SH7727 Datasheet, PDF (545/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

16.3 RTC Operation
Section 16 Realtime Clock (RTC)
16.3.1 Initial Settings of Registers after Power-On
All RTC registers should be set initially after the power is turned on.
16.3.2 Setting the Time
Figures 16.2 (a) and 16.2 (b) show how to set the time after stopping the clock. This procedure can
be used to set the entire calendar and clock function. It can be programmed easily.
Usage Notes
1. Initialization Timing for 64 Hz Counter (R64CNT)
If it is necessary, after initializing the counter by means of the RESET bit in the RTC’s RCR2
register, to confirm that the change has taken effect by reading the R64CNT value, wait at least
107 µs after setting the RESET bit to 1 before reading the R64CNT counter. Note that the
divider circuit (RTC prescaler) is also initialized when the RESET bit is set to 1.
2. Incrementing RSECCNT by Initializing R64CNT
Either method (a) or method (b) below may be used.
(a) After setting the RESET bit to 1 and confirming that R64CNT has been initialized, set the
START bit to 1. This process is shown in figure 16.2 (a).
(b) Set the START bit to 1 and the RESET bit to 1 at the same time. This process is shown in
figure 16.2 (b). Note that the processing indicated by the asterisk (*) in figure 16.2 (b) may
be omitted if nothing is written to the RCR2 register during an interval of approximately
107 µs after the START bit is set to 1.
Rev. 5.00 Dec 12, 2005 page 473 of 1034
REJ09B0254-0500