HD64F3687GHV Datasheet, PDF (210/566 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 10 Realtime Clock (RTC)
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 are not reset by a RES
input. Therefore, all registers must be set to their initial values after power-on. Once the register
setting 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.
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
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.
Figure 10.3 Initial Setting Procedure
Rev. 3.00 Sep. 10, 2007 Page 176 of 528
REJ09B0216-0300