LCD Type MCU
RES Pin Reset
This type of reset occurs when the microcontroller is already running and the RES pin is forcefully
pulled low by external hardware such as an external switch. In this case as in the case of other re-
set, the Program Counter will reset to zero and program execution initiated from this point.
R E S
S S T T im e - o u t
In te rn a l R e s e t
0 .4 V
0 .9 V
D D
D D
t
R
S T D
RES Reset Timing Chart
Low Voltage Reset
-
LVR
The microcontroller contains a low voltage reset circuit in order to monitor the supply voltage of the
device. If the supply voltage of the device drops to within a range of 0.9V~V
LVR
such as might occur
when changing the battery, the LVR will automatically reset the device internally. For a valid LVR
signal, a low voltage, i.e. a voltage in the range between 0.9V~V
LVR
must exist for greater than
1ms. If the low voltage state does not exceed 1ms, the LVR will ignore it and will not perform a re-
set function.
L V R
S S T T im e - o u t
In te rn a l R e s e t
t
R
S T D
Low Voltage Reset Timing Chart
Watchdog Time-out Reset during Normal Operation
The Watchdog time-out reset during normal operation is the same as RES reset except that the
Watchdog time-out flag TO will be set to
²1².
W D T T im e - o u t
S S T T im e - o u t
In te rn a l R e s e t
t
R
S T D
WDT Time-out Reset during Normal Operation Timing Chart
Watchdog Time-out Reset during HALT
The Watchdog time-out reset during HALT is a little different from other kinds of reset. Most of the
conditions remain unchanged except that the Program Counter and the Stack Pointer will be
cleared to
²0²
and the TO flag will be set to
²1².
Refer to A.C. Characteristics for t
SST
details.
W D T T im e - o u t
t
S
S S T T im e - o u t
S T
WDT Time-out Reset during HALT Timing Chart
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