This module is very simple motor driver to be run on Raspberry Pi

main.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-

from __future__ import print_function
from motor import MotorDriver
from time import sleep


K = [10.0, 0.0]
CONTROLLERS = []


def init():
    """ モーターコントローラを初期化してインスタンスを返す """
    r = MotorDriver(pin_to_in1=17, pin_to_in2=27, pwm_hz=50)
    l = MotorDriver(pin_to_in1=23, pin_to_in2=24, pwm_hz=50)

    r.start()
    l.start()

    CONTROLLERS.extend([r, l])


def go_straight(speed, time_):
    """ 前に進む """
    print("go straight...")

    for i, ctrl in enumerate(CONTROLLERS):
        ctrl.set_duty(speed + K[i], MotorDriver.FORWARD)

    sleep(time_)


def go_back(speed, time_):
    """ 後ろ向きに進む """
    print("go back...")

    for i, ctrl in enumerate(CONTROLLERS):
        ctrl.set_duty(speed + K[i], MotorDriver.INVERSE)

    sleep(time_)


def turn_right(speed=30.0, time_=3.0):
    """ 右に曲がる """
    print("turn right...")

    DIRS = [MotorDriver.FORWARD, MotorDriver.INVERSE]

    for i, ctrl in enumerate(CONTROLLERS):
        ctrl.set_duty(speed + K[i], DIRS[i])

    sleep(time_)


def turn_left(speed=30.0, time_=3.0):
    """ 左に曲がる """
    print("turn left...")

    DIRS = [MotorDriver.FORWARD, MotorDriver.INVERSE]

    for i, ctrl in enumerate(CONTROLLERS):
        ctrl.set_duty(speed + K[i], DIRS[i])

    sleep(time_)


def deinit():
    """ 使い終わったら後始末 """

    for i, ctrl in enumerate(CONTROLLERS):
        ctrl.destroy()


def main():
    """ ロボットカーを動かす """

    init()

    #################################################
    # これ以降のプログラムを変更してみてね
    #################################################

    go_straight(speed=40.0, time_=3.0)

    go_back(speed=40.0, time_=3.0)

    turn_right(speed=30.0, time_=2.0)

    go_straight(speed=40.0, time_=3.0)

    turn_left(speed=30.0, time_=2.0)

    go_straight(speed=40.0, time_=3.0)

    turn_left(speed=30.0, time_=2.0)

    go_straight(speed=60.0, time_=2.0)

    #################################################
    # 変更していいのはここまで
    #################################################

    deinit()


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        deinit()

motor.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-

from __future__ import print_function
import RPi.GPIO as gpio


"""
This module is very simple motor driver to be run on Raspberry Pi
and can be used for TA7291P and maybe DRV8871.
Refer to below documentation about GPIO pin assignment.
https://sourceforge.net/p/raspberry-gpio-python/wiki/PWM/
"""


class MotorDriver(object):
    INVERSE = 0
    FORWARD = 1

    STATE_IDLE = 0
    STATE_MOVING = 1
    STATE_BRAKING = 2
    STATE_DESTROYED = 3

    def __init__(self, pin_to_in1, pin_to_in2, pwm_hz, init_dir=FORWARD, warning=False):
        gpio.setwarnings(warning)

        self._pin_to_in1 = pin_to_in1
        self._pin_to_in2 = pin_to_in2

        self._dir = init_dir
        self._duty = 0.0

        gpio.setmode(gpio.BCM)
        gpio.setup(pin_to_in1, gpio.OUT)
        gpio.setup(pin_to_in2, gpio.OUT)

        self._p_in1 = gpio.PWM(pin_to_in1, pwm_hz)
        self._p_in2 = gpio.PWM(pin_to_in2, pwm_hz)

        self._state = self.STATE_IDLE

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.destroy()
        if exc_type:
            return True

    def set_duty(self, duty, dir_=FORWARD):
        """ Arguments: duty is in 0.0(stop) to 100.0 """

        if self._state in [self.STATE_DESTROYED, ]:
            return

        self._duty = duty
        self._dir = dir_

        self._p_in1.ChangeDutyCycle(0.0 if dir_ == self.INVERSE else duty)
        self._p_in2.ChangeDutyCycle(duty if dir_ == self.INVERSE else 0.0)

        self._state = self.STATE_MOVING if duty > 0.0 else self.STATE_IDLE

    def start(self):
        if self._state in [self.STATE_MOVING, self.STATE_DESTROYED]:
            return

        self._p_in1.start(0.0)
        self._p_in2.start(0.0)

    def stop(self):
        if self._state in [self.STATE_DESTROYED, ]:
            return

        self._p_in1.stop()
        self._p_in2.stop()

        self._state = self.STATE_IDLE

    def brake(self):
        if self._state in [self.STATE_DESTROYED, ]:
            return

        self.stop()
        gpio.output(self._gpio_in1, gpio.HIGH)
        gpio.output(self._gpio_in2, gpio.HIGH)

        self._state = self.STATE_BRAKING

    def destroy(self):
        self.stop()
        gpio.cleanup()

        self._state = self.STATE_DESTROYED

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