Holtek HT66F20 - Control Register

Rev. 2.50 58 June 22, 2017 Rev. 2.50 59 June 22, 2017
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
• IDLE0Mode
TheIDLE0ModeisenteredwhenaHALTinstructionisexecutedandwhentheIDLENbitin
theSMODregisterishighandtheFSYSONbitintheWDTCregisterislow.IntheIDLE0Mode
thesystemoscillatorwillbeinhibitedfromdrivingtheCPUbutsomeperipheralfunctionswill
remainoperationalsuchastheWatchdogTimer,TMsandSIM.IntheIDLE0Mode,thesystem
oscillatorwillbestopped.IntheIDLE0ModetheWatchdogTimerclock,f
S
,willeitherbeonor
offdependinguponthef
S
clocksource.Ifthesourceisf
SYS
/4thenthef
S
clockwillbeoff,andif
thesourcecomesfromf
SUB
thenf
S
willbeon.
• IDLE1Mode
TheIDLE1ModeisenteredwhenanHALTinstructionisexecutedandwhentheIDLENbit
intheSMODregisterishighandtheFSYSONbitintheWDTCregisterishigh.IntheIDLE1
ModethesystemoscillatorwillbeinhibitedfromdrivingtheCPUbutmaycontinuetoprovidea
clocksourcetokeepsomeperipheralfunctionsoperationalsuchastheWatchdogTimer,TMsand
SIM.IntheIDLE1Mode,thesystemoscillatorwillcontinuetorun,andthissystemoscillator
maybehighspeedorlowspeedsystemoscillator.IntheIDLE1ModetheWatchdogTimer
clock,f
S
,willbeon.Ifthesourceisf
SYS
/4thenthef
S
clockwillbeon,andifthesourcecomes
fromf
SUB
thenf
S
willbeon.
Control Register
Asingleregister,SMOD,isusedforoverallcontroloftheinternalclockswithinthedevice.
SMOD Register
Bit 7 6 5 4 3 2 1 0
Name CKS2
CKS1 CKS0 FSTEN LTO HTO IDLEN HLCLK
R/W R/W R/W R/W R/W R R R/W R/W
POR 0 0 0 0 0 0
1 1
Bit7~5 CKS2~CKS0:ThesystemclockselectionwhenHLCLKis"0"
000:f
L
(f
LXT
orf
LIRC
)
001:f
L
(f
LXT
orf
LIRC
)
010:f
H
/64
011:f
H
/32
100:f
H
/16
101:f
H
/8
110:f
H
/4
111:f
H
/2
Thesethreebitsareusedtoselectwhichclockisusedasthesystemclocksource.In
additiontothesystemclocksource,whichcanbeeithertheLXTorLIRC,adivided
versionofthehighspeedsystemoscillatorcanalsobechosenasthesystemclock
source.
Bit4 FSTEN:FastWake-upControl(onlyforHXT)
0:Disable
1:Enable
ThisistheFastWake-upControlbitwhichdeterminesifthef
SUB
clocksourceis
initiallyusedafterthedevicewakesup.Whenthebitishigh,thef
SUB
clocksourcecan
beusedasatemporarysystemclocktoprovideafasterwakeuptimeasthef
SUB
clock
isavailable.