3069RF-ZTAT Datasheet, PDF (472/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

12.3.4 Timing of Setting of Watchdog Timer Reset Bit (WRST)
The WRST bit in RSTCSR is valid when bits WT/IT and TME are both set to 1 in TCSR.
Figure 12.7 shows the timing of setting of WRST and the internal reset timing. The WRST bit is
set to 1 when TCNT overflows and OVF is set to 1. At the same time an internal reset signal is
generated for the entire H8/3069R chip. This internal reset signal clears OVF to 0, but the WRST
bit remains set to 1. The reset routine must therefore clear the WRST bit.
φ
TCNT
H'FF
H'00
Overflow signal
OVF
WDT internal
reset
WRST
Figure 12.7 Timing of Setting of WRST Bit and Internal Reset
Rev. 5.0, 09/04, page 450 of 978