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INSTRUCTION SET
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 .
Flags:
No flags are affected.
Format:
opc
Example:
The following sample program structure shows the sequence of operations that follow a "WFI"
statement:
6-86
Main program
.
.
.
EI
WFI
(Next instruction)
.
.
.
Interrupt occurs
Interrupt service routine
.
.
.
Clear interrupt flag
IRET
Service routine completed
S3C8248/C8245/P8245/C8247/C8249/P8249
Bytes
Cycles
Opcode
1
4n
(
n = 1, 2, 3, ... )
(Enable global interrupt)
(Wait for interrupt)
(Hex)
3F
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