When global interrupts are disabled (GIE cleared) and any interrupt source has both its interrupt enable bit and interrupt flag bit set, one of the following will occur:
SLEEP
instruction:SLEEP
instruction will execute as a
NOP
SLEEP
instruction:SLEEP
instruction will be completely
executedEven if the flag bits were checked before executing a
SLEEP
instruction, it may be possible for flag bits to become set
before the SLEEP
instruction completes. To determine whether a
SLEEP
instruction executed, test the PD bit. If the PD bit is
set, the SLEEP
instruction was executed as a NOP
.