HD64F3048VTF8 Datasheet, PDF (478/903 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip

Section 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
WT/ IT = 0
TME = 1
Interval
timer
interrupt
Interval
timer
interrupt
Interval
timer
interrupt
Interval
timer
interrupt
Figure 12.5 Interval Timer Operation
Time t
12.3.3 Timing of Setting of Overflow Flag (OVF)
Figure 12.6 shows the timing of setting of the OVF flag in TCSR. 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. 3.00 Sep 27, 2006 page 450 of 872
REJ09B0325-0300