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:
/*
Don’t forget to keep VBAT 3v */
