
C8051F040/1/2/3/4/5/6/7
150
Rev. 1.5
12.2.7. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic 1. Future product versions may use these bits to implement new features, in
which case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descrip-
tions of the remaining SFRs are included in the sections of the data sheet associated with their corre-
sponding system function.
SFR Definition 12.5. SP: Stack Pointer
SFR Definition 12.6. DPL: Data Pointer Low Byte
SFR Definition 12.7. DPH: Data Pointer High Byte
Bits7-0:
SP: Stack Pointer.
The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 after reset.
R/W
Reset Value
00000111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
SFR Page:
0x81
All Pages
Bits7-0:
DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
SFR Page:
0x82
All Pages
Bits7-0:
DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
SFR Page:
0x83
All Pages