HT68F03 datasheet(116/139 Pages) HOLTEK

116 / 139 page

HT66F03/HT66F04/HT68F03/HT68F04

Rev. 1.00

116

April 16, 2010

External Interrupt

The external interrupt is controlled by signal transitions

on the INT pin. An external interrupt request will take

place when the external interrupt request flag, INTF, is

set, which will occur when a transition, whose type is

chosen by the edge select bits, appears on the external

interrupt pin. To allow the program to branch to its re-

spective interrupt vector address, the global interrupt

enable bit, EMI, and respective external interrupt enable

bit, INTE, must first be set. Additionally the correct inter-

rupt edge type must be selected using the INTEG regis-

ter to enable the external interrupt function and to

choose the trigger edge type. As the external interrupt

pin is pin-shared with I/O pin, it can only be configured

as external interrupt pin if the external interrupt enable

bit in the corresponding interrupt register has been set.

The pin must also be setup as an input by setting the

corresponding bit in the port control register. When the

interrupt is enabled, the stack is not full and the correct

transition type appears on the external interrupt pin, a

subroutine call to the external interrupt vector, will take

place. When the interrupt is serviced, the external inter-

rupt request flag, INTF, will be automatically reset and

the EMI bit will be automatically cleared to disable other

interrupts. Note that any pull-high resistor selections on

the external interrupt pin will remain valid even if the pin

is used as an external interrupt input.

The INTEG register is used to select the type of active

edge that will trigger the external interrupt. A choice of

either rising or falling or both edge types can be chosen

to trigger an external interrupt. Note that the INTEG reg-

ister can also be used to disable the external interrupt

function.

Comparator Interrupt

The comparator interrupt is controlled by the internal

comparator. A comparator interrupt request will take

place when the comparator interrupt request flag, CPF,

is set, a situation that will occur when the comparator

output changes state. To allow the program to branch to

its respective interrupt vector address, the global inter-

rupt enable bit, EMI, and comparator interrupt enable

bit, CPE, must first be set. When the interrupt is en-

abled, the stack is not full and the comparator inputs

generate a comparator output transition, a subroutine

call to the comparator interrupt vector, will take place.

When the interrupt is serviced, the comparator interrupt

request flag, will be automatically reset and the EMI bit

will be automatically cleared to disable other interrupts.

Multi-function Interrupt

Within these devices there are up to three Multi-function

interrupts. Unlike the other independent interrupts,

these interrupts have no independent source, but rather

are formed from other existing interrupt sources, namely

the TM Interrupts, SIM Interrupt, External Peripheral In-

terrupt, LVD interrupt and EEPROM Interrupt.

A Multi-function interrupt request will take place when

any of the Multi-function interrupt request flags, MFnF

are set. The Multi-function interrupt flags will be set

when any of their included functions generate an inter-

rupt request flag. To allow the program to branch to its

respective interrupt vector address, when the

Multi-function interrupt is enabled and the stack is not

full, and either one of the interrupts contained within

each of Multi-function interrupt occurs, a subroutine call

to one of the Multi-function interrupt vectors will take

place. When the interrupt is serviced, the related

Multi-Function request flag, will be automatically reset

and the EMI bit will be automatically cleared to disable

other interrupts.

However, it must be noted that, although the

Multi-function Interrupt flags will be automatically reset

when the interrupt is serviced, the request flags from the

original source of the Multi-function interrupts, namely

the TM Interrupts, LVD interrupt and EEPROM Interrupt

will not be automatically reset and must be manually re-

set by the application program.

A/D Converter Interrupt

Some devices contain an A/D converter which has its

own independent interrupt. The A/D Converter Interrupt

is controlled by the termination of an A/D conversion

process. An A/D Converter Interrupt request will take

place when the A/D Converter Interrupt request flag,

ADF, is set, which occurs when the A/D conversion pro-

cess finishes. To allow the program to branch to its re-

spective interrupt vector address, the global interrupt

enable bit, EMI, and A/D Interrupt enable bit, ADE, must

first be set. When the interrupt is enabled, the stack is

not full and the A/D conversion process has ended, a

subroutine call to the A/D Converter Interrupt vector, will

take place. When the interrupt is serviced, the A/D Con-

verter Interrupt flag, ADF, will be automatically cleared.

The EMI bit will also be automatically cleared to disable

other interrupts.

Time Base Interrupts

The function of the Time Base Interrupts is to provide reg-

ular time signal in the form of an internal interrupt. They

are controlled by the overflow signals from their respec-

tive timer functions. When these happens their respec-

tive interrupt request flags, TB0F or TB1F will be set. To

allow the program to branch to their respective interrupt

vector addresses, the global interrupt enable bit, EMI and

Time Base enable bits, TB0E or TB1E, must first be set.

When the interrupt is enabled, the stack is not full and the

Time Base overflows, a subroutine call to their respective

vector locations will take place. When the interrupt is ser-

viced, the respective interrupt request flag, TB0F or

TB1F, will be automatically reset and the EMI bit will be

cleared to disable other interrupts.

HT68F03 Datasheet(PDF) 116 Page - Holtek Semiconductor Inc

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