SH7205 Datasheet, PDF (757/1904 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series

15.4.4 Alarm Function
Figure 15.4 shows how to use the alarm function.
Section 15 Realtime Clock (RTC)
Clock running
Disable alarm interrupt
Write 0 to AIE in RCR1
to prevent errorneous interrupt
Set alarm time
Clear alarm flag
Always clear, since the flag may have been
set while the alarm time was being set.
Enable alarm interrupt
Write 1 to AIE in RCR1
Monitor alarm time
(wait for interrupt or
check alarm flag)
Figure 15.4 Using Alarm Function
Alarms can be generated using seconds, minutes, hours, day of the week, date, 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.
Rev. 1.00 Mar. 25, 2008 Page 725 of 1868
REJ09B0372-0100