Datasheet

Using WAKEUPEN[x]=1 with INTENSET=0 is not recommended.
In sleep modes, an EXTINTx pin can wake up the device if the corresponding condition matches the
configuration in CONFIGn register, and the corresponding bit in the Interrupt Enable Set register
(INTENSET) is written to '1'. WAKEUP.WAKEUPEN[x]=1 can enable the wake-up from pin EXTINTx.
Figure 21-3. Wake-Up Operation Example (High-Level Detection, No Filter, WAKEUPEN[x]=1)
CLK_EIC_APB
EXTINTx
intwake_extint[x]
intreq_extint[x]
clear INTFLAG.EXTINT[x]
wake from sleep mode
21.6.9 Synchronization
Due to asynchronicity between the main clock domain and the peripheral clock domains, some registers
need to be synchronized when written or read.
When executing an operation that requires synchronization, the Synchronization Busy bit in the Status
register (STATUS.SYNCBUSY) will be set immediately, and cleared when synchronization is complete.
If an operation that requires synchronization is executed while STATUS.SYNCBUSY is one, the bus will
be stalled. All operations will complete successfully, but the CPU will be stalled, and interrupts will be
pending as long as the bus is stalled.
The following bits are synchronized when written:
Software Reset bit in the Control register (CTRL.SWRST)
Enable bit in the Control register (CTRL.ENABLE)
Related Links
14.3 Register Synchronization
SAM D21 Family
EIC – External Interrupt Controller
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 371