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M0A21/M0A23 Series
May 06, 2022
Page
329
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
Write 0x00005AA5 to
WWDT_RLD
WWDT_CLK
WWDTIF
(WWDT_STATUS[0])
WWDTRF
(WWDT_STATUS[1])
T
WWDT
WWDTVAL
0F
0E
3F
3E
3D
Note :
PSCSEL (WWDT_CTL[11:8]) = 0x0,
CMPDAT (WWDT_CTL[21:16]) = 0x10
11
10
3C
3B
3A
Figure 6.9-5 WWDT Reload Counter When WWDT_CNT < WINCMP
WWDTIF = 1
(if CMPDAT = 0x10)
WWDT_CLK
WWDTIF
(WWDT_STATUS[0])
WWDTRF
(WWDT_STATUS[1])
T
WWDT
WWDTVAL
12 11 10 0F 0E
02 01 00
WWDTRF = 1
Note :
PSCSEL (WWDT_CTL[11:8]) = 0x0, CMPDAT (WWDT_CTL[21:16]) = 0x10
14 13
15
Figure 6.9-6 WWDT Interrupt and Reset Signals
WWDT Window Setting Limitation
When user writes 0x00005AA5 to WWDT_RLDCNT register to reload WWDT counter value to 0x3F, it
needs 3 WWDT clocks to sync the reload command to actually perform reload action. Note that if user
sets PSCSEL (WWDT_CTL[11:8]) to 0000, the counter prescale value should be as 1, and the CMPDAT
(WWDT_CTL[21:16]) must be larger than 2. Otherwise, writing WWDT_RLDCNT register to reload
WWDT counter value to 0x3F is unavailable, WWDTIF (WWDT_STATUS[0]) is generated, and WWDT
reset system event always happened. The WWDT CMPDAT setting limitation is shown in Table 6.9-2.
If user sets CMPDATA as 0x3F and 0x0, the interrupt doesn
’t occur. The reset occurs when WWDT
counts to 0x0, so the interrupt doesn
’t occur when CMPDATA is 0x0.
PSCSEL
Prescale Value
Valid CMPDAT Value
0000
1
0x3 ~ 0x3E
0001
2
0x2 ~ 0x3E