NuMicro® NUC029LEE/NUC029SEE
32-bit Arm
®
Cortex
®
-M0 Microcontroller
Aug, 2018
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6.11 Window Watchdog Timer (WWDT)
6.11.1 Overview
The Window Watchdog Timer is used is to perform a system reset within a specified window
period to prevent software run to uncontrollable status by any unpredictable condition.
6.11.2 Features
6-bit down counter value (WWDTVAL[5:0]) and 6-bit compare window value
(WWDTCR[21:16]) to make the WWDT time-out window period flexible
Supports 4-bit value to programmable maximum 11-bit prescale counter period of
WWDT counter
6.11.3 Block Diagram
The Window Watchdog Timer clock control and block diagram are shown as follows.
Note:
Before clock switching, both the pre-selected and newly selected
clock sources must be turned on and stable.
10
HCLK/2048
10 kHz LIRC
WWDT_S (CLKSEL2[17:16])
WDT_EN (APBCLK[0])
WWDT_CLK
11
Legend:
LIRC = Low-Speed Internal clock signal
Figure 6.11-1 Window Watchdog Timer Clock Control
6-bit down counter
11-bit
Prescale
6-bit compare value
(WINCMP)
WWDT_CLK
0x3F
Write
WWDTRLD =
0x00005AA5
comparator
WWDTCNT = WINCMP
WWDTIF
(WWDTSTS[0])
WWDTCNT > WINCMP
INTEN
(WWDTCR[1])
WWDT
Interrupt
WWDT
Reset
WWDTCNT = 0
Write WWDTRLD
WWDTRF
(WWDTSTS[1])
PERIODSEL
(WWDTCR[11:8])
6-bit down
counter value
(WWDTCVAL)
synchronizer