How to Interface Stepper Motor with 8051

Stepper motor is a variable reluctance DC motor. When correct input sequence of signal is given to the motor, it starts rotation in steps. ULN2003 is high voltage, high current Darlington arrays each containing seven open collector Darlington pairs with common emitters. Here it is used as a current driving IC. This IC is required because stepper motor require more than 60mA current and since controller doesn’t work at this current rating so this IC provides high current to the stepper motor. In the circuit port P2 as output port which provide input sequence to four input pins of ULN3003 and output of ULN2003 drives the motor.

Input sequences:

Simplest sequence

0001

0010

0100

1000

And for half step size

0001

0011

0010

0110

0100

1100

1000

1001

Circuit :

Code: 

#include<reg51.h>
sfr stepper=0xA0;

void delay(unsigned int count)
{
 int i;
 for(i=0;i<count;i++);
}

void main()
{
 while(1)
 {
  stepper=0x01;
  delay(350);
  stepper=0x02;
  delay(350);
  stepper=0x04;
  delay(350);
  stepper=0x08;
  delay(350);
 }
}
/*****************************/

/**** Half Drive Stepping ****/
#include<reg51.h>
sfr stepper=0xA0;

void delay(unsigned int count)
{ 
 int i;
 for(i=0;i<count;i++);
}

void main()
{
 while(1)
 {
  stepper=0x01;
  delay(300);
  stepper=0x03;
  delay(300);
  stepper=0x02;
  delay(300);
  stepper=0x06;
  delay(300);
  stepper=0x04;
  delay(300);
  stepper=0x0C;
  delay(300);
  stepper=0x08;
  delay(300);
  stepper=0x09;
  delay(300);
 }
}
/*****************************/