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6 Reset Timing
CMT2189C has several different Resets:
1.
Power-on Reset(POR)
2.
WDT Reset during normal operation
3.
WDT Wake-up during Sleep
4.
/MCLR Reset during normal operation
5.
/MCLR Reset during Sleep
6.
Brown-out Reset
（
BOR/LVR
）
7.
Error instruction Reset (Disable)
Some registers are not affected in any Reset condition.The status of these registers is unknown on POR, and
is not affected by the Reset event.Most of the other registers are restored to their "reset status" at the time of
the following reset event.
Power-on Reset
WDT Reset during normal operation
WDT Reset during Sleep
/MCLR Reset during normal operation
Brown-out Reset
（
BOR
）
Error instruction Reset
When WDT is used as a timer, it can wake up MCU from Sleep. The MCU continues to run after Wake-up
from Sleep, while in normal operation, WDT (watchdog) is timeout and reset, so the system will run over again.
Because WDT Sleep Wake-up means that MCU continues to run rather than clear the settings of the /TO and
/PD bits. The reset action under different conditions is different. See Table 6-1 and Table 6-2 in details.
The /MCLRB pin corresponding circuit has the anti shake function. It can filter the sharp pulse signal caused
by the interference. The following figure is the overall block diagram of the reset circuit:
WDT
Module
/MCLRB
/Sleep
WDT Time-out Reset
VDD Rise
Detect
Brown Out
Reset
LFINTOSC
11-bit ripple counter
LVR_EN
IRERR
Detect
IRR_ENB
Enable PWRT
Q
Q
SET
CLR
S
R
VDD
Chip
Reset
Figure 6-1. Reset Function Block Diagram
