Initialize AT89C2051 port!!!

[c3cube]

What should I write to initialize port 3 as input port in assembler language??? Actually, I only need P3.0 to turn on a stepper motor using a remote control.

 

[kannan.k]

Hi

To make a port as an input port you have to just write '1' to that pin/port and then read the status.

       setb P3.1   ;write 1 to the port
       jb p3.1 set   ;check if it is 1 or 0
       nop ;bit is not set ie input is 0
       sjmp con
set:   nop ;bit is set ie input is 1

con:
       ;rest of the code

 

[c3cube]

I've tried, but it's not working!!! Any other mothods????

 

[silvio]

I've tried, but it's not working!!! Any other mothods????

c3cube can you post your code / schematics ?

You only need P3.0 to turn on a stepper motor ???? How do you suppose to do that ? A stepper motor ?
However, if P3.0 is used as output why do you need to initialize port P3 as input ?

 

[c3cube]

The P3.0 is used to give a switch ON signal to turn on the stepper motor which is connected to Port 1.

 

[IanP]

Assuming that a momentary switch is connected between P3.0 and GND ..

SETB P3.0

LOOP: JB P3.0, LOOP
..
cont ..

when you press the switch P3.0 becomes "0" for a while, microcontroller will leave the LOOP and continue with Stepper Motor control ..

Regards,
IanP

 

[eehero]

Re: Initialize AT89C2051 port!!! by eehero

Try my standard code for AT89c

;#############written by Ali Mustafa Naas for help#######################
;########################################################################
$TITLE(LED flashing.asm)
$MOD51
$NOPRINT ; to see error on screen, if any errors found
$INCLUDE(MYPAULM2.EQU) ;address of PAULMON2 utility routines
$LIST ; overrided by $NOPRINT

;####################################################
;RESET ROUTINE
ORG 0000H ;locate routine at 00H
AJMP MAIN ;jump to START

;####################################################
;Interrupts (i will not use them here)

ORG 03H ;external interrupt 0
RETI
ORG 0BH ;timer 0 interrupt
RETI
ORG 13H ;external interrupt 1
RETI
ORG 1BH ;timer 1 interrupt
RETI
ORG 23H ;serial port interrupt
RETI
ORG 25H ;locate beginning of rest of program


;#####################################################

INITIALIZE: ;set up control registers & ports
MOV TCON,#00H
MOV TMOD,#00H
MOV PSW,#00H
MOV IE,#00H ;disable interrupts


RET


;######################################################

;**************************************************************************
;
DELAYMS: ;millisecond delay routine
; ;
MOV R7,#00H ;put value of 0 in register R7
LOOPA:
INC R7 ;increase R7 by one (R7 = R7 +1)
MOV A,R7 ;move value in R7 to Accumlator (also known as A)
CJNE A,#0FFH,LOOPA ;compare A to FF hex (256). If not equal go to LOOPA
RET ;return to the point that this routine was called from
;
;**************************************************************************

;#######################################################

loop:
ACALL INITIALIZE
SETB p1.0 ; here port p1.0 is initialized as input
SETB p1.2 ; here port p1.2 is initialized as input also
;note: the initialization of the ports may be done in the INITIALIZE sub-routine
; instead of the main loop,there is no difference,.
; At the normal case all ports are initailized output port.

#######write your code here#####################
END

good luck