Donkey Car differential steering with dual MCP4725 DAC

actuator.py

class MCP4725_DAC(object):
    '''
    MCP4725 Digital to Analog Convertor to emulate throttle driving ebike ESC.
    '''

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

        import board
        import busio
        import Adafruit_MCP4725

        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 = I2C

        self.dac = Adafruit_MCP4725.MCP4725(address=aaddress, i2c=i2c)

        self.speed = 0
        self.throttle = 0
        self.dac.set_voltage(0)

    def run(self, speed):
        '''
        Update the speed of the motor where 1 is full forward and
        -1 is full backwards.
        DAC uses max 12-bit number: 0xFFF = 4095
        '''
        if speed > 1 or speed < -1:
            raise ValueError("Speed must be between 1(forward) and -1(reverse)")

        self.speed = speed
        self.throttle = int(speed * 4095)

        if self.throttle > 0:
            self.dac.set_voltage(self.throttle)
        elif self.throttle <= 0:
            self.dac.set_voltage(0)

    def shutdown(self):
        self.dac.set_voltage(0)

complete.py

    elif cfg.DRIVE_TRAIN_TYPE == "DUAL_MCP4725_DAC_STEER_THROTTLE":
        from donkeycar.parts.actuator import TwoWheelSteeringThrottle, MCP4725_DAC

        left_motor = MCP4725_DAC(cfg.LEFT_MCP4725_DAC_I2C_ADDRESS, cfg.LEFT_MCP4725_DAC_I2C_BUS)
        right_motor = MCP4725_DAC(cfg.RIGHT_MCP4725_DAC_I2C_ADDRESS, cfg.RIGHT_MCP4725_DAC_I2C_BUS)
        two_wheel_control = TwoWheelSteeringThrottle()

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

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

config.py

# sudo pip3 install adafruit-circuitpython-mcp4725
# pip3 install adafruit-blinka
# pip install adafruit_mcp4725
# https://www.youtube.com/watch?v=4rC7EPV7wis

DRIVE_TRAIN_TYPE = "DUAL_MCP4725_DAC_STEER_THROTTLE"

LEFT_MCP4725_DAC_I2C_ADDRESS=0x60 # Sparkfun MCP4725 default address 0x60; Adafruit default is 0x62.
RIGHT_MCP4725_DAC_I2C_ADDRESS=0x61

LEFT_MCP4725_DAC_I2C_BUS=1 # I2C bus 1 uses Nano GPIO pins 3,5 for SDA,SCL.
RIGHT_MCP4725_DAC_I2C_BUS=1