User’s Manual U15331EJ4V1UD
161
CHAPTER 8 WATCH TIMER
8.1 Watch Timer Functions
The watch timer has the following functions.
•
Watch timer
•
Interval timer
The watch and interval timers can be used at the same time.
Figure 8-1 shows a block diagram of the watch timer.
Figure 8-1. Block Diagram of Watch Timer
f
X
/2
7
f
XT
/2
f
XT
Selector
Selector
f
W
f
W
2
4
f
W
2
5
f
W
2
6
f
W
2
7
f
W
2
8
f
W
2
9
Clear
9-bit prescaler
Selector
Clear
5-bit counter
INTWT
INTWTI
WTM7
WTS
WTM6 WTM5 WTM4 WTM1 WTM0
Watch timer mode
control register (WTM)
Watch timer interrupt
time selection
register (WTIM)
Internal bus
1/2