Datasheet

Table Of Contents
Section 12 Watchdog Timer (WDT)
REJ09B0140-0900 Rev. 9.00 Page 379 of 846
Sep 16, 2010
H8S/2215 Group
12.5.5 Internal Reset in Watchdog Timer Mode
This LSI is not reset internally if TCNT overflows while the RSTE bit is cleared to 0 during
watchdog timer operation, however TCNT and TCSR of the WDT are reset.
TCNT, TCSR, or RSTCR cannot be written to for 132 states following an overflow. During this
period, any attempt to read the WOVF flag is not acknowledged. Accordingly, wait 132 states
after overflow to write 0 to the WOVF flag for clearing.
12.5.6 OVF Flag Clearing in Interval Timer Mode
When the OVF flag setting conflicts with the OVF flag reading in interval timer mode, writing 0
to the OVF flag may not clear the flag even though the OVF flag has been read while it is 1. If
there is a possibility that the OVF flag setting and reading will conflict, such as when the OVF
flag is polled with the interval timer interrupt disabled, read the OVF flag while it is 1 at least
twice before writing 0 to the OVF flag to clear the flag.