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Rev. 1.71
40
April 11, 2017
Rev. 1.71
41
April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
Bit 4
Unimplemented, read as "0"
B
it 3
LTO
: Low speed system oscillator ready flag
0: Not ready
1: Ready
This is the low speed system oscillator ready flag which indicates when the low speed system
oscillator is stable after power on reset or a wake-up has occurred. The flag will be low when in
the SLEEP0 mode, but after a wake-up has occurred the flag will change to a high level after 1~2
cycles if the LIRC oscillator is used.
B
it 2
HTO
: High speed system oscillator ready flag
0: Not ready
1: Ready
This is the high speed system oscillator ready flag which indicates when the high speed system
oscillator is stable. This flag is cleared to “0” by hardware when the device is powered on and
then changes to a high level after the high speed system oscillator is stable.
T
herefore this flag
will always be read as “
1
” by the application program after device power-on.
B
it 1
IDLEN
: IDLE Mode Control
0: Disable
1: Enable
This is the IDLE Mode Control bit and determines what happens when the HALT instruction is
executed. If this bit is high, when a HALT instruction is executed the device will enter the IDLE
Mode. In the IDLE1 Mode the CPU will stop running but the system clock will continue to keep
the peripheral functions operational, if FSYSON bit is high. If FSYSON bit is low, the CPU and
the system clock will all stop in IDLE0 mode. If the bit is low the device will enter the SLEEP
Mode when a HALT instruction is executed.
B
it 0
HLCLK
: System Clock Selection
0: f
H
/2 ~ f
H
/64 or f
L
1: f
H
This bit is used to select if the f
H
clock or the f
H
/2 ~ f
H
/64 or f
L
clock is used as the system clock.
When the bit is high the f
H
clock will be selected and if low the f
H
/2 ~ f
H
/64 or f
L
clock will be
selected. When system clock switches from the f
H
clock to the f
L
clock and the f
H
clock will be
automatically switched off to conserve power.
SMOD1 Register
Bit
7
6
5
4
3
2
1
0
Name
FSYSON
—
—
—
D3
LVRF
—
WRF
R/W
R/W
—
—
—
R/W
R/W
—
R/W
POR
0
—
—
—
0
x
—
0
“x” unknown
B
it 7
FSYSON
: f
SYS
Control in IDLE Mode
0: Disable
1: Enable
Bit 6~4
Unimplemented, read as 0
Bit
3
D3
: Reserved bit
B
it 2
LVRF
: LVR function reset flag
0: Not active
1: Active
This bit can be clear to “0”, but can not be set to “1”.
B
it 1
Unimplemented, read as 0