PIC16C771-20I/SS Microchip Technology, PIC16C771-20I/SS Datasheet - Page 16

• Manufacturer Part Number: PIC16C771-20I/SS
• Description: 18/20-Pin/ 8-Bit CMOS Microcontrollers with 10/12-Bit A/D
• Manufacturer: Microchip Technology

PIC16C717/770/771
2.2.2.1
The STATUS register, shown in
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:
DS41120A-page 16
bit7
bit 7:
bit 6-5: RP<1:0>: Register Bank Select bits (used for direct addressing)
bit 4:
bit 3:
bit 2:
bit 1:
bit 0:
Note:
R/W-0
IRP
STATUS REGISTER
IRP: Register Bank Select bit (used for indirect addressing)
1 = Bank 2, 3 (100h - 1FFh)
0 = Bank 0, 1 (00h - FFh)
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
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 (ADDWF, ADDLW,SUBLW,SUBWF instructions) (for borrow the polarity is reversed)
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
C: Carry/borrow bit (ADDWF, ADDLW,SUBLW,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
For borrow, the polarity is reversed. A subtraction is executed by adding the two’s complement of the sec-
ond operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high or low order bit of
the source register.
R/W-0
RP1
STATUS REGISTER (STATUS: 03h, 83h, 103h, 183h)
R/W-0
RP0
Register
R-1
TO
2-1, contains
Advanced Information
R-1
PD
R/W-x
Z
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 not affecting any status bits, see the
"Instruction Set Summary."
Note 2: The C and DC bits operate as a borrow and
R/W-x
DC
digit borrow bit, respectively, in subtraction.
See the SUBLW and SUBWF instructions for
examples.
R/W-x
C
bit0
R = Readable bit
W = Writable bit
U = Unimplemented bit,
- n = Value at POR reset
1999 Microchip Technology Inc.
read as ‘0’