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NUC126
Aug. 08, 2018
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Rev 1.03
NUC12
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6.24 Watchdog Timer (WDT)
6.24.1
Overview
The Watchdog Timer (WDT) is used to perform a system reset when system runs into an unknown
state. This prevents system from hanging for an infinite period of time. Besides, the Watchdog Timer
supports the function to wake up system from Idle/Power-down mode.
6.24.2
Features
Supports 18-bit free running up counter
Selectable time-out interval (2
4
~ 2
18
) and the time-out interval is 1.6 ms ~ 26.214s if
WDT_CLK is
10 kHzSupports selectable WDT reset delay period between WDT time-out
event to WDT reset system event, and it includes 1026
、
130
、
18 or 3 * WDT_CLK delay
period
System kept in reset state about 63 * WDT_CLK period time after system reset event
occurred
Supports to force WDT function enabled after chip powered on or reset by setting
CWDTEN[2:0] in Config0 register
Supports WDT time-out wake-up function only if WDT clock source is selected as
LIRC or
LXT
6.24.3
Block Diagram
0
….. 15
.. 3
16 17
RSTCNT
(WDT_RSTCNT[31:0])
Write 0x00005AA5 to reset counter
Time-Out
Interval
Period
Select
WDT_CLK
000
001
110
111
...
Reset
Delay
Period
Select
Time-out interrupt
IF
(WDT_CTL[3])
INTEN
(WDT_CTL[6])
TOUTSEL
(WDT_CTL[10:8])
RSTEN
(WDT_CTL[1])
Time-out reset system
RSTF
(WDT_CTL[2])
WKEN
(WDT_CTL[4])
WKF
(WDT_CTL[5])
Time-out wakeup CPU
WDTEN
(WDT_CTL[7])
Figure 6.24-1 Watchdog Timer Block Diagram
6.24.4
Basic Configuration
Clock Source Configuration
–
Select the source of WDT peripheral clock on WDTSEL (CLK_CLKSEL1[1:0]).
–
Enable WDT peripheral clock in WDTCKEN (CLK_APBCLK0[0]).
The WDT clock control is shown in Figure 6.24-2.