SH7261 datasheet(697/1348 Pages) RENESAS

697 / 1348 page

Section 15 Realtime Clock (RTC)

Rev. 2.00 Sep. 07, 2007 Page 665 of 1312

REJ09B0320-0200

15.5

Usage Notes

15.5.1

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 PES0 to PES2,

and clear PEF to 0,

in RCR2

Clear PEF to 0

Set PES, clear PEF

Elapse of time set by PES

Clear PEF

Figure 15.5 Using Periodic Interrupt Function

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