MPMC unit-5 .ppt

7/21/2019 MPMC unit-5 .ppt

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MP&MC R09 III/IV-ECE

UNIT – VCOMMUNICATION INTERFACE

1

JNTUH



INDEX

• About Serial communication

• Serial Communication Standards

• RS 232

• USART (8251)

• !!! "88

•2#mA Current $oo%

2



About Serial cou!icatio!

• Trans&errin' o& ata oer lon' distances usin' %arallel communication is cost e&&ectie and it is not %ossible &or slo*er deices+

• n serial communication one bit is trans&erred at atime oer a sin'le c,annel+

• Serial communication is classi&ied in to

• 1+ Sim%le-

• 2+ u%le-

• 3+ Hal& u%le-3



About Serial cou!icatio! "Co!t#$

T*o Transmission .ormats1+As/nc,ronous

2+S/nc,ronous

"



About Serial cou!icatio! (Contd)

5



RS %%

It i' t(e o't coo!l) u'e#

RS *%%

It i' a (i+( ',ee# #i+ital i!terace

RS *%

It ca! be u'e# or +reater #i'ta!ce'.

RS **9

U'e# or ,oi!t to ,oi!t or ulti#ro, "o!e 'e!#er u, to 0reci,ie!t'$ cou!icatio!'.

RS *12

It ca! (a!#le (i+( ',ee#' a!# lo!+ cable #i'ta!ce' u, to *000 eet.

Serial Communication Standards

0



RS 232

RS232 (Recommended standard232) is a standard inter&acea%%roed b/ t,e !lectronic ndustries Association (!A) &orconnectin' serial deices+

RS232 is t,e inter&ace t,at /our com%uter uses to tal to ande-c,an'e data *it, /our modem and ot,er serial deices+ T,e serial

%orts on most com%uters use a subset o& t,e RS232C standard+

!A introduced RS232 in 1402





RS 232 (Contd) $ine riers6 Receiers

4



RS 232 (Contd) $imitations

• ue to t,e sin'le 7N connection t,e C! andT! must lie in same %lace+

• As t,e aud rate and line len't, increases6 T ,ee&&ect o& ca%acitance bet*een t,e cables causesnoise+

1#



USART "1%2$ 3loc4 5ia+ra

11



USART "1%2$ PIN 5ia+ra

12

1%2 i' ,ro+rae# b) u'i!+ t(ree co!trol

re+i'ter'.Mo#e Re+i'ter%.Statu' Re+i'ter

.Coa!# Re+i'ter



Asynchronous Mode 8251

Tra!'i''io!9

• :,en data c,aracter is sent b/ C;U to 8251 6it adds

start bits6 o%tional %arit/ and sto% bits usin'

As/nc,ronous mode control re'ister &ormat+

• T,is se<uence is t,en transmitted usin' T= out%ut

%in on t,e &allin' ed'e o& T=C+

• Transmission re<uires 1 or 2 sto% bits

• T= out%ut remains ,i', until it detects brea+

13



Asynchronous Mode 8251 (Contd)

Reception:

• In Asynchronous mode the CLK frequency

(RXC and TXC i/p) is equa to ! or !" or "#times the $aud rate%

• &aud rate' o% of data $its transmitted/receiedper sec%

• The $it counter ocates start * parity and stop$its%

• Receier requires ony one stop $it%1"



Asynchronous Mode 8251 (Contd)

• Reception:Reception:

• If +arity ,rror occurs* +arity ,rror -a. is set%

• If a o ee is detected as the stop $it *-ramin. ,rror -a. is set

• If the preious character in the receier $ufferhas not $een read $y the C+0* that data isoerride $y the ne1t data and 2er Run -a. isset%

• A these fa.s are ocated in 3tatus Re.ister of

456!15

USART "1%2$ A ( M #



USART "1%2$ A')!c(ro!ou' Mo#eI!'tructio! Forat"Mo#e Re+i'ter$

10

USART "1%2$ S ( M # I t ti



USART "1%2$ S)!c(ro!ou' Mo#e I!'tructio!Forat"Mo#e Re+i'ter$

1



3tatus Re.ister -ormat for 03ART



IEEE *11

• I,,,7#44 is a short7ran.e di.itacommunications $us specification%

•I,,,7#44 is an 47$it 5# pin $us%

• The $us empoys si1teen si.na ines

• ,i.ht used for $i7directiona data transfer

• Three for handsha8e

• -ie for $us mana.ement

• ,i.ht .round return ines% 14



IEEE *11 Co!!ector

T,is standard *as &irst establis,ed in 148US $N!ST,e !!!"88 bus is a multidro% inter&ace in *,ic, all connecteddeices ,ae access to t,e bus lines+ T,e 2" bus lines 'rou% into&our cate'ories9 ata $ines !i',t lines (>1 t,rou', >8) used to trans&erin&ormation (data and commands) bet*een deices on t,e bus6 one

b/te at a time+

Hands,ae $ines T,ree lines used to ,ands,ae t,e trans&er o&in&ormation across t,e data lines9

A?9 ata ?alid NAC9 Not ata Acce%ted NR.9 Not Read/ &or ata 2#



us @ana'ement $ines .ie lines used &or 'eneral controland coordination o& bus actiities9 ATN9 Attention .C9 nter&ace Clear R!N9 Remote !nable SR9 Serice Re<uest !>9 !nd or denti&/ 7round $ines !i',t lines used &or s,ieldin' and si'nal

returns9 >ne S,ield >ne 7eneral Si'nal 7round Si- lo'ic 'round lines %aired o&& *it, ATN6 SR6 .C6

NAC6 NR. and A?

IEEE *11 Co!!ector "c!t#6$



IEEE *11 Advantaes

3impe hardare interface

,ase of connectin. mutipe deice to a sin.e

host Aos mi1in. of so and fast deices

9e7esta$ished and mature* idey supported

Ru..ed connectors* hed in pace $y scres*means ca$es cant easiy $e accidentayremoed as they can ith -ire ire and 03&

22



IEEE *11 Disadvantaes

;echanicay $u8y connectors and ca$es

Limited speed and e1pansion

Lac8 of command protoco standards

o mandatory .aanic isoation $eteen $us anddeices

<i.h cost (compared to R3 5=5/03&/

-ire ire/,thernet)

Limited aaia$iity (a.ain compared to R3 5=5 /03&/

-ireire/,thernet) 23

%0 A C 7



%0A Curre!t 7oo,

.or di'ital serial communications6 a current loo% is acommunication inter&ace t,at uses current instead o& olta'e&or si'nalin'+

Current loo%s can be used oer moderatel/ lon' distances(tens o& ilometres)+

$on' be&ore t,e RS232 standard6 current loo%s *ere used tosend di'ital data in serial &orm &or tele%rinters+

>lder telet/%es used a 0# mA current loo%+ $ater mac,ineso%erated on a lo*er 2# mA current leel+

@ost earl/ minicom%uters &eatured a 2# mA current loo%inter&ace6 *it, an RS232 %ort 'enerall/ aailable as a more

e-%ensie o%tion+2"



!u""#dup"e$ 2% &A Curre!t 7oo, Circuit

Anot,er *a/ &or leaa'e current control is inserts

25



'i&p"e$ 2% &A Curre!t 7oo, Circuit

20



AN* +,-

2

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MPMC unit-5 .ppt