PIC16F88

Manufacturer Part NumberPIC16F88
ManufacturerMicrochip Technology Inc.
PIC16F88 datasheet
 
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Page 19/228:

STATUS Register

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2.2.2.1

STATUS Register

The STATUS register, shown in Register 2-1, contains
the arithmetic status of the ALU, the Reset status and
the bank select bits for data memory.
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.
REGISTER 2-1:
STATUS: ARITHMETIC STATUS REGISTER (ADDRESS 03h, 83h, 103h, 183h)
R/W-0
R/W-0
IRP
bit 7
bit 7
IRP: Register Bank Select bit (used for indirect addressing)
1 = Bank 2, 3 (100h-1FFh)
0 = Bank 0, 1 (00h-FFh)
bit 6-5
RP<1:0>: Register Bank Select bits (used for direct addressing)
11 = Bank 3 (180h-1FFh)
10 = Bank 2 (100h-17Fh)
01 = Bank 1 (80h-FFh)
00 = Bank 0 (00h-7Fh)
Each bank is 128 bytes.
bit 4
TO: Time-out bit
1 = After power-up, CLRWDT instruction or SLEEP instruction
0 = A WDT time-out occurred
bit 3
PD: Power-Down bit
1 = After power-up or by the CLRWDT instruction
0 = By execution of the SLEEP instruction
bit 2
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
bit 1
DC: Digit carry/borrow bit (ADDWF, ADDLW, SUBLW and SUBWF instructions)
1 = A carry-out from the 4th low-order bit of the result occurred
0 = No carry-out from the 4th low-order bit of the result
bit 0
C: Carry/borrow bit (ADDWF, ADDLW, SUBLW and SUBWF instructions)
1 = A carry-out from the Most Significant bit of the result occurred
0 = No carry-out from the Most Significant bit of the result occurred
Note 1:
For borrow, the polarity is reversed. A subtraction is executed by adding the two’s
complement of the second operand.
2:
For rotate (RRF, RLF) instructions, this bit is loaded with either the high or low-order
bit of the source register.
Legend:
R = Readable bit
-n = Value at POR
 2005 Microchip Technology Inc.
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).
It is recommended, therefore, that only BCF, BSF, SWAPF
and MOVWF instructions are used to alter the STATUS
register because these instructions do not affect the Z, C
or DC bits from the STATUS register. For other
instructions
Section 16.0 “Instruction Set Summary”.
Note:
The C and DC bits operate as a borrow
and digit borrow bit, respectively, in
subtraction. See the SUBLW and SUBWF
instructions for examples.
R/W-0
R-1
R-1
RP1
RP0
TO
W = Writable bit
U = Unimplemented bit, read as ‘0’
‘1’ = Bit is set
‘0’ = Bit is cleared
PIC16F87/88
not
affecting
any
Status
bits,
see
R/W-x
R/W-x
R/W-x
PD
Z
DC
C
bit 0
(1)
(1,2)
x = Bit is unknown
DS30487C-page 17