
2002 Microchip Technology Inc.
Preliminary
DS30485A-page 227
PIC18FXX39
CLRF
Clear f
Syntax:
[ label ] CLRF f [,a]
Operands:
0
≤ f ≤ 255
a
∈ [0,1]
Operation:
000h
→ f
1
→ Z
Status Affected:
Z
Encoding:
0110
101a
ffff
Description:
Clears the contents of the specified
register. If ‘a’ is 0, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will
be selected as per the BSR value
(default).
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register 'f'
Process
Data
Write
register 'f'
Example:
CLRF
FLAG_REG,1
Before Instruction
FLAG_REG
=
0x5A
After Instruction
FLAG_REG
=
0x00
CLRWDT
Clear Watchdog Timer
Syntax:
[ label ] CLRWDT
Operands:
None
Operation:
000h
→ WDT,
000h
→ WDT postscaler,
1
→ TO,
1
→ PD
Status Affected:
TO, PD
Encoding:
0000
0100
Description:
CLRWDT
instruction resets the
Watchdog Timer. It also resets the
postscaler of the WDT. Status bits
TO and PD are set.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
Process
Data
No
operation
Example:
CLRWDT
Before Instruction
WDT Counter
=
?
After Instruction
WDT Counter
=
0x00
WDT Postscaler
=
0
TO
=1
PD
=1