Interval Timer Operation; Timing Of Setting Of Overflow Flag (Ovf); Figure 11.5 Interval Timer Operation; Figure 11.6 Timing Of Setting Of Ovf - Hitachi H8/3062 Hardware Manual

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
IT
WT/ = 0
TME = 1
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
Overflow signal
OVF
358
Interval Interval
timer timer
interrupt interrupt

Figure 11.5 Interval Timer Operation

H'FF

Figure 11.6 Timing of Setting of OVF

Interval Interval
timer timer
interrupt interrupt
H'00
Time t