uln2003.py

import machine

LOW = 0
HIGH = 1
FULL_ROTATION = int(4075.7728395061727 / 8)  # http://www.jangeox.be/2013/10/stepper-motor-28byj-48_25.html

HALF_STEP = [
    [LOW, LOW, LOW, HIGH],
    [LOW, LOW, HIGH, HIGH],
    [LOW, LOW, HIGH, LOW],
    [LOW, HIGH, HIGH, LOW],
    [LOW, HIGH, LOW, LOW],
    [HIGH, HIGH, LOW, LOW],
    [HIGH, LOW, LOW, LOW],
    [HIGH, LOW, LOW, HIGH]
]

FULL_STEP = [
    [HIGH, LOW, HIGH, LOW],
    [LOW, HIGH, HIGH, LOW],
    [LOW, HIGH, LOW, HIGH],
    [HIGH, LOW, LOW, HIGH]
]


class Command:
    """Tell a stepper to move X many steps in direction"""

    def __init__(self, stepper, steps, direction=1):
        self.stepper = stepper
        self.steps = steps
        self.direction = direction


class Driver:
    """Drive a set of motors, each with their own commands"""

    @staticmethod
    def run(commands):
        """Takes a list of commands and interleaves their step calls"""

        # Work out total steps to take
        max_steps = sum([c.steps for c in commands])

        count = 0
        while count != max_steps:
            for command in commands:
                # we want to interleave the commands
                if command.steps > 0:
                    command.stepper.step(1, command.direction)
                    command.steps -= 1
                    count += 1


class Stepper:
    def __init__(self, mode, pin1, pin2, pin3, pin4, delay=2):
        self.mode = mode
        self.pin1 = pin1
        self.pin2 = pin2
        self.pin3 = pin3
        self.pin4 = pin4
        self.delay = delay  # Recommend 10+ for FULL_STEP, 1 is OK for HALF_STEP

        # Initialize all to 0
        self.reset()

    def step(self, count, direction=1):
        """Rotate count steps. direction = -1 means backwards"""

        for x in range(count):
            for bit in self.mode[::direction]:
                p0=self.Pin(pin1,Pin.OUT,value=(bit[0]))
                self.pin2.write_digital(bit[1])
                self.pin3.write_digital(bit[2])
                self.pin4.write_digital(bit[3])
                microbit.sleep(self.delay)
        self.reset()

    def reset(self):
        # Reset to 0, no holding, these are geared, you can't move them
        import machine
        p0 = self.machine.Pin(pin1, Pin.OUT, value=0)
        p1 = self.Pin(pin2, Pin.OUT, value=0)
        p2 = self.Pin(pin3, Pin.OUT, value=0)
        p3 = self.Pin(pin4, Pin.OUT, value=0)


if __name__ == '__main__':
    s1 = Stepper(HALF_STEP, 16, 15, 14, 13, delay=5)
    s2 = Stepper(HALF_STEP, 6, 5, 4, 3, delay=5)
    # s1.step(FULL_ROTATION)
    # s2.step(FULL_ROTATION)

    runner = Driver()
    runner.run([Command(s1, FULL_ROTATION, 1), Command(s2, FULL_ROTATION / 2, -1)])