SH7713 Datasheet, PDF (569/904 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series

15.5 Usage Notes
Section 15 Realtime Clock (RTC)
15.5.1 Register Writing during RTC Count
The following RTC registers cannot be written to during an RTC count (while the START bit = 1
in RCR2).
RSECCNT, RMINCNT, RHRCNT, RDAYCNT, RWKCNT, RMONCNT, RYRCNT
The RTC count must be stopped before writing to any of the above registers.
15.5.2 Use of Realtime Clock (RTC) Periodic Interrupts
The method of using the periodic interrupt function is shown in figure 15.6.
A periodic interrupt can be generated periodically at the interval set by the periodic interrupt flag
(PES0−PES2) in RCR2. When the time set by the PES0−PES2 has elapsed, the PEF is set to 1.
The PEF is cleared to 0 upon periodic interrupt generation or when the periodic interrupt flag
(PES0 to PES2) is set. Periodic interrupt generation can be confirmed by reading this bit, but
normally the interrupt function is used.
Set PES, clear PEF
Set PES0 to PES2,
and clear PEF to 0,
in RCR2
Elapse of time set by PES
Clear PEF
Clear PEF to 0
Figure 15.6 Using Periodic Interrupt Function
15.5.3 Transition to Standby Mode after Setting Register
When a transition to standby mode is made after registers in the RTC are set, sometimes counting
is not performed correctly. In case the registers are set, be sure to make a transition to standby
mode after waiting for two RTC clocks or more.
Rev.1.50 Aug. 30, 2006 Page 529 of 860
REJ09B0288-0150