HD64F2145 Datasheet, PDF (374/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

14.4.2 Interval Timer Mode
When the WDT is used as an interval timer, an interval timer interrupt (WOVI) is generated each
time the TCNT overflows, as shown in figure 14.3. Therefore, an interrupt can be generated at
intervals.
When the TCNT overflows in interval timer mode, an interval timer interrupt (WOVI) is requested
at the same time the OVF bit of TCSR is set to 1. The timing is shown figure 14.4.
TCNT value
H'FF
Overflow
Overflow
Overflow
Overflow
H'00
WT/ = 0
TME = 1
WOVI
WOVI
WOVI
WOVI
Time
WOVI : Internal timer interrupt request occurrence
Figure 14.3 Interval Timer Mode Operation
ø
TCNT
Overflow signal
(internal signal)
OVF
H'FF
H'00
Figure 14.4 OVF Flag Set Timing
Rev. 2.0, 08/02, page 334 of 788