AT89C55WD-33AC ATMEL Corporation, AT89C55WD-33AC Datasheet - Page 6

• Manufacturer Part Number: AT89C55WD-33AC
• Description: 8-bit Microcontroller with 20K Bytes Flash
• Manufacturer: ATMEL Corporation

Table 1. AT89C55WD SFR Map and Reset Values
Special
Function
Registers
6
0D8H
0D0H
0C8H
0C0H
0E8H
0E0H
0B8H
0B0H
0A8H
0A0H
0F8H
0F0H
98H
90H
88H
80H
AT89C55WD
XX000000
0X000000
00000000
00000000
00000000
00000000
11111111
11111111
00000000
11111111
00000000
11111111
T2CON
SCON
TCON
PSW
ACC
P3
P2
P1
P0
IP
IE
B
XXXXXXXX
XXXXXX00
00000000
00000111
T2MOD
TMOD
SBUF
SP
A map of the on-chip memory area called the Special Function Register (SFR) space is shown
in Table 1.
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 in general 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.
Timer 2 Registers: Control and status bits are contained in registers T2CON (shown in Table
2) and T2MOD (shown in Table 2) for Timer 2. The register pair (RCAP2H, RCAP2L) are the
Capture/Reload registers for Timer 2 in 16-bit capture mode or 16-bit auto-reload mode.
XXXXXXX0
00000000
00000000
00000000
RCAP2L
AUXR1
DP0L
TL0
00000000
00000000
00000000
RCAP2H
DP0H
TL1
00000000
00000000
00000000
DP1L
TH0
TL2
00000000
00000000
00000000
DP1H
TH2
TH1
XXXXXXXX
XXX00XX0
WDTRST
AUXR
0XXX0000
PCON
1921B–MICRO–09/02
0FFH
0F7H
0EFH
0E7H
0DFH
0D7H
0CFH
0C7H
0BFH
0B7H
0AFH
0A7H
9FH
97H
8FH
87H