Datasheet

Table Of Contents
FDS 6531/6532 005 Data Sheet 71M6531D/F-71M6532D/F
Rev 2 21
An alternative data pointer is available in the form of the PDATA register (SFR 0xBF), sometimes referred
to as USR2). It defines the high byte of a 16-bit address when reading or writing XDATA with the instruction
MOVX A,@Ri or MOVX @Ri,A.
Internal Data Memory Map and Access
The Internal data memory provides 256 bytes (0x00 to 0xFF) of data memory. The internal data memory
address is always 1 byte wide. Table 8 shows the internal data memory map.
The Special Function Registers (SFR) occupy the upper 128 bytes. The SFR area of internal data memory
is available only by direct addressing. Indirect addressing of this area accesses the upper 128 bytes of
Internal RAM. The lower 128 bytes contain working registers and bit addressable memory. The lower 32
bytes form four banks of eight registers (R0-R7). Two bits on the program memory status word (PSW) select
which bank is in use. The next 16 bytes form a block of bit addressable memory space at bit addresses
0x00-0x7F. All of the bytes in the lower 128 bytes are accessible through direct or indirect addressing.
Table 8: Internal Data Memory Map
Address Range
Direct addressing
Indirect addressing
0x80
0xFF
Special Function Registers (SFRs)
RAM
0x30
0x7F
Byte addressable area
0x20
0x2F
Bit addressable area
0x00
0x1F
Register banks R0…R7
1.4.2 Special Function Registers (SFRs)
A map of the Special Function Registers is shown in Table 9.
Only a few addresses in the SFR memory space are occupied, the others are not implemented. A read
access to unimplemented addresses will return undefined data, while a write access will have no effect.
SFRs specific to the 71M6531D/F and 71M6532D/F are shown in bold print on a gray field. The registers
at 0x80, 0x88, 0x90, etc., are bit addressable, all others are byte addressable. See the restrictions for the
INTBITS register in Table 14.
Table 9: Special Function Register Map
Hex/
Bin
Bit
Addressable
Byte Addressable
Bin/
Hex
X000
X001
X010
X011
X100
X101
X110
X111
F8
INTBITS
FF
F0
B
F7
E8
IFLAGS
EF
E0
A
E7
D8
WDCON
DF
D0
PSW
D7
C8
T2CON
CF
C0
IRCON
C7
B8
IEN1
IP1
S0RELH
S1RELH
PDATA
BF
B0
P3
FLSHCTL
FL_BANK
PGADR
B7
A8
IEN0
IP0
S0RELL
AF
A0
P2
DIR2
DIR0
A7
98
S0CON
S0BUF
IEN2
S1CON
S1BUF
S1RELL
EEDATA
EECTRL
9F
90
P1
DIR1
DPS
ERASE
97
88
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
8F
80
P0
SP
DPL
DPH
DPL1
DPH1
PCON
87