Stepper motor
=============

Recipe
~~~~~~

.. code:: Python

    ##
    # Stepper motor driver for 28BYJ-48 and small controller board
    #

    from gpiozero import DigitalOutputDevice as stepper
    from time import sleep
    from random import choice, randint


    # key is step, tuples are stepper motor lines 1-4
    # 8 half step per one revolution of internal motor shaft
    # gear ration is ~64:1 therefore 4096 step per one revolution of motor

    # Define the GPIO pis to use
    IN1 = stepper(6)
    IN2 = stepper(13)
    IN3 = stepper(19)
    IN4 = stepper(26)
    step_pins = [IN1, IN2, IN3, IN4]

    # Either 8 half steps (half) or 4 full steps (full)
    speed = 'full'

    # Sequence for the pins
    if speed == 'half':
        SEQUENCE = [
            [1, 0, 0, 1],
            [1, 0, 0, 0],
            [1, 1, 0, 0],
            [0, 1, 0, 0],
            [0, 1, 1, 0],
            [0, 0, 1, 0],
            [0, 0, 1, 1],
            [0, 0, 0, 1]
        ]
    else:
        SEQUENCE = [
            [1, 0, 0, 0],
            [0, 1, 0, 0],
            [0, 0, 1, 0],
            [0, 0, 0, 1]
        ]


    def oneStep(step_counter):
        """
        Send motor one step sequence
        """

        for pin in range(0, 4):
            gpio_pin = step_pins[pin]

            if SEQUENCE[step_counter][pin] != 0:
                gpio_pin.on()
            else:
                gpio_pin.off()


    def main(number_of_steps, direction, delay):
        step_count = len(SEQUENCE)
        sequence_count = 0

        for i in range(number_of_steps + 1):
            oneStep(sequence_count)
            sequence_count += direction

            # Start sequence again
            if (sequence_count >= step_count):
                sequence_count = 0

            if (sequence_count < 0):
                sequence_count = step_count + direction

            # 1.4ms is minimum
            sleep(0.002 + delay)


    if __name__ == '__main__':
        # Set the speed
        delay = 0.001

        # Set to 1 for clockwise, -1 for anti-clockwise
        direction = 1

        # ~4096 for one revolution
        no_of_steps = 4096

        # Move stepper motor randomly
        while True:
            dir = choice(1, -1)
            main(randint(0, 4096), dir, delay)
            sleep(0.3)