Samsung P8245 Manuel D’Utilisation
S3C8245/P8245/C8249/P8249
INSTRUCTION SET
6-87
WFI
—
Wait for Interrupt
WFI
Operation:
The CPU is effectively halted until an interrupt occurs, except that DMA transfers can still take
place during this wait state. The WFI status can be released by an internal interrupt, including a fast
interrupt .
place during this wait state. The WFI status can be released by an internal interrupt, including a fast
interrupt .
Flags:
No flags are affected.
Format:
Bytes
Cycles
Opcode
(Hex)
opc
1
4n
3F
(
n = 1, 2, 3, … )
Example:
The following sample program structure shows the sequence of operations that follow a "WFI"
statement:
statement:
EI
WFI
(Next instruction)
WFI
(Next instruction)
Main program
.
.
.
.
.
.
Interrupt occurs
Interrupt service routine
.
.
.
Clear interrupt flag
IRET
IRET
Service routine completed
(Enable global interrupt)
(Wait for interrupt)
(Wait for interrupt)