PIC14000 datasheet(17/153 Pages) MICROCHIP

17 / 153 page

Preliminary

DS40122B-page 17

PIC14000

4.2.2.1

STATUS REGISTER

The STATUS register, shown in Figure 4-3, 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

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).

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 1: The IRP and RP1 bits (STATUS<7:6>) are

not used by the PIC14000 and should be

programmed as cleared. Use of these bits

as general purpose R/W bits is NOT

recommended, since this may affect

upward compatibility with future products.

Note 2: The C and DC bits operate as a borrow

and digit borrow out bit, respectively, in

subtraction. See the SUBLW and SUBWF

instructions for examples.

FIGURE 4-3:

STATUS REGISTER

83h

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

STATUS

IRP

RP1

RP0

Read/Write

R/W

POR value FFh

011

Bit

Name

Function

IRP

Not used. This bit should be programmed as ‘0’.

Use of this bit as a general purpose read/write bit is not recommended, since this may

affect upward compatibility with future products.

RP1

Not used. This bit should be programmed as ‘0’.

Use of this bit as a general purpose read/write bit is not recommended, since this may

affect upward compatibility with future products.

RP0

1 = Bank1 (80h - FFh)

0 = Bank0 (00h - 7Fh)

Each page is 128 bytes. Only the RP0 bit is used.

Time-out bit.

1 = After power-up and by the CLRWDT and SLEEP instruction.

0 = A watchdog timer time-out has occurred.

Power down bit.

1 = After power-up or by a CLRWDT instruction.

0 = By execution of the SLEEP instruction.

Zero bit.

1 = The result of an arithmetic or logic operation is zero.

0 = The result of an arithmetic or logical operation is not zero.

Digit carry / borrow bit.

For ADDWF and ADDLW instructions.

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

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

Note: For Borrow, the polarity is reversed.

Carry / borrow bit.

For ADDWF and ADDLW instructions.

1 = A carry-out from the most signiﬁcant bit of the result occurred. Note that 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 or low order bit of

the source register.

0 = No carry-out from the most signiﬁcant bit of the result.

Note: For Borrow the polarity is reversed.

PIC14000 Datasheet(PDF) 17 Page - Microchip Technology

PIC14000 Datasheet(HTML) 17 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL