HT67F60 datasheet(202/242 Pages) HOLTEK

202 / 242 page

Rev. 1.50

202

March 06 , 2012

Rev. 1.50

203

March 06 , 2012

HT67F30/HT67F40/HT67F50/HT67F60

TinyPowerTM A/D Flash Type 8-Bit MCU with LCD & EEPRO

Interrupt Wake-up Function

Each of the interrupt functions has the capability of waking up the microcontroller when in the

SLEEP or IDLE Mode. A wake-up is generated when an interrupt request flag changes from low to

high and is independent of whether the interrupt is enabled or not. Therefore, even though the device

is in the SLEEP or IDLE Mode and its system oscillator stopped, situations such as external edge

transitions on the external interrupt pins, a low power supply voltage or comparator input change

may cause their respective interrupt flag to be set high and consequently generate an interrupt. Care

must therefore be taken if spurious wake-up situations are to be avoided. If an interrupt wake-up

function is to be disabled then the corresponding interrupt request flag should be set high before the

device enters the SLEEP or IDLE Mode. The interrupt enable bits have no effect on the interrupt

wake-up function.

Programming Considerations

By disabling the relevant interrupt enable bits, a requested interrupt can be prevented from being

serviced, however, once an interrupt request flag is set, it will remain in this condition in the

interrupt register until the corresponding interrupt is serviced or until the request flag is cleared by

the application program.

Where a certain interrupt is contained within a Multi-function interrupt, then when the interrupt

service routine is executed, as only the Multi-function interrupt request flags, MF0F~MF3F, will be

automatically cleared, the individual request flag for the function needs to be cleared by the

application program.

It is recommended that programs do not use the “CALL” instruction within the interrupt service

subroutine. Interrupts often occur in an unpredictable manner or need to be serviced immediately. If

only one stack is left and the interrupt is not well controlled, the original control sequence will be

damaged once a CALL subroutine is executed in the interrupt subroutine.

Every interrupt has the capability of waking up the microcontroller when it is in SLEEP or IDLE

Mode, the wake up being generated when the interrupt request flag changes from low to high. If it is

required to prevent a certain interrupt from waking up the microcontroller then its respective request

flag should be first set high before enter SLEEP or IDLE Mode.

As only the Program Counter is pushed onto the stack, then when the interrupt is serviced, if the

contents of the accumulator, status register or other registers are altered by the interrupt service

program, their contents should be saved to the memory at the beginning of the interrupt service

routine.

To return from an interrupt subroutine, either a RET or RETI instruction may be executed. The RETI

instruction in addition to executing a return to the main program also automatically sets the EMI bit

high to allow further interrupts. The RET instruction however only executes a return to the main

program leaving the EMI bit in its present zero state and therefore disabling the execution of further

interrupts.

HT67F60 Datasheet(PDF) 202 Page - Holtek Semiconductor Inc

HT67F60 Datasheet(HTML) 202 Page - Holtek Semiconductor Inc

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