Internal Reset In Watchdog Timer Mode - Renesas H8S/2319 series Hardware Manual

System Reset by WDTOVF
11.5.4
If the WDTOVF output signal * is input to the RES pin of the chip, the chip 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 11-9.
Note: * The WDTOVF output function is not available in the F-ZTAT versions.
Reset signal to entire system
Note: * The WDTOVF output function is not available in F-ZTAT versions.
Figure 11-9 Circuit for System Reset by WDTOVF
11.5.5

Internal Reset in Watchdog Timer Mode

The chip 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 RSTCSR after the WDTOVF signal * goes high, then write 0 to the WOVF flag.
Note: * The WDTOVF output function is not available in the F-ZTAT versions.
Rev. 5.00, 12/03, page 420 of 1088
WDTOVF Signal *
WDTOVF WDTOVF
Reset input
WDTOVF Signal (Example)
WDTOVF WDTOVF
Chip
RES
WDTOVF *