STC89LE53RC datasheet(86/165 Pages) STC

Teilenummer	STC89LE53RC

Bauteilbeschribung	Enhanced 80C51 Central Processing Unit ,6T or 12T per machine cycle

PDF	165 Pages

Scroll/Zoom	100%

Hersteller	STC [STCmicro Technology Co,.Ltd]

Direct Link	http://www.stcmicro.com/

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86 / 165 page

Example: Design an intrusion warning system using interrupts that sounds a 400Hz tone for 1 second (using a

loudspeaker connected to P1.7) whenever a door sensor connected to INT0 makes a high-to-low transition.

Assembly Language Solution

ORG

LJMP

MAIN

;3-byte instruction

LJMP

INT0INT

;EXT 0 vector address

ORG

000BH

;Timer 0 vector

LJMP

T0INT

ORG

001BH

;Timer 1 vector

LJMP

T1INT

ORG

0030H

MAIN:

SETB

IT0

;negative edge activated

MOV

TMOD, #11H

;16-bit timer mode

MOV

IE,

#81H

;enable EXT 0 only

SJMP

;now relax

;

INT0INT:

MOV

R7,

#20

;20 ' 5000 us = 1 second

SETB

TF0

;force timer 0 interrupt

SETB

TF1

;force timer 1 interrupt

SETB

ET0

;begin tone for 1 second

SETB

ET1

;enable timer interrupts

RETI

;

T0INT:

CLR

TR0

;stop timer

DJNZ

R7,

SKIP

;if not 20th time, exit

CLR

ET0

;if 20th, disable tone

CLR

ET1

;disable itself

LJMP

EXIT

SKIP:

MOV

TH0,

#HIGH (-50000)

;0.05sec. delay

MOV

TL0,

#LOW (-5000)

SETB

TR0

EXIT:

RETI

;

T1INT:

CLR

TR1

MOV

TH1,

#HIGH (-1250)

;count for 400Hz

MOV

TL1,

#LOW (-1250)

CPL

P1.7

;music maestro!

SETB

TR1

RETI

END

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