NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
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Revision V1.30
NUC97
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Windowed Watchdog Timer (WWDT)
5.14
5.14.1 Overview
The Window Watchdog Timer (WWDT) is used to perform a system reset within a specified
window period to prevent software run to uncontrollable status by any unpredictable condition.
5.14.2 Features
6-bit down counter value (CNTDAT) and 6-bit compare value (CMPDAT) to make the
WWDT time-out window period flexible.
Supports 4-bit value (PSCSEL) to programmable maximum 11-bit prescale counter period of
WWDT counter.
5.14.3 Block Diagram
6-bit down counter
11-bit
Prescale
6-bit compare value
(CMPDAT)
WWDT_CLK
0x3F
Write
RLDCNT =
0x00005AA5
comparator
CNTDAT = CMPDAT
WWDTIF
(STATUS[0])
CNTDAT > CMPDAT
INTEN
(WWDT_CTL[1])
WWDT
Interrupt
WWDT
Reset
CNTDAT = 0
Write RLDCNT
WWDTRF
(STATUS[1])
PSCSEL
(WWDT_CTL[11:8])
6-bit down
counter value
(CNTDAT)
synchronizer
Figure 5.14-1 WWDT Block Diagram
5.14.4 Basic Configuration
The WWDT clock control and block diagram are shown as follows.
01
10
PCLK/4096
WWDT_S(CLKDIV8[11:10])
WWDT_CLK
00
12MHz/128
32.768 kHz (LXT)
WWDT(PCLKEN0[1])
11
12MHz(HXT)
Figure 5.14-2 WWDT Clock Control