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Chapter 49 real-time clock, Overview, Features – FUJITSU MB91460 SERIES FR60 User Manual

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Chapter 49 Real-Time Clock

1.Overview

Chapter 49 Real-Time Clock

1. Overview

Real-time Clock (RTC) continues to count elapsed time even in the STOP mode to provide the current real
time (HH/MM/SS) based on main oscillation (4MHz), sub oscillation (32kHz) or RC oscillation (~100kHz).

This allows precise time counting without a return from an interrupt during stand by periods.

2. Features

• Information: Time count (HH/MM/SS). (This clock continues to operate even in the STOP mode.)

• Operational on main clock (4MHz), sub clock (32kHz) or RC clock (~100kHz)

• Quantity: 1

• Time unit: Clock divided by 2

• Operation clock:

For register access: CLKP

For time count:

Mainclock, Subclock, RC clock

• Time: Initial setting and adjustment are possible.

• Interrupt: Interrupts can be generated at any of the five intervals: 1 half-second, 1 second, 1 minute, 1 hour

and 1 day.

• Others: By changing the value of the sub-second register, interrupts can be generated at any interval (from

short to long).

1/2

21

h)

Oscillation

1/2

21 Bit
Down Counter

Sub-Second

Registers

Second Minute

Hour

Reload

Counter

Second Minute

Hour

Update

clock