
2009 Microchip Technology Inc.
DS39636D-page 275
PIC18F2X1X/4X1X
CLRF
Clear f
Syntax:
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 is selected.
If ‘a’ is ‘1’, the BSR is used to select the
GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction operates
in Indexed Literal Offset Addressing
mode whenever f
≤ 95 (5Fh). See
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
=
5Ah
After Instruction
FLAG_REG
=
00h
CLRWDT
Clear Watchdog Timer
Syntax:
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
=
00h
WDT Postscaler
=
0
TO
=1
PD
=1