HTG2190 datasheet(18/50 Pages) HOLTEK

18 / 50 page

HTG2190

Rev. 1.20

July 5, 2002

the interrupt control register (INTC0/INTC1) located at

0BH/1EH in the data memory. EMI, EEI, ET0I, ET1I, ET2I,

ET3I, PWMI, are used to control the enabling/disabling of

interrupts. These bits prevent the requested interrupt be-

ing serviced. Once the interrupt request flags (T0F, T1F,

T2F, T3F, EIF, PWMF) are set, they will remain in the

INTC0/INTC1 register until the interrupts are serviced or

cleared by a software instruction.

It is recommended that application programs do not

use CALL subroutines within an interrupt subroutine.

Interrupts often occur in an unpredictable manner or need

to be serviced immediately in some applications. If only

one stack is left and the interrupt enable is not well

controlled, once a CALL subroutine if used in the interrupt sub-

routine will corrupt the original control sequence.

Oscillator configuration

There are two oscillator circuit in the HTG2190.

The RC oscillator signal provides the internal system

clock. The HALT mode stops the system oscillator and

ignores any external signal to conserve power. Only the

RC oscillator is designed to drive the internal system

clock. The RTC oscillator provides the timer3 and LCD

driver clock source.

The RC oscillator needs an external resistor connected

between OSCI and VSS. The resistance value must

range from 50k

W~400kW

However, the frequency of the oscillator may vary with

VDD, temperature and the chip itself due to process vari-

ations. It is, therefore, not suitable for timing sensitive

operations where accurate oscillator frequency is de-

sired.

The RTC oscillator is used to provide clock source for

LCD driver and Timer3. It can be enabled or disabled by

mask option.

There is another oscillator circuit designed for the real

time clock. In this case, only the 32768Hz crystal oscilla-

tor can be applied. The crystal should be connected be-

tween and XOUT, and two external capacitors along

with one external resistor are required for the oscillator

circuit in order to get a stable frequency.

Bit No.

Label

Function

INTC0

EMI

Master (Global) interrupt (1=enable; 0=disable)

EEI

External interrupt (1=enable; 0=disable)

ET0I

Timer/Event Counter 0 interrupt (1=enable; 0=disable)

ET1I

Timer/Event Counter 1 interrupt (1=enable; 0=disable)

EIF

External interrupt request flag (1=active; 0=inactive)

T0F

Internal Timer/Event Counter 0 request flag. (1=active; 0=inactive)

T1F

Internal Timer/Event Counter 1 request flag. (1=active; 0=inactive)

Unused bit, read as

²0²

INTC0 register

Bit No.

Label

Function

INTC1

ET2I

Controls the Timer 2 interrupt. (1=enable; 0=disable)

ET3I

Controls the Timer 3 interrupt. (1=enable; 0=disable)

PWMI

PWM D/A interrupt (1=enable; 0=disable)

Should be set

²0² always.

T2F

Internal Timer 2 request flag. (1=active; 0=inactive)

T3F

Internal Timer 3 request flag. (1=active; 0=inactive)

PWMF

PWM D/A flag (1=enable; 0=disable)

Should be set

²0² always.

INTC1 register

R C O s c i l l a t o r

O S C I

3 2 7 6 8 H z

R T C O s c i l l a t o r

X I N

X O U T

System and RTC oscillator

HTG2190 Datasheet(PDF) 18 Page - Holtek Semiconductor Inc

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