HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 644

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 17 Realtime Clock (RTC)
17.4.4
Figure 17.4 shows how to use the 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.
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Alarm Function
(wait for interrupt or
Monitor alarm time
check alarm flag)
Clear alarm flag
Set alarm time
Clock running
Disable alarm
Enable alarm
interrupt
interrupt
Figure 17.4 Using Alarm Function
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