156
CHAPTER 8 WATCH TIMER
Preliminary User’s Manual U13420EJ2V0UM00
(1) Watch timer
When the main system clock or subsystem clock is used, interrupt requests (INTWT) are generated at 0.5 second
or 0.25 second intervals.
(2) Interval timer
Interrupt requests (INTWTI) are generated at the preset time interval.
Table 8-1. Interval Timer Interval Time
Interval Time
When Operated at
When Operated at
When Operated at
f
X
= 8.38 MHz
f
X
= 4.19 MHz
f
XT
= 32.768 kHz
2
11
×
1/f
X
2
4
×
1/f
XT
244
µ
s
489
µ
s
488
µ
s
2
12
×
1/f
X
2
5
×
1/f
XT
489
µ
s
978
µ
s
977
µ
s
2
13
×
1/f
X
2
6
×
1/f
XT
978
µ
s
1.96 ms
1.95 ms
2
14
×
1/f
X
2
7
×
1/f
XT
1.96 ms
3.91 ms
3.91 ms
2
15
×
1/f
X
2
8
×
1/f
XT
3.91 ms
7.82 ms
7.81 ms
2
16
×
1/f
X
2
9
×
1/f
XT
7.82 ms
15.6 ms
15.6 ms
Remark
f
X
:
Main system clock oscillation frequency
f
XT
: Subsystem clock oscillation frequency
8.2 Watch Timer Configuration
The watch timer consists of the following hardware.
Table 8-2. Watch Timer Configuration
Item
Configuration
Counter
5 bits
×
1
Prescaler
9 bits
×
1
Control register
Watch timer mode control register (WTM)
Содержание mPD780065 Series
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