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RL78/G1A CHAPTER 7 REAL-TIME CLOCK
Figure 7-22. Procedure for Writing Real-time Clock
Writing MIN
RWAIT = 1
Writing SEC
Start
RWST = 1?
Stops SEC to YEAR counters.
Mode to read and write count values
No
Yes
Writing HOUR
Writing WEEK
Writing DAY
Writing MONTH
Writing YEAR
RWAIT = 0
RWST = 0?
Note
No
Yes
Sets counter operation.
Checks wait status of counter.
End
Writes second count register.
Writes minute count register.
Writes hour count register.
Writes week count register.
Writes day count register.
Writes month count register.
Writes year count register.
Note Be sure to confirm that RWST = 0 before setting STOP mode.
Cautions 1. Complete the series of operations of setting the RWAIT bit to 1 to clearing the RWAIT bit to 0
within 1 second.
2. When changing the values of the SEC, MIN, HOUR, WEEK, DAY, MONTH, and YEAR register
while the counter operates (RTCE = 1), rewrite the values of the MIN register after disabling
interrupt servicing INTRTC by using the interrupt mask flag register. Furthermore, clear the
WAFG, RIFG and RTCIF flags after rewriting the MIN register.
Remark The second count register (SEC), minute count register (MIN), hour count register (HOUR), week count
register (WEEK), day count register (DAY), month count register (MONTH), and year count register (YEAR)
may be written in any sequence.
All the registers do not have to be set and only some registers may be written.
R01UH0305EJ0200 Rev.2.00 313
Jul 04, 2013