Toshiba H1 Series - Manual (Page 618)

TMP92CZ26A
92CZ26A-615
3.24 Watchdog Timer (Runaway detection timer)
The TMP92CZ26A 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.
(The level of external
RESET pin is not changed.)
3.24.1 Configuration
Figure 3.24.1 is a block diagram of the watchdog timer (WDT).
Figure 3.24.1 Block Diagram of Watchdog Timer
Note: It needs to care designing the total machine set, because Watchdog timer can’t operate completely by
external noise.
WDMOD
<WDTE>
RESET pin
Selector
2 15 2 17 2 19 2 21
Binary counter
(22 stages)
Q
R S
WDT control register WDCR
Write
B1H
Write
4EH
Reset control
WDMOD<RESCR>
Internal reset
INTWD interrupt
Internal reset
f
IO
WDMOD
<WDTP1:0>
Internal data bus
Reset