Datasheet

PIC18F2220/2320/4220/4320
DS39599G-page 292 © 2007 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 0000 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 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 ‘d’ (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
Before Instruction
REG = 0x03
W = 0x02
C = 0x01
After Instruction
REG = 0xFF
W = 0x02
C = 0x00
Z = 0x00
N = 0x01 ; 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