AT89S8253
5. Special Function Registers
A map of the on-chip memory area called the Special Function Register (SFR) space is shown in
Note that not all of the addresses are occupied, and unoccupied addresses may not be imple-
mented on the chip. Read accesses to these addresses will generally return random data, and
write accesses will have an indeterminate effect.
User software should not write 1s to these unlisted locations, since they may be used in future
products to invoke new features. In that case, the reset or inactive values of the new bits will
always be 0.
Table 5-1.
0F8H
0F0H
0E8H
0E0H
0D8H
0D0H
0C8H
0C0H
0B8H
IP
XX000000
P3
11111111
IE
0X000000
P2
11111111
SCON
00000000
P1
11111111
TCON
00000000
P0
11111111
TMOD
00000000
SP
00000111
TL0
00000000
DP0L
00000000
TL1
00000000
DP0H
00000000
TH0
00000000
DP1L
00000000
TH1
00000000
DP1H
00000000
SBUF
XXXXXXXX
EECON
XX000011
AUXR
XXXXXXX0
SPDR
########
CLKREG
XXXXXXX0
PCON
00XX0000
SADDR
00000000
SPSR
000XXX00
WDTRST
(Write Only)
WDTCON
0000 0000
SADEN
00000000
IPH
XX000000
PSW
00000000
T2CON
00000000
T2MOD
XXXXXX00
RCAP2L
00000000
RCAP2H
00000000
TL2
00000000
SPCR
00000100
TH2
00000000
ACC
00000000
B
00000000
AT89S8253 SFR Map and Reset Values
0FFH
0F7H
0EFH
0E7H
0DFH
0D7H
0CFH
0C7H
0BFH
0B0H
0B7H
0A8H
0AFH
0A0H
98H
90H
88H
80H
0A7H
9FH
97H
8FH
87H
Note:
# means: 0 after cold reset and unchanged after warm reset.
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