SH7708 Datasheet, PDF (329/625 Pages) Renesas Technology Corp – SuperH™ RISC engine

Section 12 Realtime Clock (RTC)
12.1 Overview
The SH7708 Series has a realtime clock (RTC) with its own 32.768-kHz crystal oscillator.
12.1.1 Features
• Clock and calendar functions (BCD display): seconds, minutes, hours, date, day of the week,
month, and year
• 1-Hz to 64-Hz timer (binary display)
• Start/stop function
• 30-second adjust function
• Alarm interrupt: frame comparison of seconds, minutes, hours, date, day of the week, and
month can be used as conditions for the alarm interrupt
• Cyclic interrupts: the interrupt cycle may be 1/256 second, 1/64 second, 1/16 second, 1/4
second, 1/2 second, 1 second, or 2 seconds
• Carry interrupt: a carry interrupt indicates when a carry occurs during a counter read
• Automatic leap year correction
1 2 . 1 . 2 Block Diagram
The following abbreviations are used in the block diagram of the RTC (figure 12.1):
R64CNT: 64-Hz counter
RSECCNT: Second counter
RMINCNT: Minute counter
RHRCNT: Hour counter
RWKCNT: Day of the week counter
RDAYCNT: Date counter
RMONCNT: Month counter
RYRCNT: Year counter
RSECAR: Second alarm register
RMINAR: Minute alarm register
RHRAR: Hour alarm register
RWKAR: Day of the week alarm register
RDAYAR: Date alarm register
RMONAR: Month alarm register
RCR1: RTC control register 1
RCR2: RTC control register 2
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