SH7730 Datasheet, PDF (592/1188 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7780 Series

Section 17 Realtime Clock (RTC)
17.4.4 Alarm Function
Figure 17.4 shows how to use the alarm function.
Clock running
Disable alarm
interrupt
Set alarm time
Clear alarm flag
Enable alarm
interrupt
Monitor alarm time
(wait for interrupt or
check alarm flag)
Write 0 to AIE in RCR1
to prevent errorneous interrupt
Always clear, since the flag may have been
set while the alarm time was being set.
Write 1 to AIE in RCR1
Figure 17.4 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 Sep. 19, 2007 Page 544 of 1136
REJ09B0359-0100