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
SLOW Mode
This is also a mode where the microcontroller operates normally although now with a slower
speed clock source. The clock source used will be from the low speed oscillator LIRC. Running
the microcontroller in this mode allows it to run with much lower operating currents. In the SLOW
Mode, the f
H
is off.
SLEEP0 Mode
The SLEEP Mode is entered when an HALT instruction is executed and when the IDLEN bit in the
SMOD register is low. In the SLEEP0 mode the CPU will be stopped, and the f
LIRC
clock will be
stopped too, and the Watchdog Timer function is disabled.
SLEEP1 Mode
The SLEEP Mode is entered when an HALT instruction is executed and when the IDLEN bit in the
SMOD register is low. In the SLEEP
1
mode the CPU will be stopped. However the f
LIRC
clocks will
continue to operate if the Watchdog Timer function is enabled.
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
SMOD1
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 and TMs. In the IDLE0 Mode, the system oscillator will be
stopped.
IDLE1 Mode
The IDLE1 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
SMOD1
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 and TMs. 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
LIRC
, 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
—
LTO
HTO
IDLEN
HLCLK
R/W
R/W
R/W
R/W
—
R
R
R/W
R/W
POR
0
0
0
—
0
0
1
1
B
it 7 ~ 5
CKS2 ~ CKS0
: The system clock selection when HLCLK is “0”
000: f
L
(
f
LIRC
)
001: f
L
(
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 the LIRC, a divided version of the high speed system
oscillator can also be chosen as the system clock source.