158
CHAPTER 9 WATCHDOG TIMER
Preliminary User’s Manual U16035EJ1V0UM
(1) Watchdog timer mode
A program loop is detected. Upon detection of the program loop, a non-maskable interrupt request or RESET
can be generated.
Table 9-1. Watchdog Timer Program Loop Detection Time
Program Loop Detection Time
2
12
×
1/f
X
(489
µ
s)
2
13
×
1/f
X
(978
µ
s)
2
14
×
1/f
X
(1.96 ms)
2
15
×
1/f
X
(3.91 ms)
2
16
×
1/f
X
(7.82 ms)
2
17
×
1/f
X
(15.6 ms)
2
18
×
1/f
X
(31.3 ms)
2
20
×
1/f
X
(125 ms)
Remarks 1.
f
X
: Main system clock oscillation frequency
2.
Figures in parentheses are for operation with f
X
= 8.38 MHz
(2) Interval timer mode
Interrupt requests are generated at the preset time intervals.
Table 9-2. Interval Time
Interval Time
2
12
×
1/f
X
(489
µ
s)
2
13
×
1/f
X
(978
µ
s)
2
14
×
1/f
X
(1.96 ms)
2
15
×
1/f
X
(3.91 ms)
2
16
×
1/f
X
(7.82 ms)
2
17
×
1/f
X
(15.6 ms)
2
18
×
1/f
X
(31.3 ms)
2
20
×
1/f
X
(125 ms)
Remarks 1.
f
X
: Main system clock oscillation frequency
2.
Figures in parentheses are for operation with f
X
= 8.38 MHz