The alarm option allows you to use the Nintendo DSi as an alarm clock. Please note that when the alarm is turned on, you cannot use the Nintendo DSi in any other mode until the alarm is turned off.
How to set the alarm
Tap the up/down arrows to select the time you would like the alarm to go off, then select "OK" to turn the alarm on.
Once the alarm has sounded, the alarm will enter Snooze Mode, and will continue to sound every five minutes until it has been turned off. Snooze Mode ends automatically after one hour.
How to cancel or turn off the alarm
While the alarm is on, tap the Touch Screen or press any button other than L and R to cancel the alarm.