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(1) Watch timer
When the main system clock is used, interrupt requests (INTWT) are generated at 0.25 second (at f
MHz operation) intervals.
(2) Interval timer
Interrupt requests (INTWT) are generated at the preset time interval.
Remark f
: Main system clock oscillation frequency
X
9.2 Watch Timer Configuration
The watch timer consists of the following hardware.
Counter
Prescaler
Control register
138
CHAPTER 9 WATCH TIMER
Table 9-1. Interval Timer Interval Time
Interval Time
12
2
/f
X
13
2
/f
X
14
2
/f
X
15
2
/f
X
16
2
/f
X
17
2
/f
X
Table 9-2. Watch Timer Configuration
Item
5 bits × 1
9 bits × 1
Watch timer mode control register (WTM)
Preliminary User's Manual U14581EJ3V0UM00
When Operated at
f
= 8.38 MHz
X
489 µ s
978 µ s
1.96 ms
3.91 ms
7.82 ms
15.65 ms
Configuration
= 8.38-
X
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