Fujitsu FR81S User Manual
CHAPTER 28: REAL-TIME CLOCK(RTC)
1. Overview
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: REAL-TIME CLOCK(RTC)
FUJITSU SEMICONDUCTOR CONFIDENTIAL
3
1. Overview
This section explains the overview of the real-time clock (RTC).
The real-time clock (watch timer) consists of the timer control register, sub-second register, Second/ Minute/
Hour/ Day registers, 1/2 clock frequency divider, sub-second counter(22-bit down counter) and Second/
Minute/ Hour/ Day counters. The real-time clock operates as the real-world timer and provides the real-world
timer information.
Figure 1-1 Block Diagram (Overview)
Sub-second register
Sub-second counter
0.5
Second
Counter
Second
Counter
Interrupt
RTC clock
WOT
External pin
1/2
divider
Minute
Hour Day
MB91520 Series
MN705-00010-1v0-E
1042