PIC的 STATUS Register

PIC16(L)F18857/77

Ver 0.1

STATUS Register

name Bit access reset
TO 4 R 1
PD 3 R 1
Z 2 R/W 0
DC 1 R/W 0
C 0 R/W 0

Time-Out

Watchdog overflow.
Bit is set after turning on the supply and execution of CLRWDT and SLEEP instructions.
Bit is reset when watchdog gets to the end signaling that overflow took place.

1 = overflow did not occur
0 = overflow did occur

datasheet

Reset States: POR/BOR = 1
All Other Reset = q

Value Description
1 Set at power-up or by execution of CLRWDT or SLEEP instruction
0 A WDT time-out occurred

Power-Down

This bit is set whenever power supply is brought to a microcontroller : as it starts running, after each regular reset and after execution of instruction CLRWDT.
Instruction SLEEP resets it when microcontroller falls into low consumption mode.
Its repeated setting is possible via reset or by turning the supply off/on .
Setting can be triggered also by a signal on RB0/INT pin, change on RB port, upon writing to internal DATA EEPROM, and by a Watchdog.

1 = after supply has been turned on
0 = executing SLEEP instruction

datasheet

Reset States: POR/BOR = 1
All Other Resets = q

Value Description
1 Set at power-up or by execution of CLRWDT instruction
0 Cleared by execution of the SLEEP instruction

Zero

Indication of a zero result

This bit is set when the result of an executed arithmetic or logic operation is zero.

1 = result equals zero
0 = result does not equal zero

datasheet

Reset States: POR/BOR = 0
All Other Resets = u

Value Description
1 The result of an arithmetic or logic operation is zero
0 The result of an arithmetic or logic operation is not zero

Digit Carry/Borrow

DC Transfer

Bit affected by operations of addition, subtraction. Unlike C bit, this bit represents transfer from the fourth resulting place.
It is set in case of subtracting smaller from greater number and is reset in the other case.

1 = transfer occurred on the fourth bit according to the order of the result
0 = transfer did not occur

DC bit is affected by ADDWF, ADDLW, SUBLW, SUBWF instructions.

datasheet

ADDWF, ADDLW, SUBLW, SUBWF instructions
Reset States: POR/BOR = 0
All Other Resets = u

Value Description
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

Carry/Borrow

Bit that is affected by operations of addition, subtraction and shifting.

1 = transfer occurred from the highest resulting bit
0 = transfer did not occur

C bit is affected by ADDWF, ADDLW, SUBLW, SUBWF instructions.

datasheet

ADDWF, ADDLW, SUBLW, SUBWF instructions
Reset States: POR/BOR = 0
All Other Resets = u

Value Description
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

Ref