OPTION_REG datasheet(69/222 Pages) MICROCHIP

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 2013 Microchip Technology Inc.

DS22331A-page 69

MCP19111

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,

SWAPF

and MOVWF instructions are used to alter the

STATUS register, because these instructions do not

affect any Status bits. For other instructions not

affecting any Status bits, see the Section 29.0

“Instruction Set Summary”.

11.2.1

SPECIAL FUNCTION REGISTERS

The Special Function Registers are registers used by

the CPU and peripheral functions for controlling the

desired operation of the device (see Table 11-1). These

registers are static RAM.

The special registers can be classified into two sets:

core and peripheral. The Special Function Registers

associated with the microcontroller core are described

in this section. Those related to the operation of the

peripheral features are described in the section of that

peripheral feature.

Note 1: The C and DC bits operate as Borrow

and Digit Borrow out bits, respectively, in

subtraction.

STATUS: STATUS REGISTER

R/W-0

R-1

R/W-x

IRP

RP1

RP0

ZDC(1)

C(1)

bit 7

bit 0

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

IRP: Register Bank Select bit (used for Indirect addressing)

= Reserved

= Bank 0, 1, 2, 3 (00h - FFh)

bit 6-5

RP<1:0>: Register Bank Select bits (used for Direct addressing)

= Bank 0 (00h - 7Fh)

= Bank 1 (80h - FFh)

= Bank 2 (100h - 17Fh)

= Bank 3 (180h - 1FFh)

bit 4

TO: Time-out bit

= After power-up, CLRWDT instruction or SLEEP instruction

= A WDT time-out occurred

bit 3

PD: Power-down bit

= After power-up or by the CLRWDT instruction

= By execution of the SLEEP instruction

bit 2

Z: Zero bit

= The result of an arithmetic or logic operation is zero

= The result of an arithmetic or logic operation is not zero

bit 1

DC: Digit Carry/Digit Borrow bit(1) (ADDWF, ADDLW, SUBLW, SUBWF instructions)

= A carry-out from the 4th low-order bit of the result occurred

= No carry-out from the 4th low-order bit of the result

bit 0

C: Carry/Borrow bit(1) (ADDWF, ADDLW, SUBLW, SUBWF instructions)(1)

= A carry-out from the Most Significant bit of the result occurred

= 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. For rotate (RRF, RLF) instructions, this bit is loaded with either the high-order or low-order

bit of the source register.

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