S�Stem Operation Modes - Holtek HT68F Series Manual

HT68F20/HT68F30/HT68F40/HT68F50/HT68F60
HT68FU30/HT68FU40/HT68FU50/HT68FU60
Enhanced I/O Flash Type 8-Bit MCU with EEPROM
System Operation Modes
There are six different modes of operation for the microcontroller, each one with its own
special characteristics and which can be chosen according to the specific performance and
power requirements of the application. There are two modes allowing normal operation of the
microcontroller, the NORMAL Mode and SLOW Mode. The remaining four modes, the SLEEP0,
SLEEP1, IDLE0 and IDLE1 Mode are used when the microcontroller CPU is switched off to
conserve power.
Operation Mode
NORMAL Mode
SLOW Mode
IDLE0 Mode
IDLE1 Mode
SLEEP0 Mode
SLEEP1 Mode
• 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 one of the high speed oscillators, either the HXT, ERC or HIRC
oscillators. 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 one of the low speed oscillators, either
the LXT or the LIRC. Running the microcontroller in this mode allows it to run with much lower
operating currents. In the SLOW Mode, the f
• 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
f clocks will be stopped too, and the Watchdog Timer function is disabled. In this mode, the
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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
f clocks will continue to operate if the LVDEN is "1" or the Watchdog Timer function is enabled
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and if its clock source is chosen via configuration option to come from the f
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