Raspberry Pi - GPIO Stepper Motor Example

/*
 * **********************************************************************
 * ORGANIZATION  :  Pi4J
 * PROJECT       :  Pi4J :: Java Examples
 * FILENAME      :  StepperMotorGpioExample.java
 *
 * This file is part of the Pi4J project. More information about
 * this project can be found here:  http://www.pi4j.com/
 * **********************************************************************
 * Copyright (C) 2012 Pi4J
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import com.pi4j.component.motor.impl.GpioStepperMotorComponent;
import com.pi4j.io.gpio.GpioController;
import com.pi4j.io.gpio.GpioFactory;
import com.pi4j.io.gpio.GpioPinDigitalOutput;
import com.pi4j.io.gpio.PinState;
import com.pi4j.io.gpio.RaspiPin;

/**
 * This example code demonstrates how to control a stepper motor
 * using the GPIO pins on the Raspberry Pi.
 *
 * @author Robert Savage
 */
public class StepperMotorGpioExample
{
    public static void main(String[] args) throws InterruptedException
    {
        System.out.println("<--Pi4J--> GPIO Stepper Motor Example ... started.");

        // create gpio controller
        final GpioController gpio = GpioFactory.getInstance();

        // provision gpio pins #00 to #03 as output pins and ensure in LOW state
        final GpioPinDigitalOutput[] pins = {
                gpio.provisionDigitalOutputPin(RaspiPin.GPIO_00, PinState.LOW),
                gpio.provisionDigitalOutputPin(RaspiPin.GPIO_01, PinState.LOW),
                gpio.provisionDigitalOutputPin(RaspiPin.GPIO_02, PinState.LOW),
                gpio.provisionDigitalOutputPin(RaspiPin.GPIO_03, PinState.LOW)};

        // this will ensure that the motor is stopped when the program terminates
        gpio.setShutdownOptions(true, PinState.LOW, pins);

        // create motor component
        GpioStepperMotorComponent motor = new GpioStepperMotorComponent(pins);

        // @see http://www.lirtex.com/robotics/stepper-motor-controller-circuit/
        //      for additional details on stepping techniques

        // create byte array to demonstrate a single-step sequencing
        // (This is the most basic method, turning on a single electromagnet every time.
        //  This sequence requires the least amount of energy and generates the smoothest movement.)
        byte[] single_step_sequence = new byte[4];
        single_step_sequence[0] = (byte) 0b0001;
        single_step_sequence[1] = (byte) 0b0010;
        single_step_sequence[2] = (byte) 0b0100;
        single_step_sequence[3] = (byte) 0b1000;

        // create byte array to demonstrate a double-step sequencing
        // (In this method two coils are turned on simultaneously.  This method does not generate
        //  a smooth movement as the previous method, and it requires double the current, but as
        //  return it generates double the torque.)
        byte[] double_step_sequence = new byte[4];
        double_step_sequence[0] = (byte) 0b0011;
        double_step_sequence[1] = (byte) 0b0110;
        double_step_sequence[2] = (byte) 0b1100;
        double_step_sequence[3] = (byte) 0b1001;

        // create byte array to demonstrate a half-step sequencing
        // (In this method two coils are turned on simultaneously.  This method does not generate
        //  a smooth movement as the previous method, and it requires double the current, but as
        //  return it generates double the torque.)
        byte[] half_step_sequence = new byte[8];
        half_step_sequence[0] = (byte) 0b0001;
        half_step_sequence[1] = (byte) 0b0011;
        half_step_sequence[2] = (byte) 0b0010;
        half_step_sequence[3] = (byte) 0b0110;
        half_step_sequence[4] = (byte) 0b0100;
        half_step_sequence[5] = (byte) 0b1100;
        half_step_sequence[6] = (byte) 0b1000;
        half_step_sequence[7] = (byte) 0b1001;

        // define stepper parameters before attempting to control motor
        // anything lower than 2 ms does not work for my sample motor using single step sequence
        motor.setStepInterval(2);
        motor.setStepSequence(single_step_sequence);

        // There are 32 steps per revolution on my sample motor,
        // and inside is a ~1/64 reduction gear set.
        // Gear reduction is actually: (32/9)/(22/11)x(26/9)x(31/10)=63.683950617
        // This means is that there are really 32*63.683950617 steps per revolution
        // =  2037.88641975 ~ 2038 steps!
        motor.setStepsPerRevolution(2038);

        // test motor control : STEPPING FORWARD
        System.out.println("   Motor FORWARD for 2038 steps.");
        motor.step(2038);
        System.out.println("   Motor STOPPED for 2 seconds.");
        Thread.sleep(2000);

        // test motor control : STEPPING REVERSE
        System.out.println("   Motor REVERSE for 2038 steps.");
        motor.step(-2038);
        System.out.println("   Motor STOPPED for 2 seconds.");
        Thread.sleep(2000);

        // test motor control : ROTATE FORWARD
        System.out.println("   Motor FORWARD for 2 revolutions.");
        motor.rotate(2);
        System.out.println("   Motor STOPPED for 2 seconds.");
        Thread.sleep(2000);

        // test motor control : ROTATE REVERSE
        System.out.println("   Motor REVERSE for 2 revolutions.");
        motor.rotate(-2);
        System.out.println("   Motor STOPPED for 2 seconds.");
        Thread.sleep(2000);

        // test motor control : TIMED FORWARD
        System.out.println("   Motor FORWARD for 5 seconds.");
        motor.forward(5000);
        System.out.println("   Motor STOPPED for 2 seconds.");
        Thread.sleep(2000);

        // test motor control : TIMED REVERSE
        System.out.println("   Motor REVERSE for 5 seconds.");
        motor.reverse(5000);
        System.out.println("   Motor STOPPED for 2 seconds.");
        Thread.sleep(2000);

        // test motor control : ROTATE FORWARD with different timing and sequence
        System.out.println("   Motor FORWARD with slower speed and higher torque for 1 revolution.");
        motor.setStepSequence(double_step_sequence);
        motor.setStepInterval(10);
        motor.rotate(1);
        System.out.println("   Motor STOPPED.");

        // final stop to ensure no motor activity
        motor.stop();
    }
}