Philips Semiconductors
Product specification
89C51/89C52/89C54/89C58
80C51 8-bit microcontroller family
4K/8K/16K/32K Flash
1999 Oct 27
6
Table 1.
89C51/89C52/89C54/89C58 Special Function Registers
SYMBOL
DESCRIPTION
DIRECT
ADDRESS
E0H
8EH
A2H
F0H
BIT ADDRESS, SYMBOL, OR ALTERNATIVE PORT FUNCTION
MSB
LSB
E0
AO
DPS
F0
RESET
VALUE
00H
xxxxxxx0B
xxxx00x0B
00H
ACC*
AUXR#
AUXR1#
B*
DPTR:
DPH
DPL
Accumulator
Auxiliary
Auxiliary 1
B register
Data Pointer (2 bytes)
Data Pointer High
Data Pointer Low
E7
–
–
F7
E6
–
–
F6
E5
–
–
F5
E4
–
–
F4
E3
–
GF2
F3
E2
–
0
F2
E1
–
–
F1
83H
82H
00H
00H
AF
EA
BF
–
B7
–
87
AD7
97
–
A7
AD15
B7
RD
AE
–
BE
–
B6
–
86
AD6
96
–
A6
AD14
B6
WR
AD
ET2
BD
PT2
B5
PT2H
85
AD5
95
–
A5
AD13
B5
T1
AC
ES
BC
PS
B4
PSH
84
AD4
94
–
A4
AD12
B4
T0
AB
ET1
BB
PT1
B3
PT1H
83
AD3
93
–
A3
AD11
B3
INT1
AA
EX1
BA
PX1
B2
PX1H
82
AD2
92
–
A2
AD10
B2
INT0
A9
ET0
B9
PT0
B1
PT0H
81
AD1
91
T2EX
A1
AD9
B1
TxD
A8
EX0
B8
PX0
B0
PX0H
80
AD0
90
T2
A0
AD8
B0
RxD
IE*
Interrupt Enable
A8H
0x000000B
IP*
Interrupt Priority
B8H
xx000000B
IPH#
Interrupt Priority High
B7H
xx000000B
P0*
Port 0
80H
FFH
P1*
Port 1
90H
FFH
P2*
Port 2
A0H
FFH
P3*
Port 3
B0H
FFH
PCON#
1
Power Control
87H
SMOD1
D7
CY
SMOD0
D6
AC
–
POF
2
D4
RS1
GF1
D3
RS0
GF0
D2
OV
PD
D1
–
IDL
D0
P
00xxx000B
D5
F0
PSW*
RACAP2H
#
RACAP2L
#
SADDR#
SADEN#
SBUF
Program Status Word
Timer 2 Capture High
Timer 2 Capture Low
Slave Address
Slave Address Mask
Serial Data Buffer
D0H
CBH
CAH
A9H
B9H
99H
000000x0B
00H
00H
00H
00H
xxxxxxxxB
9F
9E
SM1
9D
SM2
9C
REN
9B
TB8
9A
RB8
99
TI
98
RI
SCON*
SP
Serial Control
Stack Pointer
98H
81H
SM0/FE
00H
07H
8F
TF1
CF
TF2
–
8E
TR1
CE
EXF2
–
8D
TF0
CD
RCLK
–
8C
TR0
CC
TCLK
–
8B
IE1
CB
8A
IT1
CA
TR2
–
89
IE0
C9
C/T2
T2OE
88
IT0
C8
TCON*
Timer Control
88H
00H
T2CON*
T2MOD#
TH0
TH1
TH2#
TL0
TL1
TL2#
TMOD
SFRs are bit addressable.
SFRs are modified from or added to the 80C51 SFRs.
Reserved bits.
1. Reset value depends on reset source.
2. Bit will not be affected by reset.
Timer 2 Control
Timer 2 Mode Control
Timer High 0
Timer High 1
Timer High 2
Timer Low 0
Timer Low 1
Timer Low 2
Timer Mode
C8H
C9H
8CH
8DH
CDH
8AH
8BH
CCH
89H
EXEN2
–
CP/RL2
DCEN
00H
xxxxxx00B
00H
00H
00H
00H
00H
00H
00H
GATE
C/T
M1
M0
GATE
C/T
M1
M0
*
#
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