DC Stepper motor Interfacing

Stepper Motor

A stepper motor is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps. When commutated electronically, the motor's position can be controlled precisely, without any feedback mechanism.

Figure 1 : Stepper motor function

Figure 2 : stator winding configuration

HALF STEP 8-STEP SEQUENCE

Code for stepper motor

/* connections

PORT1   P1.24 connected to SW1

PORT1   P1.25connected to SW2

PORT1   P1.26 connected to SW3

Connect PORT1  P1.16  P1.17  P1.18 to the Stepper motor*/

#include<LPC214x.h>     // Define LPC2148 Header File

#include <stdio.h>

#define SW1    24    //SW1 (P1.24)

#define SW2    25    //SW2 (P1.25)

#define SW3    26    //SW3 (P1.26)

#define COIL_A 16    //change the Stepper Motor Port!

void motor_cw(void);

void motor_ccw(void);

void delay(int);

  

unsigned char STEP[] = {0x09, 0x08, 0x0C, 0x04, 0x06, 0x02, 0x03, 0x01};// from the above table

void main(void)

{

       unsigned char i = 0;         

   PINSEL2 &= 0xFFFFFFF3;   // P1.16 - P1.31 as GPIO

   IODIR1 = 0x000F0000;        // P1.16 - P1.19 as Output

 

   while(1)                           // Loop forever

   {

           if (!(IOPIN1 & (1<<SW1)))    //  check Switch SW1 ON/OFF

      {

         motor_cw();            // Stepper Motor clockwise

           }

      else if (!(IOPIN1 & (1<<SW2)))   //check for  Switch SW2 ON/OFF

      {

         motor_ccw();     // Stepper Motor anticlockwise

           }

      else if (!(IOPIN1 & (1<<SW3)))  // check for Switch SW3 ON/OFF

 {

             while (i < 12)

             {

            motor_cw (); // clockwise for req. angle

               i++;

            } 

     }

          else

         i = 0;

  }

}

void delay(int n)   // for delay

{

   int i,j;

   for(i=0;i<n;i++)

   {

      for(j=0;j<0x3FF0;j++)

           {;}

   }

}

 void motor_ccw(void)   // anti- clockwise rotation

{

   unsigned int i=0;

   while (STEP[i] != '\0')

   {

      IOSET1 = STEP[i] << COIL_A;

      delay(1);

      IOCLR1 = STEP[i] << COIL_A;

      delay(1);

      i++;

   }

}

  

void motor_cw(void)   // clock wise rotation

{

   int i = 7;

   while (i >= 0)

   {

      IOSET1 = STEP[i] << COIL_A;

      delay(1);

      IOCLR1 = STEP[i] << COIL_A;

      delay(1);

      i--;

   }

}

Connections:

 Output :

/* Don’t forget to keep VBAT 3v */