SH7261 Datasheet, PDF (697/1348 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

Section 15 Realtime Clock (RTC)
15.5 Usage Notes
15.5.1 Register Writing during RTC Count
Do not write to the count registers (RSECCNT, RMINCNT, RHRCNT, RDAYCNT, RWKCNT,
RMONCNT, and RYRCNT) during the RTC counting (while the START bit in RCR2 is 1). If any
of the count registers is written to during the RTC counting, the count register may not be read
correctly immediately after the execution of a write instruction. The RTC counting must be
stopped before writing to any of the count registers.
15.5.2 Use of Realtime 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 the flags PES0 to PES2 in
RCR2. When the time set by the PES0 to PES2 has elapsed, the PEF is set to 1.
The PEF is cleared to 0 upon periodic interrupt generation or when the flags PES0 to PES2 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 PES0 to PES2,
and clear PEF to 0,
in RCR2
Clear PEF to 0
Figure 15.5 Using Periodic Interrupt Function
Rev. 2.00 Sep. 07, 2007 Page 665 of 1312
REJ09B0320-0200