit b ngoi vi ca my vi tnh nh chut, bn phm, joystick, camera. n gin ha vic ghp ni, mn hnh v bn phm cn c cy thm mt hub c th ni tip sn cc thit b khc. Mi thit b USB u phi tun th theo quy c USB my ch c th pht hin c chng. Nhn chung, mi thit b USB u c thit k t ba thnh phn chnh: - Mt c cu giao din tun t SIE (serial interface engine), l mt vi mch tch hp. Thnh phn ny chu trch nhim nhn v gi d liu theo giao thc USB.

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- Mt t hp gia phn cng v firmware chu trch nhim truyn d liu gia SIE v im cui ca thit b qua nhng giao din (hay cn gi l ng ng) thch hp ca chng. - Thnh phn th ba l phn chc nng ca thit b ngoi vi (chc nng bn phm, chc nng chut) im cui l u ngun hay u pht ca mt thit b ngoi vi USB, c th coi chng l nhng thanh ghi d liu c th c c hoc ghi ln ty theo chiu truyn d liu. ng ng (pipe) l phn mm qun l im cui ca thit b USB ch (my tnh). Cng c th hiu chng l nhng knh phn mm, c gi ln trong phn mm iu hnh USB v c nhim v truyn tin n im cui ca thit b ngoi vi. Mi thit b trong mng USB s cng chia di tn qua mt giao thc khung truy nhp my ch (host-scheduled token-based protocol). Khi my ch a ra mt khung truy nhp (token) vo mng USB, thit b tng ng s pht hin ra a ch ca n c gi trong khung v tr li li my ch. My USB ch s gi bus hot ng lin tc bng cch truyn mt gi (packet) khi u khung SOF (start or frame) trong chu k 1ms. Di tn ca bus s c chia bi cc thit b USB trong khong thi gian 1ms ny (1KHz). Nhn chung, mt ln truyn tin USB cn n 3 gi: - Gi khung (token packet), - Gi d liu (data packet), - V gi bt tay (handshack packet). 8 bit PID 8 bit PID 8 bit PID 8 bit PID Bt tay 11 bit S khung 5 bit CRC50 Khi u khung 7 bit ADDR 4 bit ENDP 0-1023 byte DATA 5 bit CRC5 Khung (token) 16 bit CRC16 D liu

Hnh 4.12: Cu trc giao thc USB (PID: loi gi (packet identification); ADDR: a ch (address); ENP: im cui (endpoin); CRC: m kim tra quay vng d (cyclic redudancy code); d liu (data)

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Mi gi u c mt m 8 bit nhn dng gi. Mt cuc truyn bt u khi b iu khin ch gi mt gi khung (token packet) gm a ch thit b ADDR, s hiu im cui ENP, hng ca cuc truyn v dng ng. Thit b c a ch tng ng s chn bng cch gii m a ch ca n t gi khung. Trng ghi hng cuc gi truyn trong gi khung s khin my ch yu cu thit b ngoi vi pht d liu. Thit b ngoi vi s tr li bng gi d liu (data packet), nu khng my ch s tip tc bng vic truyn d liu. Ni chung, sau khi nhn c d liu, ni nhn (ch hoc ngoi vi) s gi li mt gi bt tay. Gi ny c th c ngha: chp nhn d liu ACK (acknowledge), khng chp nhn d liu NACK (non- acknowledge) hay tc STALL. Truyn d liu USB l giai on nm gia phn mm my ch v im cui ca mt thit b ngoi vi. Thng tin c th i theo hai chiu hay mt chiu. My ch x l vic trao i d liu vi tng thit b ngoi vi mt cch c lp. USB qun l bn loi d liu : iu khin, ngt, ng b cch ly (isochronous) v khi. Truyn iu khin (control transfer) l truyn hai chiu. Loi truyn ny c s dng ci t thit b ngoi vi. Giao thc truyn iu khin bao gm mt giai on khung, giai on d liu v giai on tr li. Mi thit b ngoi vi USB u phi x l c loi truyn ny. Truyn ngt (interrupt transfer) l truyn mt chiu. Loi truyn ny c dng cho cc thit b ngoi vi nh bn phm, chut, v joystick,. V ch USB (my tnh) khng th b ngt nn cc ngt t thit b ngoi vi c x l trong vng i. Chng trnh h thng c nhim v x l vng i ny. Giao thc truyn ngt khi ng khi my ch bt u bng mt khung IN ( IN token). Thit b ngoi vi tr li bng mt gi NAK nu khng c ngt. Nu c ngt, thit b ngoi vi tr li bng mt gi d liu. Khi nhn ht d liu my ch s tr li bng mt gi ACK nu d liu khng c li hoc khng tr li nu c li. Nu b nghn im cui ca thit b ngoi vi, n s gi n my ch gi STALL v i phn mm h thng x l . Truyn ng b cch ly thc hin truyn mt chiu. Hng cuc truyn c th t thit b ngoi vi ra my ch hoc ngc li. V th cn hai im cui thit b ngoi vi hoc hai ng ng phn mm pha my ch. Giao thc truyn ng b cch ly bt u bng mt gi IN hoc OUT t my ch ty theo hng truyn v loi im cui. V d, trong trong trng hp gi IN thit b ngoi vi truyn d liu v.Ttrng hp gi OUT my ch tip tc bng cch truyn d liu. Truyn ng b cch ly khng dng gi bt tay thng bo kt qu truyn. V th thng tin c th b tht lc. Loi truyn ny thng c dng cho in thoi hay loa. Truyn khi thc hin truyn hai chiu. Hng truyn c th t im cui v my ch hay ngc li. Nh vy mt thit b ngoi vi cn c hai chiu d liu s cn c hai im cui. Giao thc truyn khi gm c hai giai on: khung, d liu v bt tay. Nu thit b kt gia s khng c giai on d liu m ch co khung v bt tay. D liu s 95

c truyn qua ng t mt vng m d liu trong b nh ca chng trnh tng ng mt im cui ca thit b ngoi vi. Ngay sau khi mt thit b ngoi vi c cm vo mng USB, my ch s c bo da vo s thay i din th cc u D+, D-. My ch coi l mt s kin thay i trng thi cng USB v coi thit b ngoi vi nh c trong bus. Nu my ch ang trng thi ngh (suspend) th thit b ngoi vi s nh thc n. Khi my ch pht hin ra thit b mi trong mng, n s kim tra chnh xc cng thit b v cho php n. My ch sau s truyn tn hiu khi ng (reset) v thit b ngoi vi v i t nht trong 10 mili giy. Sau 10 mili giy cng thit b c coi l sn sng hot ng. Nu thit b ngoi vi ang hot ng trong thi im cm, n khng th khi ng li c. gii quyt vn ny, b vi iu khin USB cho php khi ng ri. t im ny cho php mt mt b vi iu khin tip tc thc hin nhim v ca thit b ngoi vi, mt khc pha giao din USB s tip nhn tn hiu khi ng t my ch v tr li n. Sau khi khi ng , my ch c th cung cp cho thit b ngun in ti 100mA qua hai dy dn Vbus v GND. Ti thi im ny, thit b c ang trng thi hot ng. Qu trnh nh s (enumertion process) bao gm: nhn thng tin t thit b ngoi vi, gn a ch cho thit b v gn gi tr cu hnh cho thit b. Qu trnh ny tri qua bn bc: Bc 1: my ch a ra lnh Get_Descriptor n a ch mc nh qua mt ng ng iu khin. Thit b ngoi vi s truyn li my ch thng tin v n nh: hng thit b, hng sn xut, kch thc gi ti a ca im cui Bc 2: My ch gn cho thit b mt a ch bng lnh Set_Address. Thit b (hay vi x l 8x930) s nhn a ch ny ti im cui s 0 v lu tr vo mt thanh ghi tng ng. Bc 3: My ch yu cu v c cu hnh cc thit b ngoi vi bng lnh Get_Configuration. Thit b s tr li vi s giao din, s im cui, loi truyn im cui, kch thc gi, hng truyn, nhu cu in v.v. Bc 4: Bc cui cng ca qu trnh lit k l vic gn cu hnh cho thit b qua lnh Set_Configuation.

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Sau khi qu trnh lit k c hon thnh, thit b ngoi vi sn sng thu v pht d liu trn USB. Trong qu trnh lit k, thng tin v thit b ngoi vi c truyn v phn mm h thng. Phn mm h thng s np driver thch hp iu khin chc nng ca thit b ngoi vi cho n khi n c ngt ra khi mng USB. Ngay sau khi thit b ngoi vi c g khi cng USB, thay i v hiu in th trn D+ v D- s bo cho my ch bit v s kin ny. My ch s cm cng tng ng qua b iu khin USB. Phn mm h thng USB (l mt phn ca h iu hnh) s pht hin ra l thit b c g v gii phng ti nguyn phn cng m thit b ginh ly. Nu thit b dng in bus, ngun in s b ngt dnh cho cc thit b 96

khc. Thit b c g s lm vic tip trong ch ng mt mnh (stand-alone), chng hn in thoi USB s tip tc c s dng nh mt in thoi thng. Nu thit b c g l mt hub th mi thit b c cm vo hub ny c coi nh g ra khi mng, h iu hnh s gii phng ti nguyn ca cc thit b ny. iu khin cng USB cc thit b thng s dng vi iu khin USB 8x930 ca Intel. Vi iu khin USB 8x930 l mt vi iu khin 8 bit vi b nh v cng ngoi vi cy bn trong. Ngoi ra vi iu khin ny cn c mt b iu khin USB. Vi mch 8x930 x l c c bn loi truyn d liu: iu khin, ngt ng b cch bit v khi. Truyn d liu gia thit b v my ch c thc hin qua mt cp im cui bn trn trong b iu khin USB. Mi cp im cui c trang b mt b m FIFO pht v mt b m FIFO thu. Ty theo tng ng dng v loi truyn d liu ngi s dng c th chn kch thc FIFO khc nhau.Driver thit b

iu khin cu hnh iu khin cu hnh ph

Phn mm h iu hnh, lp cu hnh (Windows 95)

Hub driver

USB driver

Universal Host Control Intertace Driver

Hnh 4.13: Cu trc phn mm USB trong h iu hnh Windows Vi mch 8x930 dng cho hub c giao din USB vi thit b ngoi vi v kh nng hub cho php ni thit b ngoi vi hay hub. Dng 8x930 ta s c 4 cng xui ngoi (ra thit b) v 1 cng xui trong. Hot ng ca b iu khin USB c lp trnh qua cc thanh ghi chc nng c bit SFR (special function registers). Giao thc USB c cy trong ROM ca 8x930, ngi lp trnh 8x930 khng cn n vn ny. Chng trnh iu khin 8x930 c th chia ra thnh cc phn sau: 97

- Khi ng, ghi ln cc thanh ghi SRF. - Lit k (tr li lnh lit k ca my ch nh Get_Descriptor, Set_Adress, Get_Configuration v Set_Configuration). - Pht gm ba bc: bc tin pht (pre-transmit) chun b d liu, bc truyn d liu qua phn cng b iu khin USB v bc hu pht (post transmit). - Thu gm hai bc: bc tin thu (post receive) v bc nhn d liu qua phn cng. - Phn cui cng ca firmware trong 8x930 l chng trnh iu khin thit b ngoi vi. Chng hn, nu thit b ngoi vi l mt bn phm th 8x930 s m nhim cng vic ca 8048 c in nh qut bn phm cc chc nng iu hnh bn phm khc. 4.5 SCSI Ngoi cc chun kt ni thng thng cc PC nh: IDE, SATA, IEEE 1394, USB. Chun giao tip SCSI (Small Computer System Interface, c l skuzzy) thc cht l mt loi bus song song tc cao. Tng t EIDE, SCSI l bus iu khin dng d liu (I/O) gia b x l v thit b ngoi vi (thng dng nht chnh l a cng). Nhng khc EIDE, SCSI ni vo bus PCI thng qua host adapter thit b khng gi chc nng iu khin m ch iu phi, lin kt thit b SCSI thnh chui lun l. Nu xt v s lng thit b qun l, SCSI thc s mnh v c th qun l n 16 thit b (tnh c host adapter); trong khi IDE ch qun l c 2 a cng v EIDE h tr 4 thit b. Hn na, giao tip SCSI cn thch hp vi nhiu chng loi thit b: a cng, CD-ROM, CD-R, quang, my in, my qut, b chuyn a, card mng, Thng ta hay ni cc thit b nh a cng, CD-ROM vo my tnh qua hai lai cng IDE v SCSI. Trong khi cng IDE ch cho php ni vi hai thit b th SCSI cho php ni vi 16 thit b khc nhau. Trong khi cng IDE thng gn lin vi Mainboard th SCSI li dng card ring bit gi l SCSI-Control vi mt on cp bn chuyn dng (c mt s Mainbord c sn SCSI-Control). Mi thit b trong chui, k c host adapter, u c cp mt nh danh duy nht phn bit. nh danh thit b phi khng trng nhau v khng cn tng ng theo th t vt l. Hu ht host adapter SCSI u c cng trong v ngoi ngi dng linh hot m rng chui thit b. Khc vi cc chun giao tip a cng khc, bn phi t thit lp kt thc (terminate) ti hai thit b u v cui chui nhm loi b hin tng di tn hiu v m bo s ton vn d liu truyn trn bus. Thit lp terminate cng linh hot: c th dng jumper vt l hoc thit lp t phn mm. Chui thit b SCSI chun h tr n 8 thit b, s dng ID t 0 n 7. Card SCSI (host) thng chn ID 7 v khi ng h iu hnh t thit b c ID nh nht. Hu ht h thng SCSI t ID a cng khi ng bng 0, gi tr ID t 1 n 6 c dnh cho nhng thit b khng khi ng. Khi h thng SCSI khi ng, tt c thit b trn bus c lit k km vi gi tr ID.

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Card SCSI ch ly mt IRQ t h thng cn cc thit b gn vo adapter ny th khng cn. V th, h thng cho php m rng kh d dng. Ch cn gn thm card SCSI th hai, bn c th m rng thm 7 thit b na. Tuy nhin, dng adpater SCSI i (twin-channel) li hp dn hn: 15 thit b ngoi vi ch yu cu mt IRQ. c bit, thit b ngoi vi SCSI c th giao tip vi my tnh qua cng song song nhng tc thp.

Hnh 4.14: Kt ni trn bus SCSI V vt l SCSI l chun giao tip song song cho ti nay c mt s chun sau: SCSI-1 c lp vt l v giao thc 8 bit cn ng , khng cn bng, giao tip n s dng u ni 50 chn. C d liu v lnh u c truyn trn 8 ng dy data vi tc 5 MBps (5Mhz), chun ny cho php kt ni 7 thit b, n s dng cp A vi u ni 50 dy nh m t trong bng 4.6. SCSI 2 hay cn gi l FAST SCSI l bus s dng ch cn ng b cho lnh v ng b cho d liu. N c th truyn 8 bit vi tc 10 MBps (clock 10 Mhz) vi cp A u ni 50 chn, hoc truyn 16 bit vi tc 20 MBps (clock 10 Mhz) s dng cp B vi u ni 68 chn. S thit b s dng trn bus c th tng ln 15 thit b. ch cp B, s dng tn hiu vt l sai lch vi cp xon i c th tng khong cch truyn. Cc tn hiu cp B m t trn bng 4.6. Vi SCSI 3 d liu c truyn 8 bit vi tc 20 MBps trn cp 50 chn, hoc 16 bit vi tc 40 MBps vi chun cp 68 chn. S thit b c th s dng trn bus 99

tng ln 16 (cho chun fast 10). Chun ny s dng cp P vi chun truyn tn hiu sai lch. (bng 4.7) Ngoi ra chun ny cn c mt s tc truyn nhn khc ty thuc vo b truyn nhn d liu nh: - SE (Single End): hot ng ch cn ng b n c cc ch Fast-5, Fast-10, Fast-20 tt c u truyn ch n cc tnh. - MSE (Multi Single End): cng l loi truyn cn ng b vi cc ch Fast-5, Fast10 v Fast-20 n cc. - LVD (Low Voltage Diffirence): truyn cn ng b c cc ch Fast-5, Fast-10, Fast-20 v Fast-40 n cc hoc Fast-10 v Fast-80 cn bng. - HVD (High Voltage Diffirence): l loi bus 32 bit nhng khng cn s dng.

Hnh 4.14: Kt ni cc thit b trn bus SCSI Fast-20 chy vi tc 20 MBps (8bit) hoc 40 MBps (16 bit). Fast-40 chy vi tc 40 MBps (8bit) hoc 80 MBps (16 bit). Fast-80 chy vi tc 80 MBps (8bit) hoc 160 MBps (16 bit). Ultra SCSI [Fast-20] vi tc 20 MBps (8bit) hoc 40 MBps (16 bit). Thng thng cc chun nay s dng cp cc i 10 mt cho 4 thit b hoc 15 mt cho 5 thit b. Ultra2 SCSI [Fast-40] chy vi tc 40 MBps (8bit) hoc 80 MBps (16 bit), cp di cc i 12 mt. Ultra3 SCSI [Fast-80] chy vi tc 80 MBps (8bit) hoc 160 MBps (16 bit), bus ny bao gm kim tra CRC. SCSI-4 cn gi l Ultra 320 hay Fast-160 chay vi tc 320 MBps vi bus rng 16 bit. Chun ny s dng cp P 68 ng vi cc tn hiu nh m t trn bng 4.7. SCSI-5 c tc truyn ging SCSI-4 nhng s dng loi cp c bit VHDCI (Very High Density Cable Interconnect) vi u ni P 68 chn.

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Chn 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Bng 4.6: Cc tn hiu trn cp A v cp B SCSI khng cn bng Cp A n cc Cp B sai lch Tn hiu Chn Tn hiu Chn Tn hiu Chn Tn hiu GND 26 D01 GND 2 GND GND 27 D13 GND 4 Data bit 8 GND 28 D25 GND 6 Data bit 9 GND 29 D37 GND 8 Data bit 10 GND 30 D49 GND 10 Data bit 11 GND 31 D511 GND 12 Data bit 12 GND 32 D613 GND 14 Data bit 13 GND 33 D715 GND 16 Data bit 14 GND 34 Dparity 17 GND 18 Data bit 15 GND 35 GND 19 GND 20 Parity P1 GND 36 GND 21 GND 22 -ACKB Reserved 37 Reserved 23 GND 24 GND Open 38 TRMPWR 25 GND 26 -REQB Reserved 39 Reserved 27 GND 28 Data bit 16 GND 40 GND 29 GND 30 Data bit 17 GND 41 ATN31 GND 32 Data bit 18 GND 42 GND 33 TERMPWRB 34 TERMPWRB GND 43 BSY35 TERMPWRB 36 TERMPWRB GND 44 ACK37 GND 38 Data bit 19 GND 45 RST39 GND 40 Data bit 20 GND 46 MSG41 GND 42 Data bit 21 GND 47 SEL43 GND 44 Data bit 22 GND 48 C/D45 GND 46 Data bit 23 GND 49 REG47 GND 48 Parity P2 GND 50 I/O49 GND 50 Data bit 24 51 GND 52 Data bit 25 53 GND 54 Data bit 26 55 GND 56 Data bit 27 57 GND 58 Data bit 28 59 GND 60 Data bit 29 61 GND 62 Data bit 30 63 GND 64 Data bit 31 65 GND 66 Parity P3 67 GND 68 GND Bng 4.7: Cc tn hiu u ni P chun SCSI 101

Cp P n cc Chn Tn hiu Chn 1 GND 35 2 GND 36 3 GND 37 4 GND 38 5 GND 39 6 GND 40 7 GND 41 8 GND 42 9 GND 43 10 GND 44 11 GND 45 12 GND 46 13 Open 47 14 GND 48 15 GND 49 16 GND 50 17 TRMPWR 51 18 TRMPWR 52 19 RESERVED 53 20 GND 54 21 GND 55 22 GND 56 23 GND 57 24 GND 58 25 GND 59 26 GND 60 27 GND 61 28 GND 62 29 GND 63 30 GND 64 31 GND 65 32 GND 66 33 GND 67 34 GND 68

Cp P sai lch Tn hiu Chn Tn hiu Chn Tn hiu D121 D12+ 35 D12D132 D13+ 36 D13D143 D14+ 37 D14D154 D15+ 38 D15DPATH5 DPATH+ 39 DPATHD06 GND 40 GND D17 D0+ 41 D0D28 D1+ 42 D1D39 D2+ 43 D2D410 D3+ 44 D3D511 D4+ 45 D4D612 D5+ 46 D5D713 D6+ 47 D6DPARITY14 D7+ 48 D7GND 15 DPARITY+ 49 DPARITYGND 16 DIFFSENS 50 GND TRMPWR 17 TRMPWR 51 TRMPWR TRMPWR 18 TRMPWR 52 TRMPWR RESERVED 19 RESERVED 53 RESERVED GND 20 ATN+ 54 ATNATN21 GND 55 GND GND 22 BSY + 56 BSY BSY 23 ACK+ 57 ACKACK24 RST + 58 RST RST 25 MSG+ 59 MSGMSG26 SEL+ 60 SELSEL27 C/D+ 61 C/DC/D28 REQ+ 62 REQREQ29 I/O+ 63 I/OI/O30 GND 64 GND D831 D8+ 65 D8D932 D9+ 66 D9D1033 D10+ 67 D10D1134 D11+ 68 D11-

102

4.6 IEEE1394 BUS Chun giao din tun t cao tc 1394 (high performance serial interface) ra i nm 1995. Tng t nh USB, giao din IEEE 1394 l mt bus tun t cao tc. Chun 1394 ca IEEE l mt h bus tun t cho php truyn d liu vi tc 100, 200 hay 400 Mbit/s (so vi 1 Mbit/s v 12 Mbit/s ca USB). Chun b sung 1394b (ra i nm 1999) cn quy nh tc t 800 n 3200 Mbit/s. Chun ny cho php truyn d liu hnh nh chuyn ng trong thi gian thc, cho php ni v ngt cc thit b ngoi vi nh a, my in, my qut hnh, my nh s v.v Bus 1394 l mt bus thng minh v lm vic c lp vi my tnh ch. Giao tip tun t IEEE 1394 l mt gii php r tin so vi h mng cc b LAN hay mng rng WAN. Nguyn tc truyn d liu ca IEEE 1394 (cng nh USB) da trn nguyn tc truyn gi d liu. IEEE 1394 c u im so vi SCSI l kh nng ngt ni thit b ngoi vi m khng cn phi khi ng li my tnh ch. Tc truyn ca IEEE 1394 c th snh vi cc chun mng cao tc nh ATM, HPPI v cp quang. Giao din IEEE 1394 khng thay th m b sung cho giao din USB. Trong khi USB c dng lm giao din chun cho cc thit b ngoi vi chm nh in thoi, bn phm, chut th IEEE 1394 c dng cho cc thit b cn truyn d liu nhanh nh my quay phim s, a DVD, a cng. Trong tng lai gn, hai giao din USB v IEEE 1394 s thay th ton b cc chun giao din c in ca my vi tnh c nhn tng thch IBM. Bng 4.8 so snh hai giao din hin i ny. Bng 4.8: So snh USB v IEEE 1394 Tham s Tc truyn USB IEEE 1394

Trung bnh, 1 Mbit/s n 12 Nhanh, 100 Mbit/s n 32 Mbit/s Mbit/s Va phi (15 dollar M)

Gi thnh (thi R tin (t hn 1 dollar M) im 1999) Cu hnh

Hnh sao, vi my tnh c R nhnh, c lp vi my nhn lm ch trung tm tnh c nhn Chut, bn phm, cn iu My quay phim s, my quay khin, mn hnh, hub, thit b phim DVD. Thit b lu tr m thanh, my qut nh, my d liu, my qut hnh. nh s n gin n gin

ng dng

S dng

103

Nhng c im u vit ca 1394 l: Kh nng c nhiu ch bus. Tho g khi my ang hot ng (hot plugging), tho g thit b khin h bus t ng khi ng, ci t v lm vic tip. Kt ni cp chun. a ch im ni thay ng (thay i c). Tc nhanh (100 Mbps n 400 Mbps)

Tng t nh USB, mi im ni c tc dng nh b lp (repeater) v c kh nng phn nhnh thnh mt mng dng thn cy. Khong cch ti a gia hai im ni l 4,5 m v chiu su r nhnh l 16 im (chiu di ti a mt mng 1394 l 72 m). Tn hiu c truyn theo m NRZ.Bus song 2 CP U B nh I/O CP U 1 Cu ni

Bus ni tip (mi trng Bus song 2 CP U B nh I/O CP U

I/

I/O

I/O

Bus ni tip (mi trng

Cu ni

1

Hnh 4.15: Cu trc mng bus IEEE 1394 1) im ni, 2) Mun, 3) Cng giao din Cu trc bus IEEE 1394 c nh ngha theo cc im ni (node). Mt im ni trong bus l mt n v c gn a ch. Cc im ni c th c khi ng v xc nh c lp vi cc im ni trong mng, nhiu im ni nm trong mt m un. Cn phn bit cu trc cc thit b trong bus IEEE 1394: Cu trc m un l cu trc vt l ca cc thit b (cng nm trong mt v my), cc im ni trong m un c th dng chung mt cm ni vi mng bus. Cu trc im ni l cu trc logic (c a ch ring bit, c kh nng khi ng c lp). Mt im ni c mt a ch ring, mt b nh ROM ghi m hiu v chc 104

nng im ni v b nh RAM cha cc thanh ghi trng thi/iu khin theo quy nh ca chun IEEE 1394. Mt im ni c th c nhiu n v chc nng hot ng c lp vi nhau nhng cng c khi ng khi vn hnh im ni. Cu trc mng bus (topology) c phn bit thnh 2 mi trng: - Mi trng cp ni l mt mng cp khng u vng. Cp IEEE 1394 gm ba i dy dn: hai i tn hiu v mt i ngun in. Mi cng giao din gm c mt in tr kt thc cp (termination), b pht/nhn (transceiver) m mt s mch logic n gin. Cp v cc cng giao din c tc dng nh cc b lp (repeater) c dng m phng mt mng bus duy nht. i cp ngun cung cp in th t 8 n 40 V vi dng ti a 1,5A, cho php cc cng giao din (b nhc li) vn hot ng trong khi thit b chnh (mun) ngt in. - Mi trng c s (backplane) bao gm hai dy dn song song trong h thng (trn bn mch chnh). Cc cm trn h bus ny cho php ghp cc im ni v h thng. Trong cc h thng ny, bus song song thng dng hai cm hay hai dy dn c chun IEEE d tr. Mc tn hiu trn mi trng c s tu thuc theo h thng thit b (V d Futurebus + dng BTL, VME dng TTL, Fastbus v SC1 dng ECL). Nh cp trn, cp bus IEEE 1394 gm 4 dy dn: Hai i dy tn hiu c xon thnh tng cp gim nhiu in t: /xanh lc v cam/xanh bin. i dy ngun in chy song song: dy en tip t, dy trng mang in th ngun. Cu trc c th ca cp v kt ni bus IEEE 1394 c m t c th trong hnh 4.16. Cc tn hiu trn cc u ni c m t trong bng 4.9.

Hnh 4.16: Cu trc kt ni cp IEEE 1394 Bng 4.9: Cc tn hiu chun IEEE 1394 Chn 1 2 3 Loi 4 chn TPB* TPB TPA* Loi 6 chn VP VG TPB* Loi 9 chn TPB* TPB TPA* Tn hiu Twisted Pair B, Minus Twisted Pair B, Plus Twisted Pair A, Minus

105

4 5 6 7 8 9 Plug

TPA Sheild (VG) -

TPB TPA* TPA Sheild

TPA TPA(R) VG NC VP TPB(R) Sheild

Twisted Pair A, Plus Twisted Pair A, Ground Power Ground Non Connect Power Voltage Twisted Pair B, Ground GND

Chun 1394 lm vic theo nguyn tc gi d liu cho mi trng cp dn (nh USB). Bus 1394 c t chc nh mt khng gian a ch b nh cho cc thit b ngoi vi. a ch mt thit b rng 65 bit, chia thnh cc phn sau: 10 bit m s mng. 6 bit m s im ni (node) 48 bit a ch b nh

Vi cu trc ny, bus 1394 c th qun l c 1023 mng, 63 im ni (hay thit b ngoi vi) v 281 Terabyte b nh. Ti nguyn bus c lu tr trong cc thanh ghi ca khng gian a ch, tng thanh c c v ghi nh truy nhp gia vi x l v b nh. Hnh 4.17 minh ho cch nh a ch trong h thng bus IEEE 1394. Giao thc IEEE 1394 gm 3 lp chnh hnh 4.17. Lp truyn (transaction layer) thc hin cc giao thc trao i d liu (c, ghi, kho). Lp ni LINK (link layer) c trch nhim nh ngha, kim tra d liu v ng/m gi d liu khi truyn v nhn d liu trn mng bus. Lp ny c php phc v trc tip chng trnh ng dng trong ch truyn ng b. Ti ch ny, lp LINK cng c trch nhim to ra nhp ng h ng b.

Lp vt l PHY (physical layer) c ba nhim v chnh: 1. Bin dch d liu nh phn ra tn hiu in. 2. C trch nhim lm ch o bus v ch cho php mt im ni duy nht truyn thng tin trong mt thi im. 3. nh ngha giao din vt l ( cm, chn cm v.v.). Bus 1394 cho php truyn d liu trong hai c ch: -

106

-

Khng ng b: truyn d liu theo a ch trn bus, dnh cho ng dng khng cn truyn nhanh nh my in, my quyt v.v.0 Bus s 0 Bus s 1 Bus s 0 Bus s 1 Vng d liu khi ng Cu trc CSR 512 Bus tun t 1024 1 KB ROM 2048

Vng d liu khi ng Bus s 1022 Bus s 1023 (bus ni b) im ni s 62 im ni s 62 private Thanh ghi 256M Loa a ch B nh Private Thanh ghi V d S bus S bus S bus 1023D = 3FFH S im ni S im ni S im ni 63D = 3FH Khng gian a ch K/gian private (FFFFEH) K/gian thanh ghi (FFFFEH) 1048575D = FFFFFH = FFFF FFFF F000 0200 a ch private (0 n FFFFEH) a ch thanh ghi (0 n FFFFEH) Thanh ghi CYCLE_TIME 512 = 200H

Hnh 4.16: Cch nh a ch bus IEEE 1394.

Hnh 4.17: Cc lp giao thc IEEE 1394 107

-

ng b: truyn d liu theo s knh, mt gi d liu ng b cn khong 125 microgiy nn loi ny thch hp cho ng dng cn truyn d liu nhanh (v d nh hnh chuyn ng).

4.7 PROFIBUS PROFIBUS (Process Field Bus) l mt mng trong h truyn thng m. V phng din vt l, PROFIBUS l mt mng in m cc ng dn l cable ng trc c bc kn, cp xon i hoc cable quang. PROFIBUS l mt h thng bus c pht trin ti c t nm 1987, do 21 cng ty v c quan nghin cu hp tc. Sau khi c chun ho quc gia vi DIN 19245, PROFIBUS cn c a vo trong chun IEC 61784 - mt chun m rng trn c s IEC 61158 cho cc h thng sn xut cng nghip. Vi s ra i ca cc chun mi IEC 61158 v IEC 61784 cng nh vi cc pht trin mi gn y PROFIBUS khng ch dng li l mt h thng truyn thng, m cn c coi l mt cng ngh t ng ho. PROFIBUS nh ngha cc c tnh ca mt h thng bus cho php kt ni nhiu thit b khc nhau, t cc thit b trng cho ti vo/ra phn tn, cc thit b iu khin v gim st. PROFIBUS nh ngha 3 loi giao thc l PROFIBUS-FMS, PROFIBUS-DP v PROFIBUS-PA. FMS l giao thc nguyn bn ca PROFIBUS, c dng ch yu cho vic giao tip gia cc my tnh iu khin gim st. Bc tip theo l s ra i ca DP vo nm 1993- mt giao thc n gin v nhanh hn nhiu so vi FMS. PROFIBUS - DP c xy dng ti u cho vic kt ni cc thit b vo/ra phn tn v cc thit b trng vi cc my tnh iu khin PROFIBUS-FMS v PROFIBUS-DP lc u c s dng ph bin trong cc nghnh cng nghip ch to lp rp. Tuy nhin gn y, vai tr ca PROFIBUS-FMS ngy cng m nht bi s cnh tranh ca cc h da trn nn ethernet (Ethernet/IP, Profinet, highspeed- ethernet,). Trong khi phm vi ng dng ca PROFIBUS-DP ngy cng lan rng sang nhiu lnh vc khc. PROFIBUS-PA l kiu c bit c s dng ghp ni trc tip cc thit b trng trong cc lnh vc t ng ho cc qu trnh c mi trng d chy n c bit trong cng nghip ch bin. Thc cht PROFIBUS -DP chnh l s m rng ca PROFIBUS-DP xung cp trng cho lnh vc cng nghip ch bin. Ngy nay PROFIBUS l h bus trng hng u th gii vi hn 20% th phn v vi hn 5 triu thit b lp t trong khong 500 000 ng dng. Kin trc giao thc PROFIBUS ch thc hin cc lp 1, lp 2 v lp 7 theo m hnh qui chiu OSI, nh minh ha trn hnh 4.18 Tuy nhin, PROFIBUS-DP v -PA b qua c lp 7 nhm ti u ho vic trao i d liu qu trnh gia cp iu khin vi cp chp hnh. Mt s chc nng cn thiu c b sung qua giao din s dng nm trn lp 7. Bn cnh cc hm dch v DP c s v m rng c quy nh ti lp giao din s dng, hip hi PI cn a ra mt s qui nh chuyn bit v c tnh v chc nng c th ca 108

thit b cho mt s lnh vc ng dng tiu biu. Cc c t ny nhm mc ch to kh nng tng tc v thay th ln nhau ca thit b ca nhiu nh sn xut. Bng 4.10: Kin trc giao thc ca PROFIBUS

C ba giao thc FMS, DP, PA u c chung lp lin kt d liu (Lp FDL). PROFIBUS-PA c cng giao din s dng nh DP, tuy nhin tnh nng ca cc thit b c qui nh nhm ph hp vi mi trng lm vic d chy n. K thut truyn dn MPB (Manchester Code, Bus Powered) theo ICE 1158-2 c y m bo vn an ton v cung cp ngun cho cc thit b qua cng dy dn bus. tch hp cc on mng DP vPA c th dng cc b chuyn i (DP/PA-link, DP/PA-Coupler) c sn trn th trng. Lp ng dng ca FMS bao gm 2 lp con l FMS (Fieldbus Message Specification) v LLI (Lower Layer Interface). Trong FMS chnh l tp con ca chun MMS. Lp FMS m nhim nhim v x l giao thc s dng v cung cp cc dich v truyn thng trong khi LLI c vai tr trung gian cho FMS kt ni vi lp 2 m khng ph thuc vo cc thit b ring bit. Lp LLI cn c nhim v thc hin cc chc nng bnh thng thuc lp 3-6, v d to ngt ni kim sot lu thng. Lp vt l ca PROFIBUS qui nh v k thut truyn dn tn hiu mi trng truyn dn, cu trc mng v giao din c hc, cc k thut truyn dn s dng y l RS-458, RS-558-IS (IS: Intrinsically Safe) v cp quang i vi DP v FMS cng nh MBP i vi PA. RS-458-IS c pht trin trn c s RS-458 c th s dng trong mi trng i hi an ton chy n. Lp lin kt d liu PROFIBUS c gi l FDL (Fieldbus Data Link), c chc nng kim sot truy nhp bus, cung cp cc dch v c bn cho vic trao i d liu mt cch tin cy khng ph thuc vo phng php truyn dn lp vt l. Phng php thm nhp : PROFIBUS s dng cc phng php thm nhp vo mng c qui nh EN 50170, Volume 2 bao gm cc phng php: 1. Token Bus cho cc trm ch 2. Master-Slave (ch-t) cho cc trm t 109

Phng php thm nhp ng dn hon ton khng ph thuc vo mi trng truyn thng. Hnh 2.3 minh ho phng php thm nhp ng dn ca mt mng PROFIBUS.

Hnh 4.18: Phng php thm nhp ng dn trong mng PROFIBUS

Hnh 4.19: Kt ni mng PROFIBUS Truyn thng ca cc trm ch (hay cn gi l trm tch cc) c iu khin bng mt vng logic (Logical Ring-LR). Vng ny c thit lp trc khi a mng vo hot ng. Vng ny quyt nh ti thi im no, trm ch no tch cc v tch cc trong bao lu. Trm ch c tch cc cn gi l trm chim gi token. Trong thi giam trm no chim gi token trm c quyn thm nhp vo ng dn gi cc in tn. Vng logic hon ton khng ph thuc vo cu trc ca cc trm ch vi nhau trong mng. Khong thi gian cho php mt trm ch thm nhp vo ng dn, hay ni mt cch khc khong thi gian trm ch chim gi token, c gi l thi gian token. Nu ht thi gian token m trm vn cha gi xong d liu, th ch c d liu no ca trm c mc u tin cao nht c tip tc truyn i, nu khng phi 110

trng hp nh vy, th trm ch phi ngng qu trnh truyn thng v i cho n lt sau. Nu trm no c chim gi token nhng li khng c nhu cu truyn thng th token c t ng chuyn sang trm n lt tip theo trong hng theo qui nh ca vng logic. Thng thng thi gian token c qui nh chung cho cc trm ch trong mng. Nu mt trm t c ni vi mt trm ch ang chim gi token th trong thi gian token trm t s b hi v phi nhn cc thng tin do trm ch cung cp. Mt trm t khng bao gi c chim gi token. PROFIBUS phc v cho vic trao i d liu gi cc thit b trng vi dung lng thng khng ln. Cc trm ch thc hin c vic trao i trong thi gian mng cn hot ng. Trong SIMATIC mng PROFIBUS thng c ni vi mt CP. PROFIBUS-DP cung cp dch v truyn thng gia cc trm SIMATIC S7 v cc thit b trng (DP-LAVE) thc hin trao i d liu vo/ra ca mt qu trnh. Qu trnh trao i d liu gia DP-Master v DP-Slave c thc hin theo chu trnh lp li v vi mt dung lng thng tin khng ln. Nhng tnh cht c trng ca mng PROFIBUS: 1. Thng qua PROFIBUS c th thc hin c ng thi nhng hm chc nng ca cc dch v truyn thng sau : - FDL,FMS v cc hm chc nng ca S7. - DP, FDL v cc hm chc nng ca S7. 2. Thi gian thm nhp mng do phng php token quyt nh 3. PROFIBUS-DP to ra kh nng trao i d liu gia trm ch v trm t ca cc nh sn xut khc nhau. Theo DP m khng cn c giao din c bit no. 4. i vi SIMATIC S7/M7 tn ti cc giao din tch hp PROFIBUS-DP (2 giao din i vi S7 hoc mt module giao din cho cc M7-CPU). iu c ngha l: - i vi mng ch c duy nht mt ch (Monomaster) ti giao din tch hp c thi gian p ng nh (1-2ms i vi tc truyn 12Mbit/s). - Giao din tch hp rt kinh t v c gi thnh r v chim t din tch. 5. Thi gian p ng nhanh (1-5ms) khi i hi mt trm t DP (DP-Slave) phc v trm ch. 6. PROFIBUS cho php trao i d liu gia cc thm theo FMS hoc FDL m khng cn phi c thit b lin kt c bit. D liu k thut ca mng PROFIBUS c biu din trong bng 4.11.

111

Bng 4.11: D liu k thut ca PROFIBUS

4.8 GPIB Vo u nhng nm 1970, hng Hewlett Packard a ra a ra chun giao tip (HB-IB) kt ni cc dng thit b o lng ca hng, sau chun ny c IEEE chp nhn vo nm 1975. Chun giao tip bus IEEE 488 (HP-IB), hoc bus giao tip a dng GPIB (General Purpose Interface Bus) c pht trin kt ni cc thit b o lng khc nhau, v cc thit b ny c th truyn d liu qua li di s iu khin ca mt hoc nhiu s iu khin. GPIB h tr mt di rng cc thit b o lng v cc thit b khc, t cc thit b c tc truyn d liu rt cao ti cc thit b c tc truyn d liu rt thp. GPIB cho php kt ni 15 thit b vi nhau v cho php thit lp cc thit b, bao gm c cc b iu khin nu chng l mt phn ca h thng. Mt thit b ni vo bus ny c th gi ba chc nng sau: l mt b iu khin (controller), mt b nhn d liu (listener) hoc mt b pht d liu (talker). Mt thit b c th ch c mt trong 3 chc nng trn ti mt thi im. - B nhn d liu (Listener) c th nhn d liu v cc tn hiu iu khin t mmt thit b khc ni ti bus, nhng n khng c to ra gi liu. V d, my pht sng l mt listener. - B pht tn hiu (Talker): ch c kh nng cp d liu ra bus, m khng th nhn d liu. V d in hnh cho talker l bng t, my c m vch. Ch l ti mt thi im ch c mt talker c hot ng cp d liu ra bus, nhng c th c nhiu listener tch cc cng nhn v x l d liu. - B thu pht tn hiu (Talker and Listener): Hai chc nng ny c th tch hp trong mt thit b, khi thit b va c th truyn v c th nhn d liu trn bus. 112

Mt my o a chc nng s l vi d in hnh cho mt Talker and Listener. D liu n nhn l cc gi tr thang o thch hp v cung cp ra bus cc d liu cho in p, dng in, in tr . - Cc b iu khin (Controllers): s dng gim st lung d liu trn bus v cung cp cc chc nng x l. B iu khin trong h thng IEEE 488 lun l mt b vi iu khin, mt s hng sn xut cc b iu khin chuyn dng cho GPIB. Chc nng iu khin cng c th l mt PC hoc mt my tnh tng thch PC. Mt b iu khin trc tip s iu khin cc thit b l listener hoc talker. Bus cho php c nhiu b iu khin, nhng ti mt thi im ch c mt b iu khin c php hot ng. Mt thit b trong bus cn c gn mt a ch duy nht trong di t 0 n 30. di cc i cho tng cc ng truyn trn bus l 20 mt. Cp cho mt thit b o hay mt thit b bt k ni vo mng c khuyn co l 2 mt (cc i l 4 mt). Khi s dng chun GPIB m rng th chiu di cp cc i c th di hn 20 mt. Cc thit b c cng chun bus GPIB c th kt ni trc tip vi nhau vi cc tn hiu nh trn hnh 4.20. Cc tn hiu kt ni bao gm 8 ng d liu v 8 ng iu khin. Cp thc t s dng cho chun ny s bao gm 24 dy vi 8 ng chng nhiu v GND, cp s dng u ni 24 chn vi th t cc chn m t trong bng 4.12.

Hnh 4.20: Cu hnh GPIB Bng 4.12: M t cc tn hiu trn chn cm cng GPIB IEEE 488 Chn Tn tn hiu M t tn hiu Chn Tn tn M t tn hiu hiu 1 DIO1 Data In/Out 1 13 DIO5 Data In/Out5 2 DIO2 Data In/Out 2 14 DIO6 Data In/Out 6 3 DIO3 Data In/Out 3 15 DIO7 Data In/Out 7 4 DIO4 Data In/Out 4 16 DIO8 Data In/Out 8 5 EOI End or Identify 17 REN Remote End 6 DAV Data Valid 18 Shield Ground (DVA) 7 NRFD Not Ready for Datat 19 Shield Ground (NRFD) 113

8 9 10 11 12

NDAC IFC SRQ ATN Shield

Not data Accept Interface Clear Service Requist Attention Chassis Ground

20 21 22 23 24

Shield Shield Shield Shield Single GND

Ground (NDVA) Ground (IFC) Ground (SRQ) Ground (ATN) Single Ground

Hnh 4.21: Cu to c khi u ni GPIB ANT (Attention): khi mc thp (tch cc) h thng t tt c cc thit b trong ch lnh (Command Mode), khi mc cao h thng t tt c cc thit b trong ch d liu (Data Mode). Trong ch lnh b iu khin s truyn d liu ti cc thit b, cn trong ch d liu, talker s truyn d liu cho cc listener. Tt c cc thit b trn bus cn gim st v p ng tn hiu ATN trong vng 200 ns. EOI (End or Identify): Ch th vic truyn d liu cui cng trong mt chui d liu, hoc do b iu khin cung cp ch th vng song song ti mt thit b (c kt ni vi ATN). IFC (Interface Clear): do b iu khin s dng treo trng thi hot ng hin hnh, chuyn tt c cc thit b trn bus v trng thi ri. Tt c cc talker c thit lp trng thi khng truyn d liu v tt c cc listener c thit lp trng thi khng truyn d liu. REN (Remote Enable): c b iu khin s dng t tt c cc thit b ch lp trnh (Programming mode). Cc listener s c thit lp ch hot t xa (Remote Operating) nu nhn c ng a ch ca chng. Khi REN tch cc mc thp thit b c thit lp ch iu khin cc b (Local Control). Tt c cc thit b s gim st tn hiu REN v p ng trong vng 100ns. SRQ (Service Request): c cung cp t mt thit b bt k, ch th thit b cn c phc v. Tn hiu ny c s dng nh mt tn hiu yu cu ngt, b iu

-

-

-

-

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khin c th che tn hiu ny trong vng phc v ca n. Tn hiu SRQ c xo trong vng iu khin ni tip. - DIO1 DIO8 (Data Input Output): l bus d liu hai chiu. Mi ng d liu l mt tn hiu song song ni tip (Serial byte Parallel). Tc l d liu c truyn cn ng b trn cc ng dy, v s c tt c 8 knh truyn cn ng b nh vy. Theo tiu chun d liu s di dng m ASCII 7 bit, tuy nhin IEEE khng nh ngha dng m ho cho d liu. - NRFD (Not Ready for Data): y l mt trong ba tn hiu bt tay c s dng thit b thng bo n ang trng thi khng sn sng cho vic truyn d liu, tn hiu ny tch cc mc thp. - DVA (Data Valid): cng l mt tn hiu bt tay tch cc mc thp s dng ch th c mt d liu hp l trn bus. - NDAC (Not Data Accepted): l tn hiu bt tay tch cc mc thp s dng ch th mt thit b khng chp nhn d liu. GPIB nh ngha cc ca 03 ng dy bt tay thc hin tt c vic truyn d liu trn bus. Bus hot ng ch cn ng b (Asynchronous) vi tn s 500 Khz iu kin chun, v c th ln ti 1 Mhz khi c cc iu kin c bit. Mi ln trn bus truyn 8 bit d liu, nn bus c th hot ng vi tc 4 8 MBps. Bus l knh thng tin hai chiu v d liu c th truyn theo c hai hng. Hnh 4.22 m t kt ni nhiu thit b trn bus.

Hnh 4.22: Kt ni nhiu thit b trn GPIB cc thit b hot ng trn bus, trc ht b iu khin s gi mt thng ip giao tip (interface message) trn bus chn mt thit b tch cc. Mi thit b s c mt a ch duy nht c m ho bng 5 bit BCD. Bng cc a ch ny, b iu khin c th thit lp tng thit b truyn nhn hoc khng truyn nhn d liu trn bus. Nu thit b c c chc nng truyn nhn, b iu khin ch c th chn mt chc nng ti mt thi im, cn nu thit b ch c chc nng nhn d liu n s khng th truyn d liu ti b iu khin. 115

Ba chc nng talker, listener v controller c th kt hp trong mt s ch hot ng ca h thng nh qut ni tip (serial poll), qut song song (parallel poll), thit b truyn v nhn a ch (secondary talk and listen addresses), iu khin t xa/cc b (remote/local capability), v xo mt thit b (trigger). Cc thit b s da vo cc thng ip trn bus kt hp vi cc tn hiu iu khin thc hin vic truyn d liu. Ba tn hiu iu khin DAV, NRFD v NDAC c s dng nh 3 ng bt tay lin ng iu khin vic truyn d liu. Mt talker tch cc s iu khin ng DAV (Data Valid), cc listener s iu khin cc ng NRFD v NDAC. trng thi khng hot ng cc talker s gi ng DAV mc cao (khg c d liu truyn), trong khi cc listener gi ng NRFD mc cao (sn sng nhn d liu) v NDAC mc thp (khng c d liu nhn). Sau khi t d liu ln bus talker s tc ng tn hiu DAV mc thp (d liu hp l data valid). Cc listener s tc ng NRFD mc thp v NDAC mc cao (nhn d liu data accepted). Trc khi Talker ngng cp d liu ra trn bus, tn hiu DAV s tc ng mc cao thng bo d liu trn bus khng cn hp l lu na. Nu tn hiu ATN mc cao trong qu trnh ny, th thng tin truyn trn bus c xem l mt d liu (thng iu ph thuc mt thit b), nu ATN mc thp th thng tin trn bus c hiu l mt thng ip giao tip nh: nhn, truyn, khng nhn, khng truyn. Ngoi cc ng d liu v ba tn hiu bt tay trn, nm tn hiu cn li trn bus c gi l tn hiu iu khin (hay tn hiu qun l bus). Cc tn hiu ny s dng cho php cc b iu khin v cc thit b khc trn bus cho php, ngt, bo c v treo cc hot ng trn bus. Tt c cc ng trn GPIB l tn hiu 03 trnt thi, ngoi tr cc ng SQR, NRFD v NDAC dng cc thu h. Theo tiu chun ti gi chng di ti u cui bus s s dng in tr 3K ko ln 5V v mt in tr 6.2K ni xung GND, cc in tr s dng loi sai s 5%. Tiu chun ny cng cho php nhn dng cc thit b trn bus, mi thi b cn c nhn t 1 ti 2 k t dn gn u ni GPIB nhn dng thit b, cc nhn ny bao gm: C Controller b iu khin T Talker B truyn d liu L Listener B nhn d liu AH Acceptor Handshake B nhn tn hiu bt tay SH Source Handshake Ngun co tn hiu bt tay DC Device Clear Thit bi xo DT Device Trigger thit b trigger RL Remote Local T xa cc b PP Parallel Poll Qut song song TE Talker Extended Thit b truyn m rng 116

LE Listener Extended Thit b nhn m rng Cc thit b c ni theo chui lin tip, nn mt u ni sau khi cm vo thit b bng mt u c, thng thng c thm mt u ci pha sau n kt ni cho thit b tip theo. Cc thit b c th kt ni vi nhau theo dng thng hoc dng hnh sao. Hu ht cc thit b u hot ng thng qua s iu khin ca hoc mt b iu khin bn trong thit b, hoc bng b iu khin HPIB ring. Khi s dng b iu khin bn trong cc thit b trng thi cc b (Local State), cn khi s dng b iu khin HPIB ring n c gi l thit b iu khin t xa (Remote state). Khi b iu khin h thng b reset hoc mi cp ngun, cc thit b s trng thi iu khin t xa. Khi b iu khin h thng gi thng ip b qua (Abort), hoc sau khi c a ch ho, th cc thit b cng chuyn sang ch iu khin t xa. 4.9 I2C BUS I2C (Inter-Intergrated Circuit, c l eye-two-see hoc eye-squared-see) l chun giao tip 2 dy (cn gi l Two-wired Serial interface) do Philips a ra. Mc tiu l to kt ni n gin gia cc IC vi cc IC khc hoc vi cc thit b ngoi vi. Chun I2C c h tr bi nhiu nh sn xut IC v tr thnh chun cng nghip trong giao tip iu khin.

Hnh 4.22: Kt ni nhiu thit b trn bus I2C Giao tip I2C c cc ch hot ng l: o 1 Master v 1 Slave o 1 Master v nhiu Slave o Nhiu Master v nhiu Slave I2C s dng 2 ng ni dng cc mng h l SDA - Serial Data v SCL Serial Clock, do cn c ni vi in tr ko ln. in p s dng thng l +5V hoc +3.3V. SDA l chn truyn d liu v theo 2 hng, trong khi , SCL l chn truyn xung clock v ch theo 1 hng t Master n Slaver. 117

Transmitter

SDA SCL

Receiver

Transmitter

SDA SCL

Receiver

Khi Master truyn d liu ti Slaver

Khi Master nhn d liu t Slaver

Hnh 4.23: Cc tn hiu SDA v SCL trn bus I2C Trong kt ni I2C th Master gi vai tr iu khin v gi nhp cho ton h thng bng xung clock trn chn SCL. Trong khi Slave hon ton th ng v c iu khin bi Master. Master c th truyn d liu cho Slave hoc nhn d liu t Slave. Tuy nhin, cc Slave khng th trc tip lm vic vi nhau m ch c th thng qua Master. Mi thit b tham gia vo giao tip I2C c mt a ch duy nht, bao gm 7 bits. a ch ny do nh sn xut quy nh (mt s IC c th iu chnh c a ch ca mnh bng cch thay i cc bit a ch thp). Master s s dng a ch ny giao tip vi Slave mong mun trn bus I2C. Tuy nhin trong mng cng c mt s a ch c bit khng c s dng trong bng 4.13. Bng 4.13: Cc a ch c bit trong mng I2C a ch R/W Ch thch 0000-000 0 General Call 0000-000 1 START byte 0000-001 x 0000-010 x 0000-011 x 0000-1xx x 1111-1xx x 1111-0xx x a ch slave 10 bits Tc truyn trn bus I2C bao gm 3 ch : Ch chun (Standard mode) c tc clock 100 Khz, Ch nhanh (Fast mode) c clock 400 Khz v tc cao (High Speed mode) c clock l 3.4 MHz. Hnh 4.24 m t vic truyn d liu trn bus I2C, cc bc truyn d liu bao gm: - Gi bit START (S) - Gi a ch slave mun giao tip (ADDR) - Gi bit READ(R)-1 hoc WRITE(W)-0 - Ch / gi bit ACK - Gi/nhn byte d liu (DATA) - Ch / gi bit ACK - Quay li bc 5 nu mun gi/nhn nhiu byte hoc gi bit STOP (P)

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Hnh 4.24: Khung truyn d liu trn I2C Khi truyn d liu t Master tI Slaver, Master gi chui S - ADDR - W vo bus I2C v ch tn hiu ACK. Nu c mt Slave c a ch ng vi chui ADDR th n s pht tn hiu ACK. Khi Master s gi byte DATA v ch ACK, c lp i lp li cho n khi truyn xong. Cui cng Master gi P dng hoc S bt u li qu trnh truyn (hnh 4.25).

Hnh 4.25: Cc bc truyn d liu t Master n Slaver trn I2C

Hnh 4.26: Cc bc truyn d liu t Slaver ti Mastertrn I2C Khi truyn d liu t Slaver ti Master, Master gi chui S - ADDR - R vo bus I2C v ch tn hiu ACK. Nu c mt Slave c a ch ng vi chui ADDR th n s pht tn hiu ACK v gi tip byte DATA u tin. Sau khi nhn c byte DATA, Master gi li ACK v byte DATA tip theo li c Slave gi. Khi khng mun nhn thm d liu, Master gi tn hiu NACK v P/S (hnh 4.26). Tn hiu START v STOP ch c th c to ra t Master, nh thi ca chng theo SCL c m t trn hnh 4.27. Ngay khi nhn c tn hiu ny, Slave s t reset mc gi tr logic ca mnh. iu ny cho php Master khi ng li ton b kt 119

ni bt c khi no.

Hnh 4.27: nh thi bit START v STOP Start lp (Sr): Ngay sau khi hon thnh vic gi/nhn d liu vi mt Slave, Master c th ngay lp tc khi to mt kt ni mi n mt Slave khc m khng cn phi qua giai on STOP. V d: S-ADDR-(R/W)-ACK-DATA-ACK-Sr-ADDR-(R/W)-ACK-DATA-ACK-P ng dng ch yu ca Sr l trong kt ni I2C vi nhiu Master, khi m mt Master d hon thnh vic truyn d liu nhng khng mun tr li quyn kim sot bus cho Master khc. Trong kt ni I2C mt Master th vic ny l khng cn thit. nh dng d liu truyn: Mi block truyn bao gm 8 bits theo quy tc bit c trng s cao c truyn i trc (MSB-first). Block khi to bao gm a ch 7 bits v 1 bit R/W. Mi block c i km theo sau bi 1 tn hiu ACK.

Hnh 4.28: Thay i mc tn hiu SDA Vic thay i mc tn hiu trn SDA c thc hin khi SCL mc thp nh trn hnh 4.28, v nu mc cao s trng vi tn hiu START v STOP. Bit ACK / NACK: Sau khi nhn c 8 bit DATA thnh cng, thit b nhn s gi SDA mc thp trong xung clock k tip to tn hiu ACK nhm bo hiu cho bn gi. Vic gi/nhn tn hiu li tip tc hoc dng li ty theo Master. Nu vic nhn d liu c li, bn nhn s gi SDA mc cao trong xung clock k tip nhm to tn hiu NACK. Khi , c 2 trng hp xy ra: - Slave ang gi cho Master: Master s to tn hiu STOP hoc reSTART. - Master ang gi cho Slave: thng thng, Master s to NACK sau khi nhn c byte DATA cui cng, n bo hiu cho Slave bit vic truyn d liu kt thc.

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Hnh 4.29: ACK v NACK trn I2C Ngoi ra khi s dng bus I2C cn lu : - Khi mt Slave cn thi gian thu thp d liu, x l ngt hoc v.v, n c th gi ng SCL mc thp. Master khi s phi ch cho n khi SCL c gii phng tip tc. - S lng thit b gn kt vo bus I2C khng ch ph thuc vo s lng a ch c th cung cp m cn bao gm c in dung ca ton bus. Mc in dung ti a cho php l 400 pF.

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