1

TI

Module Ethernet trn vi iu khin

PIC18F67J60 v ng dng trong o lng, iu

khin (Phn mm trn MPLAB)

Gio vin hng dn :

H tn sinh vin :

2

MC LC

M U ....................................................................................................................1

CHNG 1. TNG QUAN V ETHERNET .........................................................6

1.1. Cu trc khung tin Ethernet ..............................................................................6

1.2. Cu trc a ch Ethernet...................................................................................7

1.3. Cc loi khung Ethernet....................................................................................7

1.3.1. Cc khung unicast .....................................................................................7

1.3.2. Cc khung broadcast .................................................................................8

1.3.3. Cc khung multicast .................................................................................8

1.4. Truy nhp bus...................................................................................................8

1.5. Cc loi mng Ethernet...................................................................................10

1.5.1. Cc h thng Ethernet 10Mb/s.................................................................10

1.5.2. Cc h thng Ethernet 100 Mb/s Ethernet cao tc ( Fast Ethernet )......11

1.5.3. Cc h thng Giga Ethernet....................................................................11

1.6. Chun IEEE 802 .............................................................................................11

CHNG 2. H GIAO THC TCP/IP ...............................................................13

2.1. H giao thc TCP/IP.......................................................................................13

2.1.1. Tng ng Dng (Application Layer) ......................................................13

2.1.2. Tng Giao Vn (Transport Layer) ..........................................................14

2.1.3. Tng Internet (Internet Layer) .................................................................14

2.1.4. Lp giao tip mng..................................................................................15

2.2. Cu trc gi tin IP,TCP,UDP..........................................................................15

2.2.1. Cu trc a ch IP ..................................................................................15

2.2.2. Cu trc gi tin IP ...................................................................................16

2.2.3. Cu trc gi tin TCP ...............................................................................18

2.2.4. Cu trc gi tin UDP..............................................................................19

3

CHNG 3. PHN CNG ....................................................................................20

3.1. Vi iu khin PIC 18F67J60 ...........................................................................20

3.1.1. Cc c trng ca PIC 18F67J60 ...........................................................20

3.1.2. Module A/D 10 bit ...................................................................................21

3.1.3. Module Ethernet ......................................................................................24

3.2. Cm bin nhit LM35 ................................................................................25

3.3. Mch nguyn l ..............................................................................................26

3.3.1. Khi mch ngun.....................................................................................26

3.3.2. Khi mch RJ45 ......................................................................................27

3.3.3. Khi mch LCD.......................................................................................28

3.3.4. Khi mch vi iu khin PIC18F67J60....................................................29

3.4 Mch in ...........................................................................................................30

3.5 Mch thc t....................................................................................................31

CHNG 4. TRNH BIN DCH MPLAB C18 V WEB SERVER..................32

4.1. MPLAB C18...................................................................................................32

4.1.1. Gii thiu ................................................................................................32

4.1.2. Cc c trng ca trnh dch MPLAB C18: .............................................32

4.1.3. Qu trnh to ra file .HEX .......................................................................32

4.2. Web ng .......................................................................................................33

4.3. CSS ................................................................................................................34

4.3.1. u im ca CSS.....................................................................................35

4.3.2. Cc c tnh c bn ca CSS ...................................................................35

4.3.3. CSS c tnh k tha v tnh kt hp..........................................................37

4.4. K thut AJAX ...............................................................................................38

4.4.1. u im...................................................................................................40

4.4.2. Nhc im ............................................................................................40

4

CHNG 5. TCP/IP STACK.................................................................................41

5.1. Cu trc ca TCP/IP Stack..............................................................................41

5.2. Hot ng ca TCP/IP Stack...........................................................................42

5.2.1. Cc file cn thit......................................................................................42

5.2.2. Cu trc APP_CONFIG ..........................................................................43

5.2.3. Main file ..................................................................................................43

5.3. Cc module ca Stack v APIs .......................................................................44

5.3.1. Announce.................................................................................................44

5.3.2. HTTP2 server ..........................................................................................45

5.4. Cu hnh cho Stack .........................................................................................49

5.4.1. Cu hnh cho phn cng ..........................................................................49

5.4.2. a ch.....................................................................................................50

5.5. Demo module .................................................................................................51

5.5.1. iu khin led sng tt ............................................................................52

5.5.2. Vit ra LCD .............................................................................................55

5.5.3. o nhit ..............................................................................................61

KT LUN ..............................................................................................................64

5

M U

Ethernet l kiu mng cc b (LAN) c s dng rng ri nht hin nay, ng dng ca n c mt rt nhiu lnh vc ca i sng v trong cng nghip. Kha lun tt nghip vi ti Module Ethernet trn vi iu khin PIC18F67J60 v ng dng trong o lng, iu khin (Phn mm trn MPLAB) s dng phn mm MPLAB v th vin TCP/IP Stack ca hng Microchip lp trnh iu khin LED, LCD v o lng thng qua mng truyn thng Ethernet.

Kha lun bao gm nhng ni dung chnh c bn nh sau:

Chng 1. Tng quan v Ethernet trnh by v l thuyt Ethernet gm cc vn v cu trc khung tin Ethernet, phng php truy nhp bus (CSMA/CD), cc loi mng Ethernet v chun Ethernet IEEE 802.3.

Chng 2. H giao thc TCP/IP trnh by kin thc v h giao thc TCP/IP bao gm 5 tng: tng ng dng (Application Layer), tng giao vn (Transport Layer), tng lin mng (Internet Layer), tng giao tip mng (Network Interface Layer). Trnh by cc kin thc v gi tin IP, TCP, UDP.

Chng 3. Phn cng trnh by cc kin thc v vi iu khin PIC18F67J60 bao gm cc c trng chung v c trng Ethernet ca PIC18F67J60, b bin i A/D, module Ethernet. Cc kin thc v sensor o nhit LM35 cng c trnh by trong chng ny. Tip theo l phn nguyn l ca mch demo v phn mch in. Cui cng l hnh nh mch demo thc t s dng trong kha lun.

Chng 4. Trnh bin dch MPLAB C18 v web server gii thiu v trnh bin dch MPLAB C18 v cc ni dung lin quan n vic thit k web giao din nh l DHTML, Javascript, CSS, k thut AJAX.

Chng 5. TCP/IP Stack chng ny trnh by v nhim v chnh ca kha lun l s dng th vin TCP/IP Stack ca Microchip trn phn mm MPLAB C18 lp trnh cho mch demo thc hin o lng v iu khin thng qua mng truyn thng Ethernet.

Kt lun. Trnh by cc kt qu t c ca kha lun v nh gi cc kt qu . ng thi, nh hng mt s hng pht trin ca ti.

6

CHNG 1. TNG QUAN V ETHERNET

Ethernet l kiu mng cc b (LAN) c s dng rng ri nht hin nay. Hin thi cng ngh Ethernet thng c s dng nht l cng ngh s dng cp i xon 10Mbps.

Ethernet c pht minh ra ti trung tm nghin cu Xerox Palo Alto vo nhng nm 1970 bi tin s Robert M. Metcalfe . N c thit k vi mc ch phc v nghin cu trong h thng cng s trong tng lai, bao gm trm c nhn u tin trn th gii, trm Xerox Alto. Trm Ethernet u tin chy vi tc xp x 3Mbps. Chun Ethernet 10Mbps u tin c xut bn nm 1980 bi s phi hp pht trin ca 3 hng : DEC, Intel v Xerox. Chun ny c tn DIX Ethernet ( ly tn theo 3 ch ci u ca tn cc hng).

U ban 802.3 ca IEEE ly DIX Ethernet lm nn tng pht trin. Nm 1985, chun 802.3 u tin ra i vi tn IEEE 802.3 Carrier Sense Multiple Access with Collition Detection (CSMA/CD). Mc d khng s dng tn Ethernet nhng hu ht mi ngi u hiu l chun ca cng ngh Ethernet. Ngy nay chun IEEE 802.3 l chun chnh thc ca Ethernet. IEEE pht trin chun Ethernet trn nhiu cng ngh truyn dn khc nhau v th c nhiu loi mng Ethernet. c bit, vi phin bn 100 Mbit/s (Fast Ethernet, IEEE 802.3u), Ethernet ngy cng ng mt vai tr quan trng trong cc h thng cng nghip. Bn cnh vic s dng cp ng trc, i dy xon v cp quang, gn y Ethernet khng dy (Wireless LAN, IEEE 802.11) cng ang thu ht c s quan tm ln.

1.1. Cu trc khung tin Ethernet

Cc chun Ethernet u hot ng tng Data Link trong m hnh 7 lp OSI v th n v d liu m cc trm trao i vi nhau l cc khung (frame). Cu trc khung Ethernet nh sau:

Bng 1: Cu trc khung MAC theo IEEE 802.3/ Ethernet.

M u

5555H

SFD

(D5H)

a ch ch

a ch ngun

di kiu gi

D liu PAD FCS

7 byte 1 byte 2/6 byte 2/6 byte 2 byte 46-1500 byte 4 byte

7

- Preamble (m u): trng ny nh du s xut hin ca khung bit, n lun mang gi tr 10101010. T nhm bit ny, pha nhn c th to ra xung ng h 10 Mhz.

- SFD (start frame delimiter): trng ny mi thc s xc nh s bt u ca 1 khung. N lun mang gi tr 10101011.

- Cc trng Destination v Source: mang a ch vt l ca cc trm nhn v gi khung, xc nh khung c gi t u v s c gi ti u.

- LEN: gi tr ca trng ni ln ln ca phn d liu m khung mang theo.

- FCS mang CRC (cyclic redundancy checksum): pha gi s tnh ton trng ny trc khi truyn khung. Pha nhn tnh ton li CRC ny theo cch tng t. Nu

hai kt qu trng nhau, khung c xem l nhn ng, ngc li khung coi nh l li v b loi b.

1.2. Cu trc a ch Ethernet

Mi giao tip mng Ethernet c nh danh duy nht bi 48 bit a ch (6 octet). y l a ch c n nh khi sn xut thit b, gi l a ch MAC (Media Access Control Address ). a ch MAC c biu din bi cc ch s hexa ( h c s 16 ). V d:00:60:97:8F:4F:86 hoc 00-60-97-8F-4F-86. Khun dng a ch MAC c chia lm 2 phn:

- 3 octet u xc nh hng sn xut, chu s qun l ca t chc IEEE.

- 3 octet sau do nh sn xut n nh.

Kt hp ta l c mt a ch MAC duy nht cho mt giao tip mng Ethernet. a ch MAC c s dng lm a ch ngun v a ch ch trong khung Ethernet.

1.3. Cc loi khung Ethernet

1.3.1. Cc khung unicast

Gi s trm 1 cn truyn khung ti trm 2.

Khung Ethernet do trm 1 to ra c a ch:

- MAC ngun: 00-60-08-93-DB-C1

- MAC ch: 00-60-08-93-AB-12

8

Hnh 1: M hnh truyn thng unicast.

y l khung unicast. Khung ny c truyn ti mt trm xc nh. Tt c cc trm trong phn on mng trn s u nhn c khung ny nhng:

- Ch c trm 2 thy a ch MAC ch ca khung trng vi a ch MAC ca giao tip mng ca mnh nn tip tc x l cc thng tin khc trong khung.

- Cc trm khc sau khi so snh a ch s b qua khng tip tc x l khung na.

1.3.2. Cc khung broadcast

Cc khung broadcast c a ch MAC ch l FF-FF-FF-FF-FF-FF. Khi nhn c cc khung ny, mc d khng trng vi a ch MAC ca giao tip mng ca mnh nhng cc trm u phi nhn khung v tip tc x l.

Giao thc ARP s dng cc khung broadcast ny tm a ch MAC tng ng vi mt a ch IP cho trc. Mt s giao thc nh tuyn cng s dng cc khung broadcast cc router trao i bng nh tuyn.

1.3.3. Cc khung multicast

Trm ngun gi khung ti mt s trm nht nh ch khng phi l tt c. a ch MAC ch ca khung l a ch c bit m ch cc trm trong cng nhm mi chp nhn cc khung gi ti a ch ny.

1.4. Truy nhp bus

Mt vn ln thng gy lo ngi trong vic s dng Ethernet cp trng l phng php truy nhp bus ngu nhin CSMA/CD ( Carrier Sense Multiple Access with Collision Avoidance ) v s nh hng ti hiu sut cng nh tnh nng thi gian

9

thc ca h thng. y, mt trong nhng yu t quyt nh ti hiu sut ca h thng l thut ton tnh thi gian truy nhp li cho cc trm trong trng hp xy ra xung t.

Hnh 2: Minh ha phng php CSMA/CD.

Nguyn tc lm vic phng php CSMA/CD:

Theo phng php CSMA/CD, mi trm u c quyn truy nhp bus m khng cn mt s kim sot no. Phng php c tin hnh nh sau:

- Mi trm u phi t nghe ng dn (carrier sense), nu ng dn ri (khng c tn hiu ) th mi c pht.

- Do vic lan truyn tn hiu cn mt thi gian no , nn vn c kh nng hai trm cng pht tn hiu ln ng dn. Chnh v vy, trong khi pht th mi trm vn phi nghe ng dn so snh tn hiu pht i vi tn hiu nhn c xem c xy ra xung t hay khng (collision detection).

- Trong trng hp xy ra xung t, mi trm u phi hy b bc in ca mnh, ch mt thi gian ngu nhin v th gi li.

Mt tnh hung xy ra xung t tiu biu v cch khc phc c minh ha trn hnh... Trm A v C cng nghe ng dn. ng dn ri nn A c th gi trc. Trong khi tn hiu t trm A gi i cha kp ti nn trm C khng hay bit v cng

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gi, gy ra xung t ti mt im gn C. A v C s ln lt nhn c tn hiu phn hi, so snh vi tn hiu gi i v pht hin xung t. C hai trm s cng phi hy b bc in gi i bng cch khng pht tip, cc trm mun nhn s khng nhn c c hiu kt thc bc in v s coi nh bc in khng hp l. A v C cng c th gi i mt tn hiu jam c bit bo cho cc trm cn nhn bit. Sau mi trm s ch mt thi gian ch ngu nhin, trc khi th pht li. Thi gian ch ngu nhin y tuy nhin phi c tnh theo mt thut ton no sao cho thi gian ch ngn mt cch hp l v khng ging nhau gia cc trm cng ch. Thng thng thi gian ch ny l bi s ca hai ln thi gian lan truyn tn hiu Ts.

u im ca CSMA/CD l tnh cht n gin, linh hot. Khc vi cc phng php tin nh, vic ghp thm hay b i mt trm trong mng khng nh hng g ti hot ng ca h thng. Chnh v vy, phng php ny c p dng rng ri trong mng Ethernet.

Nhc im ca CSMA/CD l tnh cht bt nh ca thi gian phn ng. Cc trm u bnh ng nh nhau nn qu trnh ch mt trm c th lp i lp li, khng xc nh c tng i chnh xc thi gian. Hiu sut s dng ng truyn v th cng thp. R rng, nu nh khng kt hp thm vi cc k thut khc th phng php ny khng thch hp vi cc cp thp, i hi trao i d liu nh k, thi gian thc.

1.5. Cc loi mng Ethernet

IEEE pht trin chun Ethernet trn nhiu cng ngh truyn dn khc nhau v th c nhiu loi mng Ethernet. Mi loi mng c m t da theo ba yu t: tc , phng thc tn hiu s dng v c tnh ng truyn vt l.

1.5.1. Cc h thng Ethernet 10Mb/s

- 10Base5. y l tiu chun Ethernet u tin, da trn cp ng trc loi dy. Tc t c 10 Mb/s, s dng bng tn c s, chiu di cp ti a cho 1 phn on mng l 500m.

- 10Base2. C tn khc l thin Ethernet , da trn h thng cp ng trc mng vi tc 10 Mb/s, chiu di cp ti a ca phn on l 185 m (IEEE lm trn thnh 200m).

- 10BaseT. Ch T l vit tt ca twisted: cp xon cp. 10BaseT hot ng tc 10 Mb/s da trn h thng cp xon cp Cat 3 tr ln.

11

- 10BaseF. F l vit tt ca Fiber Optic ( si quang). y l chun Ethernet dng cho si quang hot ng tc 10 Mb/s , ra i nm 1993.

1.5.2. Cc h thng Ethernet 100 Mb/s Ethernet cao tc ( Fast Ethernet )

- 100BaseT. Chun Ethernet hot ng vi tc 100 Mb/s trn c cp xon cp ln cp si quang.

- 100BaseX. Ch X ni ln c tnh m ha ng truyn ca h thng ny (s dng phng php m ho 4B/5B ca chun FDDI). Bao gm 2 chun 100BaseFX v 100BaseTX:

100BaseFX. Tc 100Mb/s, s dng cp si quang a mode.

100BaseTX. Tc 100Mb/s, s dng cp xon cp.

100BaseT2 v 100BaseT4. Cc chun ny s dng 2 cp v 4 cp cp xon cp Cat 3 tr ln tuy nhin hin nay hai chun ny t c s dng.

1.5.3. Cc h thng Giga Ethernet

- 1000BaseX. Ch X ni ln c tnh m ho ng truyn ( chun ny da trn kiu m ho 8B/10B dng trong h thng kt ni tc cao Fibre Channel c pht trin bi ANSI). Chun 1000BaseX gm 3 loi:

1000Base-SX: tc 1000 Mb/s, s dng si quang vi sng ngn.

1000Base-LX: tc 1000 Mb/s, s dng si quang vi sng di.

1000Base-CX: tc 1000 Mb/s, s dng cp ng.

- 1000BaseT. Hot ng tc Giga bit, bng tn c s trn cp xon cp Cat 5 tr ln. S dng kiu m ho ng truyn ring t c tc cao trn loi cp ny.

1.6. Chun IEEE 802

IEEE 802 l h cc chun IEEE dnh cho cc mng LAN v mng MAN (metropolitan area network). C th hn, cc chun IEEE 802 c gii hn cho cc mng mang cc gi tin c kch thc a dng. (Khc vi cc mng ny, d liu trong cc mng cell-based c truyn theo cc n v nh c cng kch thc c gi l cell. Cc mng Isochronous, ni d liu c truyn theo mt dng lin tc cc octet, hoc nhm cc octet, ti cc khong thi gian u n, cng nm ngoi phm vi ca chun ny).

12

Cc dch v v giao thc c c t trong IEEE 802 nh x ti hai tng thp (tng lin kt d liu v tng vt l ca m hnh 7 tng OSI. Thc t, IEEE 802 chia tng lin kt d liu OSI thnh hai tng con LLC (iu khin lin kt lgic) v MAC (iu khin truy nhp mi trng truyn), do cc tng ny c th c lit k nh sau:

- Tng lin kt d liu

- Tng con LLC

- Tng con MAC

- Tng vt l

H chun IEEE 802 c bo tr bi Ban Tiu chun LAN/MAN IEEE 802 (IEEE 802 LAN/MAN Standards Committee (LMSC)). Cc chun c dng rng ri nht l dnh cho h Ethernet, Token Ring, mng LAN khng dy, cc mng LAN dng bridge v bridge o (Bridging and Virtual Bridged LANs). Chun dnh cho h Ethernet l chun IEEE 802.3.

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CHNG 2. H GIAO THC TCP/IP

2.1. H giao thc TCP/IP

TCP/IP l vit tt ca Transmission Control Protocol / Internet Protocol (Giao thc iu Khin Truyn Thng /Giao thc Internet). TCP/IP khng ch gm 2 giao thc m thc t n l tp hp ca nhiu giao thc. TCP/IP s dng m hnh truyn thng 4 tng hay cn gi l m hnh DoD (M hnh ca B Quc Phng M). Cc tng trong m hnh ny l:

- Tng ng Dng (Application Layer).

- Tng Giao Vn (Transport Layer).

- Tng Lin Mng (Internet Layer).

- Tng Giao Tip Mng (Network Interface Layer).

Hnh 3: Cu trc h giao thc TCP/IP.

2.1.1. Tng ng Dng (Application Layer)

Gm nhiu giao thc cung cp cho cc ng dng ngi dng. c s dng nh dng v trao i thng tin ngi dng. 1 s giao thc thng dng trong tng ny l:

- DHCP (Dynamic Host Configuration Protocol): Giao thc cu hnh trm ng.

- DNS (Domain Name System): H thng tn min.

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- SNMP (Simple Network Management Protocol): Giao thc qun l mng n gin.

- FTP (File Transfer Protocol): Giao thc truyn tp tin.

- TFTP (Trivial File Transfer Protocol): Giao truyn tp tin bnh thng.

- SMTP (Simple Mail Transfer Protocol): Giao thc gi th n gin.

- TELNET: l chng trnh m phng thit b u cui cho php ngi dng login vo mt my ch t mt my tnh no trn mng.

Tng ng dng trao i d liu vi lp di (lp vn chuyn) qua cng. Vic dng cng bng s cho php giao thc ca lp vn chuyn bit loi ni dung no cha bn trong gi d liu. Nhng cng c nh bng s v nhng ng dng chun thng dng cng cng. V d: giao thc FTP dng cng 20 cho d liu v cng 21 cho iu khin, giao thc SMTP dng cng 25

2.1.2. Tng Giao Vn (Transport Layer)

C trch nhim thit lp phin truyn thng gia cc my tnh v quy nh cch truyn d liu. 2 giao thc chnh trong tng ny gm:

- UDP (User Datagram Protocol): Cn gi l Giao Thc Gi Ngi Dng. UDP cung cp cc knh truyn thng phi kt ni nn n khng m bo truyn d liu 1 cch tin cy. Cc ng dng dng UDP thng ch truyn nhng gi c kch thc nh, tin cy d liu ph thuc vo tng ng dng.

- TCP (Transmission Control Protocol): Ngc li vi UDP, TCP cung cp cc knh truyn thng hng kt ni v m bo truyn d liu 1 cch tin cy. TCP thng truyn cc gi tin c kch thc ln v yu cu pha nhn xc nhn v cc gi tin nhn.

2.1.3. Tng Internet (Internet Layer)

Nm bn trn tng truy nhp mng. Tng ny c chc nng gn a ch, ng gi v nh tuyn (Route) d liu. 4 giao thc quan trng nht trong tng ny gm:

- IP (Internet Protocol): C chc nng gn a ch cho d liu trc khi truyn v nh tuyn chng ti ch.

- ARP (Address Resolution Protocol): C chc nng bin dch a ch IP ca my ch thnh a ch MAC.

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- ICMP (Internet Control Message Protocol): C chc nng thng bo li trong trng hp truyn d liu b hng.

- IGMP (Internet Group Management Protocol): C chc nng iu khin truyn a hng (Multicast) .

2.1.4. Lp giao tip mng

Tng giao tip mng lin quan ti vic trao i d liu gia hai trm thit b trong cng mt mng. Cc chc nng bao gm vic kim sot truy nhp mi trng truyn dn, kim sot li v lu thng d liu. Datagram c to t lp Internet s c gi xung ti lp truy nhp mng nu truyn d liu, hoc tng giao tip mng s ly d liu t mng v gi n ti lp Internet nu chng ta nhn d liu. Nh cp phn trn, Ethernet l giao thc cp di c ba lp LLC ( Logic Link Control ), MAC ( Media Access Control ) v lp vt l Physical.

2.2. Cu trc gi tin IP,TCP,UDP

2.2.1. Cu trc a ch IP

Mng Internet dng h thng a ch IP (32 bit) "nh v" cc my tnh lin kt vi n. C hai cch nh a ch ph thuc vo cch lin kt ca tng my tnh c th.

Nu cc my tnh c kt ni trc tip vi mng Internet th NIC (Network Information Centre) s cp cho cc my tnh mt a ch IP (IP Address).

Nu cc my tnh khng kt ni trc tip vi mng Internet m thng qua mt mng cc b th ngi qun tr mng s cp cho cc my tnh mt a ch IP (tuy nhin cng di s cho php ca NIC).

H thng a ch ny c thit k mm do qua mt s phn lp, c 5 lp a ch IP l : A, B, C, D, E. S khc nhau c bn gia cc lp a ch ny l kh nng t chc cc cu trc con ca n.

16

Bng 2: T chc a ch IP.

- a ch lp A: Lp A s dng byte u tin ca 4 byte nh a ch mng. Nh hnh trn, n c nhn ra bi bit u tin trong byte u tin ca a ch c gi tr 0. 3 bytes cn li c s dng nh a ch my trong mng. C 126 a ch lp A (c nh a ch trong byte th nht) vi s my tnh trong mng l 2563 - 2 = 16.777.214 my cho mi mt a ch lp A (s dng 3 bytes nh a ch my).

- a ch lp B: Mt a ch lp B c nhn ra bi 2 bit u tin ca byte th nht mang gi tr 10. Lp B s dng 2 byte u tin ca 4 byte nh a ch mng v 2 byte cui nh a ch my trong mng. C 64*256 - 2 = 16.128 a ch mng lp B vi 65.534 my cho mi mt a ch lp B.

- a ch lp C: Mt a ch lp C c nhn ra vi 3 bit u mang gi tr 110. Mng lp C s dng 3 byte u nh a ch mng v 1 byte cui nh a ch my tnh c trong mng. C 2.097.152 -2 a ch lp C, mi a ch lp C c 254 my.

- a ch lp D: Dng gi cc IP datagram ti mt nhm cc host trn mt mng.

- a ch lp E: Dng d phng v dng trong tng lai.

2.2.2. Cu trc gi tin IP

- Ver-4 bt: ch version hin hnh ca ip ang c dng, nu trng ny khc vi phin bn IP ca thit b nhn, thit b nhn s loi b cc gi tin ny.

- IHL(IP Header Length)-4bt: ch di phn header ca gi tin, tnh theo t 32 bt.

8 16 24

Class A Netid Hostid

Class B Netid Hostid

Class C Netid Hostid

Class D Multicast address

Class E Reverved for future use

17

- TOS(Type of Service)-1byte: cho bit dch v no m gi tin mun s dng chng hn nh u tin, thi hn chm tr, nng sut truyn v tin cy. C th nh sau:

3 bt u (Precedence) ch quyn u tin gi gi tin, t gi tin bnh thng l 0 n gi tin kim sot mng l 7.

1 bt tip theo (Delay) ch tr yu cu, 0 ng vi gi tin c tr bnh thng, 1 ng vi gi tin c tr thp.

1 bt tip theo (Throughput) ch thng lng yu cu s dng truyn gi tin vi la chn truyn trn ng thng sut thp hay trn ng thng sut cao, 0 ng vi thng lng bnh thng, 1 ng vi thng lng cao.

1 bt tip theo (Reliability) ch tin cy yu cu, 0 ng vi tin cy bnh thng, 1 ng vi tin cy cao.

- Total Length-2byte:ch di ton b gi tin tnh c phn header, tnh theo n v byte.

- Indentification-16 bt: cng vi cc tham s khc nh Source Address, Destination Address dng nh danh duy nht mt gi tin trong thi gian n tn ti

trn mng.

- Flags: Cc gi tin khi truyn trn ng i c th b phn thnh nhiu gi tin nh. Trng Flags dng iu khin phn on v lp ghp gi tin. C th nh sau:

Bt 0: cha s dng, lun ly gi tr 0

Bt 1: 0 ng vi gi tin b phn mnh, 1 ng vi gi tin khng b phn mnh.

Bt 2: 0 ng vi gi tin thuc phn on cui cng ca gi tin gc, 1 ng vi gi tin khng phi l phn on cui cng ca gi tin gc.

- Fragment Offset-13bt: ch v tr ca phn on trong gi tin gc, tnh theo n v 8 byte.

- Time To Live-1byte: quy nh thi gian tn ti tnh bng giy ca gi tin trong mng. Thi gian ny c t bi trm gi v gim i (thng quy c l 1) khi gi tin i qua mi router ca lin mng. Mt gi tr ti thiu phi ln mng hot ng tt.

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- Protocol: Ch tng giao thc k tip s nhn vng d liu trm ch. TCP c ng vi gi tr 6, UDP ng vi gi tr 17, 1 ng vi ICMP.

- Header Checksum-2byte: Dng pht hin li header ca gi tin xy ra trong qu trnh truyn ca n.

- Source IP Address-4byte: a ch IP ca ni truyn gi tin.

- Destination IP Address-4byte: a ch IP ca ni nhn gi tin.

- IP Option- di thay i: Khai bo cc la chn do ngi s dng yu cu, v d nh: mc bo mt, ng m gi tin c gi i, timestamp mi router.

- Padding- di thay i: Dng m bo phn header lun kt thc mt mc 32 bt.

- Data: cha thng tin lp trn ,chiu di thay i n 64Kb.

2.2.3. Cu trc gi tin TCP

n v d liu trong TCP c gi l Segment vi cu trc nh sau:

- Source Port-2 byte: s hiu cng TCP ca trm ngun.

- Destination Port-2byte: s hiu cng TCP ca trm ch.

- Sequence number: s hiu ca byte u tin ca segment, nu c SYN bt th n l s th t gi ban u v byte u tin c gi c s th t ny cng thm 1. Nu khng c c SYN th y l s th t ca byte u tin.

- Acknowledgment Number-2byte: nu c ACK bt th gi tr ca trng chnh l s th t gi tin tip theo m bn nhn cn. Bo l nhn tt cc segment m trm ch gi cho trm ngun.

- Data offset-4bit: di ca phn header tnh theo n v t 32 bit. Tham s ny ch ra v tr bt u ca ngun d liu.

- Reserved-6 bt.

- Flags: cc bt iu khin

URG: Vng con tr khn (Urgent pointer) c hiu lc

ACK: Vng bo nhn ACK number c hiu lc

PSH: Chc nng PUSH

RST: khi ng li lin kt

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SYN: ng b ho s hiu tun t

FIND: khng cn d liu t trm ngun

- Window-2byte: s byte d liu bt u t byte c ch ra trong ACK number m trm ngun sn sng nhn.

- Checksum: checksum cho c phn header ln d liu.

- Urgent Pointer-2byte: nu c URG bt th gi tr trng ny chnh l s t 16 bit m s th t gi tin (sequence number) cn dch tri.

- Option-2byte: vng tu chn, khai bo cc option ca TCP trong c di ti a ca vng TCP data trong mt segment.

- Padding: phn chn thm vo header m bo phn header lun kt thc mt mc 32 bt

- TCP data: cha d liu ca tng trn c di ti a ngm nh l 536byte. Gi tr ny c th khai bo trong trng Option.

2.2.4. Cu trc gi tin UDP

Vng header ca UDP c 64 bt vi 4 trng :

- Source Port-2byte: xc nh cng ca ngi gi thng tin v c ngha nu mun nhn thng tin phn hi t ngi nhn. Nu khng th t n bng 0.

- Destination Port-2byte: xc nh cng nhn thng tin v trng ny l cn thit.

- Length-2byte: l chiu di ca ton b gi tin(phn header v phn d liu). Chiu di ti thiu l 8 byte khi gi tin khng c d liu, ch c header.

- Checksum-2byte: dng cho vic kim tra li ca phn header v phn d liu.

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CHNG 3. PHN CNG

3.1. Vi iu khin PIC 18F67J60

3.1.1. Cc c trng ca PIC 18F67J60

Vi iu khin PIC18F67J60 l mt vi iu khin thuc dng vi iu khin PIC19F97J60, do n c cc c trng chung ca h vi iu khin ny.

3.1.1.1. Cc c trng chung:

- S dng thch anh 25MHz cho ng dng Ethernet.

- B nh chng trnh 128Kbyte ( 65532 lnh).

- B nh d liu 3808 byte.

- C 39 chn I/O thuc cc port A,B,C,D,E,F,G.

- C 5 b Timer:

Timer0 : vn hnh nh l 1 b nh thi 8 bit hoc 16 bit, 1 b m.

Timer1 : vn hnh nh l 1 b nh thi 8 bit, 1 b m.

Timer2 : vn hnh nh l 1 b nh thi 8 bit, 1 b m.

Timer3 : vn hnh nh l 1 b nh thi 16 bt, 1 b m.

Timer4 : vn hnh nh l 1 b nh thi 8 bt, 1 b m.

- C 2 module Capture/Compare/PWM.

- C 3 module EnhancedCapture/Compare/PWM.

- Cc giao tip ni tip MSSP (Master Synchronous Serial Port) v Enhanced USART (Universal asynchronous receiver/transmitter).

- C 11 knh chuyn i A/D 10 bit.

3.1.1.2. c trng Ethernet:

- S dng chun IEEE 802.3.

- Tch hp MAC v 10Base-T PHY.

- 8 kbyte b nh m SRAM lu tr cc gi tin truyn/nhn.

- C 2 led ch trng thi hot ng.