HD6413007F20 Datasheet, PDF (452/798 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

12. Watchdog Timer
12.3.2 Interval Timer Operation
Figure 12.5 illustrates interval timer operation. To use the WDT as an interval timer, clear bit
WT/IT to 0 and set bit TME to 1 in TCSR. An interval timer interrupt request is generated at each
TCNT overflow. This function can be used to generate interval timer interrupts at regular
intervals.
H'FF
TCNT
count value
H'00
Time t
WT/ IT = 0
TME = 1
Interval
timer
interrupt
Interval
timer
interrupt
Interval
timer
interrupt
Interval
timer
interrupt
Figure 12.5 Interval Timer Operation
12.3.3 Timing of Setting of Overflow Flag (OVF)
Figure 12.6 shows the timing of setting of the OVF flag. The OVF flag is set to 1 when TCNT
overflows. At the same time, a reset signal is generated in watchdog timer operation, or an interval
timer interrupt is generated in interval timer operation.
φ
TCNT
H'FF
H'00
Overflow signal
OVF
Figure 12.6 Timing of Setting of OVF
Rev.5.00 Sep. 12, 2007 Page 422 of 764
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