r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 854

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

Section 14 Watchdog Timer (WDT)
14.6.5
This LSI is not reset internally if TCNT overflows while the RSTE bit is cleared to 0 during
watchdog timer mode operation, but TCNT and TCSR 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.
14.6.6
If the WDTOVF output signal is input to the RES pin, 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 14.6.
Rev. 1.00 Sep. 19, 2008 Page 824 of 1342
REJ09B0467-0100
Reset signal to entire system
Internal Reset in Watchdog Timer Mode
System Reset by WDTOVF Signal
Figure 14.6 Circuit for System Reset by WDTOVF Signal (Example)
Reset input
WDTOVF
RES
This LSI