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M0A21/M0A23 Series
May 06, 2022
Page
328
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
Comparator
6-bit compare value
CMPDAT
6-bit down counter
value CNTDAT
from 0x3F to 0x00
Write RLDCNT
0x5AA5 will
reset system
Write RLDCNT
0x5AA5 will
reload CNTDAT
to 0x3F
CNTDAT <= CMPDAT
System reset
immediately
CNTDAT = 0
CNTDAT > CMPDAT
Figure 6.9-3 WWDT Reset and Reload Behavior
If the current CNTDAT (WWDT_CNT[5:0]) is larger than CMPDAT (WWDT_CTL[21:16]) and user writes
0x00005AA5 to the WWDT_RLDCNT register, the WWDT reset system signal will be generated
immediately to cause chip reset also. The waveform of WWDT reload counter when CNTDAT >
CMPDAT is shown in Figure 6.9-4.
WWDT_CLK
WWDTIF
(WWDT_STATUS[0])
WWDTRF
(WWDT_STATUS[1])
T
WWDT
WWDTVAL
20
1F
Note :
PSCSEL (WWDT_CTL[11:8]) = 0x0,
CMPDAT (WWDT_CTL[21:16]) = 0x10
1E
1D
3F
3E
Write 0x00005AA5 to
WWDT_RLD
3D
3C
Figure 6.9-4 WWDT Reload Counter When CNTDAT > CMPDAT
When WWDTIF (WWDT_STATUS[0]) is generated, user must reload WWDT counter value to 0x3F by
writing 0x00005AA5 to WWDT_RLDCNT register, and also to prevent WWDT counter value reached 0
and generate WWDT reset system signal to inform system reset. Figure 6.9-5 shows the waveform of
WWDT reload counter when CNTDAT < CMPDAT and Figure 6.9-6 shows that WWDT generates reset
system signal (WWDTRF) if user doesn
’t write 0x00005AA5 to WWDT_RLD before WWDT counter
value reaches 0.