PIC16F62X
CLRWDT
Syntax:
Clear Watchdog Timer
DECF
Decrement f
[ label ] DECF f,d
0 ≤ f ≤ 127
[ label ] CLRWDT
None
Syntax:
Operands:
Operands:
Operation:
d
[0,1]
00h → WDT
0 → WDT prescaler,
1 → TO
Operation:
(f) - 1 → (dest)
Status Affected:
Encoding:
Z
1 → PD
00
0011
dfff
ffff
Status Affected:
Encoding:
TO, PD
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’.
Description:
00
0000
0110
0100
CLRWDTinstruction resets the
Description:
Watchdog Timer. It also resets the
prescaler of the WDT. Status bits TO
and PD are set.
Words:
Cycles:
Example
1
1
Words:
Cycles:
Example
1
DECF
CNT, 1
1
Before Instruction
CLRWDT
CNT
Z
=
=
0x01
0
Before Instruction
After Instruction
WDT counter
After Instruction
=
=
?
CNT
Z
=
=
0x00
1
WDT counter
0x00
WDT prescaler=
0
1
1
TO
PD
=
=
COMF
Complement f
[ label ] COMF f,d
0 ≤ f ≤ 127
DECFSZ
Syntax:
Decrement f, Skip if 0
[ label ] DECFSZ f,d
0 ≤ f ≤ 127
Syntax:
Operands:
Operands:
d
[0,1]
d
[0,1]
Operation:
(f) → (dest)
Operation:
(f) - 1 → (dest); skip if result = 0
Status Affected:
Encoding:
Z
Status Affected:
Encoding:
None
00
1001
dfff
ffff
00
1011
dfff
ffff
The contents of register ’f’ are
The contents of register ’f’ are
Description:
Description:
decremented. 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
NOPis executed instead making it a
two-cycle instruction.
complemented. If ’d’ is 0 the result is
stored in W. If ’d’ is 1 the result is
stored back in register ’f’.
Words:
Cycles:
Example
1
1
COMF
REG1,0
Words:
Cycles:
Example
1
Before Instruction
1(2)
REG1
After Instruction
REG1
=
0x13
HERE
DECFSZ
GOTO
CNT, 1
LOOP
=
=
0x13
0xEC
CONTINUE •
W
•
•
Before Instruction
PC
=
address HERE
After Instruction
CNT
if CNT =
PC
if CNT ≠
PC
=
CNT - 1
0,
address CONTINUE
0,
address HERE+1
=
=
DS40300B-page 118
Preliminary
1999 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
