Rev. 1.10
38
November 26, 2019
Rev. 1.10
39
November 26, 2019
HT68FB240
USB Low Speed Flash MCU
NORMAL Mode
As the name suggests this is one of the main operating modes where the microcontroller has all of
its functions operational and where the system clock is provided by one of the high speed oscillators.
This mode operates allowing the microcontroller to operate normally with a clock source will come
from the high speed oscillator, HIRC. The high speed oscillator will however first be divided by
a ratio ranging from 1 to 64, the actual ratio being selected by the CKS2~CKS0 and HLCLK bits
in the SMOD register. Although a high speed oscillator is used, running the microcontroller at a
divided clock ratio reduces the operating current.
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
SUB
clock will be
stopped too, and the Watchdog Timer function is disabled. In this mode, the LVDEN is must set to
"0". If the LVDEN is set to "1", it won’t enter the SLEEP0 Mode.
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 SLEEP1 mode the CPU will be stopped. However the f
SUB
clock will
continue to operate if the LVDEN is "1" or 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 CTRL register is low. In the IDLE0 Mode the
system oscillator will be inhibited from driving the CPU, the system oscillator will be stopped, the
low frequency clock f
SUB
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 CTRL register is high. In the IDLE1 Mode the
system oscillator will be inhibited from driving the CPU, 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
low frequency clock f
SUB
will be on.