Holtek HT66F0175 - Reset Initial Conditions

Rev. 1.50 60 August 28, 2017 Rev. 1.50 61 August 28, 2017
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
Watchdog Time-out Reset during Normal Operation
TheWatchdogtime-outResetduringnormaloperationisthesameasthehardwareLowVoltage
ResetexceptthattheWatchdogtime-outagTOwillbesetto“1”.
WDT Time-out
Internal Reset
t
RSTD
+ t
SST
Note:t
RSTD
ispower-ondelaywithtypicaltime=16.7ms
WDT Time-out Reset during NORMAL Operation Timing Chart
Watchdog Time-out Reset during SLEEP or IDLE Mode
TheWatchdogtime-outResetduringSLEEPorIDLEMode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“0”andtheTOagwillbesetto“1”.RefertotheA.C.Characteristicsfor
t
SST
details.
WDT Time-out
Internal Reset
t
SST
WDT Time-out Reset during SLEEP or IDLE Mode Timing Chart
Reset Initial Conditions
Thedifferenttypesofresetdescribedaffecttheresetagsindifferentways.Theseags,known
asPDFandTOarelocatedinthestatusregisterandarecontrolledbyvariousmicrocontroller
operations,suchastheSLEEPorIDLEModefunctionorWatchdogTimer.Theresetflagsare
showninthetable:
TO PDF Reset Function
0 0 Power-on reset
u u LVR reset during NORMAL or SLOW Mode operation
1 u WDT time-out reset during NORMAL or SLOW Mode operation
1 1 WDT time-out reset during IDLE or SLEEP Mode operation
“u” stands for unchanged
Thefollowingtableindicatesthewayinwhichthevariouscomponentsofthemicrocontrollerare
affectedafterapower-onresetoccurs.
Item Reset Function
Program Counter Reset to zero
Interrupts All interrupts will be disabled
WDT, Time Base Clear after reset, WDT begins counting
Timer Modules Timer Modules will be turned off
Input/Output Ports I/O ports will be setup as inputs
Stack pointer Stack pointer will point to the top of the stack
Thedifferentkindsofresetsallaffecttheinternalregistersofthemicrocontrollerindifferentways.
Toensurereliablecontinuationofnormalprogramexecutionafteraresetoccurs,itisimportantto
knowwhatconditionthemicrocontrollerisinafteraparticularresetoccurs.Thefollowingtable
describeshoweachtypeofresetaffectsthemicrocontrollerinternalregisters.Notethatwheremore
thanonepackagetypeexiststhetablewillreectthesituationforthelargerpackagetype.