Module code.mini-rov.motorInterface

Author: Jonathan Rotter

Sets the motors used on the mini-rov on the desired power setting

'''
Author: Jonathan Rotter

Sets the motors used on the mini-rov
on the desired power setting
'''

from sys import stderr

if __name__ == '__main__':
    import RPi.GPIO as GPIO

    # GPIO settings
    GPIO.setmode(GPIO.BCM)
    GPIO.setwarnings(False)
else:
    # this is a dummy module of GPIO
    # so that the auto documenter pdoc3 will shut up
    class GPIO:
        def setup(*args, **kwargs): pass
        def output(*args, **kwargs): pass
        def PWM(*args, **kwargs):
            class PWM:
                def start(*args, **kwargs): pass
            return PWM
        OUT = None
        LOW = None
        HIGH = None


class motor:
    '''
    Provides interface between one motor
    and the rest of the program

    An object of this class should be
    created for each motor
    '''

    motorList = []
    '''
    list of all the connected motors.
    this is a static variable!
    '''

    def __init__(self, IN1, IN2):
        '''
        IN1 and IN2 are the pin numbers
        that the motor is connected to

        Args:
            IN1 (int) pin controlling direction
            IN2 (int): pin controlling power level

        self.IN1 = IN1
        self.IN2 = IN2
        '''

        # setup the pins to be output
        GPIO.setup(IN1, GPIO.OUT)
        GPIO.setup(IN2, GPIO.OUT)

        #
        # start up the motors
        # telling them to not spin
        #

        # set direction of motor
        GPIO.output(IN1, GPIO.LOW)

        # make a PWM object that sends pulses on pin IN2,
        # controlling the motor power
        self.p = GPIO.PWM(IN2, 50)  # the 50 was chosen arbitrarily
        # start the PWM
        self.p.start(0)

        # add this instance of the motor class to the static var list
        motor.motorList.append(self)

    def set(self, power):
        '''
        Sets the power level of the motor
        represented by this object.
        A power level of 0 is stop

        Args:
            power (int): Should be from -100 to 100
        '''
        # power should be -100 <= power <= 100
        # 0 is stop

        # check if the argument is within requirements
        if power < -100 or power > 100:
            print('power arg is not norminal: Expected value in range [-100, 100], but got {0}'.format(power), file=stderr)
            return

        # flip the power variable if opposite direction is specified
        # and set the direction based on if the power argument is positive or negative
        direction = 0
        if power < 0:
            direction = 1
            power = 100 + power

        # set the direction
        GPIO.output(self.IN1, direction)
        # set the power level
        self.p.ChangeDutyCycle(power)

    def cleanup(self):
        '''
        Stops the PWM and sets the pins
        to low. The module-level function
        `cleanup` call this method on
        all motor objects
        '''
        # call this when shutting down
        GPIO.output(self.IN1, GPIO.LOW)
        # stop the PWM
        self.p.stop()


def cleanup():
    '''
    Stops the PWM and sets the pins
    to low for all motors. Should be called when the program
    terminates.
    '''
    try:
        # try to shutdown each motor in the list of motors
        for motorObj in motor.motorList:
            motorObj.cleanup() 
    finally:
        # call this no matter what happens / crashes to cleanup the GPIO pins
        GPIO.cleanup()


if __name__ == '__main__':
    # not to be called, supporting module
    raise Exception('This module should only be imported')

Functions

def cleanup()

Stops the PWM and sets the pins to low for all motors. Should be called when the program terminates.

Expand source code

def cleanup():
    '''
    Stops the PWM and sets the pins
    to low for all motors. Should be called when the program
    terminates.
    '''
    try:
        # try to shutdown each motor in the list of motors
        for motorObj in motor.motorList:
            motorObj.cleanup() 
    finally:
        # call this no matter what happens / crashes to cleanup the GPIO pins
        GPIO.cleanup()

Classes

class GPIO (*args, **kwargs)

Expand source code

class GPIO:
    def setup(*args, **kwargs): pass
    def output(*args, **kwargs): pass
    def PWM(*args, **kwargs):
        class PWM:
            def start(*args, **kwargs): pass
        return PWM
    OUT = None
    LOW = None
    HIGH = None

Class variables

var HIGH

var LOW

var OUT

Methods

def PWM(*args, **kwargs)

Expand source code

def PWM(*args, **kwargs):
    class PWM:
        def start(*args, **kwargs): pass
    return PWM

def output(*args, **kwargs)

Expand source code

def output(*args, **kwargs): pass

def setup(*args, **kwargs)

Expand source code

def setup(*args, **kwargs): pass

class motor (IN1, IN2)

Provides interface between one motor and the rest of the program

An object of this class should be created for each motor

IN1 and IN2 are the pin numbers that the motor is connected to

Args

IN1 (int) pin controlling direction

IN2 : int

pin controlling power level

self.IN1 = IN1 self.IN2 = IN2

Expand source code

class motor:
    '''
    Provides interface between one motor
    and the rest of the program

    An object of this class should be
    created for each motor
    '''

    motorList = []
    '''
    list of all the connected motors.
    this is a static variable!
    '''

    def __init__(self, IN1, IN2):
        '''
        IN1 and IN2 are the pin numbers
        that the motor is connected to

        Args:
            IN1 (int) pin controlling direction
            IN2 (int): pin controlling power level

        self.IN1 = IN1
        self.IN2 = IN2
        '''

        # setup the pins to be output
        GPIO.setup(IN1, GPIO.OUT)
        GPIO.setup(IN2, GPIO.OUT)

        #
        # start up the motors
        # telling them to not spin
        #

        # set direction of motor
        GPIO.output(IN1, GPIO.LOW)

        # make a PWM object that sends pulses on pin IN2,
        # controlling the motor power
        self.p = GPIO.PWM(IN2, 50)  # the 50 was chosen arbitrarily
        # start the PWM
        self.p.start(0)

        # add this instance of the motor class to the static var list
        motor.motorList.append(self)

    def set(self, power):
        '''
        Sets the power level of the motor
        represented by this object.
        A power level of 0 is stop

        Args:
            power (int): Should be from -100 to 100
        '''
        # power should be -100 <= power <= 100
        # 0 is stop

        # check if the argument is within requirements
        if power < -100 or power > 100:
            print('power arg is not norminal: Expected value in range [-100, 100], but got {0}'.format(power), file=stderr)
            return

        # flip the power variable if opposite direction is specified
        # and set the direction based on if the power argument is positive or negative
        direction = 0
        if power < 0:
            direction = 1
            power = 100 + power

        # set the direction
        GPIO.output(self.IN1, direction)
        # set the power level
        self.p.ChangeDutyCycle(power)

    def cleanup(self):
        '''
        Stops the PWM and sets the pins
        to low. The module-level function
        `cleanup` call this method on
        all motor objects
        '''
        # call this when shutting down
        GPIO.output(self.IN1, GPIO.LOW)
        # stop the PWM
        self.p.stop()

Class variables

var motorList

list of all the connected motors. this is a static variable!

Methods

def cleanup(self)

Stops the PWM and sets the pins to low. The module-level function cleanup() call this method on all motor objects

Expand source code

def cleanup(self):
    '''
    Stops the PWM and sets the pins
    to low. The module-level function
    `cleanup` call this method on
    all motor objects
    '''
    # call this when shutting down
    GPIO.output(self.IN1, GPIO.LOW)
    # stop the PWM
    self.p.stop()

def set(self, power)

Sets the power level of the motor represented by this object. A power level of 0 is stop

Args

power : int

Should be from -100 to 100

Expand source code

def set(self, power):
    '''
    Sets the power level of the motor
    represented by this object.
    A power level of 0 is stop

    Args:
        power (int): Should be from -100 to 100
    '''
    # power should be -100 <= power <= 100
    # 0 is stop

    # check if the argument is within requirements
    if power < -100 or power > 100:
        print('power arg is not norminal: Expected value in range [-100, 100], but got {0}'.format(power), file=stderr)
        return

    # flip the power variable if opposite direction is specified
    # and set the direction based on if the power argument is positive or negative
    direction = 0
    if power < 0:
        direction = 1
        power = 100 + power

    # set the direction
    GPIO.output(self.IN1, direction)
    # set the power level
    self.p.ChangeDutyCycle(power)