HD6417706 Datasheet, PDF (389/709 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer Super RISC engine Family/SH7700 Series

13.4.4 Alarm Function
Figure 13.4 shows how to use the alarm function.
Alarms can be generated using seconds, minutes, hours, day of the week, date, month, or any
combination of these. Set the ENB bit (bit 7) 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
placed to 0.
When the clock and alarm times match, 1 is set in the AF bit (bit 0) in RCR1. Alarm detection can
be checked by reading this bit, but normally it is done by interrupt. If 1 is placed in the AIE bit (bit
3) in RCR1, an interrupt is generated when an alarm occurs.
Clock running
Set whether to use
alarm interrupt
Disable interrupt to prevent errorneous
interruption (AIE bit in RCR1 is cleared).
Then write 1.
Set alarm time
Clear alarm flag
Always reset, since the flag may have been
set while the alarm time was being set
(AF bit in RCR1 is cleared).
Monitor alarm time
(wait for interrupt or
check alarm flag)
Figure 13.4 Using the Alarm Function
Rev. 4.00, 03/04, page 343 of 660