Toshiba H1 Series, TLCS-900, TMP92CZ26AXBG 3.24 Watchdog Timer (Runaway detection timer)

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 stat e when it detects that
the CPU has started to malfunction (runaway) due to causes such as noise. When the watchdo g
timer detects a malfunction, it generates a non-maskable interrupt INTWD to notify the CPU of
the malfunction.
Connecting the watchdog timer outpu t 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
215 217 219 221
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
fIO
WDMOD
<WDTP1:0>
Internal data bus
Reset