Chapter 49 Real-Time Clock; Overview; Features - Fujitsu MB91460 SERIES FR60 User Manual

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.
Oscillation
clock

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:
• 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).
Sub-Second
h)
Registers
1/2 1/2 21 Bit 21
Down Counter
Mainclock, Subclock, RC clock
Reload
Counter
Second Minute Hour
Update
Second Minute Hour
Chapter 49 Real-Time Clock
1.Overview
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