PIC12C5XX
For example, CLRF STATUSwill clear the upper three
bits and set the Z bit. This leaves the STATUS register
as 000u u1uu(where u= unchanged).
4.3
STATUS Register
This register contains the arithmetic status of the ALU,
the RESET status, and the page preselect bit for
program memories larger than 512 words.
It is recommended, therefore, that only BCF, BSF and
MOVWF instructions be used to alter the STATUS
register because these instructions do not affect the Z,
DC or C bits from the STATUS register. For other
instructions, which do affect STATUS bits, see
Instruction Set Summary.
The STATUS register can be the destination for any
instruction, as with any other register. If the STATUS
register is the destination for an instruction that affects
the Z, DC or C bits, then the write to these three bits is
disabled. These bits are set or cleared according to
the device logic. Furthermore, the TO and PD bits are
not writable. Therefore, the result of an instruction with
the STATUS register as destination may be different
than intended.
FIGURE 4-4: STATUS REGISTER (ADDRESS:03h)
R/W-0
GPWUF
R/W-0
—
R/W-0
PA0
R-1
TO
R-1
PD
R/W-x
Z
R/W-x
DC
R/W-x
C
R = Readable bit
W = Writable bit
- n = Value at POR reset
bit7
6
5
4
3
2
1
bit0
bit 7:
GPWUF: GPIO reset bit
1 = Reset due to wake-up from SLEEP on pin change
0 = After power up or other reset
bit 6:
bit 5:
Unimplemented
PA0: Program page preselect bits
1 = Page 1 (200h - 3FFh) - PIC12C509, PIC12C509A, PIC12CR509A and PIC12CE519
0 = Page 0 (000h - 1FFh) - PIC12C5XX
Each page is 512 bytes.
Using the PA0 bit as a general purpose read/write bit in devices which do not use it for program
page preselect is not recommended since this may affect upward compatibility with future products.
bit 4:
bit 3:
bit 2:
bit 1:
TO: Time-out bit
1 = After power-up, CLRWDTinstruction, or SLEEPinstruction
0 = A WDT time-out occurred
PD: Power-down bit
1 = After power-up or by the CLRWDTinstruction
0 = By execution of the SLEEPinstruction
Z: Zero bit
1 = The result of an arithmetic or logic operation is zero
0 = The result of an arithmetic or logic operation is not zero
DC: Digit carry/borrow bit (for ADDWFand SUBWFinstructions)
ADDWF
1 = A carry from the 4th low order bit of the result occurred
0 = A carry from the 4th low order bit of the result did not occur
SUBWF
1 = A borrow from the 4th low order bit of the result did not occur
0 = A borrow from the 4th low order bit of the result occurred
bit 0:
C: Carry/borrow bit (for ADDWF, SUBWFand RRF, RLFinstructions)
ADDWF
SUBWF
RRF or RLF
1 = A carry occurred
0 = A carry did not occur
1 = A borrow did not occur
0 = A borrow occurred
Load bit with LSB or MSB, respectively
DS40139E-page 16
1999 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
