To put the device into a sleep mode, follow these steps:
Configure and
enable the interrupts that shall be able to wake the device from
sleep. Also, enable global interrupts.
Warning: If there are no
interrupts enabled when going to sleep, the device cannot wake
up again. Only a Reset will allow the device to continue
operation.
Select the sleep mode to be entered
and enable the Sleep Controller by writing to the Sleep Mode bits (SMODE) and the
Enable bit (SEN) in the Control A register (SLPCTRL.CTRLA). A SLEEP
instruction must be run to make the device actually go to sleep.