Datasheet

Table Of Contents
Section 10 Realtime Clock (RTC)
Rev. 2.00 Jul. 04, 2007 Page 211 of 692
REJ09B0309-0200
Section 10 Realtime Clock (RTC)
The realtime clock (RTC) is a timer used to count periods of time ranging from a second to a
week. Interrupts can be generated at intervals ranging from 0.25 seconds to a week. Figure 10.1 is
a block diagram of the RTC.
10.1 Features
Counts seconds, minutes, hours, and day-of-week
Start/stop function
Reset function
Readable/writable counter of seconds, minutes, hours, and day-of-week with BCD codes
Periodic (0.25 seconds, 0.5 seconds, one second, minute, hour, day, and week) interrupts
8-bit free running counter
Selection of clock source
Module standby mode allows this module to enter standby mode independently when it is not
in use (for details, see section 6.4, Module Standby Function).
PSS
32-kHz
oscillator
circuit
RTCCSR
RSECDR
RMINDR
RWKDR
Clock count
control circuit
Interrupt
control circuit
Interrupt
RTCCR1
RHRDR
RTCCR2
RTCFLG
Internal data bus
1/4
TMOW
[Legend]
RTCCSR:
RSECDR:
RMINDR:
RHRDR:
Clock source select register
Second date register/
free running counter data register
Minute date register
Hour date register
RWKDR:
RTCCR1:
RTCCR2:
RTCFLG:
PSS:
Day-of-week date register
RTC control register 1
RTC control register 2
RTC interrupt flag register
Prescaler S
Figure 10.1 Block Diagram of RTC