Fujitsu FR81S User Manual
CHAPTER 28: REAL-TIME CLOCK(RTC)
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: REAL-TIME CLOCK(RTC)
FUJITSU SEMICONDUCTOR CONFIDENTIAL
15
5. Operation
This section explains the operation of the real-time clock (RTC).
This section explains the operations of the real-time clock.
Figure 5-1 Operation Descriptions for the Real-time Clock
(1) Use the start bit (ST="0") to reset the sub-second counter (22-bit down counter) and Day/ Hour/ Minute/
Second timers (0), and then stop them.
Sub second counter
Clear
Clear
Clear
Clear
Clear
Clear
0.5 second counter
Second
Minute
Hour
Day
Watch mode
Day (N), hour (H), minute (M), and second (S) registervalues
65535 days
23H
59M
59S
0.5S
000000
0F423F
Sub second value
In watch mode
External interrupt input
(22-bit down counter)
ST
(3)
(16)
(17)
(17)
(17)
(17)
(17)
(17)
(17)
(5)
(5)
(4)
(4)
(4)
(4)
(7)
(8)
(8)
(9)
(10)
(10)
(11)
(11)
(12)
(13)
(9)
(1)
(1)
(1)
(1)
(1)
(1)
(2)
(2)
(6)
(14)
(15)
(15)
WOT
S
M
H
N
(real-time clock output)
Da
y,
hour
,min
ute
and
second
counters
RUN
WTBR
WTSR
WTMR
WTHR
WTDR
H
H
MB91520 Series
MN705-00010-1v0-E
1054