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3.12 Watchdog Timer (Runaway detection timer)
The TMP92CM22 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
3.12.1
Configuration
Figure 3.12.1 is a block diagram of the watchdog timer (WDT).
WDMOD
<WDTP1:0>
f
IO
Internal reset
Note:
Care must be exercised in the overall design of the apparatus since the watchdog timer may fail
to function correctly due to external noise, etc.
pin is not changed.)
RESET
Selector
15
17
19
21
2
2
2
2
Binary counter
(22-Stage)
Reset
Write
4EH
Watchdog timer register
control register WDCR
Internal data bus
Figure 3.12.1 Block Diagram of Watchdog Timer
92CM22-211
WDMOD<RESCR>
Reset
control
Q
R
S
Write
B1H
WDMOD
<WDTE>
TMP92CM22
pin
RESET
Internal reset
Interrupt
request
INTWD
2007-02-16
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