H8S-2350 RENESAS [Renesas Technology Corp], H8S-2350 Datasheet - Page 578

• Manufacturer Part Number: H8S-2350
• Description: 16-Bit Single-Chip Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 12 Watchdog Timer (WDT)
12.5.2
If bits CKS2 to CKS0 in TCSR are written to while the WDT is operating, errors could occur in
the incrementation. Software must stop the watchdog timer (by clearing the TME bit to 0) before
changing the value of bits CKS2 to CKS0.
12.5.3
If the mode is switched from watchdog timer to interval timer, or vice versa, while the WDT is
operating, errors could occur in the incrementation. Software must stop the watchdog timer (by
clearing the TME bit to 0) before switching the mode.
12.5.4
If the WDTOVF output signal is input to the RES pin of the H8S/2350 Group, the H8S/2350
Group will not be initialized correctly. Make sure that the WDTOVF signal is not input logically
to the RES pin. To reset the entire system by means of the WDTOVF signal, use the circuit shown
in figure 12.9.
12.5.5
The H8S/2350 Group is not reset internally if TCNT overflows while the RSTE bit is cleared to 0
during watchdog timer operation, but TCNT and TSCR of the WDT are reset.
TCNT, TCSR, and RSTCR cannot be written to while the WDTOVF signal is low. Also note that
a read of the WOVF flag is not recognized during this period. To clear the WOVF flag, therefore,
read TCSR after the WDTOVF signal goes high, then write 0 to the WOVF flag.
Rev. 3.00 Sep 15, 2006 page 544 of 988
REJ09B0330-0300
Reset signal to entire system
Changing Value of CKS2 to CKS0
Switching between Watchdog Timer Mode and Interval Timer Mode
System Reset by WDTOVF
Internal Reset in Watchdog Timer Mode
Figure 12.9 Circuit for System Reset by WDTOVF
Reset input
WDTOVF Signal
WDTOVF
WDTOVF
WDTOVF
WDTOVF Signal (Example)
WDTOVF
H8S/2350 Group
WDTOVF
RES