Alarm Function - Renesas RZ/A Series User Manual

RZ/A1L Group, RZ/A1LU Group, RZ/A1LC Group
13.4.4

Alarm Function

Figure 13.4 shows how to use the alarm function.
Figure 13.4 Using Alarm Function
Alarms can be generated using seconds, minutes, hours, day of the week, day, month, year, or any combination of these.
Set the ENB bit in the register on which the alarm is placed to 1, and then set the alarm time in the lower bits. Clear the
ENB bit in the register on which the alarm is not placed to 0.
When the clock and alarm times match, 1 is set in the AF bit in RCR1. Alarm detection can be checked by reading this
bit, but normally it is done by interrupt. If 1 is set in the AIE bit in RCR1, an interrupt is generated when an alarm occurs.
The alarm flag is set when the clock and alarm times match. However, the alarm flag can be cleared by writing 0.
R01UH0437EJ0600 Rev.6.00
Jan 29, 2021
Clock running
Write 0 to AIE in RCR1
Disable alarm interrupt
to prevent erroneous interrupt
Set alarm time
Always reset, since the flag may have been
Clear alarm flag
set while the alarm time was being set.
Write 1 to AIE in RCR1
Enable alarm interrupt
Monitor alarm time
(wait for interrupt or
check alarm flag)
13. Realtime Clock
13-18