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Thursday, June 7, 2012

8051 stepper motor interface

Connecting Unipolar stepper using L293D





There are actually many ways you can interface a stepper motor to your controller, out of them the most usedinterfaces are:
Interface using L293D - H-Bridge Motor Driver
Interface using ULN2003/2004 - Darlington Arrays

We will dicuss both connection techniques one by one. The above mentioned methods need 4 controller pins for interface.

As you see in the circuit above the four pins "Controller pin 1",2,3 and 4 will control the motion and direction of thestepper motor according to the step sequece programmed in the controller.

Connecting Unipolar stepper using ULN2003/2004










As already discussed in case of L293D, Here in this circuit too the four pins "Controller pin 1",2,3 and 4 will control themotion and direction of the stepper motor according to the step sequece sent by the controller.


code


/*Program to interface stepper motor*/



#include //include at89c51 microcontoller header file

#include"lcd.h"



sbit sw1=P1^0;  
sbit sw2=P1^1; 
sbit sw3=P1^2; 
 //connect p0.0 to switch
#define motor P0 //connect lower nibble of port0 to stepper motor

void delay_ms(unsigned int);

unsigned char dir;
int i=0;
void main(void)
{
init_lcd();
display_lcd("STEPPER MOTOR");
cmd_lcd(0xc0);
display_lcd("CONTROLLING");
delay_ms(2000);
while(1) //infinite loop
{
if(sw1==0)
{
   cmd_lcd(0x01);
   display_lcd("FORWARD");
  dir=0;
}
if(sw2==0)
{
   dir=1;
   cmd_lcd(0x01);
   display_lcd("REVERSE");

}
if(sw3==0)
{
dir=2;
  cmd_lcd(0x01);
   display_lcd("STOP");
  P0=0x00;
}
  if(dir==0)
  {
     for(i=0;i<12;i++)
     {
           motor=0xc0;   //for CCW direction "C639"
delay_ms(12);
     motor=0x60;
delay_ms(12);
motor=0x30;
delay_ms(12);
        motor=0x90;
delay_ms(12);
}
  }
    if(dir==1)
  {
     for(i=0;i<12;i++)
     {
         motor=0x90;   //for CCW direction "C639"
delay_ms(12);
     motor=0x30;
delay_ms(12);
motor=0x60;
delay_ms(12);
        motor=0xc0;
delay_ms(12);
 }
  }

}
}