Datasheet

Section 10 Realtime Clock (RTC)
Rev. 2.00 Jul. 04, 2007 Page 222 of 692
REJ09B0309-0200
10.4 Operation
10.4.1 Initial Settings of Registers after Power-On
The RTC registers that store second, minute, hour, and day-of-week data, control registers, and
interrupt registers are not initialized by a RES input, or by a reset source caused by a watchdog
timer. Therefore, all registers must be set to their initial values after power-on. Once the register
settings are made, the RTC provides an accurate time as long as power is supplied regardless of a
RES input.
10.4.2 Initial Setting Procedure
Figure 10.3 shows the procedure for the initial setting of the RTC. To set the RTC again, also
follow this procedure.
RTC operation is stopped.
RTC registers and clock count
controller are reset.
Clock output and clock source are
selected and second, minute, hour,
day-of-week, operating mode, and
a.m/p.m are set.
RTC operation is started.
RUN in RTCCR1 = 0
RST in RTCCR1 = 1
RST in RTCCR1 = 0
Set RTCCSR, RSECDR,
RMINDR, RHRDR,
RWKDR, 12/24 in
RTCCR1, and PM
RUN in RTCCR1 = 1
Figure 10.3 Initial Setting Procedure