HT48F06E datasheet(32/74 Pages) HOLTEK

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HT48F06E/HT48F10E/HT48F30E

Rev. 1.60

July 29, 2009

When the Timer/Event counter overflows, its corre-

sponding interrupt request flag in the interrupt control

will in turn generate an interrupt signal. However irre-

spective of whether the timer interrupt is enabled or not,

a Timer/Event counter overflow will also generate a

wake-up signal if the device is in a Power-down condi-

tion. This situation may occur if the Timer/Event Counter

is in the Event Counting Mode and if the external signal

continues to change state. In such a case, the

Timer/Event Counter will continue to count these exter-

nal events and if an overflow occurs the device will be

woken up from its Power-down condition. To prevent

such a wake-up from occurring, the timer interrupt re-

quest flag should first be set high before issuing the

HALT instruction to enter the Power Down Mode.

Timer Program Example

This program example shows how the Timer/Event

Counter registers are setup, along with how the inter-

rupts are enabled and managed. Note how the

Timer/Event Counter is turned on, by setting bit 4 of the

Timer Control Register. The Timer/Event Counter can

be turned off in a similar way by clearing the same bit.

This example program sets the Timer/Event Counter

tobe in the timer mode, which uses the internal system

clock as the clock source.

org 04h

; external interrupt vector

reti

org 08h

; Timer/Event Counter interrupt vector

jmp tmrint

; jump here when Timer overflows

org 20h

; main program

;internal Timer/Event Counter interrupt routine

tmrint:

; Timer/Event Counter main program placed here

reti

begin:

;setup Timer registers

mov a,09bh

; setup preload value

- timer counts from this value to FFH

mov tmr,a;

mov a,081h

; setup Timer control register

mov tmrc,a

; timer mode and prescaler set to /4

; setup interrupt register

mov a,005h

; enable master interrupt and timer interrupt

mov intc,a

set tmrc.4

; start Timer

- note mode bits must be previously setup

HT48F06E Datasheet(PDF) 32 Page - Holtek Semiconductor Inc

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