10 REAL-TIME CLOCK (RTCA)
S1C31D50/D51 TECHNICAL MANUAL
Seiko Epson Corporation
10-5
(Rev. 2.00)
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 10.4.4.1 Stopwatch Count-Up Patterns
10.5 Interrupts
RTCA has a function to generate the interrupts shown in Table 10.5.1.
Table 10.5.1 RTCA Interrupt Function
Interrupt
Interrupt flag
Set condition
Clear condition
Alarm
RTCAINTF.ALARMIF
Matching between the RTCAALM1–2 register
contents and the real-time clock counter contents
Writing 1
1-day
RTCAINTF.T1DAYIF
Day counter count up
Writing 1
1-hour
RTCAINTF.T1HURIF
Hour counter count up
Writing 1
1-minute
RTCAINTF.T1MINIF
Minute counter count up
Writing 1
1-second
RTCAINTF.T1SECIF
Second counter count up
Writing 1
1/2-second
RTCAINTF.T1_2SECIF See Figure 10.5.1.
Writing 1
1/4-second
RTCAINTF.T1_4SECIF See Figure 10.5.1.
Writing 1
1/8-second
RTCAINTF.T1_8SECIF See Figure 10.5.1.
Writing 1
1/32-second
RTCAINTF.T1_32SECIF See Figure 10.5.1.
Writing 1
Stopwatch 1 Hz
RTCAINTF.SW1IF
1/10-second counter overflow
Writing 1
Stopwatch 10 Hz
RTCAINTF.SW10IF
1/10-second counter count up
Writing 1
Stopwatch 100 Hz
RTCAINTF.SW100IF
1/100-second counter count up
Writing 1
Theoretical regulation
completion
RTCAINTF.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 10.5.1 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.