Table of Contents
15. Real Time Clock (RTC)
15.3 Function
Note 1: fs: Low-frequency clock [Hz]
Note 2: RTCCR can be rewritten only when RTCCR is "0". If data is written into RTCCR
SEL> when RTCCR is "1", the existing data remains effective. RTCCR 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 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 is maintained and RTCCR 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 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 to "1" enables the basic clock sup-
ply to real time clock and allows the real time clock to operate.
After reset, POFFCR2 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 to "1" in the initial setting of the
program (before the real time clock control registers are operated).
Do not change POFFCR2 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 to "1" enables the real time clock operation. Setting RTCCR to "0"
disables the real time clock operation.
RTCCR 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.
RTCCR can be rewritten only when RTCCR is "0". If data is written into
RTCCR when RTCCR is "1", the existing data remains effective.
RTCCR 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
Enables/disables the real time clock opera-
RTCRUN
tion
15
000 : 2
/fs (1.000 [s] @fs=32.768kHz)
14
001 : 2
/fs (0.500 [s] @fs=32.768kHz)
13
010 : 2
/fs (0.250 [s] @fs=32.768kHz)
12
011 : 2
/fs (125.0 [ms] @fs=32.768kHz)
11
100 : 2
/fs (62.50 [ms] @fs=32.768kHz)
10
101 : 2
/fs (31.25 [ms] @fs=32.768kHz)
9
110 : 2
/fs (15.62 [ms] @fs=32.768kHz)
8
111 : 2
/fs (7.81 [ms] @fs=32.768kHz)
0 : Disable
1 : Enable
TMP89FM42
- Quick Links:
- Table of Contents
Hide quick links:
Table of Contents
