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M0A21/M0A23 Series
May 06, 2022
Page
326
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Rev 1.02
M0
A21
/M
0
A
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SE
RIES
TEC
H
NICAL
RE
FEREN
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M
ANUAL
6.9 Window Watchdog Timer (WWDT)
6.9.1
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.
6.9.2
Features
6-bit down counter value (CNTDAT, WWDT_CNT[5:0]) and 6-bit compare value
(CMPDAT, WWDT_CTL[21:16]) to make the WWDT time-out window period flexible
Supports 4-bit value (PSCSEL, WWDT_CTL[11:8]) to programmable maximum 11-bit
prescale counter period of WWDT counter
WWDT counter suspends in Idle/Power-down mode
6.9.3
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
System
CNTDAT = 0
Write RLDCNT = 0x00005AA5
WWDTRF
(STATUS[1])
PSCSEL
(WWDT_CTL[11:8])
6-bit down
counter value
(CNTDAT)
synchronizer
WWDTEN
(WWDT_CTL[0])
Idle/Power-down
mode
Figure 6.9-1 WWDT Block Diagram
6.9.4
Basic Configuration
Clock Source Configuration
–
Select the source of WWDT peripheral clock on WWDTSEL (CLK_CLKSEL1[31:30])
–
Enable WWDT peripheral clock in WDTCKEN (CLK_APBCLK0[0]).
The WWDT clock control is shown in Figure 6.9-2.
10
HCLK/2048
WDTCKEN (CLK_APBCLK0[0])
WWDT_CLK
11
38.4 kHz (LIRC)
WWDTSEL (CLK_CLKSEL1[3:2])
Figure 6.9-2 WWDT Clock Control