Dual MC33926 Arduino Shield and 1209 Stepper Motor

Support Motor controllers/drivers and motors
4

Hello,

Below is a sample code to run a stepper motor with the MC33926 Motor Driver Shield (pololu.com/catalog/product/2503). Additionally this code shows how you can adjust the size of the step between full step, half step and quarter step. See the comments in the code for more detail.

#include "DualMC33926MotorShield.h"

DualMC33926MotorShield md;


#define QUARTER_STEP	1
#define HALF_STEP		2
#define FULL_STEP		4

unsigned char stepMode = FULL_STEP;


// Advances the stepper motor by one step either clockwise or counterclockwise
// with the direction specified by the argument dir (0 or 1).  The size of the
// step depends on stepMode and can either be a full step, a half step, or a
// quarter step.  Full stepping is produced by repeating a four-state cycle
// in which both coils are always energized to carry the same magnitude of current
// but the direction of the current is sequentially switched.  Running through the
// four-state cycle in the reverse order reverses the direction of rotation.  The
// general equation for coil current should be as follows:
// coil 1 current = I * sin(a)
// coil 2 current = I * cos(a)
// When full stepping, the four states are: 
// forwards: a = 0, 90, 180, 270 degrees
// reverse:  a = 0, 270, 180, 90 degrees
// half stepping comes from: a = 0, 45, 90, 135, 180, 225, 270, 315 degrees
// quarter stepping comes from a = the 16 multiples of 22.5 from 22.5 to 360 deg
void one_step(unsigned char dir)
{
	// this static variable lets us remember what step we're on so we
	// can change to the appropriate next state in the sequence
	static unsigned char step = 0;

	// compute the next step based on the direction argument dir
	// and the step mode.  Full stepping skips half and quarter steps,
	// and half stepping skips quarter steps.  Quarter stepping cycles
	// through all 16 steps.
	if (dir == 1)
		step += stepMode;
	else
		step -= stepMode;

	switch (step & 15)
	{
		case 0:	// full step (both coils energized at 71%)
			md.setSpeeds(180, 180);
			break;
		case 1:	// quarter step (coil 1 at 38% and coil 2 at 92%)
			md.setSpeeds(98, 236);
			break;
		case 2: // half step (coil 1 at 0% and coil 2 at 100%)
			md.setSpeeds(0, 255);
			break;
		case 3: // quarter step
			md.setSpeeds(-98, 236);
			break;
		case 4: // full step
			md.setSpeeds(-180, 180);
			break;
		case 5: // quarter step
			md.setSpeeds(-236, 98);
			break;
		case 6: // half step
			md.setSpeeds(-255, 0);
			break;
		case 7: // quarter step
			md.setSpeeds(-236, -98);
			break;
		case 8: // full step
			md.setSpeeds(-180, -180);
			break;
		case 9: // quarter step
			md.setSpeeds(-98, -236);
			break;
		case 10: // half step
			md.setSpeeds(0, -255);
			break;
		case 11: // quarter step
			md.setSpeeds(98, -236);
			break;
		case 12: // full step
			md.setSpeeds(180, -180);
			break;
		case 13: // quarter step
			md.setSpeeds(236, -98);
			break;
		case 14: // half step
			md.setSpeeds(255, 0);
			break;
		case 15: // quarter step
			md.setSpeeds(236, 98);
			break;
	}
}


// This is a blocking function that repeatedly takes a single step and then
// delays for step_delay_us microseconds.  When it finishes, the stepper motor
// coils will continued to be energized according to the final step so that
// the stepper motor maintains its position and holding torque. 
void multistep(int steps, unsigned int step_delay_us)
{
	unsigned char dir = 1;
	if (steps < 0)
	{
		dir = 0;
		steps = -steps;
	}

	while (steps--)
	{
		one_step(dir);
		delayMicroseconds(step_delay_us);
	}
}

void setup()
{
	md.init();
}


void loop()
{
	if (stepMode == FULL_STEP)
		stepMode = HALF_STEP;
	else
		stepMode = FULL_STEP;
	multistep(400, 5000);
	delayMicroseconds(500);
	unsigned char i;
	for (i = 0; i < 4; i++)
	{
		multistep(-100, 2000);
		delayMicroseconds(100);
	}
}

This code was adapted from the stepper-motor1 example for the Orangutan, which can be found at this link: github.com/pololu/libpololu-avr … or1/test.c

- Takuya Jeremy

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