PIC18FXX39 Datasheet, PDF (242/322 Pages) Microchip Technology – Enhanced FLASH Microcontrollers with Single Phase Induction Motor Control Kernel

PIC18FXX39
RETFIE
Return from Interrupt
Syntax:
Operands:
Operation:
Status Affected:
[ label ] RETFIE [s]
s  [0,1]
(TOS)  PC,
1  GIE/GIEH or PEIE/GIEL,
if s = 1
(WS)  W,
(STATUSS)  STATUS,
(BSRS)  BSR,
PCLATU, PCLATH are unchanged.
GIE/GIEH, PEIE/GIEL.
Encoding:
Description:
Words:
0000 0000 0001 000s
Return from Interrupt. Stack is
popped and Top-of-Stack (TOS) is
loaded into the PC. Interrupts are
enabled by setting either the high
or low priority global interrupt
enable bit. If ‘s’ = 1, the contents of
the shadow registers WS,
STATUSS and BSRS are loaded
into their corresponding registers,
W, STATUS and BSR. If ‘s’ = 0, no
update of these registers occurs
(default).
1
Cycles:
2
Q Cycle Activity:
Q1
Q2
Decode
No
operation
No
operation
No
operation
Q3
No
operation
No
operation
Q4
pop PC from
stack
Set GIEH or
GIEL
No
operation
Example:
RETFIE 1
After Interrupt
PC
=
W
=
BSR
=
STATUS
=
GIE/GIEH, PEIE/GIEL =
TOS
WS
BSRS
STATUSS
1
RETLW
Return Literal to W
Syntax:
Operands:
Operation:
[ label ] RETLW k
0  k  255
k  W,
(TOS)  PC,
PCLATU, PCLATH are unchanged
Status Affected: None
Encoding:
0000 1100 kkkk kkkk
Description:
W is loaded with the eight-bit literal
'k'. The program counter is loaded
from the top of the stack (the return
address). The high address latch
(PCLATH) remains unchanged.
Words:
1
Cycles:
2
Q Cycle Activity:
Q1
Decode
Q2
Read
literal 'k'
No
operation
No
operation
Q3
Process
Data
No
operation
Q4
pop PC from
stack, Write
to W
No
operation
Example:
CALL TABLE ; W contains table
; offset value
; W now has
; table value
:
TABLE
ADDWF PCL ; W = offset
RETLW k0 ; Begin table
RETLW k1 ;
:
:
RETLW kn ; End of table
Before Instruction
W
= 0x07
After Instruction
W
= value of kn
DS30485B-page 242
Preliminary
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