SH7205 Datasheet, PDF (758/1904 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series

Section 15 Realtime Clock (RTC)
15.5 Usage Notes
15.5.1 Register Writing during RTC Count
The following RTC registers cannot be written to during an RTC count (while bit 0 = 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 Real-time Clock (RTC) Periodic Interrupts
The method of using the periodic interrupt function is shown in figure 15.5.
A periodic interrupt can be generated periodically at the interval set by bits PES2 to PES0 in
RCR2. When the time set by bits PES2 to PES0 has elapsed, the PEF is set to 1.
The PEF is cleared to 0 upon periodic interrupt generation or when bits PES2 to PES0 are set.
Periodic interrupt generation can be confirmed by reading this bit, but normally the interrupt
function is used.
Set PES, clear PEF
Elapse of time set by PES
Clear PEF
Set PES2 to PES0
and clear PEF to 0
in RCR2
Clear PEF to 0
Figure 15.5 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. 1.00 Mar. 25, 2008 Page 726 of 1868
REJ09B0372-0100