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8
Real-Time Clock (RTC)
note: The RTC is available only in the S1C17624/604.
8.1
RTC Module Overview
The S1C17624/604 incorporates a real-time clock (RTC) with a perpetual calendar, and an OSC1 oscillator circuit
to generate the operating clock for the RTC.
The RTC and OSC1 oscillator circuit (CLG) operate in SLEEP mode. Moreover, the RTC can periodically generate
interrupt requests to the CPU.
The main features of the RTC are outlined below.
• Contains time counters (seconds, minutes, and hours) and calendar counters (days, days of the week, months, and
year).
• BCD data can be read from and written to both counters.
• Includes read buffers to prevent carry over at reading.
• Capable of controlling the starting and stopping of time clocks.
• 24-hour or 12-hour mode can be selected.
• A 30-second correction function can be implemented in software.
• Periodic interrupts are possible.
• Interrupt period can be selected from 1/512 second, 1/256 second, 1/128 second, 1/64 second, 1 second, 1 min-
ute, or 1 hour. (Level/edge interrupt mode)
Figure 8.1.1 shows a block diagram of the RTC.
CLG
OSC1
32 kHz
oscillator
To ITC
S1C17624/604/622/602/621 TeChniCal Manual
1/512–1/64
second
Interrupt
control
1 second
1 minute
1 hour
24H/12H
Figure 8.
1.1 RTC Block Diagram
Seiko epson Corporation
8 Real-TiMe ClOCK (RTC)
RTC
Controller
Divider
1 Hz
1-second counter
10-second counter
1-minute counter
10-minute counter
1-hour counter
10-hour counter
AM/PM
Days of week counter
1-day counter
10-day counter
1-month counter
10-month counter
1-year counter
10-year counter
8-1
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