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CHAPTER 9 WATCH TIMER
Preliminary User’s Manual U14581EJ3V0UM00
(1) Watch timer
When the main system clock is used, interrupt requests (INTWT) are generated at 0.25 second (at f
X
= 8.38-
MHz operation) intervals.
(2) Interval timer
Interrupt requests (INTWT) are generated at the preset time interval.
Table 9-1. Interval Timer Interval Time
Interval Time
When Operated at
f
X
= 8.38 MHz
2
12
/f
X
489
µ
s
2
13
/f
X
978
µ
s
2
14
/f
X
1.96 ms
2
15
/f
X
3.91 ms
2
16
/f
X
7.82 ms
2
17
/f
X
15.65 ms
Remark
f
X
: Main system clock oscillation frequency
9.2 Watch Timer Configuration
The watch timer consists of the following hardware.
Table 9-2. Watch Timer Configuration
Item
Configuration
Counter
5 bits
×
1
Prescaler
9 bits
×
1
Control register
Watch timer mode control register (WTM)
Содержание mPD780851
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