User’s Manual U15075EJ2V1UD
182
CHAPTER 9 WATCHDOG TIMER
9.1 Watchdog Timer Functions
The watchdog timer has the following functions.
•
Watchdog timer
•
Interval timer
Caution Select the watchdog timer mode or interval timer mode by using the watchdog timer mode
register (WDTM).
(1) Watchdog
timer
The watchdog timer is used to detect a program runaway. When a runaway is detected, a non-maskable
interrupt or the RESET signal can be generated.
Table 9-1. Watchdog Timer Runaway Detection Time
Runaway Detection Time
At f
X
= 5.0 MHz
2
11
×
1/f
X
410
µ
s
2
13
×
1/f
X
1.64 ms
2
15
×
1/f
X
6.55 ms
2
17
×
1/f
X
26.2 ms
f
X
: Main system clock oscillation frequency
(2) Interval timer
The interval timer generates an interrupt at an arbitrary preset interval.
Table 9-2. Interval Time
Interval At
f
X
= 5.0 MHz
2
11
×
1/f
X
410
µ
s
2
13
×
1/f
X
1.64 ms
2
15
×
1/f
X
6.55 ms
2
17
×
1/f
X
26.2 ms
f
X
: Main system clock oscillation frequency
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