Donkey Car differential steering with dual DS3502 Digital Potentiometer

actuator.py

class DS3502_DIGITAL_POTENTIOMETER(object):
    '''
    DS3502 Digital Potentiometer to emulate throttle driving ebike ESC.
    https://www.adafruit.com/product/4286
    https://learn.adafruit.com/ds3502-i2c-potentiometer/arduino
    https://cdn-learn.adafruit.com/downloads/pdf/ds3502-i2c-potentiometer.pdf
    https://youtu.be/II0kozLDRyI

    pip install adafruit-circuitpython-ds3502
    https://github.com/adafruit/Adafruit_CircuitPython_DS3502
    '''

    def __init__(self, aaddress, busnum=1):

        import board
        import busio
        import adafruit_ds3502

        if busnum is not None:
            from Adafruit_GPIO import I2C

            # replace the get_bus function with our own
            def get_bus():
                return busnum

        I2C.get_default_bus = get_bus

        i2c_bus = busio.I2C(board.SCL, board.SDA)

        self.ds3502 = adafruit_ds3502.DS3502(i2c_bus, address=aaddress)

        self.speed = 0
        self.throttle = 0

        self.ds3502.wiper = 0

    def run(self, speed):
        '''
        Update the speed of the motor where 1 is full forward and
        -1 is full backwards.
        DAC uses range 0-127
        '''
        if speed > 1 or speed < -1:
            raise ValueError("Speed must be between 1(forward) and -1(reverse)")

        self.speed = speed
        self.throttle = int(speed * 127)

        if self.throttle > 0:
            self.ds3502.wiper = self.throttle
        elif self.throttle <= 0:
            self.ds3502.wiper = 0

    def shutdown(self):
        self.ds3502.wiper = 0

complete.py

    elif cfg.DRIVE_TRAIN_TYPE == "DUAL_DS3502_DIGITAL_POTENTIOMETER_STEER_THROTTLE":
        from donkeycar.parts.actuator import TwoWheelSteeringThrottle, DS3502_DIGITAL_POTENTIOMETER

        left_motor = DS3502_DIGITAL_POTENTIOMETER(cfg.LEFT_DS3502_DIGITAL_POTENTIOMETER_I2C_ADDRESS, cfg.LEFT_DS3502_DIGITAL_POTENTIOMETER_I2C_BUS)
        right_motor = DS3502_DIGITAL_POTENTIOMETER(cfg.RIGHT_DS3502_DIGITAL_POTENTIOMETER_I2C_ADDRESS, cfg.RIGHT_DS3502_DIGITAL_POTENTIOMETER_I2C_BUS)
        two_wheel_control = TwoWheelSteeringThrottle()

        V.add(two_wheel_control,
              inputs=['angle', 'throttle'],
              outputs=['left_motor_speed', 'right_motor_speed'])

        V.add(left_motor, inputs=['left_motor_speed'])
        V.add(right_motor, inputs=['right_motor_speed'])

config.py

# https://youtu.be/II0kozLDRyI

DRIVE_TRAIN_TYPE = "DUAL_DS3502_DIGITAL_POTENTIOMETER_STEER_THROTTLE"

LEFT_DS3502_DIGITAL_POTENTIOMETER_I2C_ADDRESS=0x28 # Default address 0x28
RIGHT_DS3502_DIGITAL_POTENTIOMETER_I2C_ADDRESS=0x29

LEFT_DS3502_DIGITAL_POTENTIOMETER_I2C_BUS=1 # I2C bus 1 uses Nano GPIO pins 3,5 for SDA,SCL.
RIGHT_DS3502_DIGITAL_POTENTIOMETER_I2C_BUS=1