TMP89FS60 datasheet(218/410 Pages) TOSHIBA

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Page 204

15. Real Time Clock (RTC)

15.3 Function

TMP89FS60

RA000

Note 1: fs: Low-frequency clock [Hz]

Note 2: RTCCR<RTCSEL> can be rewritten only when RTCCR<RTCRUN> is "0". If data is written into RTCCR<RTC-

SEL> when RTCCR<RTCRUN> is "1", the existing data remains effective. RTCCR<RTCSEL> can be rewritten at

the same time as enabling the real time clock, but it cannot be rewritten at the same time as disabling the real time

clock.

Note 3: If the real time clock is enabled and when 1) SYSCR2<XTEN> is cleared to "0" to stop the low-frequency clock

oscillation circuit or 2) the operation is changed to the STOP mode or the SLEEP0 mode, the data in

RTCCR<RTCSEL> is maintained and RTCCR<RTCRUN> is cleared to "0".

15.3 Function

15.3.1 Low Power Consumption Function

Real time clock has the low power consumption registers (POFFCR2) that save power when the real time

clock is not being used.

Setting POFFCR2<RTCEN> to "0" disables the basic clock supply to real time clock to save power. Note

that this renders the real time clock unusable. Setting POFFCR2<RTCEN> to "1" enables the basic clock sup-

ply to real time clock and allows the real time clock to operate.

After reset, POFFCR2<RTCEN> are initialized to "0", and this renders the real time clock unusable. When

using the real time clock for the first time, be sure to set POFFCR2<RTCEN> to "1" in the initial setting of the

program (before the real time clock control registers are operated).

Do not change POFFCR2<RTCEN> to "0" during the real time clock operation. Otherwise real time clock

may operate unexpectedly.

15.3.2 Enabling/disabling the real time clock operation

Setting RTCCR<RTCRUN> to "1" enables the real time clock operation. Setting RTCCR<RTCRUN> to "0"

disables the real time clock operation.

RTCCR<RTCRUN> is cleared to "0" just after reset release.

15.3.3 Selecting the interrupt generation interval

The interrupt generation interval can be selected at RTCCR<RTCSEL>.

RTCCR<RTCSEL> can be rewritten only when RTCCR<RTCRUN> is "0". If data is written into

RTCCR<RTCSEL> when RTCCR<RTCRUN> is "1", the existing data remains effective.

RTCCR<RTCSEL> can be rewritten at the same time as enabling the real time clock operation, but it cannot

be rewritten at the same time as disabling the real time clock operation.

RTCSEL

Selects the interrupt generation interval

000 : 215/fs (1.000 [s] @fs=32.768kHz)

001 : 214/fs (0.500 [s] @fs=32.768kHz)

010 : 213/fs (0.250 [s] @fs=32.768kHz)

011 : 212/fs (125.0 [ms] @fs=32.768kHz)

100 : 211/fs (62.50 [ms] @fs=32.768kHz)

101 : 210/fs (31.25 [ms] @fs=32.768kHz)

110 : 29/fs (15.62 [ms] @fs=32.768kHz)

111 : 28/fs (7.81 [ms] @fs=32.768kHz)

RTCRUN

Enables/disables the real time clock opera-

tion

0 : Disable

1 : Enable

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