BS83B08A-3/BS83B12A-3/BS83B16A-3
BS83B08A-4/BS83B12A-4/BS83B16A-4
8-Bit Touch Key Flash MCU
C
R
L
W
T
D
C
R
L
f
S
W
W
0
0
0
0
1
1
1
1
T
D
m
T
-
i
e
u
o
t
f
S
B
U
1
1
s
g
t
e
D
a
v
i
d
i
r
e
[
S
2
:
0
]
=
8
1
1
1
1
1
1
1
0
0
1
1
0
0
1
1
2
2
2
2
2
2
2
2
0
1
0
1
0
1
0
1
/
S
f
:
:
:
:
:
:
:
:
0
2
4
5
6
7
8
/
/
/
/
/
/
/
S
S
S
S
S
S
S
f
f
f
f
f
f
f
8
t
-
-
o
1
M
U
X
7
s
-
a
t
g
e
D
v
i
d
i
r
e
W
2
S
~
W
0
S
1
1
1
(
S
/
f
2
~
S
f
/
2
)
Watchdog Timer
Reset and Initialisation
Aꢀresetꢀfunctionꢀisꢀaꢀfundamentalꢀpartꢀofꢀanyꢀmicrocontrollerꢀensuringꢀthatꢀtheꢀdeviceꢀcanꢀbeꢀsetꢀ
toꢀsomeꢀpredeterminedꢀconditionꢀirrespectiveꢀofꢀoutsideꢀparameters.ꢀTheꢀmostꢀimportantꢀresetꢀ
conditionꢀisꢀafterꢀpowerꢀisꢀfirstꢀappliedꢀtoꢀtheꢀmicrocontroller.ꢀInꢀthisꢀcase,ꢀinternalꢀcircuitryꢀwillꢀ
ensureꢀthatꢀtheꢀmicrocontroller,ꢀafterꢀaꢀshortꢀdelay,ꢀwillꢀbeꢀinꢀaꢀwellꢀdefinedꢀstateꢀandꢀreadyꢀtoꢀ
executeꢀtheꢀfirstꢀprogramꢀinstruction.ꢀAfterꢀthisꢀpower-onꢀreset,ꢀcertainꢀimportantꢀinternalꢀregistersꢀ
willꢀbeꢀsetꢀtoꢀdefinedꢀstatesꢀbeforeꢀtheꢀprogramꢀcommences.ꢀOneꢀofꢀtheseꢀregistersꢀisꢀtheꢀProgramꢀ
Counter,ꢀwhichꢀwillꢀbeꢀresetꢀtoꢀzeroꢀforcingꢀtheꢀmicrocontrollerꢀtoꢀbeginꢀprogramꢀexecutionꢀfromꢀtheꢀ
lowestꢀProgramꢀMemoryꢀaddress.ꢀ
AnotherꢀtypeꢀofꢀresetꢀisꢀwhenꢀtheꢀWatchdogꢀTimerꢀoverflowsꢀandꢀresetsꢀtheꢀmicrocontroller.ꢀAllꢀ
typesofꢀresetꢀoperationsꢀresultꢀinꢀdifferentꢀregisterꢀconditionsꢀbeingꢀsetup.ꢀAnotherꢀresetꢀexistsꢀinꢀtheꢀ
formꢀofꢀaꢀLowꢀVoltageꢀReset,ꢀLVR,ꢀwhereꢀaꢀfullꢀresetꢀisꢀimplementedꢀinꢀsituationsꢀwhereꢀtheꢀpowerꢀ
supplyꢀvoltageꢀfallsꢀbelowꢀaꢀcertainꢀthreshold.
Reset Functions
Thereꢀareꢀfiveꢀwaysꢀinꢀwhichꢀaꢀmicrocontrollerꢀresetꢀcanꢀoccur,ꢀthroughꢀeventsꢀoccurringꢀinternally:
•ꢀ Power-onꢀReset
Theꢀmostꢀfundamentalꢀandꢀunavoidableꢀresetꢀisꢀtheꢀoneꢀthatꢀoccursꢀafterꢀpowerꢀisꢀfirstꢀappliedꢀtoꢀ
theꢀmicrocontroller.ꢀAsꢀwellꢀasꢀensuringꢀthatꢀtheꢀProgramꢀMemoryꢀbeginsꢀexecutionꢀfromꢀtheꢀfirstꢀ
memoryꢀaddress,ꢀaꢀpower-onꢀresetꢀalsoꢀensuresꢀthatꢀcertainꢀotherꢀregistersꢀareꢀpresetꢀtoꢀknownꢀ
conditions.ꢀAllꢀtheꢀI/Oꢀportꢀandꢀportꢀcontrolꢀregistersꢀwillꢀpowerꢀupꢀinꢀaꢀhighꢀconditionꢀensuringꢀ
thatꢀallꢀpinsꢀwillꢀbeꢀfirstꢀsetꢀtoꢀinputs.
VDD
Power-on
tRSTD
Reset
SST Time-out
Power-On Reset Timing Chart
Rev. 1.00
47
�aꢀ 0ꢁꢂ ꢁ01ꢃ
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
