HD64F2636F20 Datasheet, PDF (491/1512 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2600 Series

H8S/2639, H8S/2638, H8S/2636,
H8S/2630, H8S/2635 Group
Section 12 Watchdog Timer
12.3.2 Interval Timer Operation
To use the WDT as an interval timer, clear the WT/IT bit in TCSR to 0 and set the TME bit to 1.
An interval timer interrupt (WOVI) is generated each time TCNT overflows, provided that the
WDT is operating as an interval timer, as shown in figure 12-5. This function can be used to
generate interrupt requests at regular intervals.
TCNT value
H'FF
Overflow
Overflow
Overflow
Overflow
H'00
WT/IT = 0
TME = 1
WOVI
WOVI
WOVI
WOVI
Time
Legend:
WOVI: Interval timer interrupt request generation
Figure 12-5 Interval Timer Operation
12.3.3 Timing of Setting Overflow Flag (OVF)
The OVF flag is set to 1 if TCNT overflows during interval timer operation. At the same time, an
interval timer interrupt (WOVI) is requested. This timing is shown in figure 12-6.
With WDT1, the OVF bit of the TCSR is set to 1 and a simultaneous NMI interrupt is requested
when the TCNT overflows if the NMI request has been chosen in the watchdog timer mode.
REJ09B0103-0800 Rev. 8.00
May 28, 2010
Page 441 of 1458