Atmel SAM4S Series, Preliminary Data Sheet

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11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
11.5.2.2 Wakeup from WFE
The processor wakes up if:
• it detects an exception with sufficient priority to cause an exception entry
• it detects an external event signal. See “External Event Input”
• in a multiprocessor system, another processor in the system executes an SEV instruction.
In addition, if the SEVONPEND bit in the SCR is set to 1, any new pending interrupt triggers an
event and wakes up the processor, even if the interrupt is disabled or has insufficient priority to
cause an exception entry. For more information about the SCR, see
“System Control Register” .
11.5.2.3 External Event Input
The processor provides an external event input signal. Peripherals can drive this signal, either to
wake the processor from WFE, or to set the internal WFE event register to 1 to indicate that the
processor must not enter sleep mode on a later WFE instruction. See
“Wait For Event” for more
information.
11.5.3 Power Management Programming Hints
ISO/IEC C cannot directly generate the WFI and WFE instructions. The CMSIS provides the fol-
lowing functions for these instructions:
void __WFE(void) // Wait for Event
void __WFE(void) // Wait for Interrupt