3. Stepper motor interface

PartB
3.Interface a Stepper motor and rotate it in clockwise and anti-clockwise direction.
Theory:

Stepper motor:Stepper motors are the motors that move in discrete steps or convert electrical pulses into rotatory motion. They have multiple coils(4coils) that are organized in groups called "phases"(stators named as A,B,C and D). By energizing each phase in sequence, the motor will rotate, one step at a time.

fig: Interfacing diagram of Stepper motor with LPC1768 

fig: Wave Drive sequence

//Stepper motor

#include <LPC17xx.h>

int main( void )

{

                int i=0, n=10000,j;

                SystemInit();                        // System initialization

                SystemCoreClockUpdate(); // Clock initialization

                // Function Selection

                LPC_PINCON->PINSEL4 = 0X00000000;   // PORT 2, 12th bit as zero, P2.12 as GPIO

                // set Direction

                LPC_GPIO2->FIODIR = 0x0000000f;        // p2.0 to p2.3 as output

               

                for(j=0;j<50;j++)

                {

                                                                               

                                LPC_GPIO2->FIOSET = 0X00000008;    //set p2.3

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                  LPC_GPIO2->FIOSET = 0X00000004; //set p2.2

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                  LPC_GPIO2->FIOSET = 0X00000002; //set p2.1

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                  LPC_GPIO2->FIOSET = 0X00000001; //set p2.0

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                }                                                                                                                                      }

************************************************************************
To rotate stepper motor in opposite direction (reverse the order 8421 to 1248)

#include <LPC17xx.h>

int main( void )

{

                int i=0, n=10000,j;

                SystemInit();                        // System initialization

                SystemCoreClockUpdate(); // Clock initialization

                // Function Selection

                LPC_PINCON->PINSEL4 = 0X00000000;   // PORT 2, 12th bit as zero, P2.12 as GPIO

                // set Direction

                LPC_GPIO2->FIODIR = 0x0000000f;        // p2.0 to p2.3 as output

               

                for(j=0;j<50;j++)

                {

                                                                               

                                LPC_GPIO2->FIOSET = 0X00000008;    //set p2.3

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                  LPC_GPIO2->FIOSET = 0X00000004; //set p2.2

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                  LPC_GPIO2->FIOSET = 0X00000002; //set p2.1

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                  LPC_GPIO2->FIOSET = 0X00000001; //set p2.0

                                for( i = 0; i < n; i++ );        // delay

                                  LPC_GPIO2->FIOCLR = 0X0000000f; //clear all the bits

                                }                                                                                                                                      }
*********************************************************************************
for Optimal/ Efficient coding make use of Shift operator (this requires less memory and hence high performance)

#include <LPC17xx.H>

void clock_wise(void);
void anti_clock_wise(void);
unsigned long int var1,var2;
unsigned int i=0,j=0,k=0;

int main(void)
{
SystemInit();
SystemCoreClockUpdate();

LPC_PINCON->PINSEL4 = 0x00000000; //P2.0 to P2.3 GPIO
LPC_GPIO2->FIODIR = 0x0000000F; //P2.0 to P2.3 output

while(1)
{
for(j=0;j<50;j++)            //50 times in Clock wise Rotation
clock_wise();

for(k=0;k<65000;k++);         //Delay to show  anti_clock Rotation

for(j=0;j<50;j++)           //50 times in  Anti Clock wise Rotation
anti_clock_wise();

for(k=0;k<65000;k++);         //Delay to show clock Rotation
}  //End of while(1)
}  //End of main

void clock_wise(void)
{
var1 = 0x00000001;          //For Clockwise
    for(i=0;i<=3;i++)          //for A B C D Stepping
{
   LPC_GPIO2->FIOCLR =  0X0000000F;
   LPC_GPIO2->FIOSET =  var1;
var1 = var1<<1;         //For Clockwise
        for(k=0;k<15000;k++);  //for step speed variation
    }
}

void anti_clock_wise(void)
{
var1 = 0x0000008;       //For Anticlockwise
    for(i=0;i<=3;i++)        //for A B C D Stepping
    {

    LPC_GPIO2->FIOCLR =  0X0000000F;
LPC_GPIO2->FIOSET =  var1;
var1 = var1>>1;       //For Anticlockwise
        for(k=0;k<15000;k++);  //for step speed variation
    }
}

*********************************************************************************
/*stepper motor rotation based on push button status*/

 #include <LPC17xx.h>

int main( void )

{

  unsigned int key;

  SystemInit();                                      // System initialization

  SystemCoreClockUpdate();              // Clock initialization

// Function Selection

 LPC_PINCON->PINSEL4 = 0X00000000;   // PORT 2 GPIO functionality selection

// set Direction of [P2.0],[P2.1],[P2.2],[P2.3]^th pin as output by passing 1

// set Direction of 11^th pin as input by passing 0

 LPC_GPIO2->FIODIR = 0x0000000F;

// reading key status continuously

while( 1 )

          {

               Key = LPC_GPIO2->FIOPIN; //reading status of Port2 and storing it in variable key

               key = key & 0x00000800 ;    //bitwise and operation, as I need to check only 11^th bit value

                                   if(key == 0x00000800)   //KEY IS NOT PRESSED   if(key & 0x00008000)

                                                 {

                                                     // Do nothing     

                                                 }

                                   else                   

                                                 {                                                               

                                                   for(j=0;j<50;j++)     //50 times in Clock wise Rotation

                                                   clock_wise();

          

                                                  }                                           

                   }                          

}

void clock_wise(void)

{

 var1 = 0x00000001;          //For Clockwise

    for(i=0;i<=3;i++)          //for A B C D Stepping

 {

    LPC_GPIO2->FIOCLR =  0X0000000F;

    LPC_GPIO2->FIOSET =  var1;

 var1 = var1<<1;         //For Clockwise

        for(k=0;k<15000;k++);  //for step speed variation

    }

}

*********************************************************************************

Explanation:




Download:Control Stepper motor (Wave Drive)