9 REAL-TIME CLOCK (RTCA)
S1C17M20/M21/M22/M23/M24/M25
Seiko Epson Corporation
9-5
TECHNICAL MANUAL (Rev. 1.0)
26/256
×
6 + 25/256
×
4 = 1 second
1/100-second
counter
26/256 seconds
25/256 seconds
3/256
s
0
1/10-second
counter
26/256 s
0
26/256 s
1
25/256 s
2
25/256 s
3
26/256 s
4
26/256 s
5
25/256 s
6
25/256 s
7
26/256 s
8
26/256 s
9
3/256
s
0
3/256
s
1
2/256
s
1
3/256
s
2
2/256
s
3
3/256
s
4
2/256
s
5
3/256
s
6
2/256
s
7
3/256
s
8
2/256
s
9
3/256
s
2
2/256
s
3
3/256
s
4
2/256
s
5
3/256
s
6
2/256
s
7
3/256
s
8
2/256
s
9
Figure 9.4.4.1 Stopwatch Count-Up Patterns
9.5 Interrupts
RTCA has a function to generate the interrupts shown in Table 9.5.1.
Table 9.5.1 RTCA Interrupt Function
Interrupt
Interrupt flag
Set condition
Clear condition
Alarm
RTCINTF.ALARMIF
Matching between the RTCALM1–2 register contents
and the real-time clock counter contents
Writing 1
1-day
RTCINTF.1DAYIF
Day counter count up
Writing 1
1-hour
RTCINTF.1HURIF
Hour counter count up
Writing 1
1-minute
RTCINTF.1MINIF
Minute counter count up
Writing 1
1-second
RTCINTF.1SECIF
Second counter count up
Writing 1
1/2-second
RTCINTF.1_2SECIF See Figure 9.5.1.
Writing 1
1/4-second
RTCINTF.1_4SECIF See Figure 9.5.1.
Writing 1
1/8-second
RTCINTF.1_8SECIF See Figure 9.5.1.
Writing 1
1/32-second
RTCINTF.1_32SECIF See Figure 9.5.1.
Writing 1
Stopwatch 1 Hz
RTCINTF.SW1IF
1/10-second counter overflow
Writing 1
Stopwatch 10 Hz
RTCINTF.SW10IF
1/10-second counter count up
Writing 1
Stopwatch 100 Hz
RTCINTF.SW100IF
1/100-second counter count up
Writing 1
Theoretical regulation
completion
RTCINTF.RTCTRMIF At the end of theoretical regulation operation
Writing 1
1 Hz counter
256 Hz
128 Hz
64 Hz
32 Hz
16 Hz
8 Hz
4 Hz
2 Hz
1 Hz
Interrupt flags
1/32-second interrupt
1/8-second interrupt
1/4-second interrupt
1/2-second interrupt
1-second interrupt
1-minute interrupt
1-hour interrupt
1-day interrupt
At counter count-up timing
Figure 9.5.1 RTCA Interrupt Timings
Notes: • 1-second to 1/32-second interrupts occur after a lapse of 1/256 second from change of the
1 Hz counter value.
• An alarm interrupt occurs after a lapse of 1/256 second from matching between the AM/PM (in
12H mode), hour, minute, and second counter value and the alarm setting value.