DF2211NP24V Renesas Technology / Hitachi Semiconductor, DF2211NP24V Datasheet - Page 402

• Manufacturer Part Number: DF2211NP24V
• Description: H8S/2200 Series, 2212 Group, USB, RTC, HSS TNP-64B; Vcc= 2.7 to 3.6 volts, Temp= -20 to 75 C; Package: PVQN0064LB-A
• Manufacturer: Renesas Technology / Hitachi Semiconductor

10.5.3
If bits CKS0 to CKS2 in TCSR are written to while the WDT is operating, errors could occur in
the incrementation. Software must be used to stop the watchdog timer (by clearing the TME bit to
0) before changing the value of bits CKS0 to CKS2.
10.5.4
If the mode is switched from watchdog timer to interval timer while the WDT is operating, errors
could occur in the incrementation. Software must be used to stop the watchdog timer (by clearing
the TME bit to 0) before switching the mode.
10.5.5
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.
10.5.6
When the OVF flag setting conflicts with the OVF flag reading in interval timer mode, writing 0 to
the OVF bit may not clear the flag even though the OVF bit 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 bit while it is 1 at least twice before
writing 0 to the OVF bit to clear the flag.
Rev.7.00 Dec. 24, 2008 Page 348 of 698
REJ09B0074-0700
Changing Value of CKS2 to CKS0
Switching between Watchdog Timer Mode and Interval Timer Mode
Internal Reset in Watchdog Timer Mode
OVF Flag Clearing in Interval Timer Mode