HT66F40 datasheet(44/244 Pages) HOLTEK

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HT68F20/HT68F30/HT68F40/HT68F50/HT68F60

HT68FU30/HT68FU40/HT68FU50/HT68FU60

Rev. 1.60

October 24, 2011

Together with fSYS/4 it is also used as one of the clock

sources for the Watchdog timer. The fTBC clock is used

as a source for the Time Base interrupt functions and for

the TMs.

System Operation Modes

There are six different modes of operation for the

microcontroller, each one with its own special character-

istics and which can be chosen according to the specific

performance and power requirements of the applica-

tion. 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

Description

CPU

fSYS

fSUB

fTBC

NORMAL Mode

fH~fH/64

SLOW Mode

IDLE0 Mode

Off

On/Off

IDLE1 Mode

Off

SLEEP0 Mode

Off

SLEEP1 Mode

Off

· NORMAL Mode

As the name suggests this is one of the main operat-

ing 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 os-

cillator is used, running the microcontroller at a di-

vided clock ratio reduces the operating current.

· SLOW Mode

This is also a mode where the microcontroller oper-

ates 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 fH is off.

· SLEEP0 Mode

The SLEEP Mode is entered when an HALT instruc-

tion is executed and when the IDLEN bit in the SMOD

stopped, and the fSUB and fS clocks will be stopped too,

and the Watchdog Timer function is disabled. In this

mode, the LVDEN is must set to

²0². If the LVDEN is

set to

²1²,itwon¢t enter the SLEEP0 Mode.

· SLEEP1 Mode

The SLEEP Mode is entered when an HALT instruc-

tion is executed and when the IDLEN bit in the SMOD

stopped. However the fSUB and fS clocks will continue

to operate if the LVDEN is

²1² or the Watchdog Timer

function is enabled and if its clock source is chosen

via configuration option to come from the fSUB.

· IDLE0 Mode

The IDLE0 Mode is entered when a HALT instruction

is executed and when the IDLEN bit in the SMOD reg-

ister 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 Watch-

dog Timer, TMs and SIM. In the IDLE0 Mode, the sys-

tem oscillator will be stopped. In the IDLE0 Mode the

Watchdog Timer clock, fS, will either be on or off de-

pending upon the fS clock source. If the source is

fSYS/4 then the fS clock will be off, and if the source co-

mes from fSUB then fS will be on.

· IDLE1 Mode

The IDLE1 Mode is entered when an HALT instruction

is executed and when the IDLEN bit in the SMOD reg-

ister 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 func-

tions 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, fS, will be on. If the

source is fSYS/4 then the fS clock will be on, and if the

source comes from fSUB then fS will be on.

HT66F40 数据表(PDF) 44 Page - Holtek Semiconductor Inc

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