Datasheet

Section 19 Watchdog Timer (WDT)
REJ09B0465-0300 Rev. 3.00 Page 665 of 982
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
Section 19 Watchdog Timer (WDT)
The watchdog timer (WDT) is an 8-bit timer that can generate an internal reset signal for this LSI
if a system crash prevents the CPU from writing to the timer counter, thus allowing it to overflow.
The block diagram of the watchdog timer is shown in figure 19.1.
φ
Prescaler
Prescaler
Prescaler
TMWD
TICRWD
TIFRWD
Internal reset signal
WDT interrupt
Subclock
Low-speed OCO
Internal data bus
TCSRWD
TCWD
Figure 19.1 Block Diagram of Watchdog Timer