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User’s Manual U15798EJ2V0UD
CHAPTER 9 WATCH TIMER
9.1 Outline of Watch Timer
The watch timer generates interrupt requests (INTWTN0 and INTWTNI0) at the preset time interval.
9.2 Watch Timer Functions
The watch timer has the following functions.
• Watch timer
• Interval timer
The watch timer and the interval timer can be used simultaneously.
Figure 9-1 shows the watch timer block diagram.
Figure 9-1. Watch Timer Block Diagram
Remark
f
X
:
Main system clock oscillation frequency
f
XT
: Subsystem clock oscillation frequency
f
W
: Watch timer clock frequency
f
X
/
2
8
f
XT
f
W
f
W
2
4
WTNM07
WTS
1/2
WTNM06 WTNM05 WTNM04 WTNM03 WTNM02 WTNM01 WTNM00
Selector
Selector
Selector
Selector
Selector
11-bit prescaler
3
5-bit counter
Clear
Clear
f
W
2
5
f
W
2
6
f
W
2
7
f
W
2
8
f
W
2
4
f
W
2
5
f
W
2
13
f
W
2
14
f
W
2
10
f
W
2
11
f
W
2
9
INTWTN0
INTWTNI0
Internal bus
Watch timer operation
mode register 0 (WTNM0)
Watch timer
interrupt time
select register
(WTIM)
