Datasheet

Section 10 Realtime Clock (RTC)
Rev. 3.00 Mar. 15, 2006 Page 147 of 526
REJ09B0060-0300
Section 10 Realtime Clock (RTC)
The realtime clock (RTC) is a timer used to count time ranging from a second to a week. Figure
10.1 shows the 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 (seconds, minutes, hours, days, and weeks) interrupts
• 8-bit free running counter
• Selection of clock source
PSS
32-kHz
oscillator
circuit
RTCCSR
RSECDR
RMINDR
RWKDR
Clock count
control circuit
Interrupt
control circuit
Interrupt
RTCCR1
RHRDR
RTCCR2
Internal data bus
1/4
TMOW
[Legend]
RTCCSR:
RSECDR:
RMINDR:
RHRDR:
RWKDR:
RTCCR1:
RTCCR2:
PSS:
Clock source select register
Second date register/free running counter data register
Minute date register
Hour date register
Day-of-week date register
RTC control register 1
RTC control register 2
Prescaler S
Figure 10.1 Block Diagram of RTC