Datasheet

PIC16F8X
DS30430B-page 60 1996 Microchip Technology Inc.
CLRWDT Clear Watchdog Timer
Syntax: [
label
] CLRWDT
Operands: None
Operation: 00h WDT
0 WDT prescaler,
1 T
O
1 PD
Status Affected: TO, PD
Encoding:
00 0000 0110 0100
Description:
The CLRWDT instruction resets the
watchdog timer. It also resets the
prescaler of the WDT. Status bits TO
and PD are set.
Words: 1
Cycles: 1
Example
CLRWDT
Before Instruction
WDT counter = ?
After Instruction
WDT counter = 0x00
WDT prescale = 0
TO =1
PD =1
COMF Complement f
Syntax: [
label
] COMF f,d
Operands: 0 f 127
d [0,1]
Operation: (dest)
Status Affected: Z
Encoding:
00 1001 dfff ffff
Description:
The contents of register 'f' are comple-
mented. If 'd' is 0 the result is stored in
W. If 'd' is 1 the result is stored back in
register 'f'.
Words: 1
Cycles: 1
Example
COMF REG1,0
Before Instruction
REG1 = 0x13
After Instruction
REG1 = 0x13
W = 0xEC
(f)
DECF Decrement f
Syntax: [
label
] DECF f,d
Operands: 0 f 127
d [0,1]
Operation: (f) – 1 (dest)
Status Affected: Z
Encoding:
00 0011 dfff ffff
Description:
Decrement register 'f'. If 'd' is 0 the
result is stored in the W register. If 'd'
is 1 the result is stored back in register
'f'
.
Words: 1
Cycles: 1
Example
DECF CNT, 1
Before Instruction
CNT = 0x01
Z=0
After Instruction
CNT = 0x00
Z=1
DECFSZ Decrement f, Skip if 0
Syntax: [
label
] DECFSZ f,d
Operands: 0 f 127
d [0,1]
Operation: (f) – 1 (dest); skip if result = 0
Status Affected: None
Encoding:
00 1011 dfff ffff
Description:
The contents of register 'f' are decre-
mented. If 'd' is 0 the result is placed in
the W register. If 'd' is 1 the result is
placed back in register 'f'. If the result is
0, the next instruction, which is already
fetched, is discarded. A NOP is executed
instead making it a two cycle instruction.
Words: 1
Cycles: 1(2)
Example
HERE DECFSZ CNT, 1
GOTO LOOP
CONTINUE •
Before Instruction
PC = addressHERE
After Instruction
CNT = CNT - 1
if CNT = 0,
PC = address CONTINUE
if CNT 0,
PC = address HERE+1