Operation Of Watchdog Timer (Watchdog Timer Interrupt) - Renesas M16C Series User Manual

M30245 Group

2.12.2 Operation of Watchdog Timer (Watchdog timer interrupt)

The following is an operation of the watchdog timer using watchdog timer interrupt. Figure 2.12.3 shows
the operation timing, and Figure 2.12.4 shows the set-up procedure.
Operation
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Write signal to the
watchdog timer
start register
Figure 2.12.3. Operation timing of watchdog timer (watchdog timer interrupt)
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
(1) Writing to the watchdog timer start register initializes the watchdog timer to 7FFF
causes it to start a down count.
(2) With a count in progress, writing to the watchdog timer start register again initializes the
watchdog timer to 7FFF
(3) Either executing the WAIT instruction or going to the stopped state causes the watchdog
timer to hold the count in progress and to stop counting. The watchdog timer resumes count-
ing after returning from the execution of the WAIT instruction or from the stopped state.
(4) If the watchdog timer underflows, it is initialized to 7FFF
time, a watchdog timer interrupt occurs.
(1) Start count
7FFF
16
0000
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and causes it to resume counting.
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(3) In stopped state, or WAIT
instruction is executing, etc
(2) Write operation
2. Watchdog Timer
and continues counting. At this
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(4) Generate
watchdog timer
interrupt
and
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