1 architecture of 8051 microcontroller.pdf

8/10/2019 1 ARCHITECTURE OF 8051 MICROCONTROLLER.pdf

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It $"s "&"**%* I@O o&t: o&t0 o&t1 o&t? o&t3. E"'$ o&t is 82#it

i&%'tio)"* I@O o&t. E"'$ o&t is #it@#!t% " &%ss"#*%.

It $"s t+o 16 #it mu*ti2mo % &o,&"mm"#*% tim%&@'ou)t%&

It $"s mu*ti2mo % $i,$ s %% &o,&"mm"#*% (u** u *% s%&i"* o&t. It $"s 5 $"& +"&% i)t%&&u t: 3 i)t%&)"* i)t%&&u t ") ? % t%&)"*

i)t%&&u t. A** 5 i)t%&&u t "&% o %&"t% i) t+o &io&it! *%/%*

It $"s o) '$i o+%& s"/i), 'i&'uit o %&"t% i) t+o mo %s: 1. i *% mo % ?.

Po+%& o+) mo %.

It $"s 11 s %'i"* (u)'tio) &%,ist%&. It $"s 111 i)st&u'tio)s 6 i)st&u'tio)s "&% si),*% '!'*%.

It $"s o) '$i ;oo*%") &o'%sso& (o& si),*% #it m")i u*"tio).

;*o'= Di",&"m o( 8051 Mi'&o'o)t&o**%&:

T$% #o'= i",&"m o( 8051 mi'&o'o)t&o**%& is % *"i)% #%*o+:

CPU (Central Processor Unit):

T$% C%)t&"* P&o'%sso& U)it o& CPU is t$% mi) o( ")! &o'%ssi), m"'$i)%. It

s'&uti)i9%s ") m")",%s "** &o'%ss%s t$"t "&% '"&&i% out i) t$%

Mi'&o'o)t&o**%&. Us%& $"s )o o+%& o/%& t$% (u)'tio)i), o( CPU. It i)t%& &%ts

&o,&"m &i)t% i) sto&",% s "'% ROMB ") '"&&i%s out "** o( t$%m ") o

t$% &o


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i)iti"t%s "utom"ti'"**! "s usu"*. T$%&% "&% 5 i)t%&&u t su *i%s i) 8051

Mi'&o'o)t&o**%& t+o out o( (i/% "&% %&i $%&"* i)t%&&u ts t+o "&% tim%&

i)t%&&u ts ") o)% is s%&i"* o&t i)t%&&u t.

Memory:

Mi'&o2'o)t&o**%& )%% s " &o,&"m +$i'$ is " s%t o( 'omm") s. T$is &o,&"m

%)*i,$t%)s Mi'&o'o)t&o**%& to %&(o&m &%'is% t"s=s. T$%s% &o,&"ms )%% "

sto&",% s "'% o) +$i'$ t$%! '") #% "''umu*"t% ") i)t%& &%t #!

Mi'&o'o)t&o**%& to "'t u o) ")! s %'i(i' &o'%ss. T$% m%mo&! +$i'$ is

#&ou,$t i)to *"! to "''umu*"t% t$% &o,&"m o( Mi'&o'o)t&o**%& is &%'o,)i9%

"s P&o,&"m m%mo&! o& 'o % m%mo&!. I) 'ommo) *"),u",% it s "*so =)o+) "s

R%" O)*! M%mo&! o& ROM.

Mi'&o2'o)t&o**%& "*so )%% s " m%mo&! to "m"ss "t" o& o %&") s (o& t$% s$o&t

t%&m. T$% sto&",% s "'% +$i'$ is %m *o!% to mom%)t"&i*! "t" sto&",% (o&

(u)'tio)i), is "'=)o+*% ,% "s D"t" M%mo&! ") +% %m *o! R") om A''%ss

M%mo&! o& RAM (o& t$is &i)'i *% &%"so). Mi'&o'o)t&o**%& 8051 'o)t"i)s 'o %

m%mo&! o& &o,&"m m%mo&! so t$"t it $"s ; Rom ") it "*so 'om &is%

o( "t" m%mo&! RAMB o( 1?8 #!t%s.

Bus:

Fu) "m%)t"**! ;us is " ,&ou o( +i&%s +$i'$ (u)'tio)s "s " 'ommu)i'"tio)

'")"* o& m%") (o& t$% t&")s(%& D"t". T$%s% #us%s 'om &is% o( 8 16 o& mo&%

'"#*%s. As " &%su*t " #us '") #%"& 8 #its 16 #its "** to,%t$%&. T$%&% "&% t+o

t! %s o( #us%s:

1. Address Bus: Mi'&o'o)t&o**%& 8051 'o)sists o( 16 #it " &%ss #us. It is

#&ou,$t i)to *"! to " &%ss m%mo&! ositio)s. It is "*so uti*i9% to

t&")smit t$% " &%ss (&om C%)t&"* P&o'%ssi), U)it to M%mo&!.

2. Data Bus: Mi'&o'o)t&o**%& 8051 'om &is% o( 8 #its "t" #us. It is

%m *o!% to '"&t "t".

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Oscillator:

Mi'&o'o)t&o**%& 8051 'o)sists o( ") o)2'$i os'i**"to& +$i'$ toi*s "s " tim%

sou&'% (o& CPU C%)t&"* P&o'%ssi), U)itB. As t$% &o u'ti/it! t$um s o(

os'i**"to& "&% st%" ! "s " &%su*t it ("'i*it"t%s $"&mo)i9% %m *o!m%)t o( "**

i%'%s o( 8051 Mi'&o'o)t&o**%&.

Input output Port:

Mi'&o2'o)t&o**%& 8051 'o)sists o( i) ut@out ut o&ts to u)it% it to ot$%&

%&i $%&"*s.

!imers Counters:Mi'&o2'o)t&o**%& 8051 is i)'o& o&"t% +it$ t+o 16 #it 'ou)t%&s tim%&s. T$%

'ou)t%&s "&% s% "&"t% i)to 8 #it &%,ist%&s. T$% tim%&s "&% uti*i9% (o&

m%"su&i), t$% i)t%&/"*s to (i) out u*s% +i t$ %t'.

"pecial #unction $e%isters ("#$s)

%'i"* Fu)'tio) R%,ist%&s FRsB "&% " so&t o( 'o)t&o* t"#*% us% (o& &u))i),

") mo)ito&i), t$% o %&"tio) o( t$% mi'&o'o)t&o**%&. E"'$ o( t$%s% &%,ist%&s"s +%** "s %"'$ #it t$%! i)'*u % $"s its )"m% " &%ss i) t$% s'o % o( RAM

") &%'is%*! %(i)% u& os% su'$ "s tim%& 'o)t&o* i)t%&&u t 'o)t&o* s%&i"*

'ommu)i'"tio) 'o)t&o* %t'. E/%) t$ou,$ t$%&% "&% 1?8 m%mo&! *o'"tio)s

i)t%) % to #% o''u i% #! t$%m t$% #"si' 'o&% s$"&% #! "** t! %s o( 8051

mi'&o'o)t&o**%&s $"s o)*! ?1 su'$ &%,ist%&s. R%st o( *o'"tio)s "&%

i)t%)tio)"**! *%(t u)o''u i% i) o& %& to %)"#*% t$% m")u("'tu&%&s to (u&t$%&

%/%*o mi'&o'o)t&o**%&s =%% i), t$%m 'om "ti#*% +it$ t$% &%/ious /%&sio)s.

A $e%ister (Accumulator)

A &%,ist%& is " ,%)%&"*2 u& os% &%,ist%& us% (o& sto&i), i)t%&m% i"t% &%su*ts

o#t"i)% u&i), o %&"tio). P&io& to % %'uti), ") i)st&u'tio) u o) ")!

)um#%& o& o %&") it is )%'%ss"&! to sto&% it i) t$% "''umu*"to& (i&st. A**

&%su*ts o#t"i)% (&om "&it$m%ti'"* o %&"tio)s %&(o&m% #! t$% ALU "&%

sto&% i) t$% "''umu*"to&. D"t" to #% mo/% (&om o)% &%,ist%& to ")ot$%&must ,o t$&ou,$ t$% "''umu*"to&. I) ot$%& +o& s t$% A &%,ist%& is t$% most

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#$"! #$1 - #egister ban% select bits. These two bits are used to select one of

four register ban%s of #&'. B setting and clearing these bits! registers #"-#)

are stored in one of four ban%s of #&'.

*" - *lag ". This is a general-purpose bit available for use.

&+ - &u,iliar +arr *lag is used for B+ operations onl .

+ - +arr *lag is the (ninth au,iliar bit used for all arithmetical

operations and shift instructions.

Data Pointer $e%ister (DP!$)

DPTR &%,ist%& is )ot " t&u% o)% #%'"us% it o%s) t $!si'"**! % ist. It 'o)sistso( t+o s% "&"t% &%,ist%&s: DPH D"t" Poi)t%& Hi,$B ") D"t" Poi)t%& Lo+B.

Fo& t$is &%"so) it m"! #% t&%"t% "s " 162#it &%,ist%& o& "s t+o i) % %) %)t 82

#it &%,ist%&s. T$%i& 16 #its "&% &im"&i*! us% (o& % t%&)"* m%mo&!

" &%ssi),. ;%si %s t$% DPTR R%,ist%& is usu"**! us% (o& sto&i), "t" ")

i)t%&m% i"t% &%su*ts.

"tac+ Pointer ("P) $e%ister

A /"*u% sto&% i) t$% t"'= Poi)t%& oi)ts to t$% (i&st (&%% st"'= " &%ss ")

%&mits st"'= "/"i*"#i*it!. t"'= us$%s i)'&%m%)t t$% /"*u% i) t$% t"'=

Poi)t%& #! 1. Li=%+is% st"'= o s %'&%m%)t its /"*u% #! 1. U o) ")! &%s%t

") o+%&2o) t$% /"*u% 7 is sto&% i) t$% t"'= Poi)t%& +$i'$ m%")s t$"t

t$% s "'% o( RAM &%s%&/% (o& t$% st"'= st"&ts "t t$is *o'"tio). I( ")ot$%&

/"*u% is +&itt%) to t$is &%,ist%& t$% %)ti&% t"'= is mo/% to t$% )%+ m%mo&!

*o'"tio).

P&, P1, P2, P- ' Input output $e%isters

I( )%it$%& % t%&)"* m%mo&! )o& s%&i"* 'ommu)i'"tio) s!st%m "&% us% t$%)

o&ts +it$i) tot"* o( 3? i) ut@out ut i)s "&% "/"i*"#*% (o& 'o))%'tio) to

%&i $%&"* %)/i&o)m%)t. E"'$ #it +it$i) t$%s% o&ts "((%'ts t$% st"t% ")

%&(o&m")'% o( " &o &i"t% i) o( t$% mi'&o'o)t&o**%&. T$us #it *o,i' st"t% is

&%(*%'t% o) " &o &i"t% i) "s " /o*t",% 0 o& 5 B ") /i'% /%&s" /o*t",% o)

" i) &%(*%'ts t$% st"t% o( " &o &i"t% o&t #it.

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E *")"tio) o) 8051 Pi) Di",&"m:

T$% 8051 i) i",&"m is % *"i)% #%*o+:

Pins 1 /:' &%'o,)i9% "s Po&t 1. Po&t 1 is " om%sti'"**! u**% u >u"si #i

i&%'tio)"* I) ut@out ut o&t.

Pin 0:' As m" % '*%"& &%/ious*! RE ET i) is uti*i9% to s%t t$% mi'&o2

'o)t&o**%& 8051 to its &im"&! /"*u%s +$%&%"s t$% mi'&o2'o)t&o**%& is

(u)'tio)i), o& "t t$% %"&*! #%,i))i), o( " *i'"tio). T$% RE ET i) $"s to #%

s%t %*%/"t% (o& t+o m"'$i)% &ot"tio)s.

Pins 1& 1 :' &%'o,)i9% "s Po&t 3. T$is o&t "*so su *i%s " )um#%& o( ot$%&

(u)'tio)s su'$ "s tim%& i) ut i)t%&&u ts s%&i"* 'ommu)i'"tio) i) i'"to&s

T D R D 'o)t&o* i) i'"to&s (o& outsi % m%mo&! i)t%&("'i), R RD %t'.

T$is is " om%sti' u** u o&t +it$ >u"si #i i&%'tio)"* o&t +it$i).

Pins 1/ and 10:' T$%s% "&% %m *o!% (o& i)t%&("'i), ") out%& '&!st"* to ,i/%

s!st%m '*o'=.

Pin 2&:' Tit*% "s ss it s!m#o*i9%s ,&ou) 0 B "sso'i"tio).

Pins' 21'2/:' &%'o,)i9% "s Po&t ? P ?.0 P ?.7B ot$%& t$") s%&/i), "s

I) ut@out ut o&t s%)io& o& %& " &%ss #us i) i'"to&s "&% mu*ti *% % +it$

t$is >u"si #i i&%'tio)"* o&t.

Pin' 20:' P&o,&"m to&% E)"#*% o& P EN is %m *o!% to i)t%& &%t si,) (&om

out%& &o,&"m m%mo&!.

Pin'-&:' E t%&)"* A''%ss o& EA i) ut is %m *o!% to %&mit o& &o$i#it out%&

m%mo&! i)t%&("'i),. I( t$%&% is )o out%& m%mo&! )%% t$is i) is &",,%

$i,$ #! *i)=i), it to ''.

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Pin'-1:' A &%ss L"t'$ E)"#*% o& ALE is #&ou,$t i)to *"! to %2mu*ti *%

t$% " &%ss "t" i) i'"tio) o( o&t 0 (o& out%& m%mo&! i)t%&("'i),B.

Pins -2'-0: &%'o,)i9% "s Po&t 0 P0.0 to P0.7B ot$%& t$") s%&/i), "s

I) ut@out ut o&t *o+ o& %& "t" " &%ss #us si,)"*s "&% mu*ti *% % +it$

t$is o&t to &o/i % t$% us% o( out%& m%mo&! i)t%&("'i),B. T$is i) is " #i

i&%'tio)"* I) ut@out ut o&t t$% si),*% o)% i) mi'&o'o)t&o**%& 8051B ")

out%& u** u &%sisto&s "&% )%'%ss"&! to uti*i9% t$is o&t "s I) ut@out ut.

Pin' &: t%&m% "s '' is t$% '$i%( o+%& su *!. ;! ") *"&,% it is G5 DC.

Cou)t%&s ") Tim%&s:

!MOD $e%ister (!imer Mode)

T$% TMOD &%,ist%& s%*%'ts t$% o %&"tio)"* mo % o( t$% tim%&s T0 ") T1. As

s%%) i) (i,u&% t$% *o+ #its #it0 2 #it3B &%(%& to t$% tim%& 0 +$i*% t$% $i,$

#its #it 2 #it7B &%(%& to t$% tim%& 1. T$%&% "&% o %&"tio)"* mo %s ") %"'$

o( t$%m is %s'&i#% .

!imer Control (!CO ) $e%ister

TCON &%,ist%& is "*so o)% o( t$% &%,ist%&s +$os% #its "&% i&%'t*! i) 'o)t&o* o(

tim%& o %&"tio). O)*! #its o( t$is &%,ist%& "&% us% (o& t$is u& os% +$i*%

&%st o( t$%m is us% (o& i)t%&&u t 'o)t&o*.

Po3er Control (PCO ) $e%ister

T$% u& os% o( t$% R%,ist%& PCON #its is:

MOD ;"u &"t% is t+i'% "s mu'$ $i,$%& #! s%tti), t$is #it. F1 %)%&"*2 u& os% #it "/"i*"#*% (o& us%B. F1 %)%&"*2 u& os% #it "/"i*"#*% (o& us%B. F0 %)%&"*2 u& os% #it "/"i*"#*% (o& us%B. PD ;! s%tti), t$is #it t$% mi'&o'o)t&o**%& %)t%&s t$% /ower own mo %. IDL ;! s%tti), t$is #it t$% mi'&o'o)t&o**%& %)t%&s t$% idle mo %.

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8051 ;LOC DIA RAM


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8051 PIN DIA RAM

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ATE1 %)"#*%s ") is"#*%s Tim%& 1 #! m%")s o( " si,)"* #&ou,$t to t$%INT1 i) P3.3B:1 2 Tim%& 1 o %&"t%s o)*! i( t$% INT1 #it is s%t.0 2 Tim%& 1 o %&"t%s &%,"& *%ss o( t$% *o,i' st"t% o( t$% INT1 #it.

C@T1 s%*%'ts u*s%s to #% 'ou)t% u #! t$% tim%&@'ou)t%& 1:1 2 Tim%& 'ou)ts u*s%s #&ou,$t to t$% T1 i) P3.5B.0 2 Tim%& 'ou)ts u*s%s (&om i)t%&)"* os'i**"to&.

T1M1 T1M0t$%s% t+o #its s%*%'t t$% o %&"tio)"* mo % o( t$% Tim%& 1. ATE0 %)"#*%s ") is"#*%s Tim%& 1 usi), " si,)"* #&ou,$t to t$% INT0

i) P3.?B:1 2 Tim%& 0 o %&"t%s o)*! i( t$% INT0 #it is s%t.

0 2 Tim%& 0 o %&"t%s &%,"& *%ss o( t$% *o,i' st"t% o( t$% INT0 #it. C@T0 s%*%'ts u*s%s to #% 'ou)t% u #! t$% tim%&@'ou)t%& 0:

1 2 Tim%& 'ou)ts u*s%s #&ou,$t to t$% T0 i) P3. B.0 2 Tim%& 'ou)ts u*s%s (&om i)t%&)"* os'i**"to&.

T0M1 T0M0t$%s% t+o #its s%*%'t t$% o %&"tio)"* mo % o( t$% Tim%& 0.

FLA ;IT AND THE P RE I TER

TMOD Tim%&@Cou)t%& Mo % 'o)t&o* R%,ist%&B


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TF1 #it is "utom"ti'"**! s%t o) t$% Tim%& 1 o/%&(*o+. TR1 #it %)"#*%s t$% Tim%& 1.

1 2 Tim%& 1 is %)"#*% .0 2 Tim%& 1 is is"#*% .

TF0 #it is "utom"ti'"**! s%t o) t$% Tim%& 0 o/%&(*o+. TR0 #it %)"#*%s t$% tim%& 0.

1 2 Tim%& 0 is %)"#*% .0 2 Tim%& 0 is is"#*% .

M0 2 %&i"* o&t mo % #it 0 is us% (o& s%&i"* o&t mo % s%*%'tio). M1 2 %&i"* o&t mo % #it 1. M? 2 %&i"* o&t mo % ? #it "*so =)o+) "s mu*ti &o'%sso& 'ommu)i'"tio)

%)"#*% #it. $%) s%t it %)"#*%s mu*ti &o'%sso& 'ommu)i'"tio) i) mo % ? ") 3 ")%/%)tu"**! mo % 1. It s$ou* #% '*%"&% i) mo % 0. REN 2 R%'% tio) E)"#*% #it %)"#*%s s%&i"* &%'% tio) +$%) s%t. $%) '*%"&%

s%&i"* &%'% tio) is is"#*% . T;8 2 T&")smitt%& #it 8. i)'% "** &%,ist%&s "&% 82#it +i % t$is #it so*/%s t$%

&o#*%m o( t&")smitti), t$% -t$ #it i) mo %s ? ") 3. It is s%t to t&")smit *o,i' 1 i)t$% -t$ #it.

R;8 2 R%'%i/%& #it 8 o& t$% -t$ #it &%'%i/% i) mo %s ? ") 3. C*%"&% #!$"& +"&% i( -t$ #it &%'%i/% is *o,i' 0. %t #! $"& +"&% i( -t$ #it &%'%i/% is *o,i' 1.

TI2 T&")smit I)t%&&u t (*", is "utom"ti'"**! s%t "t t$% mom%)t t$% *"st #it o(o)% #!t% is s%)t. It s " si,)"* to t$% &o'%sso& t$"t t$% *i)% is "/"i*"#*% (o& " )%+#!t% t&")smit. It must #% '*%"&% (&om +it$i) t$% so(t+"&%.

Tim%& Co)t&o* TCONB R%,ist%&

%&i"* Po&t Co)t&o* CONB R%,ist%&

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RI 2 R%'%i/% I)t%&&u t (*", is "utom"ti'"**! s%t u o) o)% #!t% &%'%i/%. It si,)"*st$"t #!t% is &%'%i/% ") s$ou* #% &%" >ui'=*! &io& to #%i), &% *"'% #! " )%+"t". T$is #it is "*so '*%"&% (&om +it$i) t$% so(t+"&%.

EA 2 ,*o#"* i)t%&&u t %)"#*%@ is"#*%:

0 2 is"#*%s "** i)t%&&u t &%>u%sts. 1 2 %)"#*%s "** i) i/i u"* i)t%&&u t &%>u%sts.E 2 %)"#*%s o& is"#*%s s%&i"* i)t%&&u t:

0 2 UART s!st%m '"))ot ,%)%&"t% ") i)t%&&u t. 1 2 UART s!st%m %)"#*%s ") i)t%&&u t.ET1 2 #it %)"#*%s o& is"#*%s Tim%& 1 i)t%&&u t:

0 2 Tim%& 1 '"))ot ,%)%&"t% ") i)t%&&u t. 1 2 Tim%& 1 %)"#*%s ") i)t%&&u t.EX1 2 #it %)"#*%s o& is"#*%s % t%&)"* 1 i)t%&&u t:

0 2 '$"),% o( t$% i) INT0 *o,i' st"t% '"))ot ,%)%&"t% ") i)t%&&u t. 1 2 %)"#*%s ") % t%&)"* i)t%&&u t o) t$% i) INT0 st"t% '$"),%.ET0 2 #it %)"#*%s o& is"#*%s tim%& 0 i)t%&&u t:

0 2 Tim%& 0 '"))ot ,%)%&"t% ") i)t%&&u t. 1 2 %)"#*%s tim%& 0 i)t%&&u t.EX0 2 #it %)"#*%s o& is"#*%s % t%&)"* 0 i)t%&&u t:

0 2 '$"),% o( t$% INT1 i) *o,i' st"t% '"))ot ,%)%&"t% ") i)t%&&u t. 1 2 %)"#*%s ") % t%&)"* i)t%&&u t o) t$% i) INT1 st"t% '$"),%

Po+%& Co)t&o* PCONB &%,ist%&

IE R%,ist%& I)t%&&u t E)"#*%B

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1 architecture of 8051 microcontroller.pdf

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