Download Microcontroller & Interfacing - Biomedical Department

Program: Write a program to rotate DC motor connected in above circuit such that when switch
SW1 is pressed, motor rotates in clockwise direction and when SW2 is pressed, motor rotates in
anti-clockwise direction. Use external interrupts for the program.
ORG 00h
AJMP START
ORG 03h
; Vector location for external interrupt 0
SETB P1.1
; Rotate motor in clockwise direction
CLR P1.0
; -- do -RETI
ORG 13h
; Vector location for external interrupt 1
SETB P1.1
; Rotate motor in anticlockwise direction
CLR P1.0
; -- do -RETI
START:
CLR P1.0
; Make P1.0 output pin
CLR P1.1
; Make P1.1 output pin
CLR P1.2
; Make P1.2 output pin
MOV IE,#85h
; Enable external interrupt 0 and 1
SETB IT0
; Negative edge triggered interrupt
SETB IT1
; Negative edge triggered interrupt
SETB P1.0
; Enable chip L293 (H-bridge)
HERE:
SJMP HERE
:: WORKSHEET ::
A. Modify previous program without using interrupts.
(Hint: using polling method to check whether switch is pressed or not like JNB P3.2,
clockwise.)
Memory
HEX
Label
Opcode
Operands
Comments
Location
code
BM Dept., Govt. Engg. College, Gandhinagar
Page 69