PIC16F54T-E View Datasheet(PDF) - Microchip Technology
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PIC16F54T-E Datasheet PDF : 88 Pages
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PIC16F5X
3.3 STATUS Register
This register contains the arithmetic status of the ALU,
the Reset status and the page preselect bits for
program memories larger than 512 words.
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.
For example, CLRF STATUS will clear the upper three
bits and set the Z bit. This leaves the STATUS register
as 000u u1uu (where u = unchanged).
Therefore, it is recommended that only BCF, BSF,
MOVWF and SWAPF 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
Section 9.0 “Instruction Set Summary”.
REGISTER 3-1: STATUS REGISTER (ADDRESS: 03h)
R/W-0
R/W-0
R/W-0
R-1
R-1
R/W-x
R/W-x
R/W-x
PA2
PA1
PA0
TO
PD
Z
DC
C
bit 7
bit 0
bit 7
bit 6-5
bit 4
bit 3
bit 2
bit 1
bit 0
PA2: Reserved, do not use
Use of the PA2 bit as a general purpose read/write bit is not recommended, since this may affect upward
compatibility with future products.
PA<1:0>: Program Page Preselect bits (PIC16F57/PIC16F59)
00 = Page 0 (000h-1FFh)
01 = Page 1 (200h-3FFh)
10 = Page 2 (400h-5FFh)
11 = Page 3 (600h-7FFh)
Each page is 512 words. Using the PA<1:0> bits as general purpose read/write bits in devices which do
not use them for program page preselect is not recommended. This may affect upward compatibility with
future products.
TO: Time-Out bit
1 = After power-up, CLRWDT instruction or SLEEP instruction
0 = A WDT time-out occurred
PD: Power-Down bit
1 = After power-up or by the CLRWDT instruction
0 = By execution of the SLEEP instruction
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 ADDWF and SUBWF instructions)
ADDWF
1 = A carry to 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 to the 4th low order bit of the result did not occur
0 = A borrow from the 4th low order bit of the result occurred
C: Carry/Borrow bit (for ADDWF, SUBWF and RRF, RLF instructions)
ADDWF
SUBWF
RRF or RLF
1 = A carry occurred
1 = A borrow did not occur Loaded with LSb or MSb, respectively
0 = A carry did not occur 0 = A borrow occurred
Legend:
R = Readable bit
- n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
© 2007 Microchip Technology Inc.
DS41213D-page 17
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