
PIC18FXX39
DS30485A-page 246
Preliminary
2002 Microchip Technology Inc.
SLEEP
Enter SLEEP mode
Syntax:
[ label ] SLEEP
Operands:
None
Operation:
00h
→ WDT,
0
→ WDT postscaler,
1
→ TO,
0
→ PD
Status Affected:
TO, PD
Encoding:
0000
0011
Description:
The power-down status bit (PD) is
cleared. The time-out status bit
(TO) is set. Watchdog Timer and
its postscaler are cleared.
The processor is put into SLEEP
mode with the oscillator stopped.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
No
operation
Process
Data
Go to
sleep
Example:
SLEEP
Before Instruction
TO =?
PD =?
After Instruction
TO =1
PD =0
If WDT causes wake-up, this bit is cleared.
SUBFWB
Subtract f from W with borrow
Syntax:
[ label ] SUBFWB
f [,d [,a]
Operands:
0
≤ f ≤ 255
d
∈ [0,1]
a
∈ [0,1]
Operation:
(W) – (f) – (C)
→ dest
Status Affected:
N, OV, C, DC, Z
Encoding:
0101
01da
ffff
Description:
Subtract register 'f' and carry flag
(borrow) from W (2’s complement
method). If 'd' is 0, the result is
stored in W. If 'd' is 1, the result is
stored in register 'f' (default). If ‘a’ is
0, the Access Bank will be selected,
overriding the BSR value. If ‘a’ is 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 to
destination
Example 1:
SUBFWB
REG, 1, 0
Before Instruction
REG
=
3
W=
2
C=
1
After Instruction
REG
=
FF
W=
2
C=
0
Z=
0
N
=
1
; result is negative
Example 2:
SUBFWB
REG, 0, 0
Before Instruction
REG
=
2
W=
5
C=
1
After Instruction
REG
=
2
W=
3
C=
1
Z=
0
N
=
0
; result is positive
Example 3:
SUBFWB
REG, 1, 0
Before Instruction
REG
=
1
W=
2
C=
0
After Instruction
REG
=
0
W=
2
C=
1
Z
=
1
; result is zero
N=
0