How to control Stepper Motor using ULN2003 and 8051 Microcontroller (AT89C51)- (Part 17/45)

This project is an extension to two-phase Unipolar Stepper motor interfacing with AT89C51. In the previous project, transistor switches were used to interface the stepper motor with the microcontroller. Here the transistors have been replaced by using a ULN2003 IC to drive the stepper with 8051 microcontroller.

Stepper motor is a variable reluctance DC motor. When correct input sequence of signal is given to the motor, it starts rotation in steps. (For more detail refer Unipolar Stepper motor interfacing with microcontroller AT89C51).

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 are same as in previous project which are

Simplest sequence

0001

0010

0100

1000

And for half step size

0001

0011

0010

0110

0100

1100

1000

1001

Project Source Code

###

// Program to control Stepper Motor with AT89C51 using ULN2003
/**** Wave 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(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);
	}
}
/*****************************/
###