HT45F12
8-Bit Flash MCU with Op Amps & Comparators
Bitꢀ2ꢀ~ꢀ0ꢀ
WS2 ~ WS0:ꢀSelectꢀWDTꢀTimeoutꢀPeriodꢀ
ꢀ 000:ꢀ28/fSꢀ
001:ꢀ210/fSꢀ
ꢀ
ꢀ 010:ꢀ212/fSꢀ
ꢀ
011:ꢀ214/fSꢀ
100:ꢀ215/fSꢀ
ꢀ
101:ꢀ216/fSꢀ
ꢀ
110:ꢀ217/fSꢀ
ꢀ
111:ꢀ218/fS
ꢀ
TheseꢀthreeꢀbitsꢀdetermineꢀtheꢀdivisionꢀratioꢀofꢀtheꢀWatchdogꢀTimerꢀsourceꢀclock,ꢀ
whichꢀinꢀturnꢀdeterminesꢀtheꢀtimeoutꢀperiod.
CTRL Register
Bit
Naꢁe
R/W
7
F�Y�ON
R/W
6
5
4
3
2
LVRF
R/W
x
1
0
WRF
R/W
0
—
—
—
—
—
—
—
—
—
—
—
—
LRF
R/W
0
POR
0
Bitꢀ7ꢀ
FSYSON:ꢀfSYSꢀControlꢀinꢀIDLEꢀModeꢀ
Describeꢀelsewhere.
Bitꢀ6~3ꢀ
Bitꢀ2ꢀ
Unimplemented,ꢀreadꢀasꢀ“0”
LVRF:ꢀLVRꢀfunctionꢀresetꢀflagꢀ
Describeꢀelsewhere.
Bitꢀ1ꢀ
Bitꢀ0ꢀ
LRF:ꢀLVRꢀControlꢀregisterꢀsoftwareꢀresetꢀflagꢀ
Describeꢀelsewhere.
WRF:ꢀWDTꢀControlꢀregisterꢀsoftwareꢀresetꢀflagꢀ
ꢀ 0:ꢀNotꢀoccurꢀ
ꢀ 1:ꢀOccurred
Thisꢀbitꢀisꢀsetꢀtoꢀ1ꢀbyꢀtheꢀWDTꢀControlꢀregisterꢀsoftwareꢀresetꢀandꢀclearedꢀbyꢀtheꢀ
applicationꢀprogram.ꢀNoteꢀthatꢀthisꢀbitꢀcanꢀonlyꢀbeꢀclearedꢀtoꢀ0ꢀbyꢀtheꢀapplicationꢀ
program.
Watchdog Timer Operation
TheꢀWatchdogꢀTimerꢀoperatesꢀbyꢀprovidingꢀaꢀdeviceꢀresetꢀwhenꢀitsꢀtimerꢀoverflows.ꢀThisꢀmeansꢀ
thatꢀinꢀtheꢀapplicationꢀprogramꢀandꢀduringꢀnormalꢀoperationꢀtheꢀuserꢀhasꢀtoꢀstrategicallyꢀclearꢀtheꢀ
WatchdogꢀTimerꢀbeforeꢀitꢀoverflowsꢀtoꢀpreventꢀtheꢀWatchdogꢀTimerꢀfromꢀexecutingꢀaꢀreset.ꢀThisꢀisꢀ
doneꢀusingꢀtheꢀclearꢀwatchdogꢀinstructions.ꢀIfꢀtheꢀprogramꢀmalfunctionsꢀforꢀwhateverꢀreason,ꢀjumpsꢀ
toꢀanꢀunknownꢀlocation,ꢀorꢀentersꢀanꢀendlessꢀloop,ꢀtheseꢀclearꢀinstructionsꢀwillꢀnotꢀbeꢀexecutedꢀinꢀtheꢀ
correctꢀmanner,ꢀinꢀwhichꢀcaseꢀtheꢀWatchdogꢀTimerꢀwillꢀoverflowꢀandꢀresetꢀtheꢀdevice.ꢀAꢀWatchdogꢀ
TimerꢀconfigurationꢀoptionꢀdeterminesꢀifꢀtheꢀWatchdogꢀTimerꢀisꢀalwaysꢀenabledꢀorꢀifꢀitꢀisꢀenabledꢀ
usingꢀtheꢀapplicationꢀprogram.ꢀWithꢀregardꢀtoꢀtheꢀWatchdogꢀTimerꢀenable/disableꢀfunction,ꢀthereꢀareꢀ
alsoꢀfiveꢀbits,ꢀWE4~WE0,ꢀinꢀtheꢀWDTCꢀregisterꢀtoꢀofferꢀadditionalꢀenable/disableꢀandꢀresetꢀcontrolꢀ
ofꢀtheꢀWatchdogꢀTimer.ꢀIfꢀtheꢀWDTꢀconfigurationꢀoptionꢀhasꢀselectedꢀthatꢀtheꢀWDTꢀfunctionꢀisꢀ
alwaysꢀenabled,ꢀthenꢀWE4~WE0ꢀbitsꢀstillꢀhaveꢀeffectꢀonꢀtheꢀWDTꢀfunction.ꢀWhenꢀtheꢀWE4~WE0ꢀ
bitsꢀvalueꢀareꢀequalꢀtoꢀ01010Bꢀorꢀ10101B,ꢀtheꢀWDTꢀfunctionꢀisꢀenabled.ꢀHowever,ꢀifꢀtheꢀWE4~WE0ꢀ
bitsꢀareꢀchangedꢀtoꢀanyꢀotherꢀvaluesꢀexceptꢀ01010Bꢀandꢀ10101B,ꢀwhichꢀcouldꢀbeꢀcausedꢀbyꢀadverseꢀ
environmentalꢀconditionsꢀsuchꢀasꢀnoise,ꢀitꢀwillꢀresetꢀtheꢀmicrocontrollerꢀafterꢀ2~3ꢀLIRCꢀclockꢀ
cycles.ꢀIfꢀtheꢀWDTꢀconfigurationꢀoptionꢀhasꢀselectedꢀthatꢀtheꢀWDTꢀfunctionꢀisꢀcontrolledꢀusingꢀtheꢀ
applicationꢀprogram,ꢀthenꢀtheꢀWDTꢀcontrolꢀregisterꢀbits,ꢀWE4~WE0,ꢀareꢀusedꢀtoꢀenableꢀorꢀdisableꢀ
theꢀWatchdogꢀTimer.ꢀInꢀthisꢀcaseꢀtheꢀWDTꢀfunctionꢀwillꢀbeꢀdisabledꢀwhenꢀtheꢀWE4~WE0ꢀbitsꢀareꢀ
Rev. 0.00
4ꢅ
�eꢀteꢁꢂeꢃ ꢄꢅꢆ ꢄ01ꢄ
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
