Interval Timer Operation; Timing Of Setting Of Overflow Flag (Ovf) - Renesas F-ZTAT H8 Series Hardware Manual

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
IT
WT/ = 0
TME = 1
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
Overflow signal
OVF
Rev. 7.00 Sep 21, 2005 page 446 of 878
REJ09B0259-0700
Interval Interval
timer timer
interrupt interrupt
Figure 12.5 Interval Timer Operation
H'FF
Figure 12.6 Timing of Setting of OVF
Interval Interval
timer timer
interrupt interrupt
H'00
Time t