HD6413008VF25 Datasheet, PDF (364/688 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

11. Watchdog Timer
11.3.2 Interval Timer Operation
Figure 11.5 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 11.5 Interval Timer Operation
11.3.3 Timing of Setting of Overflow Flag (OVF)
Figure 11.6 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 11.6 Timing of Setting of OVF
Rev.4.00 Aug. 20, 2007 Page 318 of 638
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