Watch Dog Timer - Toshiba TLCS-900/H1 Series Data Book

3.12 Watchdog Timer (Runaway Detection Timer)
The TMP92CH21 contains a watchdog timer of runaway detecting.
The watchdog timer (WDT) is used to return the CPU to the normal state when it detects that the CPU
has started to malfunction (runaway) due to causes such as noise. When the watchdog timer detects
a malfunction, it generates a non-maskable interrupt INTWD to notify the CPU of the malfunction.
Connecting the watchdog timer output to the reset pin internally forces a reset.
3.12.1 Configuration
Figure 3.12.1(1) is a block diagram of the watchdog timer (WDT).
WDMOD
<WDTP1∼WDTP0>
fsys
Internal Reset
Selector
15 17 19 21
2 2 2 2
Binary Counter
(22 Stage)
Reset
Write
4EH
WDT Control register WDCR
Internal data bus
Figure 3.12.1. (1) Block Diagram of Watchdog Timer
92CH21- 291
WDMOD <RESCR>
Reset Control
Q
R S
Write WDMOD <WDTE>
B1H
TMP92CH21
RESET
Internal Reset
INTWD interrupt