Teensy 3.0, Easy Driver and Small Stepper from SparkFun

main.c

#include "WProgram.h"

/* EasyDriver direction and step trigger pins */
#define DIR_PIN 22
#define STEP_PIN 23

/* SparkFun's "Small stepper motor" - stride angle = 7.5 deg.*/
#define STEPS_PER_REVOLUTION 48.0

#define USTEPS_PER_STEP 8.0
#define USTEPS_PER_DEGREE (360.0 / (STEPS_PER_REVOLUTION * USTEPS_PER_STEP))
#define USECS_PER_USTEP 70

void
__rotate(unsigned stp, uint8_t dir, float del)
{
     int i;

     digitalWrite(DIR_PIN, dir);

     for (i = 0; i < stp; i++){
          digitalWrite(STEP_PIN, HIGH);
          delayMicroseconds(del);

          digitalWrite(STEP_PIN, LOW);
          delayMicroseconds(del);
     }
}

/*
 * Rotate a number of usteps at a certain speed. Negative steps move in reverse.
 * Speed may be between [0,1], with 1 being fastest.
 */
void
rotate(int usteps, float speed)
{
     int dir, steps, i;
     float usec;

     steps = abs(usteps);
     dir = (usteps > 0) ? HIGH : LOW;
     usec = (1/speed) * USECS_PER_USTEP;
     __rotate(steps, dir, usec);
}

/*
 * Rotate a number of degrees at a certain speed. Negative degrees move in
 * reverse. Speed may be between [0,1], with 1 being fastest.
 */
void
rotateDeg(float deg, float speed)
{
     int dir, steps, i;
     float usec;

     dir = (deg > 0) ? HIGH : LOW;
     steps = abs(deg) * (1 / USTEPS_PER_DEGREE);
     usec = (1 / speed) * USECS_PER_USTEP;
     __rotate(steps, dir, usec);
}

int
main(void)
{
     pinMode(DIR_PIN, OUTPUT);
     pinMode(STEP_PIN, OUTPUT);

     for (;;) {
          rotateDeg(360, .01);
          rotateDeg(-360, 1);
          delay(1000);
     }
}