HD6417144 RENESAS [Renesas Technology Corp], HD6417144 Datasheet - Page 435

• Manufacturer Part Number: HD6417144
• Description: 32-Bit RISC Microcomputer SuperHTM RISC engine Family/SH7144 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

12.6.3
If the values of bits CKS2 to CKS0 in the timer control/status register (TCSR) are rewritten while
the WDT is running, the count may not increment correctly. Always stop the watchdog timer (by
clearing the TME bit to 0) before changing the values of bits CKS2 to CKS0.
12.6.4
To prevent incorrect operation, always stop the watchdog timer (by clearing the TME bit to 0)
before switching between interval timer mode and watchdog timer mode.
12.6.5
If a WDTOVF output signal is input to the RES pin, the chip cannot initialize correctly.
Avoid inputting the WDTOVF signal to the RES pin directly. To reset the entire system with the
WDTOVF signal, use the circuit shown in figure 12.9.
12.6.6
If the RSTE bit is cleared to 0 in watchdog timer mode, the chip will not be reset internally when a
TCNT overflow occurs, but TCNT and TCSR in the WDT will be reset.
Changing CKS2 to CKS0 Bit Values
Changing between Watchdog Timer and Interval Timer Modes
System Reset by WDTOVF Signal
Internal Reset in Watchdog Timer Mode
Figure 12.9 Example of System Reset Circuit Using WDTOVF Signal
Reset signal to entire system
Reset input
Rev.4.00 Mar. 27, 2008 Page 391 of 882
RES
WDTOVF
This LSI
12. Watchdog Timer
REJ09B0108-0400