Intel MCS 51 User Manual

i~.
87C51GB HARDWARE DESCRIPTION
whereROcontainsOAOH,acceasea
the data byteat ad-
Iatches,timen peripheralcontrols,etc. Theseregisters
dress OAOH,rather than P2 (whoseaddressis OAOH).
can only be accessedby direct addressing.Sixteenad-
Note that stackoperationsare
examplesofindirectad-
dressesin SFRspaceare bothbyte-andbit-addressable.
dressing,sotheupper 128byka ofdata RAMare avail-
Thebit-addressableSFRSare thosewhoseaddressends
able as stackspace.
in OOOB.Thebit addresseain this area are 80Hthrough
OFFH.
3.0 SPECIAL FUNCTION REGISTERS
Not all of the addressesare occupied.Unoccupiedad-
dressesare not implementedon the chip.Read acceases
A map of the on-chipmesnoryarea cafledby the SFR
to these addreaseswilfin generalreturn random &@
(SpecialFunctionRegister)space is shownin Table 1.
and write accesses
willhave no effect.
Special Function Registers (SFRS)include the Port
Table1.SFRMalminaandReeetValues
F8
FO
E8
EO
D8
P5
CH
00000000 00000000
+
●B
00000000
CICON CL
Oooooooo00000000
*ACC
Oooooooo
CCON I CMOD
OoxooooolOoxxxooo
CCAPOH
xXxxXXxX
CCAPOL
CCAPMO
Xooooooo
CCAPIH
CCAP2H
CCAP3H
CCAP4H
Xxxxxxxx xxxxWxx xmxxxxx
xXxxXXxX
FF
AD7
00000000 z::: ‘7
CCAP1L
CCAP2L CCAP3L
CCAP4L
Xxxxxxxx Mxxxxxx Xxxxxxxx
Xxxxxxx
EF
ADO
00000000
a E7
CCAPM1
CCAPM2 CCAPM3
CCAPM4
XoooooooXoooooooXooooooo
Xooooooo
DF
*PSW
AD5
‘0 ooom
00000000
)%$$%0 ‘7
T2CON
T2MOD
RCAP2L RCAP2H TL2
TH2
m 00000000
Xxxxxxoo 00000000 00000000 00000000 00000000
CF
P4
AD4
co Oooooooo
00000000
;%%::0 0:::;0 C7
●IP
SADEN CICAPOH CICAPIH C1CAP2H C1CAP3H C1CAP4H
CH1
‘8 Xooooooo00000000 Xxxxxxxx Xxxxxxxx Xxxxxxxx Xxxxxxx xxxxxxM 00000000 ‘F
BO
*P3
AD3 IPAH
IPA IPH B7
11111111
00000000 00000000
00000000 Xooooooo
*IE SADDR
CICAPOL CICAP1L C1CAP2L C1CAP3L
C1CAP4L
‘8 00000000
00000000 Xxxxxxxx Xwxxxxx X)wuxxx Xxxxxxxx
Xxxxxxxx 00%”00 ‘F
●P2
AD2
OSCR
WDTRST IEA
‘0 00000000
00000000 XxxXXxXo
Xxxxmxx 00000000 ‘7
*SCON “SBUF
CICAPMO CICAPM1 C1CAPM2 C1CAPM3
C1CAPM4 CIMOD
98 00000000
XXxxmxx
XoooooooXoooooooXoooooooXooooooo
XoooooooXxxxoooo‘F
90
●P1
AD1
00000000
00000000 X)%Hoo ‘7
*TCON ●TMOD *TLO “TL1
*THO
“THI
88 00000000
Oooooooo00000000 00000000 00000000 00000000
8F
●PO
●SP “DPL ●DPH
ADO
80
11111111
00000111
00000000 00000000 00000000
X2::: 87
- =
Foundinthe8051core(see8051HardwareDescriptionforexplanationsoftheseSFRS).
●* = SeedescriptionofPCONSFR.BitPCON.4isnotaffectedbyreset.
X = Undefined.
8-5

Intel MCS 51 Specifications

General

Brand	Intel
Model	MCS 51
Category	Microcontrollers
Language	English